wordexp.c revision 198406
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 27#include "namespace.h" 28#include <sys/cdefs.h> 29#include <sys/types.h> 30#include <sys/wait.h> 31#include <errno.h> 32#include <fcntl.h> 33#include <paths.h> 34#include <signal.h> 35#include <stdio.h> 36#include <stdlib.h> 37#include <string.h> 38#include <unistd.h> 39#include <wordexp.h> 40#include "un-namespace.h" 41 42__FBSDID("$FreeBSD: head/lib/libc/gen/wordexp.c 198406 2009-10-23 14:50:11Z jilles $"); 43 44static int we_askshell(const char *, wordexp_t *, int); 45static int we_check(const char *, int); 46 47/* 48 * wordexp -- 49 * Perform shell word expansion on `words' and place the resulting list 50 * of words in `we'. See wordexp(3). 51 * 52 * Specified by IEEE Std. 1003.1-2001. 53 */ 54int 55wordexp(const char * __restrict words, wordexp_t * __restrict we, int flags) 56{ 57 int error; 58 59 if (flags & WRDE_REUSE) 60 wordfree(we); 61 if ((flags & WRDE_APPEND) == 0) { 62 we->we_wordc = 0; 63 we->we_wordv = NULL; 64 we->we_strings = NULL; 65 we->we_nbytes = 0; 66 } 67 if ((error = we_check(words, flags)) != 0) { 68 wordfree(we); 69 return (error); 70 } 71 if ((error = we_askshell(words, we, flags)) != 0) { 72 wordfree(we); 73 return (error); 74 } 75 return (0); 76} 77 78static size_t 79we_read_fully(int fd, char *buffer, size_t len) 80{ 81 size_t done; 82 ssize_t nread; 83 84 done = 0; 85 do { 86 nread = _read(fd, buffer + done, len - done); 87 if (nread == -1 && errno == EINTR) 88 continue; 89 if (nread <= 0) 90 break; 91 done += nread; 92 } while (done != len); 93 return done; 94} 95 96/* 97 * we_askshell -- 98 * Use the `wordexp' /bin/sh builtin function to do most of the work 99 * in expanding the word string. This function is complicated by 100 * memory management. 101 */ 102static int 103we_askshell(const char *words, wordexp_t *we, int flags) 104{ 105 int pdes[2]; /* Pipe to child */ 106 char bbuf[9]; /* Buffer for byte count */ 107 char wbuf[9]; /* Buffer for word count */ 108 long nwords, nbytes; /* Number of words, bytes from child */ 109 long i; /* Handy integer */ 110 size_t sofs; /* Offset into we->we_strings */ 111 size_t vofs; /* Offset into we->we_wordv */ 112 pid_t pid; /* Process ID of child */ 113 pid_t wpid; /* waitpid return value */ 114 int status; /* Child exit status */ 115 int error; /* Our return value */ 116 int serrno; /* errno to return */ 117 char *ifs; /* IFS env. var. */ 118 char *np, *p; /* Handy pointers */ 119 char *nstrings; /* Temporary for realloc() */ 120 char **nwv; /* Temporary for realloc() */ 121 sigset_t newsigblock, oldsigblock; 122 123 serrno = errno; 124 if ((ifs = getenv("IFS")) == NULL) 125 ifs = " \t\n"; 126 127 if (pipe(pdes) < 0) 128 return (WRDE_NOSPACE); /* XXX */ 129 (void)sigemptyset(&newsigblock); 130 (void)sigaddset(&newsigblock, SIGCHLD); 131 (void)_sigprocmask(SIG_BLOCK, &newsigblock, &oldsigblock); 132 if ((pid = fork()) < 0) { 133 serrno = errno; 134 _close(pdes[0]); 135 _close(pdes[1]); 136 (void)_sigprocmask(SIG_SETMASK, &oldsigblock, NULL); 137 errno = serrno; 138 return (WRDE_NOSPACE); /* XXX */ 139 } 140 else if (pid == 0) { 141 /* 142 * We are the child; just get /bin/sh to run the wordexp 143 * builtin on `words'. 144 */ 145 int devnull; 146 char *cmd; 147 148 (void)_sigprocmask(SIG_SETMASK, &oldsigblock, NULL); 149 _close(pdes[0]); 150 if (_dup2(pdes[1], STDOUT_FILENO) < 0) 151 _exit(1); 152 _close(pdes[1]); 153 if (asprintf(&cmd, "wordexp%c%s\n", *ifs, words) < 0) 154 _exit(1); 155 if ((flags & WRDE_SHOWERR) == 0) { 156 if ((devnull = _open(_PATH_DEVNULL, O_RDWR, 0666)) < 0) 157 _exit(1); 158 if (_dup2(devnull, STDERR_FILENO) < 0) 159 _exit(1); 160 _close(devnull); 161 } 162 execl(_PATH_BSHELL, "sh", flags & WRDE_UNDEF ? "-u" : "+u", 163 "-c", cmd, (char *)NULL); 164 _exit(1); 165 } 166 167 /* 168 * We are the parent; read the output of the shell wordexp function, 169 * which is a 32-bit hexadecimal word count, a 32-bit hexadecimal 170 * byte count (not including terminating null bytes), followed by 171 * the expanded words separated by nulls. 