bin/sh/expand.c

   1 /*-
   2  * Copyright (c) 1991, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Kenneth Almquist.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #ifndef lint
  38 #if 0
  39 static char sccsid[] = "@(#)expand.c    8.5 (Berkeley) 5/15/95";
  40 #endif
  41 #endif /* not lint */
  42 #include <sys/cdefs.h>
  43 __FBSDID("$FreeBSD: src/bin/sh/expand.c,v 1.31.2.5 2003/01/17 07:44:01 tjr Exp $");
  44
  45 #include <sys/types.h>
  46 #include <sys/time.h>
  47 #include <sys/stat.h>
  48 #include <errno.h>
  49 #include <dirent.h>
  50 #include <unistd.h>
  51 #include <pwd.h>
  52 #include <stdlib.h>
  53 #include <limits.h>
  54 #include <stdio.h>
  55
  56 /*
  57  * Routines to expand arguments to commands.  We have to deal with
  58  * backquotes, shell variables, and file metacharacters.
  59  */
  60
  61 #include "shell.h"
  62 #include "main.h"
  63 #include "nodes.h"
  64 #include "eval.h"
  65 #include "expand.h"
  66 #include "syntax.h"
  67 #include "parser.h"
  68 #include "jobs.h"
  69 #include "options.h"
  70 #include "var.h"
  71 #include "input.h"
  72 #include "output.h"
  73 #include "memalloc.h"
  74 #include "error.h"
  75 #include "mystring.h"
  76 #include "arith.h"
  77 #include "show.h"
  78
  79 /*
  80  * Structure specifying which parts of the string should be searched
  81  * for IFS characters.
  82  */
  83
  84 struct ifsregion {
  85         struct ifsregion *next; /* next region in list */
  86         int begoff;             /* offset of start of region */
  87         int endoff;             /* offset of end of region */
  88         int nulonly;            /* search for nul bytes only */
  89 };
  90
  91
  92 char *expdest;                  /* output of current string */
  93 struct nodelist *argbackq;      /* list of back quote expressions */
  94 struct ifsregion ifsfirst;      /* first struct in list of ifs regions */
  95 struct ifsregion *ifslastp;     /* last struct in list */
  96 struct arglist exparg;          /* holds expanded arg list */
  97
  98 STATIC void argstr(char *, int);
  99 STATIC char *exptilde(char *, int);
 100 STATIC void expbackq(union node *, int, int);
 101 STATIC int subevalvar(char *, char *, int, int, int, int);
 102 STATIC char *evalvar(char *, int);
 103 STATIC int varisset(char *, int);
 104 STATIC void varvalue(char *, int, int);
 105 STATIC void recordregion(int, int, int);
 106 STATIC void removerecordregions(int);
 107 STATIC void ifsbreakup(char *, struct arglist *);
 108 STATIC void expandmeta(struct strlist *, int);
 109 STATIC void expmeta(char *, char *);
 110 STATIC void addfname(char *);
 111 STATIC struct strlist *expsort(struct strlist *);
 112 STATIC struct strlist *msort(struct strlist *, int);
 113 STATIC int pmatch(char *, char *, int);
 114 STATIC char *cvtnum(int, char *);
 115 STATIC int collate_range_cmp(int, int);
 116
 117 STATIC int
 118 collate_range_cmp (int c1, int c2)
 119 {
 120         static char s1[2], s2[2];
 121         int ret;
 122
 123         c1 &= UCHAR_MAX;
 124         c2 &= UCHAR_MAX;
 125         if (c1 == c2)
 126                 return (0);
 127         s1[0] = c1;
 128         s2[0] = c2;
 129         if ((ret = strcoll(s1, s2)) != 0)
 130                 return (ret);
 131         return (c1 - c2);
 132 }
 133
 134 /*
 135  * Expand shell variables and backquotes inside a here document.
 136  *      union node *arg         the document
 137  *      int fd;                 where to write the expanded version
 138  */
 139
 140 void
 141 expandhere(union node *arg, int fd)
 142 {
 143         herefd = fd;
 144         expandarg(arg, (struct arglist *)NULL, 0);
 145         xwrite(fd, stackblock(), expdest - stackblock());
 146 }
 147
 148
 149 /*
 150  * Perform variable substitution and command substitution on an argument,
 151  * placing the resulting list of arguments in arglist.  If EXP_FULL is true,
 152  * perform splitting and file name expansion.  When arglist is NULL, perform
 153  * here document expansion.
 154  */
 155
 156 void
 157 expandarg(union node *arg, struct arglist *arglist, int flag)
 158 {
 159         struct strlist *sp;
 160         char *p;
 161
 162         argbackq = arg->narg.backquote;
 163         STARTSTACKSTR(expdest);
 164         ifsfirst.next = NULL;
 165         ifslastp = NULL;
 166         argstr(arg->narg.text, flag);
 167         if (arglist == NULL) {
 168                 return;                 /* here document expanded */
 169         }
 170         STPUTC('\0', expdest);
 171         p = grabstackstr(expdest);
 172         exparg.lastp = &exparg.list;
 173         /*
 174          * TODO - EXP_REDIR
 175          */
 176         if (flag & EXP_FULL) {
 177                 ifsbreakup(p, &exparg);
 178                 *exparg.lastp = NULL;
 179                 exparg.lastp = &exparg.list;
 180                 expandmeta(exparg.list, flag);
 181         } else {
 182                 if (flag & EXP_REDIR) /*XXX - for now, just remove escapes */
 183                         rmescapes(p);
 184                 sp = (struct strlist *)stalloc(sizeof (struct strlist));
 185                 sp->text = p;
 186                 *exparg.lastp = sp;
 187                 exparg.lastp = &sp->next;
 188         }
 189         while (ifsfirst.next != NULL) {
 190                 struct ifsregion *ifsp;
 191                 INTOFF;
 192                 ifsp = ifsfirst.next->next;
 193                 ckfree(ifsfirst.next);
 194                 ifsfirst.next = ifsp;
 195                 INTON;
 196         }
 197         *exparg.lastp = NULL;
 198         if (exparg.list) {
 199                 *arglist->lastp = exparg.list;
 200                 arglist->lastp = exparg.lastp;
 201         }
 202 }
 203
 204
 205
 206 /*
 207  * Perform variable and command substitution.  If EXP_FULL is set, output CTLESC
 208  * characters to allow for further processing.  Otherwise treat
 209  * $@ like $* since no splitting will be performed.
