[pkgsrc.git] / devel / bmake / files / job.c

/*      $NetBSD: job.c,v 1.149 2010/04/23 00:18:50 sjg Exp $    */

/*
 * Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Adam de Boor.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Copyright (c) 1988, 1989 by Adam de Boor
 * Copyright (c) 1989 by Berkeley Softworks
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Adam de Boor.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef MAKE_NATIVE
static char rcsid[] = "$NetBSD: job.c,v 1.149 2010/04/23 00:18:50 sjg Exp $";
#else
#include <sys/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)job.c       8.2 (Berkeley) 3/19/94";
#else
__RCSID("$NetBSD: job.c,v 1.149 2010/04/23 00:18:50 sjg Exp $");
#endif
#endif /* not lint */
#endif

/*-
 * job.c --
 *      handle the creation etc. of our child processes.
 *
 * Interface:
 *      Job_Make                Start the creation of the given target.
 *
 *      Job_CatchChildren       Check for and handle the termination of any
 *                              children. This must be called reasonably
 *                              frequently to keep the whole make going at
 *                              a decent clip, since job table entries aren't
 *                              removed until their process is caught this way.
 *
 *      Job_CatchOutput         Print any output our children have produced.
 *                              Should also be called fairly frequently to
 *                              keep the user informed of what's going on.
 *                              If no output is waiting, it will block for
 *                              a time given by the SEL_* constants, below,
 *                              or until output is ready.
 *
 *      Job_Init                Called to intialize this module. in addition,
 *                              any commands attached to the .BEGIN target
 *                              are executed before this function returns.
 *                              Hence, the makefile must have been parsed
 *                              before this function is called.
 *
 *      Job_End                 Cleanup any memory used.
 *
 *      Job_ParseShell          Given the line following a .SHELL target, parse
 *                              the line as a shell specification. Returns
 *                              FAILURE if the spec was incorrect.
 *
 *      Job_Finish              Perform any final processing which needs doing.
 *                              This includes the execution of any commands
 *                              which have been/were attached to the .END
 *                              target. It should only be called when the
 *                              job table is empty.
 *
 *      Job_AbortAll            Abort all currently running jobs. It doesn't
 *                              handle output or do anything for the jobs,
 *                              just kills them. It should only be called in
 *                              an emergency, as it were.
 *
 *      Job_CheckCommands       Verify that the commands for a target are
 *                              ok. Provide them if necessary and possible.
 *
 *      Job_Touch               Update a target without really updating it.
 *
 *      Job_Wait                Wait for all currently-running jobs to finish.
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <sys/time.h>
#include "wait.h"

#include <errno.h>
#include <fcntl.h>
#if !defined(USE_SELECT) && defined(HAVE_POLL_H)
#include <poll.h>
#else
#ifndef USE_SELECT                      /* no poll.h */
# define USE_SELECT
#endif
#if defined(HAVE_SYS_SELECT_H)
# include <sys/select.h>
#endif
#endif
#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <utime.h>
#if defined(HAVE_SYS_SOCKET_H)
# include <sys/socket.h>
#endif

#include "make.h"
#include "hash.h"
#include "dir.h"
#include "job.h"
#include "pathnames.h"
#include "trace.h"
# define STATIC static

/*
 * error handling variables
 */
static int      errors = 0;         /* number of errors reported */
static int      aborting = 0;       /* why is the make aborting? */
#define ABORT_ERROR     1           /* Because of an error */
#define ABORT_INTERRUPT 2           /* Because it was interrupted */
#define ABORT_WAIT      3           /* Waiting for jobs to finish */
#define JOB_TOKENS      "+EI+"      /* Token to requeue for each abort state */

/*
 * this tracks the number of tokens currently "out" to build jobs.
 */
int jobTokensRunning = 0;
int not_parallel = 0;               /* set if .NOT_PARALLEL */

/*
 * XXX: Avoid SunOS bug... FILENO() is fp->_file, and file
 * is a char! So when we go above 127 we turn negative!
 */
#define FILENO(a) ((unsigned) fileno(a))

/*
 * post-make command processing. The node postCommands is really just the
 * .END target but we keep it around to avoid having to search for it
 * all the time.
 */
static GNode      *postCommands = NULL;
                                    /* node containing commands to execute when
                                     * everything else is done */
static int        numCommands;      /* The number of commands actually printed
                                     * for a target. Should this number be
                                     * 0, no shell will be executed. */

/*
 * Return values from JobStart.
 */
#define JOB_RUNNING     0       /* Job is running */
#define JOB_ERROR       1       /* Error in starting the job */
#define JOB_FINISHED    2       /* The job is already finished */

/*
 * Descriptions for various shells.
 *
 * The build environment may set DEFSHELL_INDEX to one of
 * DEFSHELL_INDEX_SH, DEFSHELL_INDEX_KSH, or DEFSHELL_INDEX_CSH, to
 * select one of the prefedined shells as the default shell.
 *
 * Alternatively, the build environment may set DEFSHELL_CUSTOM to the
 * name or the full path of a sh-compatible shell, which will be used as
 * the default shell.
 *
 * ".SHELL" lines in Makefiles can choose the default shell from the
 # set defined here, or add additional shells.
 */

#ifdef DEFSHELL_CUSTOM
#define DEFSHELL_INDEX_CUSTOM 0
#define DEFSHELL_INDEX_SH     1
#define DEFSHELL_INDEX_KSH    2
#define DEFSHELL_INDEX_CSH    3
#else /* !DEFSHELL_CUSTOM */
#define DEFSHELL_INDEX_SH     0
#define DEFSHELL_INDEX_KSH    1
#define DEFSHELL_INDEX_CSH    2
#endif /* !DEFSHELL_CUSTOM */

#ifndef DEFSHELL_INDEX
#define DEFSHELL_INDEX 0        /* DEFSHELL_INDEX_CUSTOM or DEFSHELL_INDEX_SH */
#endif /* !DEFSHELL_INDEX */

static Shell    shells[] = {
#ifdef DEFSHELL_CUSTOM
    /*
     * An sh-compatible shell with a non-standard name.
     *
     * Keep this in sync with the "sh" description below, but avoid
     * non-portable features that might not be supplied by all
     * sh-compatible shells.
     */
{
    DEFSHELL_CUSTOM,
    FALSE, "", "", "", 0,
    FALSE, "echo \"%s\"\n", "%s\n", "{ %s \n} || exit $?\n", "'\n'", '#',
    "",
    "",
},
#endif /* DEFSHELL_CUSTOM */
    /*
     * SH description. Echo control is also possible and, under
     * sun UNIX anyway, one can even control error checking.
     */
{
    "sh",
    FALSE, "", "", "", 0,
    FALSE, "echo \"%s\"\n", "%s\n", "{ %s \n} || exit $?\n", "'\n'", '#',
#if defined(MAKE_NATIVE) && defined(__NetBSD__)
    "q",
#else
    "",
#endif
    "",
},
    /*
     * KSH description. 
     */
{
    "ksh",
    TRUE, "set +v", "set -v", "set +v", 6,
    FALSE, "echo \"%s\"\n", "%s\n", "{ %s \n} || exit $?\n", "'\n'", '#',
    "v",
    "",
},
    /*
     * CSH description. The csh can do echo control by playing
     * with the setting of the 'echo' shell variable. Sadly,
     * however, it is unable to do error control nicely.
     */
{
    "csh",
    TRUE, "unset verbose", "set verbose", "unset verbose", 10,
    FALSE, "echo \"%s\"\n", "csh -c \"%s || exit 0\"\n", "", "'\\\n'", '#',
    "v", "e",
},
    /*
     * UNKNOWN.
     */
{
    NULL,
    FALSE, NULL, NULL, NULL, 0,
    FALSE, NULL, NULL, NULL, NULL, 0,
    NULL, NULL,
}
};
static Shell *commandShell = &shells[DEFSHELL_INDEX]; /* this is the shell to
                                                   * which we pass all
                                                   * commands in the Makefile.
                                                   * It is set by the
                                                   * Job_ParseShell function */
const char *shellPath = NULL,                     /* full pathname of
                                                   * executable image */
           *shellName = NULL;                     /* last component of shell */
static const char *shellArgv = NULL;              /* Custom shell args */


STATIC Job      *job_table;     /* The structures that describe them */
STATIC Job      *job_table_end; /* job_table + maxJobs */
static int      wantToken;      /* we want a token */
static int lurking_children = 0;
static int make_suspended = 0;  /* non-zero if we've seen a SIGTSTP (etc) */

/*
 * Set of descriptors of pipes connected to
 * the output channels of children
 */
static struct pollfd *fds = NULL;
static Job **jobfds = NULL;
static int nfds = 0;
static void watchfd(Job *);
static void clearfd(Job *);
static int readyfd(Job *);

STATIC GNode    *lastNode;      /* The node for which output was most recently
                                 * produced. */
STATIC const char *targFmt;     /* Format string to use to head output from a
                                 * job when it's not the most-recent job heard
                                 * from */
static char *targPrefix = NULL; /* What we print at the start of targFmt */
static Job tokenWaitJob;        /* token wait pseudo-job */

static Job childExitJob;        /* child exit pseudo-job */
#define CHILD_EXIT      "."
#define DO_JOB_RESUME   "R"

#define TARG_FMT  "%s %s ---\n" /* Default format */
#define MESSAGE(fp, gn) \
        (void)fprintf(fp, targFmt, targPrefix, gn->name)

static sigset_t caught_signals; /* Set of signals we handle */
#if defined(SYSV)
#define KILLPG(pid, sig)        kill(-(pid), (sig))
#else
#define KILLPG(pid, sig)        killpg((pid), (sig))
#endif

static void JobChildSig(int);
static void JobContinueSig(int);
static Job *JobFindPid(int, int);
static int JobPrintCommand(void *, void *);
static int JobSaveCommand(void *, void *);
static void JobClose(Job *);
static void JobExec(Job *, char **);
static void JobMakeArgv(Job *, char **);
static int JobStart(GNode *, int);
static char *JobOutput(Job *, char *, char *, int);
static void JobDoOutput(Job *, Boolean);
static Shell *JobMatchShell(const char *);
static void JobInterrupt(int, int);
static void JobRestartJobs(void);
static void JobTokenAdd(void);
static void JobSigLock(sigset_t *);
static void JobSigUnlock(sigset_t *);
static void JobSigReset(void);

const char *malloc_options="A";

static void
job_table_dump(const char *where)
{
    Job *job;

    fprintf(debug_file, "job table @ %s\n", where);
    for (job = job_table; job < job_table_end; job++) {
        fprintf(debug_file, "job %d, status %d, flags %d, pid %d\n",
            (int)(job - job_table), job->job_state, job->flags, job->pid);
    }
}

