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 "busybox.h"
  21
  22 /* COMPAT:  SYSV version defaults size (and has a max value of) to 470.
  23    We try to make it as large as possible. */
  24 #if !defined(ARG_MAX) && defined(_SC_ARG_MAX)
  25 #define ARG_MAX sysconf (_SC_ARG_MAX)
  26 #endif
  27 #ifndef ARG_MAX
  28 #define ARG_MAX 470
  29 #endif
  30
  31
  32 #ifdef TEST
  33 # ifndef ENABLE_FEATURE_XARGS_SUPPORT_CONFIRMATION
  34 #  define ENABLE_FEATURE_XARGS_SUPPORT_CONFIRMATION 1
  35 # endif
  36 # ifndef ENABLE_FEATURE_XARGS_SUPPORT_QUOTES
  37 #  define ENABLE_FEATURE_XARGS_SUPPORT_QUOTES 1
  38 # endif
  39 # ifndef ENABLE_FEATURE_XARGS_SUPPORT_TERMOPT
  40 #  define ENABLE_FEATURE_XARGS_SUPPORT_TERMOPT 1
  41 # endif
  42 # ifndef ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
  43 #  define ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM 1
  44 # endif
  45 #endif
  46
  47 /*
  48    This function has special algorithm.
  49    Don't use fork and include to main!
  50 */
  51 static int xargs_exec(char *const *args)
  52 {
  53         pid_t p;
  54         volatile int exec_errno = 0;    /* shared vfork stack */
  55         int status;
  56
  57         p = vfork();
  58         if (p < 0)
  59                 bb_perror_msg_and_die("vfork");
  60
  61         if (p == 0) {
  62                 /* vfork -- child */
  63                 BB_EXECVP(args[0], args);
  64                 exec_errno = errno;     /* set error to shared stack */
  65                 _exit(1);
  66         }
  67
  68         /* vfork -- parent */
  69         while (wait(&status) == (pid_t) -1)
  70                 if (errno != EINTR)
  71                         break;
  72         if (exec_errno) {
  73                 errno = exec_errno;
  74                 bb_perror_msg("%s", args[0]);
  75                 return exec_errno == ENOENT ? 127 : 126;
  76         }
  77         if (WEXITSTATUS(status) == 255) {
  78                 bb_error_msg("%s: exited with status 255; aborting", args[0]);
  79                 return 124;
  80         }
  81         if (WIFSTOPPED(status)) {
  82                 bb_error_msg("%s: stopped by signal %d",
  83                         args[0], WSTOPSIG(status));
  84                 return 125;
  85         }
  86         if (WIFSIGNALED(status)) {
  87                 bb_error_msg("%s: terminated by signal %d",
  88                         args[0], WTERMSIG(status));
  89                 return 125;
  90         }
  91         if (WEXITSTATUS(status))
  92                 return 123;
  93         return 0;
  94 }
  95
  96
  97 typedef struct xlist_t {
  98         char *data;
  99         size_t length;
 100         struct xlist_t *link;
 101 } xlist_t;
 102
 103 static smallint eof_stdin_detected;
 104
 105 #define ISBLANK(c) ((c) == ' ' || (c) == '\t')
 106 #define ISSPACE(c) (ISBLANK(c) || (c) == '\n' || (c) == '\r' \
 107                     || (c) == '\f' || (c) == '\v')
 108
 109 #if ENABLE_FEATURE_XARGS_SUPPORT_QUOTES
 110 static xlist_t *process_stdin(xlist_t *list_arg,
 111         const char *eof_str, size_t mc, char *buf)
 112 {
 113 #define NORM      0
 114 #define QUOTE     1
 115 #define BACKSLASH 2
 116 #define SPACE     4
 117
 118         char *s = NULL;         /* start word */
 119         char *p = NULL;         /* pointer to end word */
 120         char q = 0;             /* quote char */
 121         char state = NORM;
 122         char eof_str_detected = 0;
 123         size_t line_l = 0;      /* size loaded args line */
 124         int c;                  /* current char */
 125         xlist_t *cur;
 126         xlist_t *prev;
 127
 128         cur = list_arg;
 129         while (1) {
 130                 prev = cur;
 131                 if (!cur) break;
 132                 line_l += cur->length;
 133                 cur = cur->link;
 134         }
 135
 136         while (!eof_stdin_detected) {
 137                 c = getchar();
 138                 if (c == EOF) {
 139                         eof_stdin_detected = 1;
 140                         if (s)
 141                                 goto unexpected_eof;
 142                         break;
