lib/libc/gen/wordexp.c

   1 /*      $NetBSD: wordexp.c,v 1.2 2005/11/29 03:11:59 christos Exp $     */
   2
   3 /*-
   4  * Copyright (c) 2002 Tim J. Robbins.
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  */
  28
  29 #include "namespace.h"
  30 #include <sys/cdefs.h>
  31 #include <sys/types.h>
  32 #include <assert.h>
  33 #include <sys/wait.h>
  34 #include <fcntl.h>
  35 #include <paths.h>
  36 #include <stdio.h>
  37 #include <stdlib.h>
  38 #include <string.h>
  39 #include <unistd.h>
  40 #include <wordexp.h>
  41
  42 #if defined(LIBC_SCCS) && !defined(lint)
  43 #if 0
  44 __FBSDID("$FreeBSD: /repoman/r/ncvs/src/lib/libc/gen/wordexp.c,v 1.5 2004/04/09 11:32:32 tjr Exp $");
  45 #else
  46 __RCSID("$NetBSD: wordexp.c,v 1.2 2005/11/29 03:11:59 christos Exp $");
  47 #endif
  48 #endif /* LIBC_SCCS and not lint */
  49
  50 static int      we_askshell(const char *, wordexp_t *, int);
  51 static int      we_check(const char *, int);
  52
  53 /*
  54  * wordexp --
  55  *      Perform shell word expansion on `words' and place the resulting list
  56  *      of words in `we'. See wordexp(3).
  57  *
  58  */
  59 int
  60 wordexp(const char * __restrict words, wordexp_t * __restrict we, int flags)
  61 {
  62         int error;
  63
  64         _DIAGASSERT(we != NULL);
  65         _DIAGASSERT(words != NULL);
  66         if (flags & WRDE_REUSE)
  67                 wordfree(we);
  68         if ((flags & WRDE_APPEND) == 0) {
  69                 we->we_wordc = 0;
  70                 we->we_wordv = NULL;
  71                 we->we_strings = NULL;
  72                 we->we_nbytes = 0;
  73         }
  74         if ((error = we_check(words, flags)) != 0) {
  75                 wordfree(we);
  76                 return (error);
  77         }
  78         if ((error = we_askshell(words, we, flags)) != 0) {
  79                 wordfree(we);
  80                 return (error);
  81         }
  82         return (0);
  83 }
  84
  85 /*
  86  * we_askshell --
  87  *      Use the `wordexp' /bin/sh builtin function to do most of the work
  88  *      in expanding the word string. This function is complicated by
  89  *      memory management.
  90  */
  91 static int
  92 we_askshell(const char *words, wordexp_t *we, int flags)
  93 {
  94         int pdes[2];                    /* Pipe to child */
  95         size_t nwords, nbytes;          /* Number of words, bytes from child */
  96         int i;                          /* Handy integer */
  97         unsigned int ui;                /* For array iteration */
  98         size_t sofs;                    /* Offset into we->we_strings */
  99         size_t vofs;                    /* Offset into we->we_wordv */
 100         pid_t pid;                      /* Process ID of child */
 101         int status;                     /* Child exit status */
 102         const char *ifs;                /* IFS env. var. */
 103         char *np, *p;                   /* Handy pointers */
 104         char *nstrings;                 /* Temporary for realloc() */
 105         char **nwv;                     /* Temporary for realloc() */
 106         FILE *fp;                       /* Stream to read pipe */
 107         extern char **environ;
 108         char *cmd;
 109
 110         if ((ifs = getenv("IFS")) == NULL)
 111                 ifs = " \t\n";
 112         if (asprintf(&cmd, "wordexp%c%s\n", *ifs, words) < 0)
 113                 return (WRDE_NOSPACE);
 114         if (pipe(pdes) < 0) {
 115                 free(cmd);
 116                 return (WRDE_ERRNO);
 117         }
 118         if ((fp = fdopen(pdes[0], "r")) == NULL) {
 119                 free(cmd);
 120                 return (WRDE_ERRNO);
 121         }
 122         if ((pid = fork()) < 0) {
 123                 free(cmd);
 124                 fclose(fp);
 125                 close(pdes[1]);
 126                 return (WRDE_ERRNO);
 127         }
 128         else if (pid == 0) {
 129                 /*
 130                  * We are the child; just get /bin/sh to run the wordexp
 131                  * builtin on `words'.
