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32 * @(#)redir.c 8.2 (Berkeley) 5/4/95
33 * $FreeBSD: head/bin/sh/redir.c 246288 2013-02-03 15:54:57Z jilles $
36 #include <sys/types.h>
46 * Code for dealing with input/output redirection.
60 #define EMPTY -2 /* marks an unused slot in redirtab */
61 #define CLOSED -1 /* fd was not open before redir */
62 #define PIPESIZE 4096 /* amount of buffering in a pipe */
67 struct redirtab *next;
72 MKINIT struct redirtab *redirlist;
75 * We keep track of whether or not fd0 has been redirected. This is for
76 * background commands, where we want to redirect fd0 to /dev/null only
77 * if it hasn't already been redirected.
79 static int fd0_redirected = 0;
81 static void openredirect(union node *, char[10 ]);
82 static int openhere(union node *);
86 * Process a list of redirection commands. If the REDIR_PUSH flag is set,
87 * old file descriptors are stashed away so that the redirection can be
88 * undone by calling popredir. If the REDIR_BACKQ flag is set, then the
89 * standard output, and the standard error if it becomes a duplicate of
90 * stdout, is saved in memory.
94 redirect(union node *redir, int flags)
97 struct redirtab *sv = NULL;
100 char memory[10]; /* file descriptors to write to memory */
102 for (i = 10 ; --i >= 0 ; )
104 memory[1] = flags & REDIR_BACKQ;
105 if (flags & REDIR_PUSH) {
106 sv = ckmalloc(sizeof (struct redirtab));
107 for (i = 0 ; i < 10 ; i++)
108 sv->renamed[i] = EMPTY;
109 sv->next = redirlist;
112 for (n = redir ; n ; n = n->nfile.next) {
114 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
116 continue; /* redirect from/to same file descriptor */
118 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
120 if ((i = fcntl(fd, F_DUPFD, 10)) == -1) {
127 error("%d: %s", fd, strerror(errno));
131 (void)fcntl(i, F_SETFD, FD_CLOEXEC);
137 openredirect(n, memory);
147 openredirect(union node *redir, char memory[10])
150 int fd = redir->nfile.fd;
156 * We suppress interrupts so that we won't leave open file
157 * descriptors around. Because the signal handler remains
158 * installed and we do not use system call restart, interrupts
159 * will still abort blocking opens such as fifos (they will fail
160 * with EINTR). There is, however, a race condition if an interrupt
161 * arrives after INTOFF and before open blocks.
165 switch (redir->nfile.type) {
167 fname = redir->nfile.expfname;
168 if ((f = open(fname, O_RDONLY)) < 0)
169 error("cannot open %s: %s", fname, strerror(errno));
172 if (dup2(f, fd) == -1) {
175 error("%d: %s", fd, strerror(e));
181 fname = redir->nfile.expfname;
182 if ((f = open(fname, O_RDWR|O_CREAT, 0666)) < 0)
183 error("cannot create %s: %s", fname, strerror(errno));
187 fname = redir->nfile.expfname;
188 if (stat(fname, &sb) == -1) {
189 if ((f = open(fname, O_WRONLY|O_CREAT|O_EXCL, 0666)) < 0)
190 error("cannot create %s: %s", fname, strerror(errno));
191 } else if (!S_ISREG(sb.st_mode)) {
192 if ((f = open(fname, O_WRONLY, 0666)) < 0)
193 error("cannot create %s: %s", fname, strerror(errno));
194 if (fstat(f, &sb) != -1 && S_ISREG(sb.st_mode)) {
196 error("cannot create %s: %s", fname,
200 error("cannot create %s: %s", fname,
206 fname = redir->nfile.expfname;
207 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
208 error("cannot create %s: %s", fname, strerror(errno));
211 fname = redir->nfile.expfname;
212 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
213 error("cannot create %s: %s", fname, strerror(errno));
217 if (redir->ndup.dupfd >= 0) { /* if not ">&-" */
218 if (memory[redir->ndup.dupfd])
221 if (dup2(redir->ndup.dupfd, fd) < 0)
222 error("%d: %s", redir->ndup.dupfd,
241 * Handle here documents. Normally we fork off a process to write the
242 * data to a pipe. If the document is short, we can stuff the data in
243 * the pipe without forking.
247 openhere(union node *redir)
254 error("Pipe call failed: %s", strerror(errno));
256 if (redir->type == NXHERE)
257 p = redir->nhere.expdoc;
259 p = redir->nhere.doc->narg.text;
261 if (len <= PIPESIZE) {
262 xwrite(pip[1], p, len);
266 if (forkshell(NULL, NULL, FORK_NOJOB) == 0) {
268 signal(SIGINT, SIG_IGN);
269 signal(SIGQUIT, SIG_IGN);
270 signal(SIGHUP, SIG_IGN);
271 signal(SIGTSTP, SIG_IGN);
272 signal(SIGPIPE, SIG_DFL);
273 xwrite(pip[1], p, len);
284 * Undo the effects of the last redirection.
290 struct redirtab *rp = redirlist;
293 for (i = 0 ; i < 10 ; i++) {
294 if (rp->renamed[i] != EMPTY) {
297 if (rp->renamed[i] >= 0) {
298 dup2(rp->renamed[i], i);
299 close(rp->renamed[i]);
306 redirlist = rp->next;
312 * Undo all redirections. Called on error or interrupt.
326 /* Return true if fd 0 has already been redirected at least once. */
328 fd0_redirected_p(void)
330 return fd0_redirected != 0;
334 * Discard all saved file descriptors.
343 for (rp = redirlist ; rp ; rp = rp->next) {
344 for (i = 0 ; i < 10 ; i++) {
345 if (rp->renamed[i] >= 0) {
346 close(rp->renamed[i]);
348 rp->renamed[i] = EMPTY;