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