usr.bin/xargs/xargs.c

   1 /*      $NetBSD: xargs.c,v 1.20 2010/12/17 11:32:57 plunky Exp $        */
   2
   3 /*-
   4  * Copyright (c) 1990, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * John B. Roll Jr.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * $xMach: xargs.c,v 1.6 2002/02/23 05:27:47 tim Exp $
  35  */
  36
  37 #include <sys/cdefs.h>
  38 #ifndef lint
  39 __COPYRIGHT("@(#) Copyright (c) 1990, 1993\
  40  The Regents of the University of California.  All rights reserved.");
  41 #if 0
  42 static char sccsid[] = "@(#)xargs.c     8.1 (Berkeley) 6/6/93";
  43 __FBSDID("$FreeBSD: src/usr.bin/xargs/xargs.c,v 1.62 2006/01/01 22:59:54 jmallett Exp $");
  44 #endif
  45 __RCSID("$NetBSD: xargs.c,v 1.20 2010/12/17 11:32:57 plunky Exp $");
  46 #endif /* not lint */
  47
  48 #include <sys/param.h>
  49 #include <sys/wait.h>
  50
  51 #include <err.h>
  52 #include <errno.h>
  53 #include <fcntl.h>
  54 #include <langinfo.h>
  55 #include <locale.h>
  56 #include <paths.h>
  57 #include <regex.h>
  58 #include <stdio.h>
  59 #include <stdlib.h>
  60 #include <string.h>
  61 #include <signal.h>
  62 #include <unistd.h>
  63
  64 #include "pathnames.h"
  65
  66 static void     parse_input(int, char *[]);
  67 static void     prerun(int, char *[]);
  68 static int      prompt(void);
  69 static void     run(char **);
  70 static void     usage(void) __dead;
  71 void            strnsubst(char **, const char *, const char *, size_t);
  72 static void     waitchildren(const char *, int);
  73
  74 static char echo[] = _PATH_ECHO;
  75 static char **av, **bxp, **ep, **endxp, **xp;
  76 static char *argp, *bbp, *ebp, *inpline, *p, *replstr;
  77 static const char *eofstr;
  78 static int count, insingle, indouble, oflag, pflag, tflag, Rflag, rval, zflag;
  79 static int cnt, Iflag, jfound, Lflag, Sflag, wasquoted, xflag;
  80 static int curprocs, maxprocs;
  81
  82 static volatile int childerr;
  83
  84 extern char **environ;
  85
  86 int
  87 main(int argc, char *argv[])
  88 {
  89         long arg_max;
  90         int ch, Jflag, nargs, nflag, nline;
  91         size_t linelen;
  92         char *endptr;
  93
  94         setprogname(argv[0]);
  95
  96         inpline = replstr = NULL;
  97         ep = environ;
  98         eofstr = "";
  99         Jflag = nflag = 0;
 100
 101         (void)setlocale(LC_ALL, "");
 102
 103         /*
 104          * SUSv3 says of the exec family of functions:
 105          *     The number of bytes available for the new process'
 106          *     combined argument and environment lists is {ARG_MAX}. It
 107          *     is implementation-defined whether null terminators,
 108          *     pointers, and/or any alignment bytes are included in this
 109          *     total.
 110          *
 111          * SUSv3 says of xargs:
 112          *     ... the combined argument and environment lists ...
 113          *     shall not exceed {ARG_MAX}-2048.
 114          *
 115          * To be conservative, we use ARG_MAX - 4K, and we do include
 116          * nul terminators and pointers in the calculation.
 117          *
 118          * Given that the smallest argument is 2 bytes in length, this
 119          * means that the number of arguments is limited to:
 120          *
 121          *       (ARG_MAX - 4K - LENGTH(env + utility + arguments)) / 2.
 122          *
 123          * We arbitrarily limit the number of arguments to 5000.  This is
 124          * allowed by POSIX.2 as long as the resulting minimum exec line is
 125          * at least LINE_MAX.  Realloc'ing as necessary is possible, but
 126          * probably not worthwhile.