/*
 * JobSigLock/JobSigUnlock
 *
 * Signal lock routines to get exclusive access. Currently used to
 * protect `jobs' and `stoppedJobs' list manipulations.
 */
static void JobSigLock(sigset_t *omaskp)
{
        if (sigprocmask(SIG_BLOCK, &caught_signals, omaskp) != 0) {
                Punt("JobSigLock: sigprocmask: %s", strerror(errno));
                sigemptyset(omaskp);
        }
}

static void JobSigUnlock(sigset_t *omaskp)
{
        (void)sigprocmask(SIG_SETMASK, omaskp, NULL);
}

static void
JobCreatePipe(Job *job, int minfd)
{
    int i, fd;

    if (pipe(job->jobPipe) == -1)
        Punt("Cannot create pipe: %s", strerror(errno));

    /* Set close-on-exec flag for both */
    (void)fcntl(job->jobPipe[0], F_SETFD, 1);
    (void)fcntl(job->jobPipe[1], F_SETFD, 1);

    /*
     * We mark the input side of the pipe non-blocking; we poll(2) the
     * pipe when we're waiting for a job token, but we might lose the
     * race for the token when a new one becomes available, so the read 
     * from the pipe should not block.
     */
    fcntl(job->jobPipe[0], F_SETFL, 
        fcntl(job->jobPipe[0], F_GETFL, 0) | O_NONBLOCK);

    for (i = 0; i < 2; i++) {
       /* Avoid using low numbered fds */
       fd = fcntl(job->jobPipe[i], F_DUPFD, minfd);
       if (fd != -1) {
           close(job->jobPipe[i]);
           job->jobPipe[i] = fd;
       }
    }
}

/*-
 *-----------------------------------------------------------------------
 * JobCondPassSig --
 *      Pass a signal to a job
 *
 * Input:
 *      signop          Signal to send it
 *
 * Side Effects:
 *      None, except the job may bite it.
 *
 *-----------------------------------------------------------------------
 */
static void
JobCondPassSig(int signo)
{
    Job *job;

    if (DEBUG(JOB)) {
        (void)fprintf(debug_file, "JobCondPassSig(%d) called.\n", signo);
    }

    for (job = job_table; job < job_table_end; job++) {
        if (job->job_state != JOB_ST_RUNNING)
            continue;
        if (DEBUG(JOB)) {
            (void)fprintf(debug_file,
                           "JobCondPassSig passing signal %d to child %d.\n",
                           signo, job->pid);
        }
        KILLPG(job->pid, signo);
    }
}

/*-
 *-----------------------------------------------------------------------
 * JobChldSig --
 *      SIGCHLD handler.
 *
 * Input:
 *      signo           The signal number we've received
 *
 * Results:
 *      None.
 *
 * Side Effects:
 *      Sends a token on the child exit pipe to wake us up from
 *      select()/poll().
 *
 *-----------------------------------------------------------------------
 */
static void
JobChildSig(int signo __unused)
{
    write(childExitJob.outPipe, CHILD_EXIT, 1);
}


/*-
 *-----------------------------------------------------------------------
 * JobContinueSig --
 *      Resume all stopped jobs.
 *
 * Input:
 *      signo           The signal number we've received
 *
 * Results:
 *      None.
 *
 * Side Effects:
 *      Jobs start running again.
 *
 *-----------------------------------------------------------------------
 */
static void
JobContinueSig(int signo __unused)
{
    /*
     * Defer sending to SIGCONT to our stopped children until we return
     * from the signal handler.
     */
    write(childExitJob.outPipe, DO_JOB_RESUME, 1);
}

/*-
 *-----------------------------------------------------------------------
 * JobPassSig --
 *      Pass a signal on to all jobs, then resend to ourselves.
 *
 * Input:
 *      signo           The signal number we've received
 *
 * Results:
 *      None.
 *
 * Side Effects:
 *      We die by the same signal.
 *
 *-----------------------------------------------------------------------
 */
static void
JobPassSig_int(int signo)
{
    /* Run .INTERRUPT target then exit */
    JobInterrupt(TRUE, signo);
}

static void
JobPassSig_term(int signo)
{
    /* Dont run .INTERRUPT target then exit */
    JobInterrupt(FALSE, signo);
}

static void
JobPassSig_suspend(int signo)
{
    sigset_t nmask, omask;
    struct sigaction act;

    /* Suppress job started/continued messages */
    make_suspended = 1;

    /* Pass the signal onto every job */
    JobCondPassSig(signo);

    /*
     * Send ourselves the signal now we've given the message to everyone else.
     * Note we block everything else possible while we're getting the signal.
     * This ensures that all our jobs get continued when we wake up before
     * we take any other signal.
     */
    sigfillset(&nmask);
    sigdelset(&nmask, signo);
    (void)sigprocmask(SIG_SETMASK, &nmask, &omask);

    act.sa_handler = SIG_DFL;
    sigemptyset(&act.sa_mask);
    act.sa_flags = 0;
    (void)sigaction(signo, &act, NULL);

    if (DEBUG(JOB)) {
        (void)fprintf(debug_file,
                       "JobPassSig passing signal %d to self.\n", signo);
    }

    (void)kill(getpid(), signo);

    /*
     * We've been continued.
     *
     * A whole host of signals continue to happen!
     * SIGCHLD for any processes that actually suspended themselves.
     * SIGCHLD for any processes that exited while we were alseep.
     * The SIGCONT that actually caused us to wakeup.
     *
     * Since we defer passing the SIGCONT on to our children until
     * the main processing loop, we can be sure that all the SIGCHLD
     * events will have happened by then - and that the waitpid() will
     * collect the child 'suspended' events.
     * For correct sequencing we just need to ensure we process the
     * waitpid() before passign on the SIGCONT.
     *
     * In any case nothing else is needed here.
     */

    /* Restore handler and signal mask */
    act.sa_handler = JobPassSig_suspend;
    (void)sigaction(signo, &act, NULL);
    (void)sigprocmask(SIG_SETMASK, &omask, NULL);
}

/*-
 *-----------------------------------------------------------------------
 * JobFindPid  --
 *      Compare the pid of the job with the given pid and return 0 if they
 *      are equal. This function is called from Job_CatchChildren
 *      to find the job descriptor of the finished job.
 *
 * Input:
 *      job             job to examine
 *      pid             process id desired
 *
 * Results:
 *      Job with matching pid
 *
 * Side Effects:
 *      None
 *-----------------------------------------------------------------------
 */
static Job *
JobFindPid(int pid, int status)
{
    Job *job;

    for (job = job_table; job < job_table_end; job++) {
        if ((job->job_state == status) && job->pid == pid)
            return job;
    }
    if (DEBUG(JOB))
        job_table_dump("no pid");
    return NULL;
}

/*-
 *-----------------------------------------------------------------------
 * JobPrintCommand  --
 *      Put out another command for the given job. If the command starts
 *      with an @ or a - we process it specially. In the former case,
 *      so long as the -s and -n flags weren't given to make, we stick
 *      a shell-specific echoOff command in the script. In the latter,
 *      we ignore errors for the entire job, unless the shell has error
 *      control.
 *      If the command is just "..." we take all future commands for this
 *      job to be commands to be executed once the entire graph has been
 *      made and return non-zero to signal that the end of the commands
 *      was reached. These commands are later attached to the postCommands
 *      node and executed by Job_End when all things are done.
 *      This function is called from JobStart via Lst_ForEach.
 *
 * Input:
 *      cmdp            command string to print
 *      jobp            job for which to print it
 *
 * Results:
 *      Always 0, unless the command was "..."
 *
 * Side Effects:
 *      If the command begins with a '-' and the shell has no error control,
 *      the JOB_IGNERR flag is set in the job descriptor.
 *      If the command is "..." and we're not ignoring such things,
 *      tailCmds is set to the successor node of the cmd.
 *      numCommands is incremented if the command is actually printed.
 *-----------------------------------------------------------------------
 */
static int
JobPrintCommand(void *cmdp, void *jobp)
{
    Boolean       noSpecials;       /* true if we shouldn't worry about
                                     * inserting special commands into
                                     * the input stream. */
    Boolean       shutUp = FALSE;   /* true if we put a no echo command
                                     * into the command file */
    Boolean       errOff = FALSE;   /* true if we turned error checking
                                     * off before printing the command
                                     * and need to turn it back on */
    const char    *cmdTemplate;     /* Template to use when printing the
                                     * command */
    char          *cmdStart;        /* Start of expanded command */
    char          *escCmd = NULL;    /* Command with quotes/backticks escaped */
    char          *cmd = (char *)cmdp;
    Job           *job = (Job *)jobp;
    char          *cp, *tmp;
    int           i, j;

    noSpecials = NoExecute(job->node);

    if (strcmp(cmd, "...") == 0) {
        job->node->type |= OP_SAVE_CMDS;
        if ((job->flags & JOB_IGNDOTS) == 0) {
            job->tailCmds = Lst_Succ(Lst_Member(job->node->commands,
                                                cmd));
            return 1;
        }
        return 0;
    }

#define DBPRINTF(fmt, arg) if (DEBUG(JOB)) {    \
        (void)fprintf(debug_file, fmt, arg);    \
    }                                           \
   (void)fprintf(job->cmdFILE, fmt, arg);       \
   (void)fflush(job->cmdFILE);

    numCommands += 1;

    cmdStart = cmd = Var_Subst(NULL, cmd, job->node, FALSE);

    cmdTemplate = "%s\n";

    /*
     * Check for leading @' and -'s to control echoing and error checking.
     */
    while (*cmd == '@' || *cmd == '-' || (*cmd == '+')) {
        switch (*cmd) {
        case '@':
            shutUp = DEBUG(LOUD) ? FALSE : TRUE;
            break;
        case '-':
            errOff = TRUE;
            break;
        case '+':
            if (noSpecials) {
                /*
                 * We're not actually executing anything...
                 * but this one needs to be - use compat mode just for it.
                 */
                CompatRunCommand(cmdp, job->node);
                return 0;
            }
            break;
        }
        cmd++;
    }

    while (isspace((unsigned char) *cmd))
        cmd++;