 210  */
 211
 212 STATIC void
 213 argstr(char *p, int flag)
 214 {
 215         char c;
 216         int quotes = flag & (EXP_FULL | EXP_CASE | EXP_REDIR);  /* do CTLESC */
 217         int firsteq = 1;
 218
 219         if (*p == '~' && (flag & (EXP_TILDE | EXP_VARTILDE)))
 220                 p = exptilde(p, flag);
 221         for (;;) {
 222                 switch (c = *p++) {
 223                 case '\0':
 224                 case CTLENDVAR: /* ??? */
 225                         goto breakloop;
 226                 case CTLQUOTEMARK:
 227                         /* "$@" syntax adherence hack */
 228                         if (p[0] == CTLVAR && p[2] == '@' && p[3] == '=')
 229                                 break;
 230                         if ((flag & EXP_FULL) != 0)
 231                                 STPUTC(c, expdest);
 232                         break;
 233                 case CTLESC:
 234                         if (quotes)
 235                                 STPUTC(c, expdest);
 236                         c = *p++;
 237                         STPUTC(c, expdest);
 238                         break;
 239                 case CTLVAR:
 240                         p = evalvar(p, flag);
 241                         break;
 242                 case CTLBACKQ:
 243                 case CTLBACKQ|CTLQUOTE:
 244                         expbackq(argbackq->n, c & CTLQUOTE, flag);
 245                         argbackq = argbackq->next;
 246                         break;
 247                 case CTLENDARI:
 248                         expari(flag);
 249                         break;
 250                 case ':':
 251                 case '=':
 252                         /*
 253                          * sort of a hack - expand tildes in variable
 254                          * assignments (after the first '=' and after ':'s).
 255                          */
 256                         STPUTC(c, expdest);
 257                         if (flag & EXP_VARTILDE && *p == '~') {
 258                                 if (c == '=') {
 259                                         if (firsteq)
 260                                                 firsteq = 0;
 261                                         else
 262                                                 break;
 263                                 }
 264                                 p = exptilde(p, flag);
 265                         }
 266                         break;
 267                 default:
 268                         STPUTC(c, expdest);
 269                 }
 270         }
 271 breakloop:;
 272 }
 273
 274 STATIC char *
 275 exptilde(char *p, int flag)
 276 {
 277         char c, *startp = p;
 278         struct passwd *pw;
 279         char *home;
 280         int quotes = flag & (EXP_FULL | EXP_CASE | EXP_REDIR);
 281
 282         while ((c = *p) != '\0') {
 283                 switch(c) {
 284                 case CTLESC:
 285                         return (startp);
 286                 case CTLQUOTEMARK:
 287                         return (startp);
 288                 case ':':
 289                         if (flag & EXP_VARTILDE)
 290                                 goto done;
 291                         break;
 292                 case '/':
 293                         goto done;
 294                 }
 295                 p++;
 296         }
 297 done:
 298         *p = '\0';
 299         if (*(startp+1) == '\0') {
 300                 if ((home = lookupvar("HOME")) == NULL)
 301                         goto lose;
 302         } else {
 303                 if ((pw = getpwnam(startp+1)) == NULL)
 304                         goto lose;
 305                 home = pw->pw_dir;
 306         }
 307         if (*home == '\0')
 308                 goto lose;
 309         *p = c;
 310         while ((c = *home++) != '\0') {
 311                 if (quotes && SQSYNTAX[(int)c] == CCTL)
 312                         STPUTC(CTLESC, expdest);
 313                 STPUTC(c, expdest);
 314         }
 315         return (p);
 316 lose:
 317         *p = c;
 318         return (startp);
 319 }
 320
 321
 322 STATIC void
 323 removerecordregions(int endoff)
 324 {
 325         if (ifslastp == NULL)
 326                 return;
 327
 328         if (ifsfirst.endoff > endoff) {
 329                 while (ifsfirst.next != NULL) {
 330                         struct ifsregion *ifsp;
 331                         INTOFF;
 332                         ifsp = ifsfirst.next->next;
 333                         ckfree(ifsfirst.next);
 334                         ifsfirst.next = ifsp;
 335                         INTON;
 336                 }
 337                 if (ifsfirst.begoff > endoff)
 338                         ifslastp = NULL;
 339                 else {
 340                         ifslastp = &ifsfirst;
 341                         ifsfirst.endoff = endoff;
 342                 }
 343                 return;
 344         }
 345
 346         ifslastp = &ifsfirst;
 347         while (ifslastp->next && ifslastp->next->begoff < endoff)
 348                 ifslastp=ifslastp->next;
 349         while (ifslastp->next != NULL) {
 350                 struct ifsregion *ifsp;
 351                 INTOFF;
 352                 ifsp = ifslastp->next->next;
 353                 ckfree(ifslastp->next);
 354                 ifslastp->next = ifsp;
 355                 INTON;
 356         }
 357         if (ifslastp->endoff > endoff)
 358                 ifslastp->endoff = endoff;
 359 }
 360
 361 /*
 362  * Expand arithmetic expression.  Backup to start of expression,
 363  * evaluate, place result in (backed up) result, adjust string position.
 364  */
 365 void
 366 expari(int flag)
 367 {
 368         char *p, *start;
 369         int result;
 370         int begoff;
 371         int quotes = flag & (EXP_FULL | EXP_CASE | EXP_REDIR);
 372         int quoted;
 373
 374
 375         /*
 376          * This routine is slightly over-complicated for
 377          * efficiency.  First we make sure there is
 378          * enough space for the result, which may be bigger
 379          * than the expression if we add exponentiation.  Next we
 380          * scan backwards looking for the start of arithmetic.  If the
 381          * next previous character is a CTLESC character, then we
 382          * have to rescan starting from the beginning since CTLESC
 383          * characters have to be processed left to right.
