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 <unistd.h>
  38 #include <wordexp.h>
  39 #include "un-namespace.h"
  40
  41 static int      we_askshell(const char *, wordexp_t *, int);
  42 static int      we_check(const char *, int);
  43
  44 /*
  45  * wordexp --
  46  *      Perform shell word expansion on `words' and place the resulting list
  47  *      of words in `we'. See wordexp(3).
  48  *
  49  *      Specified by IEEE Std. 1003.1-2001.
  50  */
  51 int
  52 wordexp(const char * __restrict words, wordexp_t * __restrict we, int flags)
  53 {
  54         int error;
  55
  56         if (flags & WRDE_REUSE)
  57                 wordfree(we);
  58         if ((flags & WRDE_APPEND) == 0) {
  59                 we->we_wordc = 0;
  60                 we->we_wordv = NULL;
  61                 we->we_strings = NULL;
  62                 we->we_nbytes = 0;
  63         }
  64         if ((error = we_check(words, flags)) != 0) {
  65                 wordfree(we);
  66                 return (error);
  67         }
  68         if ((error = we_askshell(words, we, flags)) != 0) {
  69                 wordfree(we);
  70                 return (error);
  71         }
  72         return (0);
  73 }
  74
  75 /*
  76  * we_askshell --
  77  *      Use the `wordexp' /bin/sh builtin function to do most of the work
  78  *      in expanding the word string. This function is complicated by
  79  *      memory management.
  80  */
  81 static int
  82 we_askshell(const char *words, wordexp_t *we, int flags)
  83 {
  84         int pdes[2];                    /* Pipe to child */
  85         char bbuf[9];                   /* Buffer for byte count */
  86         char wbuf[9];                   /* Buffer for word count */
  87         long nwords, nbytes;            /* Number of words, bytes from child */
  88         long i;                         /* Handy integer */
  89         size_t sofs;                    /* Offset into we->we_strings */
  90         size_t vofs;                    /* Offset into we->we_wordv */
  91         pid_t pid;                      /* Process ID of child */
  92         int status;                     /* Child exit status */
  93         char *ifs;                      /* IFS env. var. */
  94         char *np, *p;                   /* Handy pointers */
  95         char *nstrings;                 /* Temporary for realloc() */
  96         char **nwv;                     /* Temporary for realloc() */
  97
  98         if ((ifs = getenv("IFS")) == NULL)
  99                 ifs = " \t\n";
 100
 101         if (pipe2(pdes, O_CLOEXEC) < 0)
 102                 return (WRDE_NOSPACE);  /* XXX */
 103         if ((pid = fork()) < 0) {
 104                 _close(pdes[0]);
 105                 _close(pdes[1]);
 106                 return (WRDE_NOSPACE);  /* XXX */
 107         }
 108         else if (pid == 0) {
 109                 /*
 110                  * We are the child; just get /bin/sh to run the wordexp
 111                  * builtin on `words'.
 112                  */
 113                 int devnull;
 114                 char *cmd;
 115
 116                 _close(pdes[0]);
 117                 _fcntl(pdes[1], F_SETFD, 0);
 118                 if (_dup2(pdes[1], STDOUT_FILENO) < 0)
 119                         _exit(1);
 120                 _close(pdes[1]);
 121                 if (asprintf(&cmd, "wordexp%c%s\n", *ifs, words) < 0)
 122                         _exit(1);
 123                 if ((flags & WRDE_SHOWERR) == 0) {
 124                         if ((devnull = _open(_PATH_DEVNULL, O_RDWR, 0666)) < 0)
 125                                 _exit(1);
 126                         if (_dup2(devnull, STDERR_FILENO) < 0)
 127                                 _exit(1);
 128                         _close(devnull);
 129                 }
 130                 execl(_PATH_BSHELL, "sh", flags & WRDE_UNDEF ? "-u" : "+u",
 131                     "-c", cmd, NULL);
 132                 _exit(1);
 133         }
 134
 135         /*
 136          * We are the parent; read the output of the shell wordexp function,
 137          * which is a 32-bit hexadecimal word count, a 32-bit hexadecimal
 138          * byte count (not including terminating null bytes), followed by
 139          * the expanded words separated by nulls.
 140          */
 141         _close(pdes[1]);
 142         if (_read(pdes[0], wbuf, 8) != 8 || _read(pdes[0], bbuf, 8) != 8) {
 143                 _close(pdes[0]);
 144                 _waitpid(pid, &status, 0);
 145                 return (flags & WRDE_UNDEF ? WRDE_BADVAL : WRDE_SYNTAX);
 146         }
 147         wbuf[8] = bbuf[8] = '\0';
 148         nwords = strtol(wbuf, NULL, 16);
 149         nbytes = strtol(bbuf, NULL, 16) + nwords;
 150
 151         /*
 152          * Allocate or reallocate (when flags & WRDE_APPEND) the word vector
 153          * and string storage buffers for the expanded words we're about to
 154          * read from the child.