    /*
     * If the shell doesn't have error control the alternate echo'ing will
     * be done (to avoid showing additional error checking code) 
     * and this will need the characters '$ ` \ "' escaped
     */

    if (!commandShell->hasErrCtl) {
        /* Worst that could happen is every char needs escaping. */
        escCmd = bmake_malloc((strlen(cmd) * 2) + 1);
        for (i = 0, j= 0; cmd[i] != '\0'; i++, j++) {
                if (cmd[i] == '$' || cmd[i] == '`' || cmd[i] == '\\' || 
                        cmd[i] == '"')
                        escCmd[j++] = '\\';
                escCmd[j] = cmd[i];     
        }
        escCmd[j] = 0;
    }

    if (shutUp) {
        if (!(job->flags & JOB_SILENT) && !noSpecials &&
            commandShell->hasEchoCtl) {
                DBPRINTF("%s\n", commandShell->echoOff);
        } else {
            if (commandShell->hasErrCtl)
                shutUp = FALSE;
        }
    }

    if (errOff) {
        if ( !(job->flags & JOB_IGNERR) && !noSpecials) {
            if (commandShell->hasErrCtl) {
                /*
                 * we don't want the error-control commands showing
                 * up either, so we turn off echoing while executing
                 * them. We could put another field in the shell
                 * structure to tell JobDoOutput to look for this
                 * string too, but why make it any more complex than
                 * it already is?
                 */
                if (!(job->flags & JOB_SILENT) && !shutUp &&
                    commandShell->hasEchoCtl) {
                        DBPRINTF("%s\n", commandShell->echoOff);
                        DBPRINTF("%s\n", commandShell->ignErr);
                        DBPRINTF("%s\n", commandShell->echoOn);
                } else {
                        DBPRINTF("%s\n", commandShell->ignErr);
                }
            } else if (commandShell->ignErr &&
                      (*commandShell->ignErr != '\0'))
            {
                /*
                 * The shell has no error control, so we need to be
                 * weird to get it to ignore any errors from the command.
                 * If echoing is turned on, we turn it off and use the
                 * errCheck template to echo the command. Leave echoing
                 * off so the user doesn't see the weirdness we go through
                 * to ignore errors. Set cmdTemplate to use the weirdness
                 * instead of the simple "%s\n" template.
                 */
                if (!(job->flags & JOB_SILENT) && !shutUp) {
                        if (commandShell->hasEchoCtl) {
                                DBPRINTF("%s\n", commandShell->echoOff);
                        }
                        DBPRINTF(commandShell->errCheck, escCmd);
                        shutUp = TRUE;
                } else {
                        if (!shutUp) {
                                DBPRINTF(commandShell->errCheck, escCmd);
                        }
                }
                cmdTemplate = commandShell->ignErr;
                /*
                 * The error ignoration (hee hee) is already taken care
                 * of by the ignErr template, so pretend error checking
                 * is still on.
                 */
                errOff = FALSE;
            } else {
                errOff = FALSE;
            }
        } else {
            errOff = FALSE;
        }
    } else {

        /* 
         * If errors are being checked and the shell doesn't have error control
         * but does supply an errOut template, then setup commands to run
         * through it.
         */

        if (!commandShell->hasErrCtl && commandShell->errOut && 
            (*commandShell->errOut != '\0')) {
                if (!(job->flags & JOB_SILENT) && !shutUp) {
                        if (commandShell->hasEchoCtl) {
                                DBPRINTF("%s\n", commandShell->echoOff);
                        }
                        DBPRINTF(commandShell->errCheck, escCmd);
                        shutUp = TRUE;
                }
                /* If it's a comment line or blank, treat as an ignored error */
                if ((escCmd[0] == commandShell->commentChar) ||
                    (escCmd[0] == 0))
                        cmdTemplate = commandShell->ignErr;
                else
                        cmdTemplate = commandShell->errOut;
                errOff = FALSE;
        }
    }

    if (DEBUG(SHELL) && strcmp(shellName, "sh") == 0 &&
        (job->flags & JOB_TRACED) == 0) {
            DBPRINTF("set -%s\n", "x");
            job->flags |= JOB_TRACED;
    }
    
    if ((cp = Check_Cwd_Cmd(cmd)) != NULL) {
            DBPRINTF("test -d %s && ", cp);
            DBPRINTF("cd %s\n", cp);
    }

    DBPRINTF(cmdTemplate, cmd);
    free(cmdStart);
    if (escCmd)
        free(escCmd);
    if (errOff) {
        /*
         * If echoing is already off, there's no point in issuing the
         * echoOff command. Otherwise we issue it and pretend it was on
         * for the whole command...
         */
        if (!shutUp && !(job->flags & JOB_SILENT) && commandShell->hasEchoCtl){
            DBPRINTF("%s\n", commandShell->echoOff);
            shutUp = TRUE;
        }
        DBPRINTF("%s\n", commandShell->errCheck);
    }
    if (shutUp && commandShell->hasEchoCtl) {
        DBPRINTF("%s\n", commandShell->echoOn);
    }
    if (cp != NULL) {
            DBPRINTF("test -d %s && ", cp);
            DBPRINTF("cd %s\n", Var_Value(".OBJDIR", VAR_GLOBAL, &tmp));
    }
    return 0;
}

/*-
 *-----------------------------------------------------------------------
 * JobSaveCommand --
 *      Save a command to be executed when everything else is done.
 *      Callback function for JobFinish...
 *
 * Results:
 *      Always returns 0
 *
 * Side Effects:
 *      The command is tacked onto the end of postCommands's commands list.
 *
 *-----------------------------------------------------------------------
 */
static int
JobSaveCommand(void *cmd, void *gn)
{
    cmd = Var_Subst(NULL, (char *)cmd, (GNode *)gn, FALSE);
    (void)Lst_AtEnd(postCommands->commands, cmd);
    return(0);
}


/*-
 *-----------------------------------------------------------------------
 * JobClose --
 *      Called to close both input and output pipes when a job is finished.
 *
 * Results:
 *      Nada
 *
 * Side Effects:
 *      The file descriptors associated with the job are closed.
 *
 *-----------------------------------------------------------------------
 */
static void
JobClose(Job *job)
{
    clearfd(job);
    (void)close(job->outPipe);
    job->outPipe = -1;

    JobDoOutput(job, TRUE);
    (void)close(job->inPipe);
    job->inPipe = -1;
}

/*-
 *-----------------------------------------------------------------------
 * JobFinish  --
 *      Do final processing for the given job including updating
 *      parents and starting new jobs as available/necessary. Note
 *      that we pay no attention to the JOB_IGNERR flag here.
 *      This is because when we're called because of a noexecute flag
 *      or something, jstat.w_status is 0 and when called from
 *      Job_CatchChildren, the status is zeroed if it s/b ignored.
 *
 * Input:
 *      job             job to finish
 *      status          sub-why job went away
 *
 * Results:
 *      None
 *
 * Side Effects:
 *      Final commands for the job are placed on postCommands.
 *
 *      If we got an error and are aborting (aborting == ABORT_ERROR) and
 *      the job list is now empty, we are done for the day.
 *      If we recognized an error (errors !=0), we set the aborting flag
 *      to ABORT_ERROR so no more jobs will be started.
 *-----------------------------------------------------------------------
 */
/*ARGSUSED*/
static void
JobFinish (Job *job, WAIT_T status)
{
    Boolean      done, return_job_token;

    if (DEBUG(JOB)) {
        fprintf(debug_file, "Jobfinish: %d [%s], status %d\n",
                                job->pid, job->node->name, status);
    }

    if ((WIFEXITED(status) &&
         (((WEXITSTATUS(status) != 0) && !(job->flags & JOB_IGNERR)))) ||
        WIFSIGNALED(status))
    {
        /*
         * If it exited non-zero and either we're doing things our
         * way or we're not ignoring errors, the job is finished.
         * Similarly, if the shell died because of a signal
         * the job is also finished. In these
         * cases, finish out the job's output before printing the exit
         * status...
         */
        JobClose(job);
        if (job->cmdFILE != NULL && job->cmdFILE != stdout) {
           (void)fclose(job->cmdFILE);
           job->cmdFILE = NULL;
        }
        done = TRUE;
    } else if (WIFEXITED(status)) {
        /*
         * Deal with ignored errors in -B mode. We need to print a message
         * telling of the ignored error as well as setting status.w_status
         * to 0 so the next command gets run. To do this, we set done to be
         * TRUE if in -B mode and the job exited non-zero.
         */
        done = WEXITSTATUS(status) != 0;
        /*
         * Old comment said: "Note we don't
         * want to close down any of the streams until we know we're at the
         * end."
         * But we do. Otherwise when are we going to print the rest of the
         * stuff?
         */
        JobClose(job);
    } else {
        /*
         * No need to close things down or anything.
         */
        done = FALSE;
    }

    if (done) {
        if (WIFEXITED(status)) {
            if (DEBUG(JOB)) {
                (void)fprintf(debug_file, "Process %d [%s] exited.\n",
                                job->pid, job->node->name);
            }
            if (WEXITSTATUS(status) != 0) {
                if (job->node != lastNode) {
                    MESSAGE(stdout, job->node);
                    lastNode = job->node;
                }
                (void)printf("*** [%s] Error code %d%s\n",
                                job->node->name,
                               WEXITSTATUS(status),
                               (job->flags & JOB_IGNERR) ? "(ignored)" : "");
                if (job->flags & JOB_IGNERR)
                    WAIT_STATUS(status) = 0;
            } else if (DEBUG(JOB)) {
                if (job->node != lastNode) {
                    MESSAGE(stdout, job->node);
                    lastNode = job->node;
                }
                (void)printf("*** [%s] Completed successfully\n",
                                job->node->name);
            }
        } else {
            if (job->node != lastNode) {
                MESSAGE(stdout, job->node);
                lastNode = job->node;
            }
            (void)printf("*** [%s] Signal %d\n",
                        job->node->name, WTERMSIG(status));
        }
        (void)fflush(stdout);
    }

    return_job_token = FALSE;

    Trace_Log(JOBEND, job);
    if (!(job->flags & JOB_SPECIAL)) {
        if ((WAIT_STATUS(status) != 0) ||
                (aborting == ABORT_ERROR) ||
                (aborting == ABORT_INTERRUPT))
            return_job_token = TRUE;
    }

    if ((aborting != ABORT_ERROR) && (aborting != ABORT_INTERRUPT) &&
        (WAIT_STATUS(status) == 0)) {
        /*
         * As long as we aren't aborting and the job didn't return a non-zero
         * status that we shouldn't ignore, we call Make_Update to update
         * the parents. In addition, any saved commands for the node are placed
         * on the .END target.
         */
        if (job->tailCmds != NULL) {
            Lst_ForEachFrom(job->node->commands, job->tailCmds,
                             JobSaveCommand,
                            job->node);
        }
        job->node->made = MADE;
        if (!(job->flags & JOB_SPECIAL))
            return_job_token = TRUE;
        Make_Update(job->node);
        job->job_state = JOB_ST_FREE;
    } else if (WAIT_STATUS(status)) {
        errors += 1;
        job->job_state = JOB_ST_FREE;
    }

