shell/shell_common.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Adapted from ash applet code
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Kenneth Almquist.
   7  *
   8  * Copyright (c) 1989, 1991, 1993, 1994
   9  *      The Regents of the University of California.  All rights reserved.
  10  *
  11  * Copyright (c) 1997-2005 Herbert Xu <herbert@gondor.apana.org.au>
  12  * was re-ported from NetBSD and debianized.
  13  *
  14  * Copyright (c) 2010 Denys Vlasenko
  15  * Split from ash.c
  16  *
  17  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  18  */
  19 #include "libbb.h"
  20 #include "shell_common.h"
  21
  22 const char defifsvar[] ALIGN1 = "IFS= \t\n";
  23 const char defoptindvar[] ALIGN1 = "OPTIND=1";
  24
  25
  26 int FAST_FUNC is_well_formed_var_name(const char *s, char terminator)
  27 {
  28         if (!s || !(isalpha(*s) || *s == '_'))
  29                 return 0;
  30
  31         do
  32                 s++;
  33         while (isalnum(*s) || *s == '_');
  34
  35         return *s == terminator;
  36 }
  37
  38 /* read builtin */
  39
  40 /* Needs to be interruptible: shell must handle traps and shell-special signals
  41  * while inside read. To implement this, be sure to not loop on EINTR
  42  * and return errno == EINTR reliably.
  43  */
  44 //TODO: use more efficient setvar() which takes a pointer to malloced "VAR=VAL"
  45 //string. hush naturally has it, and ash has setvareq().
  46 //Here we can simply store "VAR=" at buffer start and store read data directly
  47 //after "=", then pass buffer to setvar() to consume.
  48 const char* FAST_FUNC
  49 shell_builtin_read(struct builtin_read_params *params)
  50 {
  51         struct pollfd pfd[1];
  52 #define fd (pfd[0].fd) /* -u FD */
  53         unsigned err;
  54         unsigned end_ms; /* -t TIMEOUT */
  55         int nchars; /* -n NUM */
  56         char **pp;
  57         char *buffer;
  58         char delim;
  59         struct termios tty, old_tty;
  60         const char *retval;
  61         int bufpos; /* need to be able to hold -1 */
  62         int startword;
  63         smallint backslash;
  64         char **argv;
  65         const char *ifs;
  66         int read_flags;
  67
  68         errno = err = 0;
  69
  70         argv = params->argv;
  71         pp = argv;
  72         while (*pp) {
  73                 if (!is_well_formed_var_name(*pp, '\0')) {
  74                         /* Mimic bash message */
  75                         bb_error_msg("read: '%s': not a valid identifier", *pp);
  76                         return (const char *)(uintptr_t)1;
  77                 }
  78                 pp++;
  79         }
  80
  81         nchars = 0; /* if != 0, -n is in effect */
  82         if (params->opt_n) {
  83                 nchars = bb_strtou(params->opt_n, NULL, 10);
  84                 if (nchars < 0 || errno)
  85                         return "invalid count";
  86                 /* note: "-n 0": off (bash 3.2 does this too) */
  87         }
  88
  89         end_ms = 0;
  90         if (params->opt_t && !ENABLE_FEATURE_SH_READ_FRAC) {
  91                 end_ms = bb_strtou(params->opt_t, NULL, 10);
  92                 if (errno)
  93                         return "invalid timeout";
  94                 if (end_ms > UINT_MAX / 2048) /* be safely away from overflow */
  95                         end_ms = UINT_MAX / 2048;
  96                 end_ms *= 1000;
  97         }
  98         if (params->opt_t && ENABLE_FEATURE_SH_READ_FRAC) {
  99                 /* bash 4.3 (maybe earlier) supports -t N.NNNNNN */
 100                 char *p;
 101                 /* Eat up to three fractional digits */
 102                 int frac_digits = 3 + 1;
 103
 104                 end_ms = bb_strtou(params->opt_t, &p, 10);
 105                 if (end_ms > UINT_MAX / 2048) /* be safely away from overflow */
 106                         end_ms = UINT_MAX / 2048;
 107
 108                 if (errno) {
 109                         /* EINVAL = number is ok, but not NUL terminated */
 110                         if (errno != EINVAL || *p != '.')
