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