 384          */
 385 #if INT_MAX / 1000000000 >= 10 || INT_MIN / 1000000000 <= -10
 386 #error "integers with more than 10 digits are not supported"
 387 #endif
 388         CHECKSTRSPACE(12 - 2, expdest);
 389         USTPUTC('\0', expdest);
 390         start = stackblock();
 391         p = expdest - 2;
 392         while (p >= start && *p != CTLARI)
 393                 --p;
 394         if (p < start || *p != CTLARI)
 395                 error("missing CTLARI (shouldn't happen)");
 396         if (p > start && *(p - 1) == CTLESC)
 397                 for (p = start; *p != CTLARI; p++)
 398                         if (*p == CTLESC)
 399                                 p++;
 400
 401         if (p[1] == '"')
 402                 quoted=1;
 403         else
 404                 quoted=0;
 405         begoff = p - start;
 406         removerecordregions(begoff);
 407         if (quotes)
 408                 rmescapes(p+2);
 409         result = arith(p+2);
 410         fmtstr(p, 12, "%d", result);
 411         while (*p++)
 412                 ;
 413         if (quoted == 0)
 414                 recordregion(begoff, p - 1 - start, 0);
 415         result = expdest - p + 1;
 416         STADJUST(-result, expdest);
 417 }
 418
 419
 420 /*
 421  * Expand stuff in backwards quotes.
 422  */
 423
 424 STATIC void
 425 expbackq(union node *cmd, int quoted, int flag)
 426 {
 427         struct backcmd in;
 428         int i;
 429         char buf[128];
 430         char *p;
 431         char *dest = expdest;
 432         struct ifsregion saveifs, *savelastp;
 433         struct nodelist *saveargbackq;
 434         char lastc;
 435         int startloc = dest - stackblock();
 436         char const *syntax = quoted? DQSYNTAX : BASESYNTAX;
 437         int saveherefd;
 438         int quotes = flag & (EXP_FULL | EXP_CASE | EXP_REDIR);
 439
 440         INTOFF;
 441         saveifs = ifsfirst;
 442         savelastp = ifslastp;
 443         saveargbackq = argbackq;
 444         saveherefd = herefd;
 445         herefd = -1;
 446         p = grabstackstr(dest);
 447         evalbackcmd(cmd, &in);
 448         ungrabstackstr(p, dest);
 449         ifsfirst = saveifs;
 450         ifslastp = savelastp;
 451         argbackq = saveargbackq;
 452         herefd = saveherefd;
 453
 454         p = in.buf;
 455         lastc = '\0';
 456         for (;;) {
 457                 if (--in.nleft < 0) {
 458                         if (in.fd < 0)
 459                                 break;
 460                         while ((i = read(in.fd, buf, sizeof buf)) < 0 && errno == EINTR);
 461                         TRACE(("expbackq: read returns %d\n", i));
 462                         if (i <= 0)
 463                                 break;
 464                         p = buf;
 465                         in.nleft = i - 1;
 466                 }
 467                 lastc = *p++;
 468                 if (lastc != '\0') {
 469                         if (quotes && syntax[(int)lastc] == CCTL)
 470                                 STPUTC(CTLESC, dest);
 471                         STPUTC(lastc, dest);
 472                 }
 473         }
 474
 475         /* Eat all trailing newlines */
 476         for (p--; lastc == '\n'; lastc = *--p)
 477                 STUNPUTC(dest);
 478
 479         if (in.fd >= 0)
 480                 close(in.fd);
 481         if (in.buf)
 482                 ckfree(in.buf);
 483         if (in.jp)
 484                 exitstatus = waitforjob(in.jp, (int *)NULL);
 485         if (quoted == 0)
 486                 recordregion(startloc, dest - stackblock(), 0);
 487         TRACE(("evalbackq: size=%d: \"%.*s\"\n",
 488                 (dest - stackblock()) - startloc,
 489                 (dest - stackblock()) - startloc,
 490                 stackblock() + startloc));
 491         expdest = dest;
 492         INTON;
 493 }
 494
 495
 496
 497 STATIC int
 498 subevalvar(char *p, char *str, int strloc, int subtype, int startloc,
 499   int varflags)
 500 {
 501         char *startp;
 502         char *loc = NULL;
 503         char *q;
 504         int c = 0;
 505         int saveherefd = herefd;
 506         struct nodelist *saveargbackq = argbackq;
 507         int amount;
 508
 509         herefd = -1;
 510         argstr(p, 0);
 511         STACKSTRNUL(expdest);
 512         herefd = saveherefd;
 513         argbackq = saveargbackq;
 514         startp = stackblock() + startloc;
 515         if (str == NULL)
 516             str = stackblock() + strloc;
 517
 518         switch (subtype) {
 519         case VSASSIGN:
 520                 setvar(str, startp, 0);
 521                 amount = startp - expdest;
 522                 STADJUST(amount, expdest);
 523                 varflags &= ~VSNUL;
 524                 if (c != 0)
 525                         *loc = c;
 526                 return 1;
 527
 528         case VSQUESTION:
 529                 if (*p != CTLENDVAR) {
 530                         outfmt(&errout, "%s\n", startp);
 531                         error((char *)NULL);
 532                 }
 533                 error("%.*s: parameter %snot set", p - str - 1,
 534                       str, (varflags & VSNUL) ? "null or "
 535                                               : nullstr);
 536                 return 0;
 537
 538         case VSTRIMLEFT:
 539                 for (loc = startp; loc < str; loc++) {
 540                         c = *loc;
 541                         *loc = '\0';
 542                         if (patmatch(str, startp, varflags & VSQUOTE)) {
 543                                 *loc = c;
 544                                 goto recordleft;
 545                         }
 546                         *loc = c;
 547                         if ((varflags & VSQUOTE) && *loc == CTLESC)
 548                                 loc++;
 549                 }
 550                 return 0;
 551
 552         case VSTRIMLEFTMAX:
 553                 for (loc = str - 1; loc >= startp;) {
 554                         c = *loc;
 555                         *loc = '\0';
 556                         if (patmatch(str, startp, varflags & VSQUOTE)) {
 557                                 *loc = c;
 558                                 goto recordleft;
 559                         }
 560                         *loc = c;
 561                         loc--;
 562                         if ((varflags & VSQUOTE) && loc > startp &&
 563                             *(loc - 1) == CTLESC) {
 564                                 for (q = startp; q < loc; q++)