    /*
     * Set aborting if any error.
     */
    if (errors && !keepgoing && (aborting != ABORT_INTERRUPT)) {
        /*
         * If we found any errors in this batch of children and the -k flag
         * wasn't given, we set the aborting flag so no more jobs get
         * started.
         */
        aborting = ABORT_ERROR;
    }

    if (return_job_token)
        Job_TokenReturn();

    if (aborting == ABORT_ERROR && jobTokensRunning == 0) {
        /*
         * If we are aborting and the job table is now empty, we finish.
         */
        Finish(errors);
    }
}

/*-
 *-----------------------------------------------------------------------
 * Job_Touch --
 *      Touch the given target. Called by JobStart when the -t flag was
 *      given
 *
 * Input:
 *      gn              the node of the file to touch
 *      silent          TRUE if should not print message
 *
 * Results:
 *      None
 *
 * Side Effects:
 *      The data modification of the file is changed. In addition, if the
 *      file did not exist, it is created.
 *-----------------------------------------------------------------------
 */
void
Job_Touch(GNode *gn, Boolean silent)
{
    int           streamID;     /* ID of stream opened to do the touch */
    struct utimbuf times;       /* Times for utime() call */

    if (gn->type & (OP_JOIN|OP_USE|OP_USEBEFORE|OP_EXEC|OP_OPTIONAL|OP_PHONY)) {
        /*
         * .JOIN, .USE, .ZEROTIME and .OPTIONAL targets are "virtual" targets
         * and, as such, shouldn't really be created.
         */
        return;
    }

    if (!silent || NoExecute(gn)) {
        (void)fprintf(stdout, "touch %s\n", gn->name);
        (void)fflush(stdout);
    }

    if (NoExecute(gn)) {
        return;
    }

    if (gn->type & OP_ARCHV) {
        Arch_Touch(gn);
    } else if (gn->type & OP_LIB) {
        Arch_TouchLib(gn);
    } else {
        char    *file = gn->path ? gn->path : gn->name;

        times.actime = times.modtime = now;
        if (utime(file, &times) < 0){
            streamID = open(file, O_RDWR | O_CREAT, 0666);

            if (streamID >= 0) {
                char    c;

                /*
                 * Read and write a byte to the file to change the
                 * modification time, then close the file.
                 */
                if (read(streamID, &c, 1) == 1) {
                    (void)lseek(streamID, (off_t)0, SEEK_SET);
                    (void)write(streamID, &c, 1);
                }

                (void)close(streamID);
            } else {
                (void)fprintf(stdout, "*** couldn't touch %s: %s",
                               file, strerror(errno));
                (void)fflush(stdout);
            }
        }
    }
}

/*-
 *-----------------------------------------------------------------------
 * Job_CheckCommands --
 *      Make sure the given node has all the commands it needs.
 *
 * Input:
 *      gn              The target whose commands need verifying
 *      abortProc       Function to abort with message
 *
 * Results:
 *      TRUE if the commands list is/was ok.
 *
 * Side Effects:
 *      The node will have commands from the .DEFAULT rule added to it
 *      if it needs them.
 *-----------------------------------------------------------------------
 */
Boolean
Job_CheckCommands(GNode *gn, void (*abortProc)(const char *, ...))
{
    if (OP_NOP(gn->type) && Lst_IsEmpty(gn->commands) &&
        ((gn->type & OP_LIB) == 0 || Lst_IsEmpty(gn->children))) {
        /*
         * No commands. Look for .DEFAULT rule from which we might infer
         * commands
         */
        if ((DEFAULT != NULL) && !Lst_IsEmpty(DEFAULT->commands) &&
                (gn->type & OP_SPECIAL) == 0) {
            char *p1;
            /*
             * Make only looks for a .DEFAULT if the node was never the
             * target of an operator, so that's what we do too. If
             * a .DEFAULT was given, we substitute its commands for gn's
             * commands and set the IMPSRC variable to be the target's name
             * The DEFAULT node acts like a transformation rule, in that
             * gn also inherits any attributes or sources attached to
             * .DEFAULT itself.
             */
            Make_HandleUse(DEFAULT, gn);
            Var_Set(IMPSRC, Var_Value(TARGET, gn, &p1), gn, 0);
            if (p1)
                free(p1);
        } else if (Dir_MTime(gn) == 0 && (gn->type & OP_SPECIAL) == 0) {
            /*
             * The node wasn't the target of an operator we have no .DEFAULT
             * rule to go on and the target doesn't already exist. There's
             * nothing more we can do for this branch. If the -k flag wasn't
             * given, we stop in our tracks, otherwise we just don't update
             * this node's parents so they never get examined.
             */
            static const char msg[] = ": don't know how to make";

            if (gn->flags & FROM_DEPEND) {
                fprintf(stdout, "%s: ignoring stale %s for %s\n",
                        progname, makeDependfile, gn->name);
                return TRUE;
            }

            if (gn->type & OP_OPTIONAL) {
                (void)fprintf(stdout, "%s%s %s(ignored)\n", progname,
                    msg, gn->name);
                (void)fflush(stdout);
            } else if (keepgoing) {
                (void)fprintf(stdout, "%s%s %s(continuing)\n", progname,
                    msg, gn->name);
                (void)fflush(stdout);
                return FALSE;
            } else {
                (*abortProc)("%s%s %s. Stop", progname, msg, gn->name);
                return FALSE;
            }
        }
    }
    return TRUE;
}

/*-
 *-----------------------------------------------------------------------
 * JobExec --
 *      Execute the shell for the given job. Called from JobStart
 *
 * Input:
 *      job             Job to execute
 *
 * Results:
 *      None.
 *
 * Side Effects:
 *      A shell is executed, outputs is altered and the Job structure added
 *      to the job table.
 *
 *-----------------------------------------------------------------------
 */
static void
JobExec(Job *job, char **argv)
{
    int           cpid;         /* ID of new child */
    sigset_t      mask;

    job->flags &= ~JOB_TRACED;

    if (DEBUG(JOB)) {
        int       i;

        (void)fprintf(debug_file, "Running %s %sly\n", job->node->name, "local");
        (void)fprintf(debug_file, "\tCommand: ");
        for (i = 0; argv[i] != NULL; i++) {
            (void)fprintf(debug_file, "%s ", argv[i]);
        }
        (void)fprintf(debug_file, "\n");
    }

    /*
     * Some jobs produce no output and it's disconcerting to have
     * no feedback of their running (since they produce no output, the
     * banner with their name in it never appears). This is an attempt to
     * provide that feedback, even if nothing follows it.
     */
    if ((lastNode != job->node) && !(job->flags & JOB_SILENT)) {
        MESSAGE(stdout, job->node);
        lastNode = job->node;
    }

    /* No interruptions until this job is on the `jobs' list */
    JobSigLock(&mask);

    /* Pre-emptively mark job running, pid still zero though */
    job->job_state = JOB_ST_RUNNING;

    cpid = vFork();
    if (cpid == -1)
        Punt("Cannot vfork: %s", strerror(errno));

    if (cpid == 0) {
        /* Child */
        sigset_t tmask;

        /*
         * Reset all signal handlers; this is necessary because we also
         * need to unblock signals before we exec(2).
         */
        JobSigReset();

        /* Now unblock signals */
        sigemptyset(&tmask);
        JobSigUnlock(&tmask);

        /*
         * Must duplicate the input stream down to the child's input and
         * reset it to the beginning (again). Since the stream was marked
         * close-on-exec, we must clear that bit in the new input.
         */
        if (dup2(FILENO(job->cmdFILE), 0) == -1) {
            execError("dup2", "job->cmdFILE");
            _exit(1);
        }
        (void)fcntl(0, F_SETFD, 0);
        (void)lseek(0, (off_t)0, SEEK_SET);

        if (job->node->type & OP_MAKE) {
                /*
                 * Pass job token pipe to submakes.
                 */
                fcntl(tokenWaitJob.inPipe, F_SETFD, 0);
                fcntl(tokenWaitJob.outPipe, F_SETFD, 0);                
        }
        
        /*
         * Set up the child's output to be routed through the pipe
         * we've created for it.
         */
        if (dup2(job->outPipe, 1) == -1) {
            execError("dup2", "job->outPipe");
            _exit(1);
        }
        /*
         * The output channels are marked close on exec. This bit was
         * duplicated by the dup2(on some systems), so we have to clear
         * it before routing the shell's error output to the same place as
         * its standard output.
         */
        (void)fcntl(1, F_SETFD, 0);
        if (dup2(1, 2) == -1) {
            execError("dup2", "1, 2");
            _exit(1);
        }

        /*
         * We want to switch the child into a different process family so
         * we can kill it and all its descendants in one fell swoop,
         * by killing its process family, but not commit suicide.
         */
#if defined(SYSV)
        /* XXX: dsl - I'm sure this should be setpgrp()... */
        (void)setsid();
#else
        (void)setpgid(0, getpid());
#endif

        Var_ExportVars();

        (void)execv(shellPath, argv);
        execError("exec", shellPath);
        _exit(1);
    }

    /* Parent, continuing after the child exec */
    job->pid = cpid;

    Trace_Log(JOBSTART, job);

    /*
     * Set the current position in the buffer to the beginning
     * and mark another stream to watch in the outputs mask
     */
    job->curPos = 0;

    watchfd(job);

    if (job->cmdFILE != NULL && job->cmdFILE != stdout) {
        (void)fclose(job->cmdFILE);
        job->cmdFILE = NULL;
    }

    /*
     * Now the job is actually running, add it to the table.
     */
    if (DEBUG(JOB)) {
        fprintf(debug_file, "JobExec(%s): pid %d added to jobs table\n",
                job->node->name, job->pid);
        job_table_dump("job started");
    }
    JobSigUnlock(&mask);
}

/*-
 *-----------------------------------------------------------------------
 * JobMakeArgv --
 *      Create the argv needed to execute the shell for a given job.
 *
 *
 * Results:
 *
 * Side Effects:
 *
 *-----------------------------------------------------------------------
 */
static void
JobMakeArgv(Job *job, char **argv)
{
    int           argc;
    static char args[10];       /* For merged arguments */

    argv[0] = UNCONST(shellName);
    argc = 1;

    if ((commandShell->exit && (*commandShell->exit != '-')) ||
        (commandShell->echo && (*commandShell->echo != '-')))
    {
        /*
         * At least one of the flags doesn't have a minus before it, so
         * merge them together. Have to do this because the *(&(@*#*&#$#
         * Bourne shell thinks its second argument is a file to source.
         * Grrrr. Note the ten-character limitation on the combined arguments.
         */
        (void)snprintf(args, sizeof(args), "-%s%s",
                      ((job->flags & JOB_IGNERR) ? "" :
                       (commandShell->exit ? commandShell->exit : "")),
                      ((job->flags & JOB_SILENT) ? "" :
                       (commandShell->echo ? commandShell->echo : "")));

        if (args[1]) {
            argv[argc] = args;
            argc++;
        }
    } else {
        if (!(job->flags & JOB_IGNERR) && commandShell->exit) {
            argv[argc] = UNCONST(commandShell->exit);
            argc++;
        }
        if (!(job->flags & JOB_SILENT) && commandShell->echo) {
            argv[argc] = UNCONST(commandShell->echo);
            argc++;
        }
    }
    argv[argc] = NULL;
}