 127          */
 128         nargs = 5000;
 129         if ((arg_max = sysconf(_SC_ARG_MAX)) == -1)
 130                 errx(1, "sysconf(_SC_ARG_MAX) failed");
 131         nline = arg_max - 4 * 1024;
 132         while (*ep != NULL) {
 133                 /* 1 byte for each '\0' */
 134                 nline -= strlen(*ep++) + 1 + sizeof(*ep);
 135         }
 136         maxprocs = 1;
 137         while ((ch = getopt(argc, argv, "0E:I:J:L:n:oP:pR:S:s:rtx")) != -1)
 138                 switch (ch) {
 139                 case 'E':
 140                         eofstr = optarg;
 141                         break;
 142                 case 'I':
 143                         Jflag = 0;
 144                         Iflag = 1;
 145                         Lflag = 1;
 146                         replstr = optarg;
 147                         break;
 148                 case 'J':
 149                         Iflag = 0;
 150                         Jflag = 1;
 151                         replstr = optarg;
 152                         break;
 153                 case 'L':
 154                         Lflag = atoi(optarg);
 155                         break;
 156                 case 'n':
 157                         nflag = 1;
 158                         if ((nargs = atoi(optarg)) <= 0)
 159                                 errx(1, "illegal argument count");
 160                         break;
 161                 case 'o':
 162                         oflag = 1;
 163                         break;
 164                 case 'P':
 165                         if ((maxprocs = atoi(optarg)) <= 0)
 166                                 errx(1, "max. processes must be >0");
 167                         break;
 168                 case 'p':
 169                         pflag = 1;
 170                         break;
 171                 case 'R':
 172                         Rflag = strtol(optarg, &endptr, 10);
 173                         if (*endptr != '\0')
 174                                 errx(1, "replacements must be a number");
 175                         break;
 176                 case 'r':
 177                         /* GNU compatibility */
 178                         break;
 179                 case 'S':
 180                         Sflag = strtoul(optarg, &endptr, 10);
 181                         if (*endptr != '\0')
 182                                 errx(1, "replsize must be a number");
 183                         break;
 184                 case 's':
 185                         nline = atoi(optarg);
 186                         break;
 187                 case 't':
 188                         tflag = 1;
 189                         break;
 190                 case 'x':
 191                         xflag = 1;
 192                         break;
 193                 case '0':
 194                         zflag = 1;
 195                         break;
 196                 case '?':
 197                 default:
 198                         usage();
 199         }
 200         argc -= optind;
 201         argv += optind;
 202
 203         if (!Iflag && Rflag)
 204                 usage();
 205         if (!Iflag && Sflag)
 206                 usage();
 207         if (Iflag && !Rflag)
 208                 Rflag = 5;
 209         if (Iflag && !Sflag)
 210                 Sflag = 255;
 211         if (xflag && !nflag)
 212                 usage();
 213         if (Iflag || Lflag)
 214                 xflag = 1;
 215         if (replstr != NULL && *replstr == '\0')
 216                 errx(1, "replstr may not be empty");
 217
 218         /*
 219          * Allocate pointers for the utility name, the utility arguments,
 220          * the maximum arguments to be read from stdin and the trailing
 221          * NULL.
 222          */
 223         linelen = 1 + argc + nargs + 1;
 224         if ((av = bxp = malloc(linelen * sizeof(char **))) == NULL)
 225                 errx(1, "malloc failed");
 226
 227         /*
 228          * Use the user's name for the utility as argv[0], just like the
 229          * shell.  Echo is the default.  Set up pointers for the user's
 230          * arguments.
 231          */
 232         if (*argv == NULL)
 233                 cnt = strlen(*bxp++ = echo);
 234         else {
 235                 do {
 236                         if (Jflag && strcmp(*argv, replstr) == 0) {
 237                                 char **avj;
 238                                 jfound = 1;
 239                                 argv++;
 240                                 for (avj = argv; *avj; avj++)
 241                                         cnt += strlen(*avj) + 1;
 242                                 break;
 243                         }
 244                         cnt += strlen(*bxp++ = *argv) + 1;
 245                 } while (*++argv != NULL);
 246         }
 247
 248         /*
 249          * Set up begin/end/traversing pointers into the array.  The -n
 250          * count doesn't include the trailing NULL pointer, so the malloc
 251          * added in an extra slot.
 252          */
 253         endxp = (xp = bxp) + nargs;
 254
 255         /*
 256          * Allocate buffer space for the arguments read from stdin and the
 257          * trailing NULL.  Buffer space is defined as the default or specified
 258          * space, minus the length of the utility name and arguments.  Set up
 259          * begin/end/traversing pointers into the array.  The -s count does
 260          * include the trailing NULL, so the malloc didn't add in an extra
 261          * slot.