 143                 }
 144                 if (eof_str_detected)
 145                         continue;
 146                 if (state == BACKSLASH) {
 147                         state = NORM;
 148                         goto set;
 149                 } else if (state == QUOTE) {
 150                         if (c == q) {
 151                                 q = 0;
 152                                 state = NORM;
 153                         } else {
 154                                 goto set;
 155                         }
 156                 } else { /* if(state == NORM) */
 157
 158                         if (ISSPACE(c)) {
 159                                 if (s) {
 160 unexpected_eof:
 161                                         state = SPACE;
 162                                         c = 0;
 163                                         goto set;
 164                                 }
 165                         } else {
 166                                 if (s == NULL)
 167                                         s = p = buf;
 168                                 if (c == '\\') {
 169                                         state = BACKSLASH;
 170                                 } else if (c == '\'' || c == '"') {
 171                                         q = c;
 172                                         state = QUOTE;
 173                                 } else {
 174 set:
 175                                         if ((size_t)(p - buf) >= mc)
 176                                                 bb_error_msg_and_die("argument line too long");
 177                                         *p++ = c;
 178                                 }
 179                         }
 180                 }
 181                 if (state == SPACE) {   /* word's delimiter or EOF detected */
 182                         if (q) {
 183                                 bb_error_msg_and_die("unmatched %s quote",
 184                                         q == '\'' ? "single" : "double");
 185                         }
 186                         /* word loaded */
 187                         if (eof_str) {
 188                                 eof_str_detected = (strcmp(s, eof_str) == 0);
 189                         }
 190                         if (!eof_str_detected) {
 191                                 size_t length = (p - buf);
 192
 193                                 cur = xzalloc(sizeof(xlist_t) + length);
 194                                 cur->data = memcpy(cur + 1, s, length);
 195                                 cur->length = length;
 196                                 /*cur->link = NULL;*/
 197                                 if (prev == NULL) {
 198                                         list_arg = cur;
 199                                 } else {
 200                                         prev->link = cur;
 201                                 }
 202                                 prev = cur;
 203                                 line_l += length;
 204                                 if (line_l > mc) {
 205                                         /* stop memory usage :-) */
 206                                         break;
 207                                 }
 208                         }
 209                         s = NULL;
 210                         state = NORM;
 211                 }
 212         }
 213         return list_arg;
 214 }
 215 #else
 216 /* The variant does not support single quotes, double quotes or backslash */
 217 static xlist_t *process_stdin(xlist_t *list_arg,
 218                 const char *eof_str, size_t mc, char *buf)
 219 {
 220
 221         int c;                  /* current char */
 222         char eof_str_detected = 0;
 223         char *s = NULL;         /* start word */
 224         char *p = NULL;         /* pointer to end word */
 225         size_t line_l = 0;      /* size loaded args line */
 226         xlist_t *cur;
 227         xlist_t *prev;
 228
 229         cur = list_arg;
 230         while (1) {
 231                 prev = cur;
 232                 if (!cur) break;
 233                 line_l += cur->length;
 234                 cur = cur->link;