/*-
 *-----------------------------------------------------------------------
 * JobStart  --
 *      Start a target-creation process going for the target described
 *      by the graph node gn.
 *
 * Input:
 *      gn              target to create
 *      flags           flags for the job to override normal ones.
 *                      e.g. JOB_SPECIAL or JOB_IGNDOTS
 *      previous        The previous Job structure for this node, if any.
 *
 * Results:
 *      JOB_ERROR if there was an error in the commands, JOB_FINISHED
 *      if there isn't actually anything left to do for the job and
 *      JOB_RUNNING if the job has been started.
 *
 * Side Effects:
 *      A new Job node is created and added to the list of running
 *      jobs. PMake is forked and a child shell created.
 *
 * NB: I'm fairly sure that this code is never called with JOB_SPECIAL set
 *     JOB_IGNDOTS is never set (dsl)
 *     Also the return value is ignored by everyone.
 *-----------------------------------------------------------------------
 */
static int
JobStart(GNode *gn, int flags)
{
    Job           *job;       /* new job descriptor */
    char          *argv[10];  /* Argument vector to shell */
    Boolean       cmdsOK;     /* true if the nodes commands were all right */
    Boolean       noExec;     /* Set true if we decide not to run the job */
    int           tfd;        /* File descriptor to the temp file */

    for (job = job_table; job < job_table_end; job++) {
        if (job->job_state == JOB_ST_FREE)
            break;
    }
    if (job >= job_table_end)
        Punt("JobStart no job slots vacant");

    memset(job, 0, sizeof *job);
    job->job_state = JOB_ST_SETUP;
    if (gn->type & OP_SPECIAL)
        flags |= JOB_SPECIAL;

    job->node = gn;
    job->tailCmds = NULL;

    /*
     * Set the initial value of the flags for this job based on the global
     * ones and the node's attributes... Any flags supplied by the caller
     * are also added to the field.
     */
    job->flags = 0;
    if (Targ_Ignore(gn)) {
        job->flags |= JOB_IGNERR;
    }
    if (Targ_Silent(gn)) {
        job->flags |= JOB_SILENT;
    }
    job->flags |= flags;

    /*
     * Check the commands now so any attributes from .DEFAULT have a chance
     * to migrate to the node
     */
    cmdsOK = Job_CheckCommands(gn, Error);

    job->inPollfd = NULL;
    /*
     * If the -n flag wasn't given, we open up OUR (not the child's)
     * temporary file to stuff commands in it. The thing is rd/wr so we don't
     * need to reopen it to feed it to the shell. If the -n flag *was* given,
     * we just set the file to be stdout. Cute, huh?
     */
    if (((gn->type & OP_MAKE) && !(noRecursiveExecute)) ||
            (!noExecute && !touchFlag)) {
        /*
         * tfile is the name of a file into which all shell commands are
         * put. It is removed before the child shell is executed, unless
         * DEBUG(SCRIPT) is set.
         */
        char *tfile;
        sigset_t mask;
        /*
         * We're serious here, but if the commands were bogus, we're
         * also dead...
         */
        if (!cmdsOK) {
            DieHorribly();
        }

        JobSigLock(&mask);
        tfd = mkTempFile(TMPPAT, &tfile);
        if (!DEBUG(SCRIPT))
                (void)eunlink(tfile);
        JobSigUnlock(&mask);

        job->cmdFILE = fdopen(tfd, "w+");
        if (job->cmdFILE == NULL) {
            Punt("Could not fdopen %s", tfile);
        }
        (void)fcntl(FILENO(job->cmdFILE), F_SETFD, 1);
        /*
         * Send the commands to the command file, flush all its buffers then
         * rewind and remove the thing.
         */
        noExec = FALSE;

        /*
         * We can do all the commands at once. hooray for sanity
         */
        numCommands = 0;
        Lst_ForEach(gn->commands, JobPrintCommand, job);

        /*
         * If we didn't print out any commands to the shell script,
         * there's not much point in executing the shell, is there?
         */
        if (numCommands == 0) {
            noExec = TRUE;
        }

        free(tfile);
    } else if (NoExecute(gn)) {
        /*
         * Not executing anything -- just print all the commands to stdout
         * in one fell swoop. This will still set up job->tailCmds correctly.
         */
        if (lastNode != gn) {
            MESSAGE(stdout, gn);
            lastNode = gn;
        }
        job->cmdFILE = stdout;
        /*
         * Only print the commands if they're ok, but don't die if they're
         * not -- just let the user know they're bad and keep going. It
         * doesn't do any harm in this case and may do some good.
         */
        if (cmdsOK) {
            Lst_ForEach(gn->commands, JobPrintCommand, job);
        }
        /*
         * Don't execute the shell, thank you.
         */
        noExec = TRUE;
    } else {
        /*
         * Just touch the target and note that no shell should be executed.
         * Set cmdFILE to stdout to make life easier. Check the commands, too,
         * but don't die if they're no good -- it does no harm to keep working
         * up the graph.
         */
        job->cmdFILE = stdout;
        Job_Touch(gn, job->flags&JOB_SILENT);
        noExec = TRUE;
    }
    /* Just in case it isn't already... */
    (void)fflush(job->cmdFILE);

    /*
     * If we're not supposed to execute a shell, don't.
     */
    if (noExec) {
        if (!(job->flags & JOB_SPECIAL))
            Job_TokenReturn();
        /*
         * Unlink and close the command file if we opened one
         */
        if (job->cmdFILE != stdout) {
            if (job->cmdFILE != NULL) {
                (void)fclose(job->cmdFILE);
                job->cmdFILE = NULL;
            }
        }

        /*
         * We only want to work our way up the graph if we aren't here because
         * the commands for the job were no good.
         */
        if (cmdsOK && aborting == 0) {
            if (job->tailCmds != NULL) {
                Lst_ForEachFrom(job->node->commands, job->tailCmds,
                                JobSaveCommand,
                               job->node);
            }
            job->node->made = MADE;
            Make_Update(job->node);
        }
        job->job_state = JOB_ST_FREE;
        return cmdsOK ? JOB_FINISHED : JOB_ERROR;
    }

    /*
     * Set up the control arguments to the shell. This is based on the flags
     * set earlier for this job.
     */
    JobMakeArgv(job, argv);

    /* Create the pipe by which we'll get the shell's output.  */
    JobCreatePipe(job, 3);

    JobExec(job, argv);
    return(JOB_RUNNING);
}

static char *
JobOutput(Job *job, char *cp, char *endp, int msg)
{
    char *ecp;

    if (commandShell->noPrint) {
        ecp = Str_FindSubstring(cp, commandShell->noPrint);
        while (ecp != NULL) {
            if (cp != ecp) {
                *ecp = '\0';
                if (!beSilent && msg && job->node != lastNode) {
                    MESSAGE(stdout, job->node);
                    lastNode = job->node;
                }
                /*
                 * The only way there wouldn't be a newline after
                 * this line is if it were the last in the buffer.
                 * however, since the non-printable comes after it,
                 * there must be a newline, so we don't print one.
                 */
                (void)fprintf(stdout, "%s", cp);
                (void)fflush(stdout);
            }
            cp = ecp + commandShell->noPLen;
            if (cp != endp) {
                /*
                 * Still more to print, look again after skipping
                 * the whitespace following the non-printable
                 * command....
                 */
                cp++;
                while (*cp == ' ' || *cp == '\t' || *cp == '\n') {
                    cp++;
                }
                ecp = Str_FindSubstring(cp, commandShell->noPrint);
            } else {
                return cp;
            }
        }
    }
    return cp;
}

/*-
 *-----------------------------------------------------------------------
 * JobDoOutput  --
 *      This function is called at different times depending on
 *      whether the user has specified that output is to be collected
 *      via pipes or temporary files. In the former case, we are called
 *      whenever there is something to read on the pipe. We collect more
 *      output from the given job and store it in the job's outBuf. If
 *      this makes up a line, we print it tagged by the job's identifier,
 *      as necessary.
 *      If output has been collected in a temporary file, we open the
 *      file and read it line by line, transfering it to our own
 *      output channel until the file is empty. At which point we
 *      remove the temporary file.
 *      In both cases, however, we keep our figurative eye out for the
 *      'noPrint' line for the shell from which the output came. If
 *      we recognize a line, we don't print it. If the command is not
 *      alone on the line (the character after it is not \0 or \n), we
 *      do print whatever follows it.
 *
 * Input:
 *      job             the job whose output needs printing
 *      finish          TRUE if this is the last time we'll be called
 *                      for this job
 *
 * Results:
 *      None
 *
 * Side Effects:
 *      curPos may be shifted as may the contents of outBuf.
 *-----------------------------------------------------------------------
 */
STATIC void
JobDoOutput(Job *job, Boolean finish)
{
    Boolean       gotNL = FALSE;  /* true if got a newline */
    Boolean       fbuf;           /* true if our buffer filled up */
    int           nr;             /* number of bytes read */
    int           i;              /* auxiliary index into outBuf */
    int           max;            /* limit for i (end of current data) */
    int           nRead;          /* (Temporary) number of bytes read */

    /*
     * Read as many bytes as will fit in the buffer.
     */
end_loop:
    gotNL = FALSE;
    fbuf = FALSE;

    nRead = read(job->inPipe, &job->outBuf[job->curPos],
                     JOB_BUFSIZE - job->curPos);
    if (nRead < 0) {
        if (errno == EAGAIN)
            return;
        if (DEBUG(JOB)) {
            perror("JobDoOutput(piperead)");
        }
        nr = 0;
    } else {
        nr = nRead;
    }

    /*
     * If we hit the end-of-file (the job is dead), we must flush its
     * remaining output, so pretend we read a newline if there's any
     * output remaining in the buffer.
     * Also clear the 'finish' flag so we stop looping.
     */
    if ((nr == 0) && (job->curPos != 0)) {
        job->outBuf[job->curPos] = '\n';
        nr = 1;
        finish = FALSE;
    } else if (nr == 0) {
        finish = FALSE;
    }