 111                                 return "invalid timeout";
 112                         /* Do not check the rest: bash allows "0.123456xyz" */
 113                         while (*++p && --frac_digits) {
 114                                 end_ms *= 10;
 115                                 end_ms += (*p - '0');
 116                                 if ((unsigned char)(*p - '0') > 9)
 117                                         return "invalid timeout";
 118                         }
 119                 }
 120                 while (--frac_digits > 0) {
 121                         end_ms *= 10;
 122                 }
 123         }
 124
 125         fd = STDIN_FILENO;
 126         if (params->opt_u) {
 127                 fd = bb_strtou(params->opt_u, NULL, 10);
 128                 if (fd < 0 || errno)
 129                         return "invalid file descriptor";
 130         }
 131
 132         if (params->opt_t && end_ms == 0) {
 133                 /* "If timeout is 0, read returns immediately, without trying
 134                  * to read any data. The exit status is 0 if input is available
 135                  * on the specified file descriptor, non-zero otherwise."
 136                  * bash seems to ignore -p PROMPT for this use case.
 137                  */
 138                 int r;
 139                 pfd[0].events = POLLIN;
 140                 r = poll(pfd, 1, /*timeout:*/ 0);
 141                 /* Return 0 only if poll returns 1 ("one fd ready"), else return 1: */
 142                 return (const char *)(uintptr_t)(r <= 0);
 143         }
 144
 145         if (params->opt_p && isatty(fd)) {
 146                 fputs(params->opt_p, stderr);
 147                 fflush_all();
 148         }
 149
 150         ifs = params->ifs;
 151         if (ifs == NULL)
 152                 ifs = defifs;
 153
 154         read_flags = params->read_flags;
 155         if (nchars || (read_flags & BUILTIN_READ_SILENT)) {
 156                 tcgetattr(fd, &tty);
 157                 old_tty = tty;
 158                 if (nchars) {
 159                         tty.c_lflag &= ~ICANON;
 160                         // Setting it to more than 1 breaks poll():
 161                         // it blocks even if there's data. !??
 162                         //tty.c_cc[VMIN] = nchars < 256 ? nchars : 255;
 163                         /* reads will block only if < 1 char is available */
 164                         tty.c_cc[VMIN] = 1;
 165                         /* no timeout (reads block forever) */
 166                         tty.c_cc[VTIME] = 0;
 167                 }
 168                 if (read_flags & BUILTIN_READ_SILENT) {
 169                         tty.c_lflag &= ~(ECHO | ECHOK | ECHONL);
 170                 }
 171                 /* This forces execution of "restoring" tcgetattr later */
 172                 read_flags |= BUILTIN_READ_SILENT;
 173                 /* if tcgetattr failed, tcsetattr will fail too.
 174                  * Ignoring, it's harmless. */
 175                 tcsetattr(fd, TCSANOW, &tty);
 176         }
 177
 178         retval = (const char *)(uintptr_t)0;
 179         startword = 1;
 180         backslash = 0;
 181         if (params->opt_t)
 182                 end_ms += (unsigned)monotonic_ms();
 183         buffer = NULL;
 184         bufpos = 0;
 185         delim = params->opt_d ? params->opt_d[0] : '\n';
 186         do {
 187                 char c;
 188                 int timeout;
 189
 190                 if ((bufpos & 0xff) == 0)
 191                         buffer = xrealloc(buffer, bufpos + 0x101);
 192
 193                 timeout = -1;
 194                 if (params->opt_t) {
 195                         timeout = end_ms - (unsigned)monotonic_ms();
 196                         /* ^^^^^^^^^^^^^ all values are unsigned,
 197                          * wrapping math is used here, good even if
 198                          * 32-bit unix time wrapped (year 2038+).
 199                          */
 200                         if (timeout <= 0) { /* already late? */
 201                                 retval = (const char *)(uintptr_t)1;
 202                                 goto ret;
 203                         }
 204                 }
 205
 206                 /* We must poll even if timeout is -1:
 207                  * we want to be interrupted if signal arrives,
 208                  * regardless of SA_RESTART-ness of that signal!