 565                                         if (*q == CTLESC)
 566                                                 q++;
 567                                 if (q > loc)
 568                                         loc--;
 569                         }
 570                 }
 571                 return 0;
 572
 573         case VSTRIMRIGHT:
 574                 for (loc = str - 1; loc >= startp;) {
 575                         if (patmatch(str, loc, varflags & VSQUOTE)) {
 576                                 amount = loc - expdest;
 577                                 STADJUST(amount, expdest);
 578                                 return 1;
 579                         }
 580                         loc--;
 581                         if ((varflags & VSQUOTE) && loc > startp &&
 582                             *(loc - 1) == CTLESC) {
 583                                 for (q = startp; q < loc; q++)
 584                                         if (*q == CTLESC)
 585                                                 q++;
 586                                 if (q > loc)
 587                                         loc--;
 588                         }
 589                 }
 590                 return 0;
 591
 592         case VSTRIMRIGHTMAX:
 593                 for (loc = startp; loc < str - 1; loc++) {
 594                         if (patmatch(str, loc, varflags & VSQUOTE)) {
 595                                 amount = loc - expdest;
 596                                 STADJUST(amount, expdest);
 597                                 return 1;
 598                         }
 599                         if ((varflags & VSQUOTE) && *loc == CTLESC)
 600                                 loc++;
 601                 }
 602                 return 0;
 603
 604
 605         default:
 606                 abort();
 607         }
 608
 609 recordleft:
 610         amount = ((str - 1) - (loc - startp)) - expdest;
 611         STADJUST(amount, expdest);
 612         while (loc != str - 1)
 613                 *startp++ = *loc++;
 614         return 1;
 615 }
 616
 617
 618 /*
 619  * Expand a variable, and return a pointer to the next character in the
 620  * input string.
 621  */
 622
 623 STATIC char *
 624 evalvar(char *p, int flag)
 625 {
 626         int subtype;
 627         int varflags;
 628         char *var;
 629         char *val;
 630         int patloc;
 631         int c;
 632         int set;
 633         int special;
 634         int startloc;
 635         int varlen;
 636         int easy;
 637         int quotes = flag & (EXP_FULL | EXP_CASE | EXP_REDIR);
 638
 639         varflags = *p++;
 640         subtype = varflags & VSTYPE;
 641         var = p;
 642         special = 0;
 643         if (! is_name(*p))
 644                 special = 1;
 645         p = strchr(p, '=') + 1;
 646 again: /* jump here after setting a variable with ${var=text} */
 647         if (special) {
 648                 set = varisset(var, varflags & VSNUL);
 649                 val = NULL;
 650         } else {
 651                 val = bltinlookup(var, 1);
 652                 if (val == NULL || ((varflags & VSNUL) && val[0] == '\0')) {
 653                         val = NULL;
 654                         set = 0;
 655                 } else
 656                         set = 1;
 657         }
 658         varlen = 0;
 659         startloc = expdest - stackblock();
 660         if (!set && uflag) {
 661                 switch (subtype) {
 662                 case VSNORMAL:
 663                 case VSTRIMLEFT:
 664                 case VSTRIMLEFTMAX:
 665                 case VSTRIMRIGHT:
 666                 case VSTRIMRIGHTMAX:
 667                 case VSLENGTH:
 668                         error("%.*s: parameter not set", p - var - 1, var);
 669                 }
 670         }
 671         if (set && subtype != VSPLUS) {
 672                 /* insert the value of the variable */
 673                 if (special) {
 674                         varvalue(var, varflags & VSQUOTE, flag & EXP_FULL);
 675                         if (subtype == VSLENGTH) {
 676                                 varlen = expdest - stackblock() - startloc;
 677                                 STADJUST(-varlen, expdest);
 678                         }
 679                 } else {
 680                         char const *syntax = (varflags & VSQUOTE) ? DQSYNTAX
 681                                                                   : BASESYNTAX;
 682
 683                         if (subtype == VSLENGTH) {
 684                                 for (;*val; val++)
 685                                         varlen++;
 686                         }
 687                         else {
 688                                 while (*val) {
 689                                         if (quotes &&
 690                                             syntax[(int)*val] == CCTL)
 691                                                 STPUTC(CTLESC, expdest);
 692                                         STPUTC(*val++, expdest);
 693                                 }
 694
 695                         }
 696                 }
 697         }
 698
 699         if (subtype == VSPLUS)
 700                 set = ! set;
 701
 702         easy = ((varflags & VSQUOTE) == 0 ||
 703                 (*var == '@' && shellparam.nparam != 1));
 704
 705
 706         switch (subtype) {
 707         case VSLENGTH:
 708                 expdest = cvtnum(varlen, expdest);
 709                 goto record;
 710
 711         case VSNORMAL:
 712                 if (!easy)
 713                         break;
 714 record:
 715                 recordregion(startloc, expdest - stackblock(),
 716                              varflags & VSQUOTE);
 717                 break;
 718
 719         case VSPLUS:
 720         case VSMINUS:
 721                 if (!set) {
 722                         argstr(p, flag);
 723                         break;
 724                 }
 725                 if (easy)
 726                         goto record;
 727                 break;
 728
 729         case VSTRIMLEFT:
 730         case VSTRIMLEFTMAX:
 731         case VSTRIMRIGHT:
 732         case VSTRIMRIGHTMAX:
 733                 if (!set)
 734                         break;
 735                 /*
 736                  * Terminate the string and start recording the pattern
 737                  * right after it
 738                  */
 739                 STPUTC('\0', expdest);
 740                 patloc = expdest - stackblock();