    /*
     * Look for the last newline in the bytes we just got. If there is
     * one, break out of the loop with 'i' as its index and gotNL set
     * TRUE.
     */
    max = job->curPos + nr;
    for (i = job->curPos + nr - 1; i >= job->curPos; i--) {
        if (job->outBuf[i] == '\n') {
            gotNL = TRUE;
            break;
        } else if (job->outBuf[i] == '\0') {
            /*
             * Why?
             */
            job->outBuf[i] = ' ';
        }
    }

    if (!gotNL) {
        job->curPos += nr;
        if (job->curPos == JOB_BUFSIZE) {
            /*
             * If we've run out of buffer space, we have no choice
             * but to print the stuff. sigh.
             */
            fbuf = TRUE;
            i = job->curPos;
        }
    }
    if (gotNL || fbuf) {
        /*
         * Need to send the output to the screen. Null terminate it
         * first, overwriting the newline character if there was one.
         * So long as the line isn't one we should filter (according
         * to the shell description), we print the line, preceded
         * by a target banner if this target isn't the same as the
         * one for which we last printed something.
         * The rest of the data in the buffer are then shifted down
         * to the start of the buffer and curPos is set accordingly.
         */
        job->outBuf[i] = '\0';
        if (i >= job->curPos) {
            char *cp;

            cp = JobOutput(job, job->outBuf, &job->outBuf[i], FALSE);

            /*
             * There's still more in that thar buffer. This time, though,
             * we know there's no newline at the end, so we add one of
             * our own free will.
             */
            if (*cp != '\0') {
                if (!beSilent && job->node != lastNode) {
                    MESSAGE(stdout, job->node);
                    lastNode = job->node;
                }
                (void)fprintf(stdout, "%s%s", cp, gotNL ? "\n" : "");
                (void)fflush(stdout);
            }
        }
        if (i < max - 1) {
            /* shift the remaining characters down */
            (void)memcpy(job->outBuf, &job->outBuf[i + 1], max - (i + 1));
            job->curPos = max - (i + 1);

        } else {
            /*
             * We have written everything out, so we just start over
             * from the start of the buffer. No copying. No nothing.
             */
            job->curPos = 0;
        }
    }
    if (finish) {
        /*
         * If the finish flag is true, we must loop until we hit
         * end-of-file on the pipe. This is guaranteed to happen
         * eventually since the other end of the pipe is now closed
         * (we closed it explicitly and the child has exited). When
         * we do get an EOF, finish will be set FALSE and we'll fall
         * through and out.
         */
        goto end_loop;
    }
}

static void
JobRun(GNode *targ)
{
#ifdef notyet
    /*
     * Unfortunately it is too complicated to run .BEGIN, .END,
     * and .INTERRUPT job in the parallel job module. This has
     * the nice side effect that it avoids a lot of other problems.
     */
    Lst lst = Lst_Init(FALSE);
    Lst_AtEnd(lst, targ);
    (void)Make_Run(lst);
    Lst_Destroy(lst, NULL);
    JobStart(targ, JOB_SPECIAL);
    while (jobTokensRunning) {
        Job_CatchOutput();
    }
#else
    Compat_Make(targ, targ);
    if (targ->made == ERROR) {
        PrintOnError(targ, "\n\nStop.");
        exit(1);
    }
#endif
}

/*-
 *-----------------------------------------------------------------------
 * Job_CatchChildren --
 *      Handle the exit of a child. Called from Make_Make.
 *
 * Input:
 *      block           TRUE if should block on the wait
 *
 * Results:
 *      none.
 *
 * Side Effects:
 *      The job descriptor is removed from the list of children.
 *
 * Notes:
 *      We do waits, blocking or not, according to the wisdom of our
 *      caller, until there are no more children to report. For each
 *      job, call JobFinish to finish things off.
 *
 *-----------------------------------------------------------------------
 */

void
Job_CatchChildren(void)
{
    int           pid;          /* pid of dead child */
    Job           *job;         /* job descriptor for dead child */
    WAIT_T        status;       /* Exit/termination status */

    /*
     * Don't even bother if we know there's no one around.
     */
    if (jobTokensRunning == 0)
        return;

    while ((pid = waitpid((pid_t) -1, &status, WNOHANG | WUNTRACED)) > 0) {
        if (DEBUG(JOB)) {
            (void)fprintf(debug_file, "Process %d exited/stopped status %x.\n", pid,
              WAIT_STATUS(status));
        }

        job = JobFindPid(pid, JOB_ST_RUNNING);
        if (job == NULL) {
            if (!lurking_children)
                Error("Child (%d) status %x not in table?", pid, status);
            continue;
        }
        if (WIFSTOPPED(status)) {
            if (DEBUG(JOB)) {
                (void)fprintf(debug_file, "Process %d (%s) stopped.\n",
                                job->pid, job->node->name);
            }
            if (!make_suspended) {
                    switch (WSTOPSIG(status)) {
                    case SIGTSTP:
                        (void)printf("*** [%s] Suspended\n", job->node->name);
                        break;
                    case SIGSTOP:
                        (void)printf("*** [%s] Stopped\n", job->node->name);
                        break;
                    default:
                        (void)printf("*** [%s] Stopped -- signal %d\n",
                            job->node->name, WSTOPSIG(status));
                    }
                    job->job_suspended = 1;
            }
            (void)fflush(stdout);
            continue;
        }

        job->job_state = JOB_ST_FINISHED;
        job->exit_status = WAIT_STATUS(status);

        JobFinish(job, status);
    }
}

/*-
 *-----------------------------------------------------------------------
 * Job_CatchOutput --
 *      Catch the output from our children, if we're using
 *      pipes do so. Otherwise just block time until we get a
 *      signal(most likely a SIGCHLD) since there's no point in
 *      just spinning when there's nothing to do and the reaping
 *      of a child can wait for a while.
 *
 * Results:
 *      None
 *
 * Side Effects:
 *      Output is read from pipes if we're piping.
 * -----------------------------------------------------------------------
 */
void
Job_CatchOutput(void)
{
    int nready;
    Job *job;
    int i;

    (void)fflush(stdout);

    /* The first fd in the list is the job token pipe */
    nready = poll(fds + 1 - wantToken, nfds - 1 + wantToken, POLL_MSEC);

    if (nready < 0 || readyfd(&childExitJob)) {
        char token = 0;
        nready -= 1;
        (void)read(childExitJob.inPipe, &token, 1);
        if (token == DO_JOB_RESUME[0])
            /* Complete relay requested from our SIGCONT handler */
            JobRestartJobs();
        Job_CatchChildren();
    }

    if (nready <= 0)
        return;

    if (wantToken && readyfd(&tokenWaitJob))
        nready--;

    for (i = 2; i < nfds; i++) {
        if (!fds[i].revents)
            continue;
        job = jobfds[i];
        if (job->job_state != JOB_ST_RUNNING)
            continue;
        JobDoOutput(job, FALSE);
    }
}

/*-
 *-----------------------------------------------------------------------
 * Job_Make --
 *      Start the creation of a target. Basically a front-end for
 *      JobStart used by the Make module.
 *
 * Results:
 *      None.
 *
 * Side Effects:
 *      Another job is started.
 *
 *-----------------------------------------------------------------------
 */
void
Job_Make(GNode *gn)
{
    (void)JobStart(gn, 0);
}

void
Shell_Init(void)
{
    if (shellPath == NULL) {
        /*
         * We are using the default shell, which may be an absolute
         * path if DEFSHELL_CUSTOM is defined.
         */
        shellName = commandShell->name;
#ifdef DEFSHELL_CUSTOM
        if (*shellName == '/') {
            shellPath = shellName;
            shellName = strrchr(shellPath, '/');
            shellName++;
        } else
#endif
        shellPath = str_concat(_PATH_DEFSHELLDIR, shellName, STR_ADDSLASH);
    }
    if (commandShell->exit == NULL) {
        commandShell->exit = "";
    }
    if (commandShell->echo == NULL) {
        commandShell->echo = "";
    }
}

/*-
 * Returns the string literal that is used in the current command shell
 * to produce a newline character.
 */
const char *
Shell_GetNewline(void)
{

    return commandShell->newline;
}

void
Job_SetPrefix(void)
{
    
    if (targPrefix) {
        free(targPrefix);
    } else if (!Var_Exists(MAKE_JOB_PREFIX, VAR_GLOBAL)) {
        Var_Set(MAKE_JOB_PREFIX, "---", VAR_GLOBAL, 0);
    }

    targPrefix = Var_Subst(NULL, "${" MAKE_JOB_PREFIX "}", VAR_GLOBAL, 0);
}

/*-
 *-----------------------------------------------------------------------
 * Job_Init --
 *      Initialize the process module
 *
 * Input:
 *
 * Results:
 *      none
 *
 * Side Effects:
 *      lists and counters are initialized
 *-----------------------------------------------------------------------
 */
void
Job_Init(void)
{
    GNode         *begin;     /* node for commands to do at the very start */

    /* Allocate space for all the job info */
    job_table = bmake_malloc(maxJobs * sizeof *job_table);
    memset(job_table, 0, maxJobs * sizeof *job_table);
    job_table_end = job_table + maxJobs;
    wantToken = 0;

    aborting =    0;
    errors =      0;

    lastNode =    NULL;

    if (maxJobs == 1) {
        /*
         * If only one job can run at a time, there's no need for a banner,
         * is there?
         */
        targFmt = "";
    } else {
        targFmt = TARG_FMT;
    }

    /*
     * There is a non-zero chance that we already have children.
     * eg after 'make -f- <<EOF'
     * Since their termination causes a 'Child (pid) not in table' message,
     * Collect the status of any that are already dead, and suppress the
     * error message if there are any undead ones.
     */
    for (;;) {
        int rval, status;
        rval = waitpid((pid_t) -1, &status, WNOHANG);
        if (rval > 0)
            continue;
        if (rval == 0)
            lurking_children = 1;
        break;
    }

    Shell_Init();

    JobCreatePipe(&childExitJob, 3);

    /* We can only need to wait for tokens, children and output from each job */
    fds = bmake_malloc(sizeof (*fds) * (2 + maxJobs));
    jobfds = bmake_malloc(sizeof (*jobfds) * (2 + maxJobs));

    /* These are permanent entries and take slots 0 and 1 */
    watchfd(&tokenWaitJob);
    watchfd(&childExitJob);

    sigemptyset(&caught_signals);
    /*
     * Install a SIGCHLD handler.
     */
    (void)signal(SIGCHLD, JobChildSig);
    sigaddset(&caught_signals, SIGCHLD);

#define ADDSIG(s,h)                             \
    if (signal(s, SIG_IGN) != SIG_IGN) {        \
        sigaddset(&caught_signals, s);          \
        (void)signal(s, h);                     \
    }

    /*
     * Catch the four signals that POSIX specifies if they aren't ignored.
     * JobPassSig will take care of calling JobInterrupt if appropriate.
     */
    ADDSIG(SIGINT, JobPassSig_int)
    ADDSIG(SIGHUP, JobPassSig_term)
    ADDSIG(SIGTERM, JobPassSig_term)
    ADDSIG(SIGQUIT, JobPassSig_term)

