lib/libc/gen/wordexp.c

   1 /*-
   2  * Copyright (c) 2002 Tim J. Robbins.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $FreeBSD: src/lib/libc/gen/wordexp.c,v 1.6 2004/06/30 13:55:08 tjr Exp $
  27  */
  28
  29 #include "namespace.h"
  30 #include <sys/types.h>
  31 #include <sys/wait.h>
  32 #include <fcntl.h>
  33 #include <paths.h>
  34 #include <stdio.h>
  35 #include <stdlib.h>
  36 #include <string.h>
  37 #include <fcntl.h>
  38 #include <unistd.h>
  39 #include <wordexp.h>
  40 #include "un-namespace.h"
  41
  42 static int      we_askshell(const char *, wordexp_t *, int);
  43 static int      we_check(const char *, int);
  44
  45 /*
  46  * wordexp --
  47  *      Perform shell word expansion on `words' and place the resulting list
  48  *      of words in `we'. See wordexp(3).
  49  *
  50  *      Specified by IEEE Std. 1003.1-2001.
  51  */
  52 int
  53 wordexp(const char * __restrict words, wordexp_t * __restrict we, int flags)
  54 {
  55         int error;
  56
  57         if (flags & WRDE_REUSE)
  58                 wordfree(we);
  59         if ((flags & WRDE_APPEND) == 0) {
  60                 we->we_wordc = 0;
  61                 we->we_wordv = NULL;
  62                 we->we_strings = NULL;
  63                 we->we_nbytes = 0;
  64         }
  65         if ((error = we_check(words, flags)) != 0) {
  66                 wordfree(we);
  67                 return (error);
  68         }
  69         if ((error = we_askshell(words, we, flags)) != 0) {
  70                 wordfree(we);
  71                 return (error);
  72         }
  73         return (0);
  74 }
  75
  76 /*
  77  * we_askshell --
  78  *      Use the `wordexp' /bin/sh builtin function to do most of the work
  79  *      in expanding the word string. This function is complicated by
  80  *      memory management.
  81  */
  82 static int
  83 we_askshell(const char *words, wordexp_t *we, int flags)
  84 {
  85         int pdes[2];                    /* Pipe to child */
  86         char bbuf[9];                   /* Buffer for byte count */
  87         char wbuf[9];                   /* Buffer for word count */
  88         long nwords, nbytes;            /* Number of words, bytes from child */
  89         long i;                         /* Handy integer */
  90         size_t sofs;                    /* Offset into we->we_strings */
  91         size_t vofs;                    /* Offset into we->we_wordv */
  92         pid_t pid;                      /* Process ID of child */
  93         int status;                     /* Child exit status */
  94         char *ifs;                      /* IFS env. var. */
  95         char *np, *p;                   /* Handy pointers */
  96         char *nstrings;                 /* Temporary for realloc() */
  97         char **nwv;                     /* Temporary for realloc() */
  98
  99         if ((ifs = getenv("IFS")) == NULL)
 100                 ifs = " \t\n";
 101
 102         if (pipe2(pdes, O_CLOEXEC) < 0)
 103                 return (WRDE_NOSPACE);  /* XXX */
 104         if ((pid = fork()) < 0) {
 105                 _close(pdes[0]);
 106                 _close(pdes[1]);
 107                 return (WRDE_NOSPACE);  /* XXX */
 108         }
 109         else if (pid == 0) {
 110                 /*
 111                  * We are the child; just get /bin/sh to run the wordexp
 112                  * builtin on `words'.
