findutils/xargs.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Mini xargs implementation for busybox
   4  * Options are supported: "-prtx -n max_arg -s max_chars -e[ouf_str]"
   5  *
   6  * (C) 2002,2003 by Vladimir Oleynik <dzo@simtreas.ru>
   7  *
   8  * Special thanks
   9  * - Mark Whitley and Glenn McGrath for stimulus to rewrite :)
  10  * - Mike Rendell <michael@cs.mun.ca>
  11  * and David MacKenzie <djm@gnu.ai.mit.edu>.
  12  *
  13  * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
  14  *
  15  * xargs is described in the Single Unix Specification v3 at
  16  * http://www.opengroup.org/onlinepubs/007904975/utilities/xargs.html
  17  *
  18  */
  19
  20 #include "libbb.h"
  21
  22 /* This is a NOEXEC applet. Be very careful! */
  23
  24
  25 /* COMPAT:  SYSV version defaults size (and has a max value of) to 470.
  26    We try to make it as large as possible. */
  27 #if !defined(ARG_MAX) && defined(_SC_ARG_MAX)
  28 #define ARG_MAX sysconf (_SC_ARG_MAX)
  29 #endif
  30 #ifndef ARG_MAX
  31 #define ARG_MAX 470
  32 #endif
  33
  34
  35 #ifdef TEST
  36 # ifndef ENABLE_FEATURE_XARGS_SUPPORT_CONFIRMATION
  37 #  define ENABLE_FEATURE_XARGS_SUPPORT_CONFIRMATION 1
  38 # endif
  39 # ifndef ENABLE_FEATURE_XARGS_SUPPORT_QUOTES
  40 #  define ENABLE_FEATURE_XARGS_SUPPORT_QUOTES 1
  41 # endif
  42 # ifndef ENABLE_FEATURE_XARGS_SUPPORT_TERMOPT
  43 #  define ENABLE_FEATURE_XARGS_SUPPORT_TERMOPT 1
  44 # endif
  45 # ifndef ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
  46 #  define ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM 1
  47 # endif
  48 #endif
  49
  50 /*
  51    This function has special algorithm.
  52    Don't use fork and include to main!
  53 */
  54 static int xargs_exec(char **args)
  55 {
  56         int status;
  57
  58         status = spawn_and_wait(args);
  59         if (status < 0) {
  60                 bb_simple_perror_msg(args[0]);
  61                 return errno == ENOENT ? 127 : 126;
  62         }
  63         if (status == 255) {
  64                 bb_error_msg("%s: exited with status 255; aborting", args[0]);
  65                 return 124;
  66         }
  67 /* Huh? I think we won't see this, ever. We don't wait with WUNTRACED!
  68         if (WIFSTOPPED(status)) {
  69                 bb_error_msg("%s: stopped by signal %d",
  70                         args[0], WSTOPSIG(status));
  71                 return 125;
  72         }
  73 */
  74         if (status >= 1000) {
  75                 bb_error_msg("%s: terminated by signal %d",
  76                         args[0], status - 1000);
  77                 return 125;
  78         }
  79         if (status)
  80                 return 123;
  81         return 0;
  82 }
  83
  84
  85 typedef struct xlist_t {
  86         struct xlist_t *link;
  87         size_t length;
  88         char xstr[1];
  89 } xlist_t;
  90
  91 static smallint eof_stdin_detected;
  92
  93 #define ISBLANK(c) ((c) == ' ' || (c) == '\t')
  94 #define ISSPACE(c) (ISBLANK(c) || (c) == '\n' || (c) == '\r' \
  95                     || (c) == '\f' || (c) == '\v')
  96
  97 #if ENABLE_FEATURE_XARGS_SUPPORT_QUOTES
  98 static xlist_t *process_stdin(xlist_t *list_arg,
  99         const char *eof_str, size_t mc, char *buf)
 100 {
 101 #define NORM      0
 102 #define QUOTE     1
 103 #define BACKSLASH 2
 104 #define SPACE     4
 105
 106         char *s = NULL;         /* start word */
 107         char *p = NULL;         /* pointer to end word */
 108         char q = '\0';          /* quote char */
 109         char state = NORM;
 110         char eof_str_detected = 0;
 111         size_t line_l = 0;      /* size loaded args line */
 112         int c;                  /* current char */
 113         xlist_t *cur;
 114         xlist_t *prev;
 115
 116         prev = cur = list_arg;
 117         while (1) {
 118                 if (!cur) break;
 119                 prev = cur;
 120                 line_l += cur->length;
 121                 cur = cur->link;
 122         }
 123
 124         while (!eof_stdin_detected) {