 235         }
 236
 237         while (!eof_stdin_detected) {
 238                 c = getchar();
 239                 if (c == EOF) {
 240                         eof_stdin_detected = 1;
 241                 }
 242                 if (eof_str_detected)
 243                         continue;
 244                 if (c == EOF || ISSPACE(c)) {
 245                         if (s == NULL)
 246                                 continue;
 247                         c = EOF;
 248                 }
 249                 if (s == NULL)
 250                         s = p = buf;
 251                 if ((p - buf) >= mc)
 252                         bb_error_msg_and_die("argument line too long");
 253                 *p++ = c == EOF ? 0 : c;
 254                 if (c == EOF) { /* word's delimiter or EOF detected */
 255                         /* word loaded */
 256                         if (eof_str) {
 257                                 eof_str_detected = (strcmp(s, eof_str) == 0);
 258                         }
 259                         if (!eof_str_detected) {
 260                                 size_t length = (p - buf);
 261
 262                                 cur = xzalloc(sizeof(xlist_t) + length);
 263                                 cur->data = memcpy(cur + 1, s, length);
 264                                 cur->length = length;
 265                                 /*cur->link = NULL;*/
 266                                 if (prev == NULL) {
 267                                         list_arg = cur;
 268                                 } else {
 269                                         prev->link = cur;
 270                                 }
 271                                 prev = cur;
 272                                 line_l += length;
 273                                 if (line_l > mc) {
 274                                         /* stop memory usage :-) */
 275                                         break;
 276                                 }
 277                                 s = NULL;
 278                         }
 279                 }
 280         }
 281         return list_arg;
 282 }
 283 #endif /* FEATURE_XARGS_SUPPORT_QUOTES */
 284
 285
 286 #if ENABLE_FEATURE_XARGS_SUPPORT_CONFIRMATION
 287 /* Prompt the user for a response, and
 288    if the user responds affirmatively, return true;
 289    otherwise, return false. Uses "/dev/tty", not stdin. */
 290 static int xargs_ask_confirmation(void)
 291 {
 292         FILE *tty_stream;
 293         int c, savec;
 294
 295         tty_stream = xfopen(CURRENT_TTY, "r");
 296         fputs(" ?...", stderr);
 297         fflush(stderr);
 298         c = savec = getc(tty_stream);
 299         while (c != EOF && c != '\n')
 300                 c = getc(tty_stream);
 301         fclose(tty_stream);
 302         return (savec == 'y' || savec == 'Y');
 303 }
 304 #else
 305 # define xargs_ask_confirmation() 1
 306 #endif /* FEATURE_XARGS_SUPPORT_CONFIRMATION */
 307
 308 #if ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
 309 static xlist_t *process0_stdin(xlist_t *list_arg,
 310                 const char *eof_str ATTRIBUTE_UNUSED, size_t mc, char *buf)
 311 {
 312         int c;                  /* current char */
 313         char *s = NULL;         /* start word */
 314         char *p = NULL;         /* pointer to end word */
 315         size_t line_l = 0;      /* size loaded args line */
 316         xlist_t *cur;
 317         xlist_t *prev;
 318
 319         cur = list_arg;
 320         while (1) {
 321                 prev = cur;
 322                 if (!cur) break;
 323                 line_l += cur->length;
 324                 cur = cur->link;
 325         }
 326
 327         while (!eof_stdin_detected) {
 328                 c = getchar();
 329                 if (c == EOF) {
 330                         eof_stdin_detected = 1;
 331                         if (s == NULL)
 332                                 break;
 333                         c = 0;
 334                 }
 335                 if (s == NULL)
 336                         s = p = buf;
 337                 if ((size_t)(p - buf) >= mc)
 338                         bb_error_msg_and_die("argument line too long");