 741                 if (subevalvar(p, NULL, patloc, subtype,
 742                                startloc, varflags) == 0) {
 743                         int amount = (expdest - stackblock() - patloc) + 1;
 744                         STADJUST(-amount, expdest);
 745                 }
 746                 /* Remove any recorded regions beyond start of variable */
 747                 removerecordregions(startloc);
 748                 goto record;
 749
 750         case VSASSIGN:
 751         case VSQUESTION:
 752                 if (!set) {
 753                         if (subevalvar(p, var, 0, subtype, startloc, varflags)) {
 754                                 varflags &= ~VSNUL;
 755                                 /*
 756                                  * Remove any recorded regions beyond
 757                                  * start of variable
 758                                  */
 759                                 removerecordregions(startloc);
 760                                 goto again;
 761                         }
 762                         break;
 763                 }
 764                 if (easy)
 765                         goto record;
 766                 break;
 767
 768         default:
 769                 abort();
 770         }
 771
 772         if (subtype != VSNORMAL) {      /* skip to end of alternative */
 773                 int nesting = 1;
 774                 for (;;) {
 775                         if ((c = *p++) == CTLESC)
 776                                 p++;
 777                         else if (c == CTLBACKQ || c == (CTLBACKQ|CTLQUOTE)) {
 778                                 if (set)
 779                                         argbackq = argbackq->next;
 780                         } else if (c == CTLVAR) {
 781                                 if ((*p++ & VSTYPE) != VSNORMAL)
 782                                         nesting++;
 783                         } else if (c == CTLENDVAR) {
 784                                 if (--nesting == 0)
 785                                         break;
 786                         }
 787                 }
 788         }
 789         return p;
 790 }
 791
 792
 793
 794 /*
 795  * Test whether a specialized variable is set.
 796  */
 797
 798 STATIC int
 799 varisset(char *name, int nulok)
 800 {
 801
 802         if (*name == '!')
 803                 return backgndpid != -1;
 804         else if (*name == '@' || *name == '*') {
 805                 if (*shellparam.p == NULL)
 806                         return 0;
 807
 808                 if (nulok) {
 809                         char **av;
 810
 811                         for (av = shellparam.p; *av; av++)
 812                                 if (**av != '\0')
 813                                         return 1;
 814                         return 0;
 815                 }
 816         } else if (is_digit(*name)) {
 817                 char *ap;
 818                 int num = atoi(name);
 819
 820                 if (num > shellparam.nparam)
 821                         return 0;
 822
 823                 if (num == 0)
 824                         ap = arg0;
 825                 else
 826                         ap = shellparam.p[num - 1];
 827
 828                 if (nulok && (ap == NULL || *ap == '\0'))
 829                         return 0;
 830         }
 831         return 1;
 832 }
 833
 834
 835
 836 /*
 837  * Add the value of a specialized variable to the stack string.
 838  */
 839
 840 STATIC void
 841 varvalue(char *name, int quoted, int allow_split)
 842 {
 843         int num;
 844         char *p;
 845         int i;
 846         extern int oexitstatus;
 847         char sep;
 848         char **ap;
 849         char const *syntax;
 850
 851 #define STRTODEST(p) \
 852         do {\
 853         if (allow_split) { \
 854                 syntax = quoted? DQSYNTAX : BASESYNTAX; \
 855                 while (*p) { \
 856                         if (syntax[(int)*p] == CCTL) \
 857                                 STPUTC(CTLESC, expdest); \
 858                         STPUTC(*p++, expdest); \
 859                 } \
 860         } else \
 861                 while (*p) \
 862                         STPUTC(*p++, expdest); \
 863         } while (0)
 864
 865
 866         switch (*name) {
 867         case '$':
 868                 num = rootpid;
 869                 goto numvar;
 870         case '?':
 871                 num = oexitstatus;
 872                 goto numvar;
 873         case '#':
 874                 num = shellparam.nparam;
 875                 goto numvar;
 876         case '!':
 877                 num = backgndpid;
 878 numvar:
 879                 expdest = cvtnum(num, expdest);
 880                 break;
 881         case '-':
 882                 for (i = 0 ; i < NOPTS ; i++) {
 883                         if (optlist[i].val)
 884                                 STPUTC(optlist[i].letter, expdest);
 885                 }
 886                 break;
 887         case '@':
 888                 if (allow_split && quoted) {
 889                         for (ap = shellparam.p ; (p = *ap++) != NULL ; ) {
 890                                 STRTODEST(p);
 891                                 if (*ap)
 892                                         STPUTC('\0', expdest);
 893                         }
 894                         break;
 895                 }
 896                 /* fall through */
 897         case '*':
 898                 if (ifsset() != 0)
 899                         sep = ifsval()[0];
 900                 else
 901                         sep = ' ';
 902                 for (ap = shellparam.p ; (p = *ap++) != NULL ; ) {
 903                         STRTODEST(p);
 904                         if (*ap && sep)
 905                                 STPUTC(sep, expdest);
 906                 }
 907                 break;
 908         case '0':
 909                 p = arg0;
 910                 STRTODEST(p);
 911                 break;
 912         default:
 913                 if (is_digit(*name)) {
 914                         num = atoi(name);
 915                         if (num > 0 && num <= shellparam.nparam) {
 916                                 p = shellparam.p[num - 1];
 917                                 STRTODEST(p);
 918                         }
 919                 }
 920                 break;
 921         }
 922 }
 923
 924
 925
 926 /*
 927  * Record the the fact that we have to scan this region of the
 928  * string for IFS characters.