 262          */
 263         nline -= cnt;
 264         if (nline <= 0)
 265                 errx(1, "insufficient space for command");
 266
 267         if ((bbp = malloc((size_t)(nline + 1))) == NULL)
 268                 errx(1, "malloc failed");
 269         ebp = (argp = p = bbp) + nline - 1;
 270         for (;;)
 271                 parse_input(argc, argv);
 272 }
 273
 274 static void
 275 parse_input(int argc, char *argv[])
 276 {
 277         int ch, foundeof;
 278         char **avj;
 279
 280         foundeof = 0;
 281
 282         switch (ch = getchar()) {
 283         case EOF:
 284                 /* No arguments since last exec. */
 285                 if (p == bbp) {
 286                         waitchildren(*argv, 1);
 287                         exit(rval);
 288                 }
 289                 goto arg1;
 290         case ' ':
 291         case '\t':
 292                 /* Quotes escape tabs and spaces. */
 293                 if (insingle || indouble || zflag)
 294                         goto addch;
 295                 goto arg2;
 296         case '\0':
 297                 if (zflag) {
 298                         /*
 299                          * Increment 'count', so that nulls will be treated
 300                          * as end-of-line, as well as end-of-argument.  This
 301                          * is needed so -0 works properly with -I and -L.
 302                          */
 303                         count++;
 304                         goto arg2;
 305                 }
 306                 goto addch;
 307         case '\n':
 308                 if (zflag)
 309                         goto addch;
 310                 count++;            /* Indicate end-of-line (used by -L) */
 311
 312                 /* Quotes do not escape newlines. */
 313 arg1:           if (insingle || indouble)
 314                         errx(1, "unterminated quote");
 315 arg2:
 316                 foundeof = *eofstr != '\0' &&
 317                     strncmp(argp, eofstr, (size_t)(p - argp)) == 0;
 318
 319                 /* Do not make empty args unless they are quoted */
 320                 if ((argp != p || wasquoted) && !foundeof) {
 321                         *p++ = '\0';
 322                         *xp++ = argp;
 323                         if (Iflag) {
 324                                 size_t curlen;
 325
 326                                 if (inpline == NULL)
 327                                         curlen = 0;
 328                                 else {
 329                                         /*
 330                                          * If this string is not zero
 331                                          * length, append a space for
 332                                          * separation before the next
 333                                          * argument.
 334                                          */
 335                                         if ((curlen = strlen(inpline)) != 0)
 336                                                 (void)strcat(inpline, " ");
 337                                 }
 338                                 curlen++;
 339                                 /*
 340                                  * Allocate enough to hold what we will
 341                                  * be holding in a second, and to append
 342                                  * a space next time through, if we have
 343                                  * to.
 344                                  */
 345                                 inpline = realloc(inpline, curlen + 2 +
 346                                     strlen(argp));
 347                                 if (inpline == NULL)
 348                                         errx(1, "realloc failed");
 349                                 if (curlen == 1)
 350                                         (void)strcpy(inpline, argp);
 351                                 else
 352                                         (void)strcat(inpline, argp);
 353                         }
 354                 }
 355
 356                 /*
 357                  * If max'd out on args or buffer, or reached EOF,
 358                  * run the command.  If xflag and max'd out on buffer
 359                  * but not on args, object.  Having reached the limit
 360                  * of input lines, as specified by -L is the same as
 361                  * maxing out on arguments.