172 */ 173 _close(pdes[1]); 174 if (we_read_fully(pdes[0], wbuf, 8) != 8 || 175 we_read_fully(pdes[0], bbuf, 8) != 8) { 176 error = flags & WRDE_UNDEF ? WRDE_BADVAL : WRDE_SYNTAX; 177 serrno = errno; 178 goto cleanup; 179 } 180 wbuf[8] = bbuf[8] = '\0'; 181 nwords = strtol(wbuf, NULL, 16); 182 nbytes = strtol(bbuf, NULL, 16) + 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 error = WRDE_NOSPACE; 199 goto cleanup; 200 } 201 we->we_wordv = nwv; 202 if ((nstrings = realloc(we->we_strings, we->we_nbytes)) == NULL) { 203 error = WRDE_NOSPACE; 204 goto cleanup; 205 } 206 for (i = 0; i < vofs; i++) 207 if (we->we_wordv[i] != NULL) 208 we->we_wordv[i] += nstrings - we->we_strings; 209 we->we_strings = nstrings; 210 211 if (we_read_fully(pdes[0], we->we_strings + sofs, nbytes) != nbytes) { 212 error = flags & WRDE_UNDEF ? WRDE_BADVAL : WRDE_SYNTAX; 213 serrno = errno; 214 goto cleanup; 215 } 216 217 error = 0; 218cleanup: 219 _close(pdes[0]); 220 do 221 wpid = _waitpid(pid, &status, 0); 222 while (wpid < 0 && errno == EINTR); 223 (void)_sigprocmask(SIG_SETMASK, &oldsigblock, NULL); 224 if (error != 0) { 225 errno = serrno; 226 return (error); 227 } 228 if (wpid < 0 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) 229 return (flags & WRDE_UNDEF ? WRDE_BADVAL : WRDE_SYNTAX); 230 231 /* 232 * Break the null-terminated expanded word strings out into 233 * the vector. 234 */ 235 if (vofs == 0 && flags & WRDE_DOOFFS) 236 while (vofs < we->we_offs) 237 we->we_wordv[vofs++] = NULL; 238 p = we->we_strings + sofs; 239 while (nwords-- != 0) { 240 we->we_wordv[vofs++] = p; 241 if ((np = memchr(p, '\0', nbytes)) == NULL) 242 return (WRDE_NOSPACE); /* XXX */ 243 nbytes -= np - p + 1; 244 p = np + 1; 245 } 246 we->we_wordv[vofs] = NULL; 247 248 return (0); 249} 250 251/* 252 * we_check -- 253 * Check that the string contains none of the following unquoted 254 * special characters: <newline> |&;<>(){} 255 * or command substitutions when WRDE_NOCMD is set in flags. 256 */ 257static int 258we_check(const char *words, int flags) 259{ 260 char c; 261 int dquote, level, quote, squote; 262 263 quote = squote = dquote = 0; 264 while ((c = *words++) != '\0') { 265 switch (c) { 266 case '\\': 267 quote ^= 1; 268 continue; 269 case '\'': 270 if (quote + dquote == 0) 271 squote ^= 1; 272 break; 273 case '"': 274 if (quote + squote == 0) 275 dquote ^= 1; 276 break; 277 case '`': 278 if (quote + squote == 0 && flags & WRDE_NOCMD) 279 return (WRDE_CMDSUB); 280 while ((c = *words++) != '\0' && c != '`') 281 if (c == '\\' && (c = *words++) == '\0') 282 break; 283 if (c == '\0') 284 return (WRDE_SYNTAX); 285 break; 286 case '|': case '&': case ';': case '<': case '>': 287 case '{': case '}': case '(': case ')': case '\n': 288 if (quote + squote + dquote == 0) 289 return (WRDE_BADCHAR); 290 break; 291 case '$': 292 if ((c = *words++) == '\0') 293 break; 294 else if (quote + squote == 0 && c == '(') { 295 if (flags & WRDE_NOCMD && *words != '(') 296 return (WRDE_CMDSUB); 297 level = 1; 298 while ((c = *words++) != '\0') { 299 if (c == '\\') { 300 if ((c = *words++) == '\0') 301 break; 302 } else if (c == '(') 303 level++; 304 else if (c == ')' && --level == 0) 305 break; 306 } 307 if (c == '\0' || level != 0) 308 return (WRDE_SYNTAX); 309 } else if (quote + squote == 0 && c == '{') { 310 level = 1; 311 while ((c = *words++) != '\0') { 312 if (c == '\\') { 313 if ((c = *words++) == '\0') 314 break; 315 } else if (c == '{') 316 level++; 317 else if (c == '}' && --level == 0) 318 break; 319 } 320 if (c == '\0' || level != 0) 321 return (WRDE_SYNTAX); 322 } else 323 c = *--words; 324 break; 325 default: 326 break; 327 } 328 quote = 0; 329 } 330 if (quote + squote + dquote != 0) 331 return (WRDE_SYNTAX); 332 333 return (0); 334} 335 336/* 337 * wordfree -- 338 * Free the result of wordexp(). See wordexp(3). 339 * 340 * Specified by IEEE Std. 1003.1-2001. 341 */ 342void 343wordfree(wordexp_t *we) 344{ 345 346 if (we == NULL) 347 return; 348 free(we->we_wordv); 349 free(we->we_strings); 350 we->we_wordv = NULL; 351 we->we_strings = NULL; 352 we->we_nbytes = 0; 353 we->we_wordc = 0; 354} 355