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 #if !defined(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         if (status >= 0x180) {
  68                 bb_error_msg("%s: terminated by signal %d",
  69                         args[0], status - 0x180);
  70                 return 125;
  71         }
  72         if (status)
  73                 return 123;
  74         return 0;
  75 }
  76
  77
  78 typedef struct xlist_t {
  79         struct xlist_t *link;
  80         size_t length;
  81         char xstr[1];
  82 } xlist_t;
  83
  84 static smallint eof_stdin_detected;
  85
  86 #define ISBLANK(c) ((c) == ' ' || (c) == '\t')
  87 #define ISSPACE(c) (ISBLANK(c) || (c) == '\n' || (c) == '\r' \
  88                     || (c) == '\f' || (c) == '\v')
  89
  90 #if ENABLE_FEATURE_XARGS_SUPPORT_QUOTES
  91 static xlist_t *process_stdin(xlist_t *list_arg,
  92         const char *eof_str, size_t mc, char *buf)
  93 {
  94 #define NORM      0
  95 #define QUOTE     1
  96 #define BACKSLASH 2
  97 #define SPACE     4
  98
  99         char *s = NULL;         /* start word */
 100         char *p = NULL;         /* pointer to end word */
 101         char q = '\0';          /* quote char */
 102         char state = NORM;
 103         char eof_str_detected = 0;
 104         size_t line_l = 0;      /* size loaded args line */
 105         int c;                  /* current char */
 106         xlist_t *cur;
 107         xlist_t *prev;
 108
 109         prev = cur = list_arg;
 110         while (1) {
 111                 if (!cur) break;
 112                 prev = cur;
 113                 line_l += cur->length;
 114                 cur = cur->link;
 115         }
 116
 117         while (!eof_stdin_detected) {
 118                 c = getchar();
 119                 if (c == EOF) {
 120                         eof_stdin_detected = 1;
 121                         if (s)
 122                                 goto unexpected_eof;
 123                         break;
 124                 }
 125                 if (eof_str_detected)
 126                         continue;
 127                 if (state == BACKSLASH) {
 128                         state = NORM;
 129                         goto set;
 130                 } else if (state == QUOTE) {
 131                         if (c != q)
 132                                 goto set;
 133                         q = '\0';
 134                         state = NORM;
 135                 } else { /* if (state == NORM) */
 136                         if (ISSPACE(c)) {
 137                                 if (s) {
 138  unexpected_eof:
 139                                         state = SPACE;
 140                                         c = '\0';
 141                                         goto set;
 142                                 }
 143                         } else {
 144                                 if (s == NULL)
 145                                         s = p = buf;
 146                                 if (c == '\\') {
 147                                         state = BACKSLASH;
 148                                 } else if (c == '\'' || c == '"') {
 149                                         q = c;
 150                                         state = QUOTE;
 151                                 } else {
 152  set:
 153                                         if ((size_t)(p - buf) >= mc)
 154                                                 bb_error_msg_and_die("argument line too long");
 155                                         *p++ = c;
 156                                 }
 157                         }
 158                 }
 159                 if (state == SPACE) {   /* word's delimiter or EOF detected */
 160                         if (q) {
 161                                 bb_error_msg_and_die("unmatched %s quote",
 162                                         q == '\'' ? "single" : "double");
 163                         }
 164                         /* word loaded */
 165                         if (eof_str) {
 166                                 eof_str_detected = (strcmp(s, eof_str) == 0);
 167                         }
 168                         if (!eof_str_detected) {
 169                                 size_t length = (p - buf);
 170                                 /* Dont xzalloc - it can be quite big */
 171                                 cur = xmalloc(offsetof(xlist_t, xstr) + length);
 172                                 cur->link = NULL;
 173                                 cur->length = length;
 174                                 memcpy(cur->xstr, s, length);
 175                                 if (prev == NULL) {
 176                                         list_arg = cur;
 177                                 } else {
 178                                         prev->link = cur;
 179                                 }
 180                                 prev = cur;
 181                                 line_l += length;