 929  */
 930
 931 STATIC void
 932 recordregion(int start, int end, int nulonly)
 933 {
 934         struct ifsregion *ifsp;
 935
 936         if (ifslastp == NULL) {
 937                 ifsp = &ifsfirst;
 938         } else {
 939                 ifsp = (struct ifsregion *)ckmalloc(sizeof (struct ifsregion));
 940                 ifslastp->next = ifsp;
 941         }
 942         ifslastp = ifsp;
 943         ifslastp->next = NULL;
 944         ifslastp->begoff = start;
 945         ifslastp->endoff = end;
 946         ifslastp->nulonly = nulonly;
 947 }
 948
 949
 950
 951 /*
 952  * Break the argument string into pieces based upon IFS and add the
 953  * strings to the argument list.  The regions of the string to be
 954  * searched for IFS characters have been stored by recordregion.
 955  */
 956 STATIC void
 957 ifsbreakup(char *string, struct arglist *arglist)
 958 {
 959         struct ifsregion *ifsp;
 960         struct strlist *sp;
 961         char *start;
 962         char *p;
 963         char *q;
 964         char *ifs;
 965         int ifsspc;
 966         int nulonly;
 967
 968
 969         start = string;
 970         ifsspc = 0;
 971         nulonly = 0;
 972         if (ifslastp != NULL) {
 973                 ifsp = &ifsfirst;
 974                 do {
 975                         p = string + ifsp->begoff;
 976                         nulonly = ifsp->nulonly;
 977                         ifs = nulonly ? nullstr :
 978                                 ( ifsset() ? ifsval() : " \t\n" );
 979                         ifsspc = 0;
 980                         while (p < string + ifsp->endoff) {
 981                                 q = p;
 982                                 if (*p == CTLESC)
 983                                         p++;
 984                                 if (strchr(ifs, *p)) {
 985                                         if (!nulonly)
 986                                                 ifsspc = (strchr(" \t\n", *p) != NULL);
 987                                         /* Ignore IFS whitespace at start */
 988                                         if (q == start && ifsspc) {
 989                                                 p++;
 990                                                 start = p;
 991                                                 continue;
 992                                         }
 993                                         *q = '\0';
 994                                         sp = (struct strlist *)stalloc(sizeof *sp);
 995                                         sp->text = start;
 996                                         *arglist->lastp = sp;
 997                                         arglist->lastp = &sp->next;
 998                                         p++;
 999                                         if (!nulonly) {
1000                                                 for (;;) {
1001                                                         if (p >= string + ifsp->endoff) {
1002                                                                 break;
1003                                                         }
1004                                                         q = p;
1005                                                         if (*p == CTLESC)
1006                                                                 p++;
1007                                                         if (strchr(ifs, *p) == NULL ) {
1008                                                                 p = q;
1009                                                                 break;
1010                                                         } else if (strchr(" \t\n",*p) == NULL) {
1011                                                                 if (ifsspc) {
1012                                                                         p++;
1013                                                                         ifsspc = 0;
1014                                                                 } else {
1015                                                                         p = q;
1016                                                                         break;
1017                                                                 }
1018                                                         } else
1019                                                                 p++;
1020                                                 }
1021                                         }
1022                                         start = p;
1023                                 } else
1024                                         p++;
1025                         }
1026                 } while ((ifsp = ifsp->next) != NULL);
1027                 if (*start || (!ifsspc && start > string &&
1028                         (nulonly || 1))) {
1029                         sp = (struct strlist *)stalloc(sizeof *sp);
1030                         sp->text = start;
1031                         *arglist->lastp = sp;
1032                         arglist->lastp = &sp->next;
1033                 }
1034         } else {
1035                 sp = (struct strlist *)stalloc(sizeof *sp);
1036                 sp->text = start;
1037                 *arglist->lastp = sp;
1038                 arglist->lastp = &sp->next;
1039         }
1040 }
1041
1042
1043
1044 /*
1045  * Expand shell metacharacters.  At this point, the only control characters
1046  * should be escapes.  The results are stored in the list exparg.
1047  */
1048
1049 char *expdir;
1050
1051
1052 STATIC void
1053 expandmeta(struct strlist *str, int flag __unused)
1054 {
1055         char *p;
1056         struct strlist **savelastp;
1057         struct strlist *sp;
1058         char c;
1059         /* TODO - EXP_REDIR */
1060
1061         while (str) {
1062                 if (fflag)
1063                         goto nometa;
1064                 p = str->text;
1065                 for (;;) {                      /* fast check for meta chars */
1066                         if ((c = *p++) == '\0')
1067                                 goto nometa;
1068                         if (c == '*' || c == '?' || c == '[' || c == '!')
1069                                 break;
1070                 }
1071                 savelastp = exparg.lastp;
1072                 INTOFF;
1073                 if (expdir == NULL) {
1074                         int i = strlen(str->text);
1075                         expdir = ckmalloc(i < 2048 ? 2048 : i); /* XXX */
1076                 }
1077
1078                 expmeta(expdir, str->text);
1079                 ckfree(expdir);
1080                 expdir = NULL;
1081                 INTON;
1082                 if (exparg.lastp == savelastp) {
1083                         /*
1084                          * no matches
1085                          */
1086 nometa:
1087                         *exparg.lastp = str;
1088                         rmescapes(str->text);
1089                         exparg.lastp = &str->next;
1090                 } else {
1091                         *exparg.lastp = NULL;
1092                         *savelastp = sp = expsort(*savelastp);
1093                         while (sp->next != NULL)
1094                                 sp = sp->next;
1095                         exparg.lastp = &sp->next;
1096                 }
1097                 str = str->next;
1098         }
1099 }
1100
1101
1102 /*
1103  * Do metacharacter (i.e. *, ?, [...]) expansion.
1104  */
1105
1106 STATIC void
1107 expmeta(char *enddir, char *name)
1108 {
1109         char *p;
1110         char *q;
1111         char *start;
1112         char *endname;
1113         int metaflag;
1114         struct stat statb;
1115         DIR *dirp;
1116         struct dirent *dp;
1117         int atend;
1118         int matchdot;
1119
1120         metaflag = 0;
1121         start = name;
1122         for (p = name ; ; p++) {
1123                 if (*p == '*' || *p == '?')