 362                  */
 363                 if (xp == endxp || p > ebp || ch == EOF ||
 364                     (Lflag <= count && xflag) || foundeof) {
 365                         if (xflag && xp != endxp && p > ebp)
 366                                 errx(1, "insufficient space for arguments");
 367                         if (jfound) {
 368                                 for (avj = argv; *avj; avj++)
 369                                         *xp++ = *avj;
 370                         }
 371                         prerun(argc, av);
 372                         if (ch == EOF || foundeof) {
 373                                 waitchildren(*argv, 1);
 374                                 exit(rval);
 375                         }
 376                         p = bbp;
 377                         xp = bxp;
 378                         count = 0;
 379                 }
 380                 argp = p;
 381                 wasquoted = 0;
 382                 break;
 383         case '\'':
 384                 if (indouble || zflag)
 385                         goto addch;
 386                 insingle = !insingle;
 387                 wasquoted = 1;
 388                 break;
 389         case '"':
 390                 if (insingle || zflag)
 391                         goto addch;
 392                 indouble = !indouble;
 393                 wasquoted = 1;
 394                 break;
 395         case '\\':
 396                 if (zflag)
 397                         goto addch;
 398                 /* Backslash escapes anything, is escaped by quotes. */
 399                 if (!insingle && !indouble && (ch = getchar()) == EOF)
 400                         errx(1, "backslash at EOF");
 401                 /* FALLTHROUGH */
 402         default:
 403 addch:          if (p < ebp) {
 404                         *p++ = ch;
 405                         break;
 406                 }
 407
 408                 /* If only one argument, not enough buffer space. */
 409                 if (bxp == xp)
 410                         errx(1, "insufficient space for argument");
 411                 /* Didn't hit argument limit, so if xflag object. */
 412                 if (xflag)
 413                         errx(1, "insufficient space for arguments");
 414
 415                 if (jfound) {
 416                         for (avj = argv; *avj; avj++)
 417                                 *xp++ = *avj;
 418                 }
 419                 prerun(argc, av);
 420                 xp = bxp;
 421                 cnt = ebp - argp;
 422                 (void)memcpy(bbp, argp, (size_t)cnt);
 423                 p = (argp = bbp) + cnt;
 424                 *p++ = ch;
 425                 break;
 426         }
 427 }
 428
 429 /*
 430  * Do things necessary before run()'ing, such as -I substitution,
 431  * and then call run().
 432  */
 433 static void
 434 prerun(int argc, char *argv[])
 435 {
 436         char **tmp, **tmp2, **avj;
 437         int repls;
 438
 439         repls = Rflag;
 440
 441         if (argc == 0 || repls == 0) {
 442                 *xp = NULL;
 443                 run(argv);
 444                 return;
 445         }
 446
 447         avj = argv;
 448
 449         /*
 450          * Allocate memory to hold the argument list, and
 451          * a NULL at the tail.
 452          */
 453         tmp = malloc((argc + 1) * sizeof(char**));
 454         if (tmp == NULL)
 455                 errx(1, "malloc failed");
 456         tmp2 = tmp;
 457
 458         /*
 459          * Save the first argument and iterate over it, we
 460          * cannot do strnsubst() to it.
 461          */
 462         if ((*tmp++ = strdup(*avj++)) == NULL)
 463                 errx(1, "strdup failed");
 464
 465         /*
 466          * For each argument to utility, if we have not used up
 467          * the number of replacements we are allowed to do, and
 468          * if the argument contains at least one occurrence of
 469          * replstr, call strnsubst(), else just save the string.
 470          * Iterations over elements of avj and tmp are done
 471          * where appropriate.
 472          */
 473         while (--argc) {
 474                 *tmp = *avj++;
 475                 if (repls && strstr(*tmp, replstr) != NULL) {
 476                         strnsubst(tmp++, replstr, inpline, (size_t)Sflag);
 477                         if (repls > 0)
 478                                 repls--;
 479                 } else {
 480                         if ((*tmp = strdup(*tmp)) == NULL)
 481                                 errx(1, "strdup failed");
 482                         tmp++;
 483                 }
 484         }
 485
 486         /*
 487          * Run it.
 488          */
 489         *tmp = NULL;
 490         run(tmp2);
 491
 492         /*
 493          * Walk from the tail to the head, free along the way.
 494          */
 495         for (; tmp2 != tmp; tmp--)
 496                 free(*tmp);
 497         /*
 498          * Now free the list itself.
 499          */
 500         free(tmp2);
 501
 502         /*
 503          * Free the input line buffer, if we have one.
 504          */
 505         if (inpline != NULL) {
 506                 free(inpline);
 507                 inpline = NULL;
 508         }
 509 }
 510
 511 static void
 512 run(char **argv)
 513 {
 514         int fd;
 515         char **avec;
 516
 517         /*
 518          * If the user wants to be notified of each command before it is
 519          * executed, notify them.  If they want the notification to be
 520          * followed by a prompt, then prompt them.
 521          */
 522         if (tflag || pflag) {
 523                 (void)fprintf(stderr, "%s", *argv);
 524                 for (avec = argv + 1; *avec != NULL; ++avec)
 525                         (void)fprintf(stderr, " %s", *avec);
 526                 /*
 527                  * If the user has asked to be prompted, do so.
 528                  */
 529                 if (pflag)
 530                         /*
 531                          * If they asked not to exec, return without execution
 532                          * but if they asked to, go to the execution.  If we
 533                          * could not open their tty, break the switch and drop
 534                          * back to -t behaviour.