 182                                 if (line_l > mc) {
 183                                         /* stop memory usage :-) */
 184                                         break;
 185                                 }
 186                         }
 187                         s = NULL;
 188                         state = NORM;
 189                 }
 190         }
 191         return list_arg;
 192 }
 193 #else
 194 /* The variant does not support single quotes, double quotes or backslash */
 195 static xlist_t *process_stdin(xlist_t *list_arg,
 196                 const char *eof_str, size_t mc, char *buf)
 197 {
 198
 199         int c;                  /* current char */
 200         char eof_str_detected = 0;
 201         char *s = NULL;         /* start word */
 202         char *p = NULL;         /* pointer to end word */
 203         size_t line_l = 0;      /* size loaded args line */
 204         xlist_t *cur;
 205         xlist_t *prev;
 206
 207         prev = cur = list_arg;
 208         while (1) {
 209                 if (!cur) break;
 210                 prev = cur;
 211                 line_l += cur->length;
 212                 cur = cur->link;
 213         }
 214
 215         while (!eof_stdin_detected) {
 216                 c = getchar();
 217                 if (c == EOF) {
 218                         eof_stdin_detected = 1;
 219                 }
 220                 if (eof_str_detected)
 221                         continue;
 222                 if (c == EOF || ISSPACE(c)) {
 223                         if (s == NULL)
 224                                 continue;
 225                         c = EOF;
 226                 }
 227                 if (s == NULL)
 228                         s = p = buf;
 229                 if ((size_t)(p - buf) >= mc)
 230                         bb_error_msg_and_die("argument line too long");
 231                 *p++ = (c == EOF ? '\0' : c);
 232                 if (c == EOF) { /* word's delimiter or EOF detected */
 233                         /* word loaded */
 234                         if (eof_str) {
 235                                 eof_str_detected = (strcmp(s, eof_str) == 0);
 236                         }
 237                         if (!eof_str_detected) {
 238                                 size_t length = (p - buf);
 239                                 /* Dont xzalloc - it can be quite big */
 240                                 cur = xmalloc(offsetof(xlist_t, xstr) + length);
 241                                 cur->link = NULL;
 242                                 cur->length = length;
 243                                 memcpy(cur->xstr, s, length);
 244                                 if (prev == NULL) {
 245                                         list_arg = cur;
 246                                 } else {
 247                                         prev->link = cur;
 248                                 }
 249                                 prev = cur;
 250                                 line_l += length;
 251                                 if (line_l > mc) {
 252                                         /* stop memory usage :-) */
 253                                         break;
 254                                 }
 255                                 s = NULL;
 256                         }
 257                 }
 258         }
 259         return list_arg;
 260 }
 261 #endif /* FEATURE_XARGS_SUPPORT_QUOTES */
 262
 263
 264 #if ENABLE_FEATURE_XARGS_SUPPORT_CONFIRMATION
 265 /* Prompt the user for a response, and
 266    if the user responds affirmatively, return true;
 267    otherwise, return false. Uses "/dev/tty", not stdin. */
 268 static int xargs_ask_confirmation(void)
 269 {
 270         FILE *tty_stream;
 271         int c, savec;
 272
 273         tty_stream = xfopen_for_read(CURRENT_TTY);
 274         fputs(" ?...", stderr);
 275         fflush_all();
 276         c = savec = getc(tty_stream);
 277         while (c != EOF && c != '\n')
 278                 c = getc(tty_stream);
 279         fclose(tty_stream);
 280         return (savec == 'y' || savec == 'Y');
 281 }
 282 #else
 283 # define xargs_ask_confirmation() 1
 284 #endif /* FEATURE_XARGS_SUPPORT_CONFIRMATION */
 285
 286 #if ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
 287 static xlist_t *process0_stdin(xlist_t *list_arg,
 288                 const char *eof_str UNUSED_PARAM, size_t mc, char *buf)
 289 {
 290         int c;                  /* current char */
 291         char *s = NULL;         /* start word */
 292         char *p = NULL;         /* pointer to end word */
 293         size_t line_l = 0;      /* size loaded args line */
 294         xlist_t *cur;
 295         xlist_t *prev;
 296
 297         prev = cur = list_arg;
 298         while (1) {
 299                 if (!cur) break;
 300                 prev = cur;
 301                 line_l += cur->length;
 302                 cur = cur->link;
 303         }
 304
 305         while (!eof_stdin_detected) {