 339                 *p++ = c;
 340                 if (c == 0) {   /* word's delimiter or EOF detected */
 341                         /* word loaded */
 342                         size_t length = (p - buf);
 343
 344                         cur = xzalloc(sizeof(xlist_t) + length);
 345                         cur->data = memcpy(cur + 1, s, length);
 346                         cur->length = length;
 347                         /*cur->link = NULL;*/
 348                         if (prev == NULL) {
 349                                 list_arg = cur;
 350                         } else {
 351                                 prev->link = cur;
 352                         }
 353                         prev = cur;
 354                         line_l += length;
 355                         if (line_l > mc) {
 356                                 /* stop memory usage :-) */
 357                                 break;
 358                         }
 359                         s = NULL;
 360                 }
 361         }
 362         return list_arg;
 363 }
 364 #endif /* FEATURE_XARGS_SUPPORT_ZERO_TERM */
 365
 366 /* Correct regardless of combination of CONFIG_xxx */
 367 enum {
 368         OPTBIT_VERBOSE = 0,
 369         OPTBIT_NO_EMPTY,
 370         OPTBIT_UPTO_NUMBER,
 371         OPTBIT_UPTO_SIZE,
 372         OPTBIT_EOF_STRING,
 373         USE_FEATURE_XARGS_SUPPORT_CONFIRMATION(OPTBIT_INTERACTIVE,)
 374         USE_FEATURE_XARGS_SUPPORT_TERMOPT(     OPTBIT_TERMINATE  ,)
 375         USE_FEATURE_XARGS_SUPPORT_ZERO_TERM(   OPTBIT_ZEROTERM   ,)
 376
 377         OPT_VERBOSE     = 1<<OPTBIT_VERBOSE    ,
 378         OPT_NO_EMPTY    = 1<<OPTBIT_NO_EMPTY   ,
 379         OPT_UPTO_NUMBER = 1<<OPTBIT_UPTO_NUMBER,
 380         OPT_UPTO_SIZE   = 1<<OPTBIT_UPTO_SIZE  ,
 381         OPT_EOF_STRING  = 1<<OPTBIT_EOF_STRING ,
 382         OPT_INTERACTIVE = USE_FEATURE_XARGS_SUPPORT_CONFIRMATION((1<<OPTBIT_INTERACTIVE)) + 0,
 383         OPT_TERMINATE   = USE_FEATURE_XARGS_SUPPORT_TERMOPT(     (1<<OPTBIT_TERMINATE  )) + 0,
 384         OPT_ZEROTERM    = USE_FEATURE_XARGS_SUPPORT_ZERO_TERM(   (1<<OPTBIT_ZEROTERM   )) + 0,
 385 };
 386 #define OPTION_STR "+trn:s:e::" \
 387         USE_FEATURE_XARGS_SUPPORT_CONFIRMATION("p") \
 388         USE_FEATURE_XARGS_SUPPORT_TERMOPT(     "x") \
 389         USE_FEATURE_XARGS_SUPPORT_ZERO_TERM(   "0")
 390
 391 int xargs_main(int argc, char **argv);
 392 int xargs_main(int argc, char **argv)
 393 {
 394         char **args;
 395         int i, n;
 396         xlist_t *list = NULL;
 397         xlist_t *cur;
 398         int child_error = 0;
 399         char *max_args, *max_chars;
 400         int n_max_arg;
 401         size_t n_chars = 0;
 402         long orig_arg_max;
 403         const char *eof_str = "_";
 404         unsigned opt;
 405         size_t n_max_chars;
 406 #if ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
 407         xlist_t* (*read_args)(xlist_t*, const char*, size_t, char*) = process_stdin;
 408 #else
 409 #define read_args process_stdin
 410 #endif
 411
 412         opt = getopt32(argc, argv, OPTION_STR, &max_args, &max_chars, &eof_str);
 413
 414         if (opt & OPT_ZEROTERM)
 415                 USE_FEATURE_XARGS_SUPPORT_ZERO_TERM(read_args = process0_stdin);
 416
 417         argv += optind;
 418         argc -= optind;
 419         if (!argc) {
 420                 /* default behavior is to echo all the filenames */
 421                 *argv = (char*)"echo";
 422                 argc++;
 423         }
 424
 425         orig_arg_max = ARG_MAX;
 426         if (orig_arg_max == -1)
 427                 orig_arg_max = LONG_MAX;
 428         orig_arg_max -= 2048;   /* POSIX.2 requires subtracting 2048 */
 429
 430         if (opt & OPT_UPTO_SIZE) {
 431                 n_max_chars = xatoul_range(max_chars, 1, orig_arg_max);
 432                 for (i = 0; i < argc; i++) {
 433                         n_chars += strlen(*argv) + 1;
 434                 }
 435                 if (n_max_chars < n_chars) {
 436                         bb_error_msg_and_die("cannot fit single argument within argument list size limit");
 437                 }