 125                 c = getchar();
 126                 if (c == EOF) {
 127                         eof_stdin_detected = 1;
 128                         if (s)
 129                                 goto unexpected_eof;
 130                         break;
 131                 }
 132                 if (eof_str_detected)
 133                         continue;
 134                 if (state == BACKSLASH) {
 135                         state = NORM;
 136                         goto set;
 137                 } else if (state == QUOTE) {
 138                         if (c != q)
 139                                 goto set;
 140                         q = '\0';
 141                         state = NORM;
 142                 } else { /* if (state == NORM) */
 143                         if (ISSPACE(c)) {
 144                                 if (s) {
 145  unexpected_eof:
 146                                         state = SPACE;
 147                                         c = '\0';
 148                                         goto set;
 149                                 }
 150                         } else {
 151                                 if (s == NULL)
 152                                         s = p = buf;
 153                                 if (c == '\\') {
 154                                         state = BACKSLASH;
 155                                 } else if (c == '\'' || c == '"') {
 156                                         q = c;
 157                                         state = QUOTE;
 158                                 } else {
 159  set:
 160                                         if ((size_t)(p - buf) >= mc)
 161                                                 bb_error_msg_and_die("argument line too long");
 162                                         *p++ = c;
 163                                 }
 164                         }
 165                 }
 166                 if (state == SPACE) {   /* word's delimiter or EOF detected */
 167                         if (q) {
 168                                 bb_error_msg_and_die("unmatched %s quote",
 169                                         q == '\'' ? "single" : "double");
 170                         }
 171                         /* word loaded */
 172                         if (eof_str) {
 173                                 eof_str_detected = (strcmp(s, eof_str) == 0);
 174                         }
 175                         if (!eof_str_detected) {
 176                                 size_t length = (p - buf);
 177                                 /* Dont xzalloc - it can be quite big */
 178                                 cur = xmalloc(offsetof(xlist_t, xstr) + length);
 179                                 cur->link = NULL;
 180                                 cur->length = length;
 181                                 memcpy(cur->xstr, s, length);
 182                                 if (prev == NULL) {
 183                                         list_arg = cur;
 184                                 } else {
 185                                         prev->link = cur;
 186                                 }
 187                                 prev = cur;
 188                                 line_l += length;
 189                                 if (line_l > mc) {
 190                                         /* stop memory usage :-) */
 191                                         break;
 192                                 }
 193                         }
 194                         s = NULL;
 195                         state = NORM;
 196                 }
 197         }
 198         return list_arg;
 199 }
 200 #else
 201 /* The variant does not support single quotes, double quotes or backslash */
 202 static xlist_t *process_stdin(xlist_t *list_arg,
 203                 const char *eof_str, size_t mc, char *buf)
 204 {
 205
 206         int c;                  /* current char */
 207         char eof_str_detected = 0;
 208         char *s = NULL;         /* start word */