 113                  */
 114                 int devnull;
 115                 char *cmd;
 116
 117                 _close(pdes[0]);
 118                 _fcntl(pdes[1], F_SETFD, 0);
 119                 if (_dup2(pdes[1], STDOUT_FILENO) < 0)
 120                         _exit(1);
 121                 _close(pdes[1]);
 122                 if (asprintf(&cmd, "wordexp%c%s\n", *ifs, words) < 0)
 123                         _exit(1);
 124                 if ((flags & WRDE_SHOWERR) == 0) {
 125                         if ((devnull = _open(_PATH_DEVNULL, O_RDWR, 0666)) < 0)
 126                                 _exit(1);
 127                         if (_dup2(devnull, STDERR_FILENO) < 0)
 128                                 _exit(1);
 129                         _close(devnull);
 130                 }
 131                 execl(_PATH_BSHELL, "sh", flags & WRDE_UNDEF ? "-u" : "+u",
 132                     "-c", cmd, NULL);
 133                 _exit(1);
 134         }
 135
 136         /*
 137          * We are the parent; read the output of the shell wordexp function,
 138          * which is a 32-bit hexadecimal word count, a 32-bit hexadecimal
 139          * byte count (not including terminating null bytes), followed by
 140          * the expanded words separated by nulls.
 141          */
 142         _close(pdes[1]);
 143         if (_read(pdes[0], wbuf, 8) != 8 || _read(pdes[0], bbuf, 8) != 8) {
 144                 _close(pdes[0]);
 145                 _waitpid(pid, &status, 0);
 146                 return (flags & WRDE_UNDEF ? WRDE_BADVAL : WRDE_SYNTAX);
 147         }
 148         wbuf[8] = bbuf[8] = '\0';
 149         nwords = strtol(wbuf, NULL, 16);
 150         nbytes = strtol(bbuf, NULL, 16) + nwords;
 151
 152         /*
 153          * Allocate or reallocate (when flags & WRDE_APPEND) the word vector
 154          * and string storage buffers for the expanded words we're about to
 155          * read from the child.
 156          */
 157         sofs = we->we_nbytes;
 158         vofs = we->we_wordc;
 159         if ((flags & (WRDE_DOOFFS|WRDE_APPEND)) == (WRDE_DOOFFS|WRDE_APPEND))
 160                 vofs += we->we_offs;
 161         we->we_wordc += nwords;
 162         we->we_nbytes += nbytes;
 163         if ((nwv = realloc(we->we_wordv, (we->we_wordc + 1 +
 164             (flags & WRDE_DOOFFS ?  we->we_offs : 0)) *
 165             sizeof(char *))) == NULL) {
 166                 _close(pdes[0]);
 167                 _waitpid(pid, &status, 0);
 168                 return (WRDE_NOSPACE);
 169         }
 170         we->we_wordv = nwv;
 171         if ((nstrings = realloc(we->we_strings, we->we_nbytes)) == NULL) {
 172                 _close(pdes[0]);
 173                 _waitpid(pid, &status, 0);
 174                 return (WRDE_NOSPACE);
 175         }
 176         for (i = 0; i < vofs; i++)
 177                 if (we->we_wordv[i] != NULL)
 178                         we->we_wordv[i] += nstrings - we->we_strings;
 179         we->we_strings = nstrings;
 180
 181         if (_read(pdes[0], we->we_strings + sofs, nbytes) != nbytes) {
 182                 _close(pdes[0]);
 183                 _waitpid(pid, &status, 0);
 184                 return (flags & WRDE_UNDEF ? WRDE_BADVAL : WRDE_SYNTAX);
 185         }
 186
 187         if (_waitpid(pid, &status, 0) < 0 || !WIFEXITED(status) ||
 188             WEXITSTATUS(status) != 0) {
 189                 _close(pdes[0]);
 190                 return (flags & WRDE_UNDEF ? WRDE_BADVAL : WRDE_SYNTAX);
 191         }
 192         _close(pdes[0]);
 193
 194         /*
 195          * Break the null-terminated expanded word strings out into
 196          * the vector.