 209                  */
 210                 errno = 0;
 211                 pfd[0].events = POLLIN;
 212                 if (poll(pfd, 1, timeout) <= 0) {
 213                         /* timed out, or EINTR */
 214                         err = errno;
 215                         retval = (const char *)(uintptr_t)1;
 216                         goto ret;
 217                 }
 218                 if (read(fd, &buffer[bufpos], 1) != 1) {
 219                         err = errno;
 220                         retval = (const char *)(uintptr_t)1;
 221                         break;
 222                 }
 223
 224                 c = buffer[bufpos];
 225                 if (c == '\0')
 226                         continue;
 227                 if (!(read_flags & BUILTIN_READ_RAW)) {
 228                         if (backslash) {
 229                                 backslash = 0;
 230                                 if (c != '\n')
 231                                         goto put;
 232                                 continue;
 233                         }
 234                         if (c == '\\') {
 235                                 backslash = 1;
 236                                 continue;
 237                         }
 238                 }
 239                 if (c == delim) /* '\n' or -d CHAR */
 240                         break;
 241
 242                 /* $IFS splitting. NOT done if we run "read"
 243                  * without variable names (bash compat).
 244                  * Thus, "read" and "read REPLY" are not the same.
 245                  */
 246                 if (!params->opt_d && argv[0]) {
 247 /* http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_05 */
 248                         const char *is_ifs = strchr(ifs, c);
 249                         if (startword && is_ifs) {
 250                                 if (isspace(c))
 251                                         continue;
 252                                 /* it is a non-space ifs char */
 253                                 startword--;
 254                                 if (startword == 1) /* first one? */
 255                                         continue; /* yes, it is not next word yet */
 256                         }
 257                         startword = 0;
 258                         if (argv[1] != NULL && is_ifs) {
 259                                 buffer[bufpos] = '\0';
 260                                 bufpos = 0;
 261                                 params->setvar(*argv, buffer);
 262                                 argv++;
 263                                 /* can we skip one non-space ifs char? (2: yes) */
 264                                 startword = isspace(c) ? 2 : 1;
 265                                 continue;
 266                         }
 267                 }
 268  put:
 269                 bufpos++;
 270         } while (--nchars);
 271
 272         if (argv[0]) {
 273                 /* Remove trailing space $IFS chars */
 274                 while (--bufpos >= 0
 275                  && isspace(buffer[bufpos])
 276                  && strchr(ifs, buffer[bufpos]) != NULL
 277                 ) {
 278                         continue;
 279                 }
 280                 buffer[bufpos + 1] = '\0';
 281
 282                 /* Last variable takes the entire remainder with delimiters
 283                  * (sans trailing whitespace $IFS),
 284                  * but ***only "if there are fewer vars than fields"(c)***!
 285                  * The "X:Y:" case below: there are two fields,
 286                  * and therefore last delimiter (:) is eaten:
 287                  * IFS=": "
 288                  * echo "X:Y:Z:"  | (read x y; echo "|$x|$y|") # |X|Y:Z:|
 289                  * echo "X:Y:Z"   | (read x y; echo "|$x|$y|") # |X|Y:Z|
 290                  * echo "X:Y:"    | (read x y; echo "|$x|$y|") # |X|Y|, not |X|Y:|
 291                  * echo "X:Y  : " | (read x y; echo "|$x|$y|") # |X|Y|
 292                  */
 293                 if (bufpos >= 0
 294                  && strchr(ifs, buffer[bufpos]) != NULL
 295                 ) {
 296                         /* There _is_ a non-whitespace IFS char */
 297                         /* Skip whitespace IFS char before it */
 298                         while (--bufpos >= 0
 299                          && isspace(buffer[bufpos])
 300                          && strchr(ifs, buffer[bufpos]) != NULL
 301                         ) {
 302                                 continue;
 303                         }
 304                         /* Are there $IFS chars? */
 305                         if (strcspn(buffer, ifs) >= ++bufpos) {