 209         char *p = NULL;         /* pointer to end word */
 210         size_t line_l = 0;      /* size loaded args line */
 211         xlist_t *cur;
 212         xlist_t *prev;
 213
 214         prev = cur = list_arg;
 215         while (1) {
 216                 if (!cur) break;
 217                 prev = cur;
 218                 line_l += cur->length;
 219                 cur = cur->link;
 220         }
 221
 222         while (!eof_stdin_detected) {
 223                 c = getchar();
 224                 if (c == EOF) {
 225                         eof_stdin_detected = 1;
 226                 }
 227                 if (eof_str_detected)
 228                         continue;
 229                 if (c == EOF || ISSPACE(c)) {
 230                         if (s == NULL)
 231                                 continue;
 232                         c = EOF;
 233                 }
 234                 if (s == NULL)
 235                         s = p = buf;
 236                 if ((size_t)(p - buf) >= mc)
 237                         bb_error_msg_and_die("argument line too long");
 238                 *p++ = (c == EOF ? '\0' : c);
 239                 if (c == EOF) { /* word's delimiter or EOF detected */
 240                         /* word loaded */
 241                         if (eof_str) {
 242                                 eof_str_detected = (strcmp(s, eof_str) == 0);
 243                         }
 244                         if (!eof_str_detected) {
 245                                 size_t length = (p - buf);
 246                                 /* Dont xzalloc - it can be quite big */
 247                                 cur = xmalloc(offsetof(xlist_t, xstr) + length);
 248                                 cur->link = NULL;
 249                                 cur->length = length;
 250                                 memcpy(cur->xstr, s, length);
 251                                 if (prev == NULL) {
 252                                         list_arg = cur;
 253                                 } else {
 254                                         prev->link = cur;
 255                                 }
 256                                 prev = cur;
 257                                 line_l += length;
 258                                 if (line_l > mc) {
 259                                         /* stop memory usage :-) */
 260                                         break;
 261                                 }
 262                                 s = NULL;
 263                         }
 264                 }
 265         }
 266         return list_arg;
 267 }
 268 #endif /* FEATURE_XARGS_SUPPORT_QUOTES */
 269
 270
 271 #if ENABLE_FEATURE_XARGS_SUPPORT_CONFIRMATION
 272 /* Prompt the user for a response, and
 273    if the user responds affirmatively, return true;
 274    otherwise, return false. Uses "/dev/tty", not stdin. */
 275 static int xargs_ask_confirmation(void)
 276 {
 277         FILE *tty_stream;
 278         int c, savec;
 279
 280         tty_stream = xfopen_for_read(CURRENT_TTY);
 281         fputs(" ?...", stderr);
 282         fflush(stderr);
 283         c = savec = getc(tty_stream);
 284         while (c != EOF && c != '\n')
 285                 c = getc(tty_stream);
 286         fclose(tty_stream);
 287         return (savec == 'y' || savec == 'Y');
 288 }
 289 #else
 290 # define xargs_ask_confirmation() 1
 291 #endif /* FEATURE_XARGS_SUPPORT_CONFIRMATION */
 292
 293 #if ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
 294 static xlist_t *process0_stdin(xlist_t *list_arg,
 295                 const char *eof_str UNUSED_PARAM, size_t mc, char *buf)
 296 {
 297         int c;                  /* current char */
 298         char *s = NULL;         /* start word */
 299         char *p = NULL;         /* pointer to end word */
 300         size_t line_l = 0;      /* size loaded args line */
 301         xlist_t *cur;
 302         xlist_t *prev;
 303
 304         prev = cur = list_arg;
 305         while (1) {
 306                 if (!cur) break;
 307                 prev = cur;