 197          */
 198         if (vofs == 0 && flags & WRDE_DOOFFS)
 199                 while (vofs < we->we_offs)
 200                         we->we_wordv[vofs++] = NULL;
 201         p = we->we_strings + sofs;
 202         while (nwords-- != 0) {
 203                 we->we_wordv[vofs++] = p;
 204                 if ((np = memchr(p, '\0', nbytes)) == NULL)
 205                         return (WRDE_NOSPACE);  /* XXX */
 206                 nbytes -= np - p + 1;
 207                 p = np + 1;
 208         }
 209         we->we_wordv[vofs] = NULL;
 210
 211         return (0);
 212 }
 213
 214 /*
 215  * we_check --
 216  *      Check that the string contains none of the following unquoted
 217  *      special characters: <newline> |&;<>(){}
 218  *      or command substitutions when WRDE_NOCMD is set in flags.
 219  */
 220 static int
 221 we_check(const char *words, int flags)
 222 {
 223         char c;
 224         int dquote, level, quote, squote;
 225
 226         quote = squote = dquote = 0;
 227         while ((c = *words++) != '\0') {
 228                 switch (c) {
 229                 case '\\':
 230                         quote ^= 1;
 231                         continue;
 232                 case '\'':
 233                         if (quote + dquote == 0)
 234                                 squote ^= 1;
 235                         break;
 236                 case '"':
 237                         if (quote + squote == 0)
 238                                 dquote ^= 1;
 239                         break;
 240                 case '`':
 241                         if (quote + squote == 0 && flags & WRDE_NOCMD)
 242                                 return (WRDE_CMDSUB);
 243                         while ((c = *words++) != '\0' && c != '`')
 244                                 if (c == '\\' && (c = *words++) == '\0')
 245                                         break;
 246                         if (c == '\0')
 247                                 return (WRDE_SYNTAX);
 248                         break;
 249                 case '|': case '&': case ';': case '<': case '>':
 250                 case '{': case '}': case '(': case ')': case '\n':
 251                         if (quote + squote + dquote == 0)
 252                                 return (WRDE_BADCHAR);
 253                         break;
 254                 case '$':
 255                         if ((c = *words++) == '\0')
 256                                 break;
 257                         else if (quote + squote == 0 && c == '(') {
 258                                 if (flags & WRDE_NOCMD && *words != '(')
 259                                         return (WRDE_CMDSUB);
 260                                 level = 1;
 261                                 while ((c = *words++) != '\0') {
 262                                         if (c == '\\') {
 263                                                 if ((c = *words++) == '\0')
 264                                                         break;
 265                                         } else if (c == '(')
 266                                                 level++;
 267                                         else if (c == ')' && --level == 0)
 268                                                 break;
 269                                 }
 270                                 if (c == '\0' || level != 0)
 271                                         return (WRDE_SYNTAX);
 272                         } else if (quote + squote == 0 && c == '{') {
 273                                 level = 1;
 274                                 while ((c = *words++) != '\0') {
 275                                         if (c == '\\') {
 276                                                 if ((c = *words++) == '\0')
 277                                                         break;
 278                                         } else if (c == '{')
 279                                                 level++;
 280                                         else if (c == '}' && --level == 0)
 281                                                 break;
 282                                 }
 283                                 if (c == '\0' || level != 0)
 284                                         return (WRDE_SYNTAX);
 285                         } else
 286                                 c = *--words;
 287                         break;
 288                 default:
 289                         break;
 290                 }
 291                 quote = 0;
 292         }
 293         if (quote + squote + dquote != 0)
 294                 return (WRDE_SYNTAX);
 295
 296         return (0);
 297 }
 298
 299 /*
 300  * wordfree --
 301  *      Free the result of wordexp(). See wordexp(3).
 302  *
 303  *      Specified by IEEE Std. 1003.1-2001.
 304  */
 305 void
 306 wordfree(wordexp_t *we)
 307 {
 308
 309         if (we == NULL)
 310                 return;
 311         free(we->we_wordv);
 312         free(we->we_strings);
 313         we->we_wordv = NULL;
 314         we->we_strings = NULL;
 315         we->we_nbytes = 0;
 316         we->we_wordc = 0;
 317 }