    /*
     * There are additional signals that need to be caught and passed if
     * either the export system wants to be told directly of signals or if
     * we're giving each job its own process group (since then it won't get
     * signals from the terminal driver as we own the terminal)
     */
    ADDSIG(SIGTSTP, JobPassSig_suspend)
    ADDSIG(SIGTTOU, JobPassSig_suspend)
    ADDSIG(SIGTTIN, JobPassSig_suspend)
    ADDSIG(SIGWINCH, JobCondPassSig)
    ADDSIG(SIGCONT, JobContinueSig)
#undef ADDSIG

    begin = Targ_FindNode(".BEGIN", TARG_NOCREATE);

    if (begin != NULL) {
        JobRun(begin);
        if (begin->made == ERROR) {
            PrintOnError(begin, "\n\nStop.");
            exit(1);
        }
    }
    postCommands = Targ_FindNode(".END", TARG_CREATE);
}

static void JobSigReset(void)
{
#define DELSIG(s)                                       \
    if (sigismember(&caught_signals, s)) {              \
        (void)signal(s, SIG_DFL);                       \
    }

    DELSIG(SIGINT)
    DELSIG(SIGHUP)
    DELSIG(SIGQUIT)
    DELSIG(SIGTERM)
    DELSIG(SIGTSTP)
    DELSIG(SIGTTOU)
    DELSIG(SIGTTIN)
    DELSIG(SIGWINCH)
    DELSIG(SIGCONT)
#undef DELSIG
    (void)signal(SIGCHLD, SIG_DFL);
}

/*-
 *-----------------------------------------------------------------------
 * JobMatchShell --
 *      Find a shell in 'shells' given its name.
 *
 * Results:
 *      A pointer to the Shell structure.
 *
 * Side Effects:
 *      None.
 *
 *-----------------------------------------------------------------------
 */
static Shell *
JobMatchShell(const char *name)
{
    Shell       *sh;

    for (sh = shells; sh->name != NULL; sh++) {
        if (strcmp(name, sh->name) == 0)
                return (sh);
    }
    return NULL;
}

/*-
 *-----------------------------------------------------------------------
 * Job_ParseShell --
 *      Parse a shell specification and set up commandShell, shellPath
 *      and shellName appropriately.
 *
 * Input:
 *      line            The shell spec
 *
 * Results:
 *      FAILURE if the specification was incorrect.
 *
 * Side Effects:
 *      commandShell points to a Shell structure (either predefined or
 *      created from the shell spec), shellPath is the full path of the
 *      shell described by commandShell, while shellName is just the
 *      final component of shellPath.
 *
 * Notes:
 *      A shell specification consists of a .SHELL target, with dependency
 *      operator, followed by a series of blank-separated words. Double
 *      quotes can be used to use blanks in words. A backslash escapes
 *      anything (most notably a double-quote and a space) and
 *      provides the functionality it does in C. Each word consists of
 *      keyword and value separated by an equal sign. There should be no
 *      unnecessary spaces in the word. The keywords are as follows:
 *          name            Name of shell.
 *          path            Location of shell.
 *          quiet           Command to turn off echoing.
 *          echo            Command to turn echoing on
 *          filter          Result of turning off echoing that shouldn't be
 *                          printed.
 *          echoFlag        Flag to turn echoing on at the start
 *          errFlag         Flag to turn error checking on at the start
 *          hasErrCtl       True if shell has error checking control
 *          newline         String literal to represent a newline char
 *          check           Command to turn on error checking if hasErrCtl
 *                          is TRUE or template of command to echo a command
 *                          for which error checking is off if hasErrCtl is
 *                          FALSE.
 *          ignore          Command to turn off error checking if hasErrCtl
 *                          is TRUE or template of command to execute a
 *                          command so as to ignore any errors it returns if
 *                          hasErrCtl is FALSE.
 *
 *-----------------------------------------------------------------------
 */
ReturnStatus
Job_ParseShell(char *line)
{
    char        **words;
    char        **argv;
    int         argc;
    char        *path;
    Shell       newShell;
    Boolean     fullSpec = FALSE;
    Shell       *sh;

    while (isspace((unsigned char)*line)) {
        line++;
    }

    if (shellArgv)
        free(UNCONST(shellArgv));

    memset(&newShell, 0, sizeof(newShell));

    /*
     * Parse the specification by keyword
     */
    words = brk_string(line, &argc, TRUE, &path);
    if (words == NULL) {
        Error("Unterminated quoted string [%s]", line);
        return FAILURE;
    }
    shellArgv = path;

    for (path = NULL, argv = words; argc != 0; argc--, argv++) {
            if (strncmp(*argv, "path=", 5) == 0) {
                path = &argv[0][5];
            } else if (strncmp(*argv, "name=", 5) == 0) {
                newShell.name = &argv[0][5];
            } else {
                if (strncmp(*argv, "quiet=", 6) == 0) {
                    newShell.echoOff = &argv[0][6];
                } else if (strncmp(*argv, "echo=", 5) == 0) {
                    newShell.echoOn = &argv[0][5];
                } else if (strncmp(*argv, "filter=", 7) == 0) {
                    newShell.noPrint = &argv[0][7];
                    newShell.noPLen = strlen(newShell.noPrint);
                } else if (strncmp(*argv, "echoFlag=", 9) == 0) {
                    newShell.echo = &argv[0][9];
                } else if (strncmp(*argv, "errFlag=", 8) == 0) {
                    newShell.exit = &argv[0][8];
                } else if (strncmp(*argv, "hasErrCtl=", 10) == 0) {
                    char c = argv[0][10];
                    newShell.hasErrCtl = !((c != 'Y') && (c != 'y') &&
                                           (c != 'T') && (c != 't'));
                } else if (strncmp(*argv, "newline=", 8) == 0) {
                    newShell.newline = &argv[0][8];
                } else if (strncmp(*argv, "check=", 6) == 0) {
                    newShell.errCheck = &argv[0][6];
                } else if (strncmp(*argv, "ignore=", 7) == 0) {
                    newShell.ignErr = &argv[0][7];
                } else if (strncmp(*argv, "errout=", 7) == 0) {
                    newShell.errOut = &argv[0][7];
                } else if (strncmp(*argv, "comment=", 8) == 0) {
                    newShell.commentChar = argv[0][8];
                } else {
                    Parse_Error(PARSE_FATAL, "Unknown keyword \"%s\"",
                                *argv);
                    free(words);
                    return(FAILURE);
                }
                fullSpec = TRUE;
            }
    }

    if (path == NULL) {
        /*
         * If no path was given, the user wants one of the pre-defined shells,
         * yes? So we find the one s/he wants with the help of JobMatchShell
         * and set things up the right way. shellPath will be set up by
         * Job_Init.
         */
        if (newShell.name == NULL) {
            Parse_Error(PARSE_FATAL, "Neither path nor name specified");
            free(words);
            return(FAILURE);
        } else {
            if ((sh = JobMatchShell(newShell.name)) == NULL) {
                    Parse_Error(PARSE_WARNING, "%s: No matching shell",
                                newShell.name);
                    free(words);
                    return(FAILURE);
            }
            commandShell = sh;
            shellName = newShell.name;
        }
    } else {
        /*
         * The user provided a path. If s/he gave nothing else (fullSpec is
         * FALSE), try and find a matching shell in the ones we know of.
         * Else we just take the specification at its word and copy it
         * to a new location. In either case, we need to record the
         * path the user gave for the shell.
         */
        shellPath = path;
        path = strrchr(path, '/');
        if (path == NULL) {
            path = UNCONST(shellPath);
        } else {
            path += 1;
        }
        if (newShell.name != NULL) {
            shellName = newShell.name;
        } else {
            shellName = path;
        }
        if (!fullSpec) {
            if ((sh = JobMatchShell(shellName)) == NULL) {
                    Parse_Error(PARSE_WARNING, "%s: No matching shell",
                                shellName);
                    free(words);
                    return(FAILURE);
            }
            commandShell = sh;
        } else {
            commandShell = bmake_malloc(sizeof(Shell));
            *commandShell = newShell;
        }
    }

    if (commandShell->echoOn && commandShell->echoOff) {
        commandShell->hasEchoCtl = TRUE;
    }

    if (!commandShell->hasErrCtl) {
        if (commandShell->errCheck == NULL) {
            commandShell->errCheck = "";
        }
        if (commandShell->ignErr == NULL) {
            commandShell->ignErr = "%s\n";
        }
    }

    /*
     * Do not free up the words themselves, since they might be in use by the
     * shell specification.
     */
    free(words);
    return SUCCESS;
}

/*-
 *-----------------------------------------------------------------------
 * JobInterrupt --
 *      Handle the receipt of an interrupt.
 *
 * Input:
 *      runINTERRUPT    Non-zero if commands for the .INTERRUPT target
 *                      should be executed
 *      signo           signal received
 *
 * Results:
 *      None
 *
 * Side Effects:
 *      All children are killed. Another job will be started if the
 *      .INTERRUPT target was given.
 *-----------------------------------------------------------------------
 */
static void
JobInterrupt(int runINTERRUPT, int signo)
{
    Job         *job;           /* job descriptor in that element */
    GNode       *interrupt;     /* the node describing the .INTERRUPT target */
    sigset_t    mask;
    GNode       *gn;

    aborting = ABORT_INTERRUPT;

    JobSigLock(&mask);

    for (job = job_table; job < job_table_end; job++) {
        if (job->job_state != JOB_ST_RUNNING)
            continue;

        gn = job->node;

        if ((gn->type & (OP_JOIN|OP_PHONY)) == 0 && !Targ_Precious(gn)) {
            char *file = (gn->path == NULL ? gn->name : gn->path);
            if (!noExecute && eunlink(file) != -1) {
                Error("*** %s removed", file);
            }
        }
        if (job->pid) {
            if (DEBUG(JOB)) {
                (void)fprintf(debug_file,
                           "JobInterrupt passing signal %d to child %d.\n",
                           signo, job->pid);
            }
            KILLPG(job->pid, signo);
        }
    }

    JobSigUnlock(&mask);

    if (runINTERRUPT && !touchFlag) {
        interrupt = Targ_FindNode(".INTERRUPT", TARG_NOCREATE);
        if (interrupt != NULL) {
            ignoreErrors = FALSE;
            JobRun(interrupt);
        }
    }
    Trace_Log(MAKEINTR, 0);
    exit(signo);
}