 308                 line_l += cur->length;
 309                 cur = cur->link;
 310         }
 311
 312         while (!eof_stdin_detected) {
 313                 c = getchar();
 314                 if (c == EOF) {
 315                         eof_stdin_detected = 1;
 316                         if (s == NULL)
 317                                 break;
 318                         c = '\0';
 319                 }
 320                 if (s == NULL)
 321                         s = p = buf;
 322                 if ((size_t)(p - buf) >= mc)
 323                         bb_error_msg_and_die("argument line too long");
 324                 *p++ = c;
 325                 if (c == '\0') {   /* word's delimiter or EOF detected */
 326                         /* word loaded */
 327                         size_t length = (p - buf);
 328                         /* Dont xzalloc - it can be quite big */
 329                         cur = xmalloc(offsetof(xlist_t, xstr) + length);
 330                         cur->link = NULL;
 331                         cur->length = length;
 332                         memcpy(cur->xstr, s, length);
 333                         if (prev == NULL) {
 334                                 list_arg = cur;
 335                         } else {
 336                                 prev->link = cur;
 337                         }
 338                         prev = cur;
 339                         line_l += length;
 340                         if (line_l > mc) {
 341                                 /* stop memory usage :-) */
 342                                 break;
 343                         }
 344                         s = NULL;
 345                 }
 346         }
 347         return list_arg;
 348 }
 349 #endif /* FEATURE_XARGS_SUPPORT_ZERO_TERM */
 350
 351 /* Correct regardless of combination of CONFIG_xxx */
 352 enum {
 353         OPTBIT_VERBOSE = 0,
 354         OPTBIT_NO_EMPTY,
 355         OPTBIT_UPTO_NUMBER,
 356         OPTBIT_UPTO_SIZE,
 357         OPTBIT_EOF_STRING,
 358         OPTBIT_EOF_STRING1,
 359         USE_FEATURE_XARGS_SUPPORT_CONFIRMATION(OPTBIT_INTERACTIVE,)
 360         USE_FEATURE_XARGS_SUPPORT_TERMOPT(     OPTBIT_TERMINATE  ,)
 361         USE_FEATURE_XARGS_SUPPORT_ZERO_TERM(   OPTBIT_ZEROTERM   ,)
 362
 363         OPT_VERBOSE     = 1 << OPTBIT_VERBOSE    ,
 364         OPT_NO_EMPTY    = 1 << OPTBIT_NO_EMPTY   ,
 365         OPT_UPTO_NUMBER = 1 << OPTBIT_UPTO_NUMBER,
 366         OPT_UPTO_SIZE   = 1 << OPTBIT_UPTO_SIZE  ,
 367         OPT_EOF_STRING  = 1 << OPTBIT_EOF_STRING , /* GNU: -e[<param>] */
 368         OPT_EOF_STRING1 = 1 << OPTBIT_EOF_STRING1, /* SUS: -E<param> */
 369         OPT_INTERACTIVE = USE_FEATURE_XARGS_SUPPORT_CONFIRMATION((1 << OPTBIT_INTERACTIVE)) + 0,
 370         OPT_TERMINATE   = USE_FEATURE_XARGS_SUPPORT_TERMOPT(     (1 << OPTBIT_TERMINATE  )) + 0,
 371         OPT_ZEROTERM    = USE_FEATURE_XARGS_SUPPORT_ZERO_TERM(   (1 << OPTBIT_ZEROTERM   )) + 0,
 372 };
 373 #define OPTION_STR "+trn:s:e::E:" \
 374         USE_FEATURE_XARGS_SUPPORT_CONFIRMATION("p") \
 375         USE_FEATURE_XARGS_SUPPORT_TERMOPT(     "x") \
 376         USE_FEATURE_XARGS_SUPPORT_ZERO_TERM(   "0")
 377
 378 int xargs_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 379 int xargs_main(int argc, char **argv)
 380 {
 381         char **args;
 382         int i, n;
 383         xlist_t *list = NULL;
 384         xlist_t *cur;
 385         int child_error = 0;
 386         char *max_args, *max_chars;
 387         int n_max_arg;
 388         size_t n_chars = 0;
 389         long orig_arg_max;
 390         const char *eof_str = NULL;
 391         unsigned opt;
 392         size_t n_max_chars;
 393 #if ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
 394         xlist_t* (*read_args)(xlist_t*, const char*, size_t, char*) = process_stdin;
 395 #else
 396 #define read_args process_stdin
 397 #endif
 398
 399         opt = getopt32(argv, OPTION_STR, &max_args, &max_chars, &eof_str, &eof_str);
 400
 401         /* -E ""? You may wonder why not just omit -E?
