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  * $DragonFly: src/lib/libc/gen/wordexp.c,v 1.1 2008/10/06 21:01:37 swildner Exp $
  28  */
  29
  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 <unistd.h>
  38 #include <wordexp.h>
  39
  40 static int      we_askshell(const char *, wordexp_t *, int);
  41 static int      we_check(const char *, int);
  42
  43 /*
  44  * wordexp --
  45  *      Perform shell word expansion on `words' and place the resulting list
  46  *      of words in `we'. See wordexp(3).
  47  *
  48  *      Specified by IEEE Std. 1003.1-2001.
  49  */
  50 int
  51 wordexp(const char * __restrict words, wordexp_t * __restrict we, int flags)
  52 {
  53         int error;
  54
  55         if (flags & WRDE_REUSE)
  56                 wordfree(we);
  57         if ((flags & WRDE_APPEND) == 0) {
  58                 we->we_wordc = 0;
  59                 we->we_wordv = NULL;
  60                 we->we_strings = NULL;
  61                 we->we_nbytes = 0;
  62         }
  63         if ((error = we_check(words, flags)) != 0) {
  64                 wordfree(we);
  65                 return (error);
  66         }
  67         if ((error = we_askshell(words, we, flags)) != 0) {
  68                 wordfree(we);
  69                 return (error);
  70         }
  71         return (0);
  72 }
  73
  74 /*
  75  * we_askshell --
  76  *      Use the `wordexp' /bin/sh builtin function to do most of the work
  77  *      in expanding the word string. This function is complicated by
  78  *      memory management.
  79  */
  80 static int
  81 we_askshell(const char *words, wordexp_t *we, int flags)
  82 {
  83         int pdes[2];                    /* Pipe to child */
  84         char bbuf[9];                   /* Buffer for byte count */
  85         char wbuf[9];                   /* Buffer for word count */
  86         long nwords, nbytes;            /* Number of words, bytes from child */
  87         long i;                         /* Handy integer */
  88         size_t sofs;                    /* Offset into we->we_strings */
  89         size_t vofs;                    /* Offset into we->we_wordv */
  90         pid_t pid;                      /* Process ID of child */
  91         int status;                     /* Child exit status */
  92         char *ifs;                      /* IFS env. var. */
  93         char *np, *p;                   /* Handy pointers */
  94         char *nstrings;                 /* Temporary for realloc() */
  95         char **nwv;                     /* Temporary for realloc() */
  96
  97         if ((ifs = getenv("IFS")) == NULL)
  98                 ifs = " \t\n";
  99
 100         if (pipe(pdes) < 0)
 101                 return (WRDE_NOSPACE);  /* XXX */
 102         if ((pid = fork()) < 0) {
 103                 _close(pdes[0]);
 104                 _close(pdes[1]);
 105                 return (WRDE_NOSPACE);  /* XXX */
 106         }
 107         else if (pid == 0) {
 108                 /*
 109                  * We are the child; just get /bin/sh to run the wordexp
 110                  * builtin on `words'.
 111                  */
 112                 int devnull;
 113                 char *cmd;
 114
 115                 _close(pdes[0]);
 116                 if (_dup2(pdes[1], STDOUT_FILENO) < 0)
 117                         _exit(1);
 118                 _close(pdes[1]);
 119                 if (asprintf(&cmd, "wordexp%c%s\n", *ifs, words) < 0)
 120                         _exit(1);
 121                 if ((flags & WRDE_SHOWERR) == 0) {
 122                         if ((devnull = _open(_PATH_DEVNULL, O_RDWR, 0666)) < 0)
 123                                 _exit(1);
 124                         if (_dup2(devnull, STDERR_FILENO) < 0)
 125                                 _exit(1);
 126                         _close(devnull);
 127                 }
 128                 execl(_PATH_BSHELL, "sh", flags & WRDE_UNDEF ? "-u" : "+u",
 129                     "-c", cmd, NULL);
 130                 _exit(1);
 131         }
 132
 133         /*
 134          * We are the parent; read the output of the shell wordexp function,
 135          * which is a 32-bit hexadecimal word count, a 32-bit hexadecimal
 136          * byte count (not including terminating null bytes), followed by
 137          * the expanded words separated by nulls.
 138          */
 139         _close(pdes[1]);
 140         if (_read(pdes[0], wbuf, 8) != 8 || _read(pdes[0], bbuf, 8) != 8) {
 141                 _close(pdes[0]);
 142                 _waitpid(pid, &status, 0);
 143                 return (flags & WRDE_UNDEF ? WRDE_BADVAL : WRDE_SYNTAX);
 144         }
 145         wbuf[8] = bbuf[8] = '\0';
 146         nwords = strtol(wbuf, NULL, 16);
 147         nbytes = strtol(bbuf, NULL, 16) + nwords;
 148
 149         /*
 150          * Allocate or reallocate (when flags & WRDE_APPEND) the word vector
 151          * and string storage buffers for the expanded words we're about to
 152          * read from the child.