 306                                 /* No: last var takes one field, not more */
 307                                 /* So, drop trailing IFS delims */
 308                                 buffer[bufpos] = '\0';
 309                         }
 310                 }
 311
 312                 /* Use the remainder as a value for the next variable */
 313                 params->setvar(*argv, buffer);
 314                 /* Set the rest to "" */
 315                 while (*++argv)
 316                         params->setvar(*argv, "");
 317         } else {
 318                 /* Note: no $IFS removal */
 319                 buffer[bufpos] = '\0';
 320                 params->setvar("REPLY", buffer);
 321         }
 322
 323  ret:
 324         free(buffer);
 325         if (read_flags & BUILTIN_READ_SILENT)
 326                 tcsetattr(fd, TCSANOW, &old_tty);
 327
 328         errno = err;
 329         return retval;
 330 #undef fd
 331 }
 332
 333 /* ulimit builtin */
 334
 335 struct limits {
 336         uint8_t cmd;            /* RLIMIT_xxx fit into it */
 337         uint8_t factor_shift;   /* shift by to get rlim_{cur,max} values */
 338         char option;
 339         const char *name;
 340 };
 341
 342 static const struct limits limits_tbl[] = {
 343 #ifdef RLIMIT_FSIZE
 344         { RLIMIT_FSIZE,         9,      'f',    "file size (blocks)" },
 345 #endif
 346 #ifdef RLIMIT_CPU
 347         { RLIMIT_CPU,           0,      't',    "cpu time (seconds)" },
 348 #endif
 349 #ifdef RLIMIT_DATA
 350         { RLIMIT_DATA,          10,     'd',    "data seg size (kb)" },
 351 #endif
 352 #ifdef RLIMIT_STACK
 353         { RLIMIT_STACK,         10,     's',    "stack size (kb)" },
 354 #endif
 355 #ifdef RLIMIT_CORE
 356         { RLIMIT_CORE,          9,      'c',    "core file size (blocks)" },
 357 #endif
 358 #ifdef RLIMIT_RSS
 359         { RLIMIT_RSS,           10,     'm',    "resident set size (kb)" },
 360 #endif
 361 #ifdef RLIMIT_MEMLOCK
 362         { RLIMIT_MEMLOCK,       10,     'l',    "locked memory (kb)" },
 363 #endif
 364 #ifdef RLIMIT_NPROC
 365         { RLIMIT_NPROC,         0,      'p',    "processes" },
 366 #endif
 367 #ifdef RLIMIT_NOFILE
 368         { RLIMIT_NOFILE,        0,      'n',    "file descriptors" },
 369 #endif
 370 #ifdef RLIMIT_AS
 371         { RLIMIT_AS,            10,     'v',    "address space (kb)" },
 372 #endif
 373 #ifdef RLIMIT_LOCKS
 374         { RLIMIT_LOCKS,         0,      'w',    "locks" },
 375 #endif
 376 #ifdef RLIMIT_NICE
 377         { RLIMIT_NICE,          0,      'e',    "scheduling priority" },
 378 #endif
 379 #ifdef RLIMIT_RTPRIO
 380         { RLIMIT_RTPRIO,        0,      'r',    "real-time priority" },
 381 #endif
 382 };
 383
 384 enum {
 385         OPT_hard = (1 << 0),
 386         OPT_soft = (1 << 1),
 387 };
 388
 389 /* "-": treat args as parameters of option with ASCII code 1 */
 390 static const char ulimit_opt_string[] ALIGN1 = "-HSa"
 391 #ifdef RLIMIT_FSIZE
 392                         "f::"
 393 #endif
 394 #ifdef RLIMIT_CPU
 395                         "t::"
 396 #endif
 397 #ifdef RLIMIT_DATA
 398                         "d::"
 399 #endif
 400 #ifdef RLIMIT_STACK
 401                         "s::"
 402 #endif
 403 #ifdef RLIMIT_CORE
 404                         "c::"
 405 #endif
 406 #ifdef RLIMIT_RSS
 407                         "m::"
 408 #endif
 409 #ifdef RLIMIT_MEMLOCK
 410                         "l::"
 411 #endif
 412 #ifdef RLIMIT_NPROC
 413                         "p::"
 414 #endif
 415 #ifdef RLIMIT_NOFILE
 416                         "n::"
 417 #endif
 418 #ifdef RLIMIT_AS
 419                         "v::"
 420 #endif
 421 #ifdef RLIMIT_LOCKS
 422                         "w::"
 423 #endif
 424 #ifdef RLIMIT_NICE
 425                         "e::"
 426 #endif
 427 #ifdef RLIMIT_RTPRIO
 428                         "r::"
 429 #endif
 430                         ;
 431
 432 static void printlim(unsigned opts, const struct rlimit *limit,
 433                         const struct limits *l)
 434 {
 435         rlim_t val;
 436
 437         val = limit->rlim_max;
 438         if (!(opts & OPT_hard))
 439                 val = limit->rlim_cur;
 440
 441         if (val == RLIM_INFINITY)
 442                 puts("unlimited");
 443         else {
 444                 val >>= l->factor_shift;
 445                 printf("%llu\n", (long long) val);
 446         }
 447 }
 448
 449 int FAST_FUNC
 450 shell_builtin_ulimit(char **argv)
 451 {
 452         unsigned opts;
 453         unsigned argc;
 454
 455         /* We can't use getopt32: need to handle commands like
 456          * ulimit 123 -c2 -l 456
 457          */
 458
 459         /* In case getopt() was already called:
 460          * reset libc getopt() internal state.