 402          * This is used for portability:
 403          * old xargs was using "_" as default for -E / -e */
 404         if ((opt & OPT_EOF_STRING1) && eof_str[0] == '\0')
 405                 eof_str = NULL;
 406
 407         if (opt & OPT_ZEROTERM)
 408                 USE_FEATURE_XARGS_SUPPORT_ZERO_TERM(read_args = process0_stdin);
 409
 410         argv += optind;
 411         argc -= optind;
 412         if (!argc) {
 413                 /* default behavior is to echo all the filenames */
 414                 *argv = (char*)"echo";
 415                 argc++;
 416         }
 417
 418         orig_arg_max = ARG_MAX;
 419         if (orig_arg_max == -1)
 420                 orig_arg_max = LONG_MAX;
 421         orig_arg_max -= 2048;   /* POSIX.2 requires subtracting 2048 */
 422
 423         if (opt & OPT_UPTO_SIZE) {
 424                 n_max_chars = xatoul_range(max_chars, 1, orig_arg_max);
 425                 for (i = 0; i < argc; i++) {
 426                         n_chars += strlen(*argv) + 1;
 427                 }
 428                 if (n_max_chars < n_chars) {
 429                         bb_error_msg_and_die("cannot fit single argument within argument list size limit");
 430                 }
 431                 n_max_chars -= n_chars;
 432         } else {
 433                 /* Sanity check for systems with huge ARG_MAX defines (e.g., Suns which
 434                    have it at 1 meg).  Things will work fine with a large ARG_MAX but it
 435                    will probably hurt the system more than it needs to; an array of this
 436                    size is allocated.  */
 437                 if (orig_arg_max > 20 * 1024)
 438                         orig_arg_max = 20 * 1024;
 439                 n_max_chars = orig_arg_max;
 440         }
 441         max_chars = xmalloc(n_max_chars);
 442
 443         if (opt & OPT_UPTO_NUMBER) {
 444                 n_max_arg = xatoul_range(max_args, 1, INT_MAX);
 445         } else {
 446                 n_max_arg = n_max_chars;
 447         }
 448
 449         while ((list = read_args(list, eof_str, n_max_chars, max_chars)) != NULL ||
 450                 !(opt & OPT_NO_EMPTY))
 451         {
 452                 opt |= OPT_NO_EMPTY;
 453                 n = 0;
 454                 n_chars = 0;
 455 #if ENABLE_FEATURE_XARGS_SUPPORT_TERMOPT
 456                 for (cur = list; cur;) {
 457                         n_chars += cur->length;
 458                         n++;
 459                         cur = cur->link;
 460                         if (n_chars > n_max_chars || (n == n_max_arg && cur)) {
 461                                 if (opt & OPT_TERMINATE)
 462                                         bb_error_msg_and_die("argument list too long");
 463                                 break;
 464                         }
 465                 }
 466 #else
 467                 for (cur = list; cur; cur = cur->link) {
 468                         n_chars += cur->length;
 469                         n++;
 470                         if (n_chars > n_max_chars || n == n_max_arg) {
 471                                 break;
 472                         }
 473                 }
 474 #endif /* FEATURE_XARGS_SUPPORT_TERMOPT */
 475
 476                 /* allocate pointers for execvp:
 477                    argc*arg, n*arg from stdin, NULL */
 478                 args = xzalloc((n + argc + 1) * sizeof(char *));
 479
 480                 /* store the command to be executed
 481                    (taken from the command line) */
 482                 for (i = 0; i < argc; i++)
 483                         args[i] = argv[i];
 484                 /* (taken from stdin) */
 485                 for (cur = list; n; cur = cur->link) {
 486                         args[i++] = cur->xstr;
 487                         n--;
 488                 }
 489
 490                 if (opt & (OPT_INTERACTIVE | OPT_VERBOSE)) {
 491                         for (i = 0; args[i]; i++) {
 492                                 if (i)
 493                                         fputc(' ', stderr);
 494                                 fputs(args[i], stderr);
 495                         }
 496                         if (!(opt & OPT_INTERACTIVE))
 497                                 fputc('\n', stderr);
 498                 }
 499                 if (!(opt & OPT_INTERACTIVE) || xargs_ask_confirmation()) {
 500                         child_error = xargs_exec(args);
 501                 }
 502
 503                 /* clean up */
 504                 for (i = argc; args[i]; i++) {
 505                         cur = list;
 506                         list = list->link;
 507                         free(cur);
 508                 }
 509                 free(args);
 510                 if (child_error > 0 && child_error != 123) {
 511                         break;
 512                 }
 513         } /* while */
 514         if (ENABLE_FEATURE_CLEAN_UP)
 515                 free(max_chars);
 516         return child_error;
 517 }
 518
 519
 520 #ifdef TEST
 521
 522 const char *applet_name = "debug stuff usage";
 523
 524 void bb_show_usage(void)
 525 {
 526         fprintf(stderr, "Usage: %s [-p] [-r] [-t] -[x] [-n max_arg] [-s max_chars]\n",
 527                 applet_name);
 528         exit(EXIT_FAILURE);
 529 }
 530
 531 int main(int argc, char **argv)
 532 {
 533         return xargs_main(argc, argv);
 534 }
 535 #endif /* TEST */