 132                  */
 133                 int devnull;
 134
 135                 close(pdes[0]);
 136                 if (pdes[1] != STDOUT_FILENO) {
 137                         if (dup2(pdes[1], STDOUT_FILENO) < 0)
 138                                 _exit(1);
 139                         close(pdes[1]);
 140                 }
 141                 if ((flags & WRDE_SHOWERR) == 0) {
 142                         if ((devnull = open(_PATH_DEVNULL, O_RDWR, 0666)) < 0)
 143                                 _exit(1);
 144                         if (dup2(devnull, STDERR_FILENO) < 0)
 145                                 _exit(1);
 146                         close(devnull);
 147                 }
 148                 execle(_PATH_BSHELL, "sh", flags & WRDE_UNDEF ? "-u" : "+u",
 149                     "-c", cmd, (char *)NULL, environ);
 150                 _exit(1);
 151         }
 152
 153         /*
 154          * We are the parent; read the output of the shell wordexp function,
 155          * which is a decimal word count, an null, a decimal byte count,
 156          * (not including terminating null bytes), a null and then followed
 157          * by the expanded words separated by nulls.
 158          */
 159         free(cmd);
 160         close(pdes[1]);
 161         /* read the word count */
 162         nwords = 0;
 163         while ((i = getc(fp)) != EOF) {
 164                 if (i == '\0')
 165                         break;
 166                 nwords *= 10;
 167                 nwords += (i - '0');
 168         }
 169         /* read the byte count */
 170         nbytes = 0;
 171         while ((i = getc(fp)) != EOF) {
 172                 if (i == '\0')
 173                         break;
 174                 nbytes *= 10;
 175                 nbytes += (i - '0');
 176         }
 177         if (i == EOF) {
 178                 fclose(fp);
 179                 waitpid(pid, &status, 0);
 180                 return (flags & WRDE_UNDEF ? WRDE_BADVAL : WRDE_SYNTAX);
 181         }
 182         nbytes += nwords;
 183
 184         /*
 185          * Allocate or reallocate (when flags & WRDE_APPEND) the word vector
 186          * and string storage buffers for the expanded words we're about to
 187          * read from the child.
 188          */
 189         sofs = we->we_nbytes;
 190         vofs = we->we_wordc;
 191         if ((flags & (WRDE_DOOFFS|WRDE_APPEND)) == (WRDE_DOOFFS|WRDE_APPEND))
 192                 vofs += we->we_offs;
 193         we->we_wordc += nwords;
 194         we->we_nbytes += nbytes;
 195         if ((nwv = realloc(we->we_wordv, (we->we_wordc + 1 +
 196             (flags & WRDE_DOOFFS ?  we->we_offs : 0)) *
 197             sizeof(char *))) == NULL) {
 198                 fclose(fp);
 199                 waitpid(pid, &status, 0);
 200                 return (WRDE_NOSPACE);
 201         }
 202         we->we_wordv = nwv;
 203         if ((nstrings = realloc(we->we_strings, we->we_nbytes)) == NULL) {
 204                 fclose(fp);
 205                 waitpid(pid, &status, 0);
 206                 return (WRDE_NOSPACE);
 207         }
 208         for (ui = 0; ui < vofs; ui++)
 209                 if (we->we_wordv[ui] != NULL)
 210                         we->we_wordv[ui] += nstrings - we->we_strings;
 211         we->we_strings = nstrings;
 212
 213         if (fread(we->we_strings + sofs, sizeof(char), nbytes, fp) != nbytes) {
 214                 fclose(fp);
 215                 waitpid(pid, &status, 0);
 216                 return (flags & WRDE_UNDEF ? WRDE_BADVAL : WRDE_SYNTAX);
 217         }
 218
 219         if (waitpid(pid, &status, 0) < 0 || !WIFEXITED(status) ||
 220             WEXITSTATUS(status) != 0) {
 221                 fclose(fp);
 222                 return (flags & WRDE_UNDEF ? WRDE_BADVAL : WRDE_SYNTAX);
 223         }
 224         fclose(fp);
 225
 226         /*
 227          * Break the null-terminated expanded word strings out into
 228          * the vector.