 306                 c = getchar();
 307                 if (c == EOF) {
 308                         eof_stdin_detected = 1;
 309                         if (s == NULL)
 310                                 break;
 311                         c = '\0';
 312                 }
 313                 if (s == NULL)
 314                         s = p = buf;
 315                 if ((size_t)(p - buf) >= mc)
 316                         bb_error_msg_and_die("argument line too long");
 317                 *p++ = c;
 318                 if (c == '\0') {   /* word's delimiter or EOF detected */
 319                         /* word loaded */
 320                         size_t length = (p - buf);
 321                         /* Dont xzalloc - it can be quite big */
 322                         cur = xmalloc(offsetof(xlist_t, xstr) + length);
 323                         cur->link = NULL;
 324                         cur->length = length;
 325                         memcpy(cur->xstr, s, length);
 326                         if (prev == NULL) {
 327                                 list_arg = cur;
 328                         } else {
 329                                 prev->link = cur;
 330                         }
 331                         prev = cur;
 332                         line_l += length;
 333                         if (line_l > mc) {
 334                                 /* stop memory usage :-) */
 335                                 break;
 336                         }
 337                         s = NULL;
 338                 }
 339         }
 340         return list_arg;
 341 }
 342 #endif /* FEATURE_XARGS_SUPPORT_ZERO_TERM */
 343
 344 /* Correct regardless of combination of CONFIG_xxx */
 345 enum {
 346         OPTBIT_VERBOSE = 0,
 347         OPTBIT_NO_EMPTY,
 348         OPTBIT_UPTO_NUMBER,
 349         OPTBIT_UPTO_SIZE,
 350         OPTBIT_EOF_STRING,
 351         OPTBIT_EOF_STRING1,
 352         IF_FEATURE_XARGS_SUPPORT_CONFIRMATION(OPTBIT_INTERACTIVE,)
 353         IF_FEATURE_XARGS_SUPPORT_TERMOPT(     OPTBIT_TERMINATE  ,)
 354         IF_FEATURE_XARGS_SUPPORT_ZERO_TERM(   OPTBIT_ZEROTERM   ,)
 355
 356         OPT_VERBOSE     = 1 << OPTBIT_VERBOSE    ,
 357         OPT_NO_EMPTY    = 1 << OPTBIT_NO_EMPTY   ,
 358         OPT_UPTO_NUMBER = 1 << OPTBIT_UPTO_NUMBER,
 359         OPT_UPTO_SIZE   = 1 << OPTBIT_UPTO_SIZE  ,
 360         OPT_EOF_STRING  = 1 << OPTBIT_EOF_STRING , /* GNU: -e[<param>] */
 361         OPT_EOF_STRING1 = 1 << OPTBIT_EOF_STRING1, /* SUS: -E<param> */
 362         OPT_INTERACTIVE = IF_FEATURE_XARGS_SUPPORT_CONFIRMATION((1 << OPTBIT_INTERACTIVE)) + 0,
 363         OPT_TERMINATE   = IF_FEATURE_XARGS_SUPPORT_TERMOPT(     (1 << OPTBIT_TERMINATE  )) + 0,
 364         OPT_ZEROTERM    = IF_FEATURE_XARGS_SUPPORT_ZERO_TERM(   (1 << OPTBIT_ZEROTERM   )) + 0,
 365 };
 366 #define OPTION_STR "+trn:s:e::E:" \
 367         IF_FEATURE_XARGS_SUPPORT_CONFIRMATION("p") \
 368         IF_FEATURE_XARGS_SUPPORT_TERMOPT(     "x") \
 369         IF_FEATURE_XARGS_SUPPORT_ZERO_TERM(   "0")
 370
 371 int xargs_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 372 int xargs_main(int argc, char **argv)
 373 {
 374         char **args;
 375         int i, n;
 376         xlist_t *list = NULL;
 377         xlist_t *cur;
 378         int child_error = 0;
 379         char *max_args, *max_chars;
 380         int n_max_arg;
 381         const char *eof_str = NULL;
 382         unsigned opt;
 383         size_t n_max_chars;
 384 #if ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
 385         xlist_t* (*read_args)(xlist_t*, const char*, size_t, char*) = process_stdin;
 386 #else
 387 #define read_args process_stdin
 388 #endif
 389
 390         opt = getopt32(argv, OPTION_STR, &max_args, &max_chars, &eof_str, &eof_str);
 391
 392         /* -E ""? You may wonder why not just omit -E?
 393          * This is used for portability:
 394          * old xargs was using "_" as default for -E / -e */
 395         if ((opt & OPT_EOF_STRING1) && eof_str[0] == '\0')
 396                 eof_str = NULL;
 397
 398         if (opt & OPT_ZEROTERM)
 399                 IF_FEATURE_XARGS_SUPPORT_ZERO_TERM(read_args = process0_stdin);
 400
 401         argv += optind;
 402         argc -= optind;
 403         if (!argc) {
 404                 /* default behavior is to echo all the filenames */
 405                 *argv = (char*)"echo";
 406                 argc++;
 407         }
 408
 409         n_max_chars = ARG_MAX; /* might be calling sysconf(_SC_ARG_MAX) */
 410         if (n_max_chars < 4*1024); /* paranoia */
 411                 n_max_chars = LONG_MAX;
 412         /* The Open Group Base Specifications Issue 6:
 413          * "The xargs utility shall limit the command line length such that
 414          * when the command line is invoked, the combined argument
 415          * and environment lists (see the exec family of functions
 416          * in the System Interfaces volume of IEEE Std 1003.1-2001)
 417          * shall not exceed {ARG_MAX}-2048 bytes".