1124                         metaflag = 1;
1125                 else if (*p == '[') {
1126                         q = p + 1;
1127                         if (*q == '!' || *q == '^')
1128                                 q++;
1129                         for (;;) {
1130                                 while (*q == CTLQUOTEMARK)
1131                                         q++;
1132                                 if (*q == CTLESC)
1133                                         q++;
1134                                 if (*q == '/' || *q == '\0')
1135                                         break;
1136                                 if (*++q == ']') {
1137                                         metaflag = 1;
1138                                         break;
1139                                 }
1140                         }
1141                 } else if (*p == '!' && p[1] == '!'     && (p == name || p[-1] == '/')) {
1142                         metaflag = 1;
1143                 } else if (*p == '\0')
1144                         break;
1145                 else if (*p == CTLQUOTEMARK)
1146                         continue;
1147                 else if (*p == CTLESC)
1148                         p++;
1149                 if (*p == '/') {
1150                         if (metaflag)
1151                                 break;
1152                         start = p + 1;
1153                 }
1154         }
1155         if (metaflag == 0) {    /* we've reached the end of the file name */
1156                 if (enddir != expdir)
1157                         metaflag++;
1158                 for (p = name ; ; p++) {
1159                         if (*p == CTLQUOTEMARK)
1160                                 continue;
1161                         if (*p == CTLESC)
1162                                 p++;
1163                         *enddir++ = *p;
1164                         if (*p == '\0')
1165                                 break;
1166                 }
1167                 if (metaflag == 0 || stat(expdir, &statb) >= 0)
1168                         addfname(expdir);
1169                 return;
1170         }
1171         endname = p;
1172         if (start != name) {
1173                 p = name;
1174                 while (p < start) {
1175                         while (*p == CTLQUOTEMARK)
1176                                 p++;
1177                         if (*p == CTLESC)
1178                                 p++;
1179                         *enddir++ = *p++;
1180                 }
1181         }
1182         if (enddir == expdir) {
1183                 p = ".";
1184         } else if (enddir == expdir + 1 && *expdir == '/') {
1185                 p = "/";
1186         } else {
1187                 p = expdir;
1188                 enddir[-1] = '\0';
1189         }
1190         if ((dirp = opendir(p)) == NULL)
1191                 return;
1192         if (enddir != expdir)
1193                 enddir[-1] = '/';
1194         if (*endname == 0) {
1195                 atend = 1;
1196         } else {
1197                 atend = 0;
1198                 *endname++ = '\0';
1199         }
1200         matchdot = 0;
1201         p = start;
1202         while (*p == CTLQUOTEMARK)
1203                 p++;
1204         if (*p == CTLESC)
1205                 p++;
1206         if (*p == '.')
1207                 matchdot++;
1208         while (! int_pending() && (dp = readdir(dirp)) != NULL) {
1209                 if (dp->d_name[0] == '.' && ! matchdot)
1210                         continue;
1211                 if (patmatch(start, dp->d_name, 0)) {
1212                         if (atend) {
1213                                 scopy(dp->d_name, enddir);
1214                                 addfname(expdir);
1215                         } else {
1216                                 char *q;
1217                                 for (p = enddir, q = dp->d_name;
1218                                      (*p++ = *q++) != '\0';)
1219                                         continue;
1220                                 p[-1] = '/';
1221                                 expmeta(p, endname);
1222                         }
1223                 }
1224         }
1225         closedir(dirp);
1226         if (! atend)
1227                 endname[-1] = '/';
1228 }
1229
1230
1231 /*
1232  * Add a file name to the list.
1233  */
1234
1235 STATIC void
1236 addfname(char *name)
1237 {
1238         char *p;
1239         struct strlist *sp;
1240
1241         p = stalloc(strlen(name) + 1);
1242         scopy(name, p);
1243         sp = (struct strlist *)stalloc(sizeof *sp);
1244         sp->text = p;
1245         *exparg.lastp = sp;
1246         exparg.lastp = &sp->next;
1247 }
1248
1249
1250 /*
1251  * Sort the results of file name expansion.  It calculates the number of
1252  * strings to sort and then calls msort (short for merge sort) to do the
1253  * work.
1254  */
1255
1256 STATIC struct strlist *
1257 expsort(struct strlist *str)
1258 {
1259         int len;
1260         struct strlist *sp;
1261
1262         len = 0;
1263         for (sp = str ; sp ; sp = sp->next)
1264                 len++;
1265         return msort(str, len);
1266 }
1267
1268
1269 STATIC struct strlist *
1270 msort(struct strlist *list, int len)
1271 {
1272         struct strlist *p, *q = NULL;
1273         struct strlist **lpp;
1274         int half;
1275         int n;
1276
1277         if (len <= 1)
1278                 return list;
1279         half = len >> 1;
1280         p = list;
1281         for (n = half ; --n >= 0 ; ) {
1282                 q = p;
1283                 p = p->next;
1284         }
1285         q->next = NULL;                 /* terminate first half of list */
1286         q = msort(list, half);          /* sort first half of list */
1287         p = msort(p, len - half);               /* sort second half */
1288         lpp = &list;
1289         for (;;) {
1290                 if (strcmp(p->text, q->text) < 0) {
1291                         *lpp = p;
1292                         lpp = &p->next;
1293                         if ((p = *lpp) == NULL) {
1294                                 *lpp = q;
1295                                 break;
1296                         }
1297                 } else {
1298                         *lpp = q;
1299                         lpp = &q->next;
1300                         if ((q = *lpp) == NULL) {
1301                                 *lpp = p;
1302                                 break;
1303                         }
1304                 }
1305         }
1306         return list;
1307 }
1308
1309
1310
1311 /*
1312  * Returns true if the pattern matches the string.