 461          */
 462         GETOPT_RESET();
 463
 464         argc = string_array_len(argv);
 465
 466         opts = 0;
 467         while (1) {
 468                 struct rlimit limit;
 469                 const struct limits *l;
 470                 int opt_char = getopt(argc, argv, ulimit_opt_string);
 471
 472                 if (opt_char == -1)
 473                         break;
 474                 if (opt_char == 'H') {
 475                         opts |= OPT_hard;
 476                         continue;
 477                 }
 478                 if (opt_char == 'S') {
 479                         opts |= OPT_soft;
 480                         continue;
 481                 }
 482
 483                 if (opt_char == 'a') {
 484                         for (l = limits_tbl; l != &limits_tbl[ARRAY_SIZE(limits_tbl)]; l++) {
 485                                 getrlimit(l->cmd, &limit);
 486                                 printf("-%c: %-30s ", l->option, l->name);
 487                                 printlim(opts, &limit, l);
 488                         }
 489                         continue;
 490                 }
 491
 492                 if (opt_char == 1)
 493                         opt_char = 'f';
 494                 for (l = limits_tbl; l != &limits_tbl[ARRAY_SIZE(limits_tbl)]; l++) {
 495                         if (opt_char == l->option) {
 496                                 char *val_str;
 497
 498                                 getrlimit(l->cmd, &limit);
 499
 500                                 val_str = optarg;
 501                                 if (!val_str && argv[optind] && argv[optind][0] != '-')
 502                                         val_str = argv[optind++]; /* ++ skips NN in "-c NN" case */
 503                                 if (val_str) {
 504                                         rlim_t val;
 505
 506                                         if (strcmp(val_str, "unlimited") == 0)
 507                                                 val = RLIM_INFINITY;
 508                                         else {
 509                                                 if (sizeof(val) == sizeof(int))
 510                                                         val = bb_strtou(val_str, NULL, 10);
 511                                                 else if (sizeof(val) == sizeof(long))
 512                                                         val = bb_strtoul(val_str, NULL, 10);
 513                                                 else
 514                                                         val = bb_strtoull(val_str, NULL, 10);
 515                                                 if (errno) {
 516                                                         bb_error_msg("invalid number '%s'", val_str);
 517                                                         return EXIT_FAILURE;
 518                                                 }
 519                                                 val <<= l->factor_shift;
 520                                         }
 521 //bb_error_msg("opt %c val_str:'%s' val:%lld", opt_char, val_str, (long long)val);
 522                                         /* from man bash: "If neither -H nor -S
 523                                          * is specified, both the soft and hard
 524                                          * limits are set. */
 525                                         if (!opts)
 526                                                 opts = OPT_hard + OPT_soft;
 527                                         if (opts & OPT_hard)
 528                                                 limit.rlim_max = val;
 529                                         if (opts & OPT_soft)
 530                                                 limit.rlim_cur = val;
 531 //bb_error_msg("setrlimit(%d, %lld, %lld)", l->cmd, (long long)limit.rlim_cur, (long long)limit.rlim_max);
 532                                         if (setrlimit(l->cmd, &limit) < 0) {
 533                                                 bb_perror_msg("error setting limit");
 534                                                 return EXIT_FAILURE;
 535                                         }
 536                                 } else {
 537                                         printlim(opts, &limit, l);
 538                                 }
 539                                 break;
 540                         }
 541                 } /* for (every possible opt) */
 542
 543                 if (l == &limits_tbl[ARRAY_SIZE(limits_tbl)]) {
 544                         /* bad option. getopt already complained. */
 545                         break;
 546                 }
 547         } /* while (there are options) */
 548
 549         return 0;
 550 }