 418          */
 419         n_max_chars -= 2048;
 420         /* Sanity check for systems with huge ARG_MAX defines (e.g., Suns which
 421          * have it at 1 meg).  Things will work fine with a large ARG_MAX but it
 422          * will probably hurt the system more than it needs to; an array of this
 423          * size is allocated.
 424          */
 425         if (n_max_chars > 20 * 1024)
 426                 n_max_chars = 20 * 1024;
 427
 428         if (opt & OPT_UPTO_SIZE) {
 429                 size_t n_chars = 0;
 430                 n_max_chars = xatoul_range(max_chars, 1, n_max_chars);
 431                 for (i = 0; i < argc; i++) {
 432                         n_chars += strlen(*argv) + 1;
 433                 }
 434                 if (n_max_chars <= n_chars) {
 435                         bb_error_msg_and_die("can't fit single argument within argument list size limit");
 436                 }
 437                 n_max_chars -= n_chars;
 438         }
 439         max_chars = xmalloc(n_max_chars);
 440
 441         if (opt & OPT_UPTO_NUMBER) {
 442                 n_max_arg = xatoul_range(max_args, 1, INT_MAX);
 443         } else {
 444                 n_max_arg = n_max_chars;
 445         }
 446
 447         while ((list = read_args(list, eof_str, n_max_chars, max_chars)) != NULL ||
 448                 !(opt & OPT_NO_EMPTY))
 449         {
 450                 size_t n_chars = 0;
 451                 opt |= OPT_NO_EMPTY;
 452                 n = 0;
 453 #if ENABLE_FEATURE_XARGS_SUPPORT_TERMOPT
 454                 for (cur = list; cur;) {
 455                         n_chars += cur->length;
 456                         n++;
 457                         cur = cur->link;
 458                         if (n_chars > n_max_chars || (n == n_max_arg && cur)) {
 459                                 if (opt & OPT_TERMINATE)
 460                                         bb_error_msg_and_die("argument list too long");
 461                                 break;
 462                         }
 463                 }
 464 #else
 465                 for (cur = list; cur; cur = cur->link) {
 466                         n_chars += cur->length;
 467                         n++;
 468                         if (n_chars > n_max_chars || n == n_max_arg) {
 469                                 break;
 470                         }
 471                 }
 472 #endif /* FEATURE_XARGS_SUPPORT_TERMOPT */
 473
 474                 /* allocate pointers for execvp:
 475                    argc*arg, n*arg from stdin, NULL */
 476                 args = xzalloc((n + argc + 1) * sizeof(char *));
 477
 478                 /* store the command to be executed
 479                    (taken from the command line) */
 480                 for (i = 0; i < argc; i++)
 481                         args[i] = argv[i];
 482                 /* (taken from stdin) */
 483                 for (cur = list; n; cur = cur->link) {
 484                         args[i++] = cur->xstr;
 485                         n--;
 486                 }
 487
 488                 if (opt & (OPT_INTERACTIVE | OPT_VERBOSE)) {
 489                         for (i = 0; args[i]; i++) {
 490                                 if (i)
 491                                         fputc(' ', stderr);
 492                                 fputs(args[i], stderr);
 493                         }
 494                         if (!(opt & OPT_INTERACTIVE))
 495                                 fputc('\n', stderr);
 496                 }
 497                 if (!(opt & OPT_INTERACTIVE) || xargs_ask_confirmation()) {
 498                         child_error = xargs_exec(args);
 499                 }
 500
 501                 /* clean up */
 502                 for (i = argc; args[i]; i++) {
 503                         cur = list;
 504                         list = list->link;
 505                         free(cur);
 506                 }
 507                 free(args);
 508                 if (child_error > 0 && child_error != 123) {
 509                         break;
 510                 }
 511         } /* while */
 512         if (ENABLE_FEATURE_CLEAN_UP)
 513                 free(max_chars);
 514         return child_error;
 515 }
 516
 517
 518 #ifdef TEST
 519
 520 const char *applet_name = "debug stuff usage";
 521
 522 void bb_show_usage(void)
 523 {
 524         fprintf(stderr, "Usage: %s [-p] [-r] [-t] -[x] [-n max_arg] [-s max_chars]\n",
 525                 applet_name);
 526         exit(EXIT_FAILURE);
 527 }
 528
 529 int main(int argc, char **argv)
 530 {
 531         return xargs_main(argc, argv);
 532 }
 533 #endif /* TEST */