 229          */
 230         if (vofs == 0 && flags & WRDE_DOOFFS)
 231                 while (vofs < we->we_offs)
 232                         we->we_wordv[vofs++] = NULL;
 233         p = we->we_strings + sofs;
 234         while (nwords-- != 0) {
 235                 we->we_wordv[vofs++] = p;
 236                 if ((np = memchr(p, '\0', nbytes)) == NULL)
 237                         return (WRDE_NOSPACE);  /* XXX */
 238                 nbytes -= np - p + 1;
 239                 p = np + 1;
 240         }
 241         we->we_wordv[vofs] = NULL;
 242
 243         return (0);
 244 }
 245
 246 /*
 247  * we_check --
 248  *      Check that the string contains none of the following unquoted
 249  *      special characters: <newline> |&;<>(){}
 250  *      or command substitutions when WRDE_NOCMD is set in flags.
 251  */
 252 static int
 253 we_check(const char *words, int flags)
 254 {
 255         char c;
 256         int dquote, level, quote, squote;
 257
 258         quote = squote = dquote = 0;
 259         while ((c = *words++) != '\0') {
 260                 switch (c) {
 261                 case '\\':
 262                         quote ^= 1;
 263                         continue;
 264                 case '\'':
 265                         if (quote + dquote == 0)
 266                                 squote ^= 1;
 267                         break;
 268                 case '"':
 269                         if (quote + squote == 0)
 270                                 dquote ^= 1;
 271                         break;
 272                 case '`':
 273                         if (quote + squote == 0 && flags & WRDE_NOCMD)
 274                                 return (WRDE_CMDSUB);
 275                         while ((c = *words++) != '\0' && c != '`')
 276                                 if (c == '\\' && (c = *words++) == '\0')
 277                                         break;
 278                         if (c == '\0')
 279                                 return (WRDE_SYNTAX);
 280                         break;
 281                 case '|': case '&': case ';': case '<': case '>':
 282                 case '{': case '}': case '(': case ')': case '\n':
 283                         if (quote + squote + dquote == 0)
 284                                 return (WRDE_BADCHAR);
 285                         break;
 286                 case '$':
 287                         if ((c = *words++) == '\0')
 288                                 break;
 289                         else if (quote + squote == 0 && c == '(') {
 290                                 if (flags & WRDE_NOCMD && *words != '(')
 291                                         return (WRDE_CMDSUB);
 292                                 level = 1;
 293                                 while ((c = *words++) != '\0') {
 294                                         if (c == '\\') {
 295                                                 if ((c = *words++) == '\0')
 296                                                         break;
 297                                         } else if (c == '(')
 298                                                 level++;
 299                                         else if (c == ')' && --level == 0)
 300                                                 break;
 301                                 }
 302                                 if (c == '\0' || level != 0)
 303                                         return (WRDE_SYNTAX);
 304                         } else if (quote + squote == 0 && c == '{') {
 305                                 level = 1;
 306                                 while ((c = *words++) != '\0') {
 307                                         if (c == '\\') {
 308                                                 if ((c = *words++) == '\0')
 309                                                         break;
 310                                         } else if (c == '{')
 311                                                 level++;
 312                                         else if (c == '}' && --level == 0)
 313                                                 break;
 314                                 }
 315                                 if (c == '\0' || level != 0)
 316                                         return (WRDE_SYNTAX);
 317                         } else
 318                                 c = *--words;
 319                         break;
 320                 default:
 321                         break;
 322                 }
 323                 quote = 0;
 324         }
 325         if (quote + squote + dquote != 0)
 326                 return (WRDE_SYNTAX);
 327
 328         return (0);
 329 }
 330
 331 /*
 332  * wordfree --
 333  *      Free the result of wordexp(). See wordexp(3).
 334  *
 335  */
 336 void
 337 wordfree(wordexp_t *we)
 338 {
 339         _DIAGASSERT(we != NULL);
 340         free(we->we_wordv);
 341         free(we->we_strings);
 342         we->we_wordv = NULL;
 343         we->we_strings = NULL;
 344         we->we_nbytes = 0;
 345         we->we_wordc = 0;
 346 }