 155          */
 156         sofs = we->we_nbytes;
 157         vofs = we->we_wordc;
 158         if ((flags & (WRDE_DOOFFS|WRDE_APPEND)) == (WRDE_DOOFFS|WRDE_APPEND))
 159                 vofs += we->we_offs;
 160         we->we_wordc += nwords;
 161         we->we_nbytes += nbytes;
 162         if ((nwv = realloc(we->we_wordv, (we->we_wordc + 1 +
 163             (flags & WRDE_DOOFFS ?  we->we_offs : 0)) *
 164             sizeof(char *))) == NULL) {
 165                 _close(pdes[0]);
 166                 _waitpid(pid, &status, 0);
 167                 return (WRDE_NOSPACE);
 168         }
 169         we->we_wordv = nwv;
 170         if ((nstrings = realloc(we->we_strings, we->we_nbytes)) == NULL) {
 171                 _close(pdes[0]);
 172                 _waitpid(pid, &status, 0);
 173                 return (WRDE_NOSPACE);
 174         }
 175         for (i = 0; i < vofs; i++)
 176                 if (we->we_wordv[i] != NULL)
 177                         we->we_wordv[i] += nstrings - we->we_strings;
 178         we->we_strings = nstrings;
 179
 180         if (_read(pdes[0], we->we_strings + sofs, nbytes) != nbytes) {
 181                 _close(pdes[0]);
 182                 _waitpid(pid, &status, 0);
 183                 return (flags & WRDE_UNDEF ? WRDE_BADVAL : WRDE_SYNTAX);
 184         }
 185
 186         if (_waitpid(pid, &status, 0) < 0 || !WIFEXITED(status) ||
 187             WEXITSTATUS(status) != 0) {
 188                 _close(pdes[0]);
 189                 return (flags & WRDE_UNDEF ? WRDE_BADVAL : WRDE_SYNTAX);
 190         }
 191         _close(pdes[0]);
 192
 193         /*
 194          * Break the null-terminated expanded word strings out into
 195          * the vector.
 196          */
 197         if (vofs == 0 && flags & WRDE_DOOFFS)
 198                 while (vofs < we->we_offs)
 199                         we->we_wordv[vofs++] = NULL;
 200         p = we->we_strings + sofs;
 201         while (nwords-- != 0) {
 202                 we->we_wordv[vofs++] = p;
 203                 if ((np = memchr(p, '\0', nbytes)) == NULL)
 204                         return (WRDE_NOSPACE);  /* XXX */
 205                 nbytes -= np - p + 1;
 206                 p = np + 1;
 207         }
 208         we->we_wordv[vofs] = NULL;
 209
 210         return (0);
 211 }
 212
 213 /*
 214  * we_check --
 215  *      Check that the string contains none of the following unquoted
 216  *      special characters: <newline> |&;<>(){}
 217  *      or command substitutions when WRDE_NOCMD is set in flags.
 218  */
 219 static int
 220 we_check(const char *words, int flags)
 221 {
 222         char c;
 223         int dquote, level, quote, squote;
 224
 225         quote = squote = dquote = 0;
 226         while ((c = *words++) != '\0') {
 227                 switch (c) {
 228                 case '\\':
 229                         quote ^= 1;
 230                         continue;
 231                 case '\'':
 232                         if (quote + dquote == 0)
 233                                 squote ^= 1;
 234                         break;
 235                 case '"':
 236                         if (quote + squote == 0)
 237                                 dquote ^= 1;
 238                         break;
 239                 case '`':
 240                         if (quote + squote == 0 && flags & WRDE_NOCMD)
 241                                 return (WRDE_CMDSUB);
 242                         while ((c = *words++) != '\0' && c != '`')
 243                                 if (c == '\\' && (c = *words++) == '\0')
 244                                         break;
 245                         if (c == '\0')
 246                                 return (WRDE_SYNTAX);
 247                         break;
 248                 case '|': case '&': case ';': case '<': case '>':
 249                 case '{': case '}': case '(': case ')': case '\n':
 250                         if (quote + squote + dquote == 0)
 251                                 return (WRDE_BADCHAR);
 252                         break;
 253                 case '$':
 254                         if ((c = *words++) == '\0')
 255                                 break;
 256                         else if (quote + squote == 0 && c == '(') {
 257                                 if (flags & WRDE_NOCMD && *words != '(')
 258                                         return (WRDE_CMDSUB);
 259                                 level = 1;
 260                                 while ((c = *words++) != '\0') {
 261                                         if (c == '\\') {
 262                                                 if ((c = *words++) == '\0')
 263                                                         break;
 264                                         } else if (c == '(')
 265                                                 level++;
 266                                         else if (c == ')' && --level == 0)
 267                                                 break;
 268                                 }
 269                                 if (c == '\0' || level != 0)
 270                                         return (WRDE_SYNTAX);
 271                         } else if (quote + squote == 0 && c == '{') {
 272                                 level = 1;
 273                                 while ((c = *words++) != '\0') {
 274                                         if (c == '\\') {
 275                                                 if ((c = *words++) == '\0')
 276                                                         break;
 277                                         } else if (c == '{')
 278                                                 level++;
 279                                         else if (c == '}' && --level == 0)
 280                                                 break;
 281                                 }
 282                                 if (c == '\0' || level != 0)
 283                                         return (WRDE_SYNTAX);
 284                         } else
 285                                 c = *--words;
 286                         break;
 287                 default:
 288                         break;
 289                 }
 290                 quote = 0;
 291         }
 292         if (quote + squote + dquote != 0)
 293                 return (WRDE_SYNTAX);
 294
 295         return (0);
 296 }
 297
 298 /*
 299  * wordfree --
 300  *      Free the result of wordexp(). See wordexp(3).
 301  *
 302  *      Specified by IEEE Std. 1003.1-2001.
 303  */
 304 void
 305 wordfree(wordexp_t *we)
 306 {
 307
 308         if (we == NULL)
 309                 return;
 310         free(we->we_wordv);
 311         free(we->we_strings);
 312         we->we_wordv = NULL;
 313         we->we_strings = NULL;
 314         we->we_nbytes = 0;
 315         we->we_wordc = 0;
 316 }