/*
 *-----------------------------------------------------------------------
 * Job_Finish --
 *      Do final processing such as the running of the commands
 *      attached to the .END target.
 *
 * Results:
 *      Number of errors reported.
 *
 * Side Effects:
 *      None.
 *-----------------------------------------------------------------------
 */
int
Job_Finish(void)
{
    if (postCommands != NULL &&
        (!Lst_IsEmpty(postCommands->commands) ||
         !Lst_IsEmpty(postCommands->children))) {
        if (errors) {
            Error("Errors reported so .END ignored");
        } else {
            JobRun(postCommands);
        }
    }
    return(errors);
}

/*-
 *-----------------------------------------------------------------------
 * Job_End --
 *      Cleanup any memory used by the jobs module
 *
 * Results:
 *      None.
 *
 * Side Effects:
 *      Memory is freed
 *-----------------------------------------------------------------------
 */
void
Job_End(void)
{
#ifdef CLEANUP
    if (shellArgv)
        free(shellArgv);
#endif
}

/*-
 *-----------------------------------------------------------------------
 * Job_Wait --
 *      Waits for all running jobs to finish and returns. Sets 'aborting'
 *      to ABORT_WAIT to prevent other jobs from starting.
 *
 * Results:
 *      None.
 *
 * Side Effects:
 *      Currently running jobs finish.
 *
 *-----------------------------------------------------------------------
 */
void
Job_Wait(void)
{
    aborting = ABORT_WAIT;
    while (jobTokensRunning != 0) {
        Job_CatchOutput();
    }
    aborting = 0;
}

/*-
 *-----------------------------------------------------------------------
 * Job_AbortAll --
 *      Abort all currently running jobs without handling output or anything.
 *      This function is to be called only in the event of a major
 *      error. Most definitely NOT to be called from JobInterrupt.
 *
 * Results:
 *      None
 *
 * Side Effects:
 *      All children are killed, not just the firstborn
 *-----------------------------------------------------------------------
 */
void
Job_AbortAll(void)
{
    Job         *job;   /* the job descriptor in that element */
    WAIT_T      foo;

    aborting = ABORT_ERROR;

    if (jobTokensRunning) {
        for (job = job_table; job < job_table_end; job++) {
            if (job->job_state != JOB_ST_RUNNING)
                continue;
            /*
             * kill the child process with increasingly drastic signals to make
             * darn sure it's dead.
             */
            KILLPG(job->pid, SIGINT);
            KILLPG(job->pid, SIGKILL);
        }
    }

    /*
     * Catch as many children as want to report in at first, then give up
     */
    while (waitpid((pid_t) -1, &foo, WNOHANG) > 0)
        continue;
}

\f
/*-
 *-----------------------------------------------------------------------
 * JobRestartJobs --
 *      Tries to restart stopped jobs if there are slots available.
 *      Called in process context in response to a SIGCONT.
 *
 * Results:
 *      None.
 *
 * Side Effects:
 *      Resumes jobs.
 *
 *-----------------------------------------------------------------------
 */
static void
JobRestartJobs(void)
{
    Job *job;

    for (job = job_table; job < job_table_end; job++) {
        if (job->job_state == JOB_ST_RUNNING &&
                (make_suspended || job->job_suspended)) {
            if (DEBUG(JOB)) {
                (void)fprintf(debug_file, "Restarting stopped job pid %d.\n",
                        job->pid);
            }
            if (job->job_suspended) {
                    (void)printf("*** [%s] Continued\n", job->node->name);
                    (void)fflush(stdout);
            }
            job->job_suspended = 0;
            if (KILLPG(job->pid, SIGCONT) != 0 && DEBUG(JOB)) {
                fprintf(debug_file, "Failed to send SIGCONT to %d\n", job->pid);
            }
        }
        if (job->job_state == JOB_ST_FINISHED)
            /* Job exit deferred after calling waitpid() in a signal handler */
            JobFinish(job, job->exit_status);
    }
    make_suspended = 0;
}

static void
watchfd(Job *job)
{
    if (job->inPollfd != NULL)
        Punt("Watching watched job");

    fds[nfds].fd = job->inPipe;
    fds[nfds].events = POLLIN;
    jobfds[nfds] = job;
    job->inPollfd = &fds[nfds];
    nfds++;
}

static void
clearfd(Job *job)
{
    int i;
    if (job->inPollfd == NULL)
        Punt("Unwatching unwatched job");
    i = job->inPollfd - fds;
    nfds--;
    /*
     * Move last job in table into hole made by dead job.
     */
    if (nfds != i) {
        fds[i] = fds[nfds];
        jobfds[i] = jobfds[nfds];
        jobfds[i]->inPollfd = &fds[i];
    }
    job->inPollfd = NULL;
}

static int
readyfd(Job *job)
{
    if (job->inPollfd == NULL)
        Punt("Polling unwatched job");
    return (job->inPollfd->revents & POLLIN) != 0;
}

/*-
 *-----------------------------------------------------------------------
 * JobTokenAdd --
 *      Put a token into the job pipe so that some make process can start
 *      another job.
 *
 * Side Effects:
 *      Allows more build jobs to be spawned somewhere.
 *
 *-----------------------------------------------------------------------
 */

static void
JobTokenAdd(void)
{
    char tok = JOB_TOKENS[aborting], tok1;

    /* If we are depositing an error token flush everything else */
    while (tok != '+' && read(tokenWaitJob.inPipe, &tok1, 1) == 1)
        continue;

    if (DEBUG(JOB))
        fprintf(debug_file, "(%d) aborting %d, deposit token %c\n",
            getpid(), aborting, JOB_TOKENS[aborting]);
    write(tokenWaitJob.outPipe, &tok, 1);
}

/*-
 *-----------------------------------------------------------------------
 * Job_ServerStartTokenAdd --
 *      Prep the job token pipe in the root make process.
 *
 *-----------------------------------------------------------------------
 */

void
Job_ServerStart(int max_tokens, int jp_0, int jp_1)
{
    int i;
    char jobarg[64];
    
    if (jp_0 >= 0 && jp_1 >= 0) {
        /* Pipe passed in from parent */
        tokenWaitJob.inPipe = jp_0;
        tokenWaitJob.outPipe = jp_1;
        return;
    }

    JobCreatePipe(&tokenWaitJob, 15);

    snprintf(jobarg, sizeof(jobarg), "%d,%d",
            tokenWaitJob.inPipe, tokenWaitJob.outPipe);

    Var_Append(MAKEFLAGS, "-J", VAR_GLOBAL);
    Var_Append(MAKEFLAGS, jobarg, VAR_GLOBAL);                  

    /*
     * Preload the job pipe with one token per job, save the one
     * "extra" token for the primary job.
     * 
     * XXX should clip maxJobs against PIPE_BUF -- if max_tokens is
     * larger than the write buffer size of the pipe, we will
     * deadlock here.
     */
    for (i = 1; i < max_tokens; i++)
        JobTokenAdd();
}

/*-
 *-----------------------------------------------------------------------
 * Job_TokenReturn --
 *      Return a withdrawn token to the pool.
 *
 *-----------------------------------------------------------------------
 */

void
Job_TokenReturn(void)
{
    jobTokensRunning--;
    if (jobTokensRunning < 0)
        Punt("token botch");
    if (jobTokensRunning || JOB_TOKENS[aborting] != '+')
        JobTokenAdd();
}

/*-
 *-----------------------------------------------------------------------
 * Job_TokenWithdraw --
 *      Attempt to withdraw a token from the pool.
 *
 * Results:
 *      Returns TRUE if a token was withdrawn, and FALSE if the pool
 *      is currently empty.
 *
 * Side Effects:
 *      If pool is empty, set wantToken so that we wake up
 *      when a token is released.
 *
 *-----------------------------------------------------------------------
 */


Boolean
Job_TokenWithdraw(void)
{
    char tok, tok1;
    int count;

    wantToken = 0;
    if (DEBUG(JOB))
        fprintf(debug_file, "Job_TokenWithdraw(%d): aborting %d, running %d\n",
                getpid(), aborting, jobTokensRunning);

    if (aborting || (jobTokensRunning >= maxJobs))
        return FALSE;

    count = read(tokenWaitJob.inPipe, &tok, 1);
    if (count == 0)
        Fatal("eof on job pipe!");
    if (count < 0 && jobTokensRunning != 0) {
        if (errno != EAGAIN) {
            Fatal("job pipe read: %s", strerror(errno));
        }
        if (DEBUG(JOB))
            fprintf(debug_file, "(%d) blocked for token\n", getpid());
        wantToken = 1;
        return FALSE;
    }

    if (count == 1 && tok != '+') {
        /* make being abvorted - remove any other job tokens */
        if (DEBUG(JOB))
            fprintf(debug_file, "(%d) aborted by token %c\n", getpid(), tok);
        while (read(tokenWaitJob.inPipe, &tok1, 1) == 1)
            continue;
        /* And put the stopper back */
        write(tokenWaitJob.outPipe, &tok, 1);
        Fatal("A failure has been detected in another branch of the parallel make");
    }

    if (count == 1 && jobTokensRunning == 0)
        /* We didn't want the token really */
        write(tokenWaitJob.outPipe, &tok, 1);

    jobTokensRunning++;
    if (DEBUG(JOB))
        fprintf(debug_file, "(%d) withdrew token\n", getpid());
    return TRUE;
}

#ifdef USE_SELECT
int
emul_poll(struct pollfd *fd, int nfd, int timeout)
{
    fd_set rfds, wfds;
    int i, maxfd, nselect, npoll;
    struct timeval tv, *tvp;
    long usecs;

    FD_ZERO(&rfds);
    FD_ZERO(&wfds);

    maxfd = -1;
    for (i = 0; i < nfd; i++) {
        fd[i].revents = 0;

        if (fd[i].events & POLLIN)
            FD_SET(fd[i].fd, &rfds);

        if (fd[i].events & POLLOUT)
            FD_SET(fd[i].fd, &wfds);

        if (fd[i].fd > maxfd)
            maxfd = fd[i].fd;
    }
    
    if (maxfd >= FD_SETSIZE) {
        Punt("Ran out of fd_set slots; " 
             "recompile with a larger FD_SETSIZE.");
    }

    if (timeout < 0) {
        tvp = NULL;
    } else {
        usecs = timeout * 1000;
        tv.tv_sec = usecs / 1000000;
        tv.tv_usec = usecs % 1000000;
        tvp = &tv;
    }

    nselect = select(maxfd + 1, &rfds, &wfds, 0, tvp);

    if (nselect <= 0)
        return nselect;

    npoll = 0;
    for (i = 0; i < nfd; i++) {
        if (FD_ISSET(fd[i].fd, &rfds))
            fd[i].revents |= POLLIN;

        if (FD_ISSET(fd[i].fd, &wfds))
            fd[i].revents |= POLLOUT;

        if (fd[i].revents)
            npoll++;
    }

    return npoll;
}
#endif /* USE_SELECT */