 153          */
 154         sofs = we->we_nbytes;
 155         vofs = we->we_wordc;
 156         if ((flags & (WRDE_DOOFFS|WRDE_APPEND)) == (WRDE_DOOFFS|WRDE_APPEND))
 157                 vofs += we->we_offs;
 158         we->we_wordc += nwords;
 159         we->we_nbytes += nbytes;
 160         if ((nwv = realloc(we->we_wordv, (we->we_wordc + 1 +
 161             (flags & WRDE_DOOFFS ?  we->we_offs : 0)) *
 162             sizeof(char *))) == NULL) {
 163                 _close(pdes[0]);
 164                 _waitpid(pid, &status, 0);
 165                 return (WRDE_NOSPACE);
 166         }
 167         we->we_wordv = nwv;
 168         if ((nstrings = realloc(we->we_strings, we->we_nbytes)) == NULL) {
 169                 _close(pdes[0]);
 170                 _waitpid(pid, &status, 0);
 171                 return (WRDE_NOSPACE);
 172         }
 173         for (i = 0; i < vofs; i++)
 174                 if (we->we_wordv[i] != NULL)
 175                         we->we_wordv[i] += nstrings - we->we_strings;
 176         we->we_strings = nstrings;
 177
 178         if (_read(pdes[0], we->we_strings + sofs, nbytes) != nbytes) {
 179                 _close(pdes[0]);
 180                 _waitpid(pid, &status, 0);
 181                 return (flags & WRDE_UNDEF ? WRDE_BADVAL : WRDE_SYNTAX);
 182         }
 183
 184         if (_waitpid(pid, &status, 0) < 0 || !WIFEXITED(status) ||
 185             WEXITSTATUS(status) != 0) {
 186                 _close(pdes[0]);
 187                 return (flags & WRDE_UNDEF ? WRDE_BADVAL : WRDE_SYNTAX);
 188         }
 189         _close(pdes[0]);
 190
 191         /*
 192          * Break the null-terminated expanded word strings out into
 193          * the vector.
 194          */
 195         if (vofs == 0 && flags & WRDE_DOOFFS)
 196                 while (vofs < we->we_offs)
 197                         we->we_wordv[vofs++] = NULL;
 198         p = we->we_strings + sofs;
 199         while (nwords-- != 0) {
 200                 we->we_wordv[vofs++] = p;
 201                 if ((np = memchr(p, '\0', nbytes)) == NULL)
 202                         return (WRDE_NOSPACE);  /* XXX */
 203                 nbytes -= np - p + 1;
 204                 p = np + 1;
 205         }
 206         we->we_wordv[vofs] = NULL;
 207
 208         return (0);
 209 }
 210
 211 /*
 212  * we_check --
 213  *      Check that the string contains none of the following unquoted
 214  *      special characters: <newline> |&;<>(){}
 215  *      or command substitutions when WRDE_NOCMD is set in flags.
 216  */
 217 static int
 218 we_check(const char *words, int flags)
 219 {
 220         char c;
 221         int dquote, level, quote, squote;
 222
 223         quote = squote = dquote = 0;
 224         while ((c = *words++) != '\0') {
 225                 switch (c) {
 226                 case '\\':
 227                         quote ^= 1;
 228                         continue;
 229                 case '\'':
 230                         if (quote + dquote == 0)
 231                                 squote ^= 1;
 232                         break;
 233                 case '"':
 234                         if (quote + squote == 0)
 235                                 dquote ^= 1;
 236                         break;
 237                 case '`':
 238                         if (quote + squote == 0 && flags & WRDE_NOCMD)
 239                                 return (WRDE_CMDSUB);
 240                         while ((c = *words++) != '\0' && c != '`')
 241                                 if (c == '\\' && (c = *words++) == '\0')
 242                                         break;
 243                         if (c == '\0')
 244                                 return (WRDE_SYNTAX);
 245                         break;
 246                 case '|': case '&': case ';': case '<': case '>':
 247                 case '{': case '}': case '(': case ')': case '\n':
 248                         if (quote + squote + dquote == 0)
 249                                 return (WRDE_BADCHAR);
 250                         break;
 251                 case '$':
 252                         if ((c = *words++) == '\0')
 253                                 break;
 254                         else if (quote + squote == 0 && c == '(') {
 255                                 if (flags & WRDE_NOCMD && *words != '(')
 256                                         return (WRDE_CMDSUB);
 257                                 level = 1;
 258                                 while ((c = *words++) != '\0') {
 259                                         if (c == '\\') {
 260                                                 if ((c = *words++) == '\0')
 261                                                         break;
 262                                         } else if (c == '(')
 263                                                 level++;
 264                                         else if (c == ')' && --level == 0)
 265                                                 break;
 266                                 }
 267                                 if (c == '\0' || level != 0)
 268                                         return (WRDE_SYNTAX);
 269                         } else if (quote + squote == 0 && c == '{') {
 270                                 level = 1;
 271                                 while ((c = *words++) != '\0') {
 272                                         if (c == '\\') {
 273                                                 if ((c = *words++) == '\0')
 274                                                         break;
 275                                         } else if (c == '{')
 276                                                 level++;
 277                                         else if (c == '}' && --level == 0)
 278                                                 break;
 279                                 }
 280                                 if (c == '\0' || level != 0)
 281                                         return (WRDE_SYNTAX);
 282                         } else
 283                                 c = *--words;
 284                         break;
 285                 default:
 286                         break;
 287                 }
 288                 quote = 0;
 289         }
 290         if (quote + squote + dquote != 0)
 291                 return (WRDE_SYNTAX);
 292
 293         return (0);
 294 }
 295
 296 /*
 297  * wordfree --
 298  *      Free the result of wordexp(). See wordexp(3).
 299  *
 300  *      Specified by IEEE Std. 1003.1-2001.
 301  */
 302 void
 303 wordfree(wordexp_t *we)
 304 {
 305
 306         if (we == NULL)
 307                 return;
 308         free(we->we_wordv);
 309         free(we->we_strings);
 310         we->we_wordv = NULL;
 311         we->we_strings = NULL;
 312         we->we_nbytes = 0;
 313         we->we_wordc = 0;
 314 }