 438                 n_max_chars -= n_chars;
 439         } else {
 440                 /* Sanity check for systems with huge ARG_MAX defines (e.g., Suns which
 441                    have it at 1 meg).  Things will work fine with a large ARG_MAX but it
 442                    will probably hurt the system more than it needs to; an array of this
 443                    size is allocated.  */
 444                 if (orig_arg_max > 20 * 1024)
 445                         orig_arg_max = 20 * 1024;
 446                 n_max_chars = orig_arg_max;
 447         }
 448         max_chars = xmalloc(n_max_chars);
 449
 450         if (opt & OPT_UPTO_NUMBER) {
 451                 n_max_arg = xatoul_range(max_args, 1, INT_MAX);
 452         } else {
 453                 n_max_arg = n_max_chars;
 454         }
 455
 456         while ((list = read_args(list, eof_str, n_max_chars, max_chars)) != NULL ||
 457                 !(opt & OPT_NO_EMPTY))
 458         {
 459                 opt |= OPT_NO_EMPTY;
 460                 n = 0;
 461                 n_chars = 0;
 462 #if ENABLE_FEATURE_XARGS_SUPPORT_TERMOPT
 463                 for (cur = list; cur;) {
 464                         n_chars += cur->length;
 465                         n++;
 466                         cur = cur->link;
 467                         if (n_chars > n_max_chars || (n == n_max_arg && cur)) {
 468                                 if (opt & OPT_TERMINATE)
 469                                         bb_error_msg_and_die("argument list too long");
 470                                 break;
 471                         }
 472                 }
 473 #else
 474                 for (cur = list; cur; cur = cur->link) {
 475                         n_chars += cur->length;
 476                         n++;
 477                         if (n_chars > n_max_chars || n == n_max_arg) {
 478                                 break;
 479                         }
 480                 }
 481 #endif /* FEATURE_XARGS_SUPPORT_TERMOPT */
 482
 483                 /* allocate pointers for execvp:
 484                    argc*arg, n*arg from stdin, NULL */
 485                 args = xzalloc((n + argc + 1) * sizeof(char *));
 486
 487                 /* store the command to be executed
 488                    (taken from the command line) */
 489                 for (i = 0; i < argc; i++)
 490                         args[i] = argv[i];
 491                 /* (taken from stdin) */
 492                 for (cur = list; n; cur = cur->link) {
 493                         args[i++] = cur->data;
 494                         n--;
 495                 }
 496
 497                 if (opt & (OPT_INTERACTIVE | OPT_VERBOSE)) {
 498                         for (i = 0; args[i]; i++) {
 499                                 if (i)
 500                                         fputc(' ', stderr);
 501                                 fputs(args[i], stderr);
 502                         }
 503                         if (!(opt & OPT_INTERACTIVE))
 504                                 fputc('\n', stderr);
 505                 }
 506                 if (!(opt & OPT_INTERACTIVE) || xargs_ask_confirmation()) {
 507                         child_error = xargs_exec(args);
 508                 }
 509
 510                 /* clean up */
 511                 for (i = argc; args[i]; i++) {
 512                         cur = list;
 513                         list = list->link;
 514                         free(cur);
 515                 }
 516                 free(args);
 517                 if (child_error > 0 && child_error != 123) {
 518                         break;
 519                 }
 520         }
 521         if (ENABLE_FEATURE_CLEAN_UP)
 522                 free(max_chars);
 523         return child_error;
 524 }
 525
 526
 527 #ifdef TEST
 528
 529 const char *applet_name = "debug stuff usage";
 530
 531 void bb_show_usage(void)
 532 {
 533         fprintf(stderr, "Usage: %s [-p] [-r] [-t] -[x] [-n max_arg] [-s max_chars]\n",
 534                 applet_name);
 535         exit(1);
 536 }
 537
 538 int main(int argc, char **argv)
 539 {
 540         return xargs_main(argc, argv);
 541 }
 542 #endif /* TEST */