1313  */
1314
1315 int
1316 patmatch(char *pattern, char *string, int squoted)
1317 {
1318 #ifdef notdef
1319         if (pattern[0] == '!' && pattern[1] == '!')
1320                 return 1 - pmatch(pattern + 2, string);
1321         else
1322 #endif
1323                 return pmatch(pattern, string, squoted);
1324 }
1325
1326
1327 STATIC int
1328 pmatch(char *pattern, char *string, int squoted)
1329 {
1330         char *p, *q;
1331         char c;
1332
1333         p = pattern;
1334         q = string;
1335         for (;;) {
1336                 switch (c = *p++) {
1337                 case '\0':
1338                         goto breakloop;
1339                 case CTLESC:
1340                         if (squoted && *q == CTLESC)
1341                                 q++;
1342                         if (*q++ != *p++)
1343                                 return 0;
1344                         break;
1345                 case CTLQUOTEMARK:
1346                         continue;
1347                 case '?':
1348                         if (squoted && *q == CTLESC)
1349                                 q++;
1350                         if (*q++ == '\0')
1351                                 return 0;
1352                         break;
1353                 case '*':
1354                         c = *p;
1355                         while (c == CTLQUOTEMARK || c == '*')
1356                                 c = *++p;
1357                         if (c != CTLESC &&  c != CTLQUOTEMARK &&
1358                             c != '?' && c != '*' && c != '[') {
1359                                 while (*q != c) {
1360                                         if (squoted && *q == CTLESC &&
1361                                             q[1] == c)
1362                                                 break;
1363                                         if (*q == '\0')
1364                                                 return 0;
1365                                         if (squoted && *q == CTLESC)
1366                                                 q++;
1367                                         q++;
1368                                 }
1369                         }
1370                         do {
1371                                 if (pmatch(p, q, squoted))
1372                                         return 1;
1373                                 if (squoted && *q == CTLESC)
1374                                         q++;
1375                         } while (*q++ != '\0');
1376                         return 0;
1377                 case '[': {
1378                         char *endp;
1379                         int invert, found;
1380                         char chr;
1381
1382                         endp = p;
1383                         if (*endp == '!' || *endp == '^')
1384                                 endp++;
1385                         for (;;) {
1386                                 while (*endp == CTLQUOTEMARK)
1387                                         endp++;
1388                                 if (*endp == '\0')
1389                                         goto dft;               /* no matching ] */
1390                                 if (*endp == CTLESC)
1391                                         endp++;
1392                                 if (*++endp == ']')
1393                                         break;
1394                         }
1395                         invert = 0;
1396                         if (*p == '!' || *p == '^') {
1397                                 invert++;
1398                                 p++;
1399                         }
1400                         found = 0;
1401                         chr = *q++;
1402                         if (squoted && chr == CTLESC)
1403                                 chr = *q++;
1404                         if (chr == '\0')
1405                                 return 0;
1406                         c = *p++;
1407                         do {
1408                                 if (c == CTLQUOTEMARK)
1409                                         continue;
1410                                 if (c == CTLESC)
1411                                         c = *p++;
1412                                 if (*p == '-' && p[1] != ']') {
1413                                         p++;
1414                                         while (*p == CTLQUOTEMARK)
1415                                                 p++;
1416                                         if (*p == CTLESC)
1417                                                 p++;
1418                                         if (   collate_range_cmp(chr, c) >= 0
1419                                             && collate_range_cmp(chr, *p) <= 0
1420                                            )
1421                                                 found = 1;
1422                                         p++;
1423                                 } else {
1424                                         if (chr == c)
1425                                                 found = 1;
1426                                 }
1427                         } while ((c = *p++) != ']');
1428                         if (found == invert)
1429                                 return 0;
1430                         break;
1431                 }
1432 dft:            default:
1433                         if (squoted && *q == CTLESC)
1434                                 q++;
1435                         if (*q++ != c)
1436                                 return 0;
1437                         break;
1438                 }
1439         }
1440 breakloop:
1441         if (*q != '\0')
1442                 return 0;
1443         return 1;
1444 }
1445
1446
1447
1448 /*
1449  * Remove any CTLESC characters from a string.
1450  */
1451
1452 void
1453 rmescapes(char *str)
1454 {
1455         char *p, *q;
1456
1457         p = str;
1458         while (*p != CTLESC && *p != CTLQUOTEMARK) {
1459                 if (*p++ == '\0')
1460                         return;
1461         }
1462         q = p;
1463         while (*p) {
1464                 if (*p == CTLQUOTEMARK) {
1465                         p++;
1466                         continue;
1467                 }
1468                 if (*p == CTLESC)
1469                         p++;
1470                 *q++ = *p++;
1471         }
1472         *q = '\0';
1473 }
1474
1475
1476
1477 /*
1478  * See if a pattern matches in a case statement.
1479  */
1480
1481 int
1482 casematch(union node *pattern, char *val)
1483 {
1484         struct stackmark smark;
1485         int result;
1486         char *p;
1487
1488         setstackmark(&smark);
1489         argbackq = pattern->narg.backquote;
1490         STARTSTACKSTR(expdest);
1491         ifslastp = NULL;
1492         argstr(pattern->narg.text, EXP_TILDE | EXP_CASE);
1493         STPUTC('\0', expdest);
1494         p = grabstackstr(expdest);
1495         result = patmatch(p, val, 0);
1496         popstackmark(&smark);
1497         return result;
1498 }
1499
1500 /*
1501  * Our own itoa().
1502  */
1503
1504 STATIC char *
1505 cvtnum(int num, char *buf)
1506 {
1507         char temp[32];
1508         int neg = num < 0;
1509         char *p = temp + 31;
1510
1511         temp[31] = '\0';
1512
1513         do {
1514                 *--p = num % 10 + '0';
1515         } while ((num /= 10) != 0);
1516
1517         if (neg)
1518                 *--p = '-';
1519
1520         while (*p)
1521                 STPUTC(*p++, buf);
1522         return buf;
1523 }