 535                          */
 536                         switch (prompt()) {
 537                         case 0:
 538                                 return;
 539                         case 1:
 540                                 goto exec;
 541                         case 2:
 542                                 break;
 543                         }
 544                 (void)fprintf(stderr, "\n");
 545                 (void)fflush(stderr);
 546         }
 547 exec:
 548         childerr = 0;
 549         switch (vfork()) {
 550         case -1:
 551                 err(1, "vfork");
 552                 /*NOTREACHED*/
 553         case 0:
 554                 if (oflag) {
 555                         if ((fd = open(_PATH_TTY, O_RDONLY)) == -1)
 556                                 err(1, "can't open /dev/tty");
 557                 } else {
 558                         fd = open(_PATH_DEVNULL, O_RDONLY);
 559                 }
 560                 if (fd > STDIN_FILENO) {
 561                         if (dup2(fd, STDIN_FILENO) != 0)
 562                                 err(1, "can't dup2 to stdin");
 563                         (void)close(fd);
 564                 }
 565                 (void)execvp(argv[0], argv);
 566                 childerr = errno;
 567                 _exit(1);
 568         }
 569         curprocs++;
 570         waitchildren(*argv, 0);
 571 }
 572
 573 static void
 574 waitchildren(const char *name, int waitall)
 575 {
 576         pid_t pid;
 577         int status;
 578
 579         while ((pid = waitpid(-1, &status, !waitall && curprocs < maxprocs ?
 580             WNOHANG : 0)) > 0) {
 581                 curprocs--;
 582                 /* If we couldn't invoke the utility, exit. */
 583                 if (childerr != 0) {
 584                         errno = childerr;
 585                         err(errno == ENOENT ? 127 : 126, "%s", name);
 586                 }
 587                 /*
 588                  * According to POSIX, we have to exit if the utility exits
 589                  * with a 255 status, or is interrupted by a signal. xargs
 590                  * is allowed to return any exit status between 1 and 125
 591                  * in these cases, but we'll use 124 and 125, the same
 592                  * values used by GNU xargs.
 593                  */
 594                 if (WIFEXITED(status)) {
 595                         if (WEXITSTATUS (status) == 255) {
 596                                 warnx ("%s exited with status 255", name);
 597                                 exit(124);
 598                         } else if (WEXITSTATUS (status) != 0) {
 599                                 rval = 123;
 600                         }
 601                 } else if (WIFSIGNALED (status)) {
 602                         if (WTERMSIG(status) < NSIG) {
 603                                 warnx("%s terminated by SIG%s", name,
 604                                     sys_signame[WTERMSIG(status)]);
 605                         } else {
 606                                 warnx("%s terminated by signal %d", name,
 607                                     WTERMSIG(status));
 608                         }
 609                         exit(125);
 610                 }
 611         }
 612         if (pid == -1 && errno != ECHILD)
 613                 err(1, "waitpid");
 614 }
 615
 616 /*
 617  * Prompt the user about running a command.
 618  */
 619 static int
 620 prompt(void)
 621 {
 622         regex_t cre;
 623         size_t rsize;
 624         int match;
 625         char *response;
 626         FILE *ttyfp;
 627
 628         if ((ttyfp = fopen(_PATH_TTY, "r")) == NULL)
 629                 return (2);     /* Indicate that the TTY failed to open. */
 630         (void)fprintf(stderr, "?...");
 631         (void)fflush(stderr);
 632         if ((response = fgetln(ttyfp, &rsize)) == NULL ||
 633             regcomp(&cre, nl_langinfo(YESEXPR), REG_BASIC) != 0) {
 634                 (void)fclose(ttyfp);
 635                 return (0);
 636         }
 637         response[rsize - 1] = '\0';
 638         match = regexec(&cre, response, 0, NULL, 0);
 639         (void)fclose(ttyfp);
 640         regfree(&cre);
 641         return (match == 0);
 642 }
 643
 644 static void
 645 usage(void)
 646 {
 647         (void)fprintf(stderr,
 648 "Usage: %s [-0opt] [-E eofstr] [-I replstr [-R replacements] [-S replsize]]\n"
 649 "             [-J replstr] [-L number] [-n number [-x]] [-P maxprocs]\n"
 650 "             [-s size] [utility [argument ...]]\n", getprogname());
 651         exit(1);
 652 }