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         unsigned err;
  61         unsigned end_ms; /* -t TIMEOUT */
  62         int fd; /* -u FD */
  63         int nchars; /* -n NUM */
  64         char **pp;
  65         char *buffer;
  66         struct termios tty, old_tty;
  67         const char *retval;
  68         int bufpos; /* need to be able to hold -1 */
  69         int startword;
  70         smallint backslash;
  71
  72         errno = err = 0;
  73
  74         pp = argv;
  75         while (*pp) {
  76                 if (!is_well_formed_var_name(*pp, '\0')) {
  77                         /* Mimic bash message */
  78                         bb_error_msg("read: '%s': not a valid identifier", *pp);
  79                         return (const char *)(uintptr_t)1;
  80                 }
  81                 pp++;
  82         }
  83
  84         nchars = 0; /* if != 0, -n is in effect */
  85         if (opt_n) {
  86                 nchars = bb_strtou(opt_n, NULL, 10);
  87                 if (nchars < 0 || errno)
  88                         return "invalid count";
  89                 /* note: "-n 0": off (bash 3.2 does this too) */
  90         }
  91         end_ms = 0;
  92         if (opt_t) {
  93                 end_ms = bb_strtou(opt_t, NULL, 10);
  94                 if (errno || end_ms > UINT_MAX / 2048)
  95                         return "invalid timeout";
  96                 end_ms *= 1000;
  97 #if 0 /* even bash has no -t N.NNN support */
  98                 ts.tv_sec = bb_strtou(opt_t, &p, 10);
  99                 ts.tv_usec = 0;
 100                 /* EINVAL means number is ok, but not terminated by NUL */
 101                 if (*p == '.' && errno == EINVAL) {
 102                         char *p2;
 103                         if (*++p) {
 104                                 int scale;
 105                                 ts.tv_usec = bb_strtou(p, &p2, 10);
 106                                 if (errno)
 107                                         return "invalid timeout";
 108                                 scale = p2 - p;
 109                                 /* normalize to usec */
 110                                 if (scale > 6)
 111                                         return "invalid timeout";
 112                                 while (scale++ < 6)
 113                                         ts.tv_usec *= 10;
 114                         }
 115                 } else if (ts.tv_sec < 0 || errno) {
 116                         return "invalid timeout";
 117                 }
 118                 if (!(ts.tv_sec | ts.tv_usec)) { /* both are 0? */
 119                         return "invalid timeout";
 120                 }
 121 #endif /* if 0 */
 122         }
 123         fd = STDIN_FILENO;
 124         if (opt_u) {
 125                 fd = bb_strtou(opt_u, NULL, 10);
 126                 if (fd < 0 || errno)
 127                         return "invalid file descriptor";
 128         }
 129
 130         if (opt_p && isatty(fd)) {
 131                 fputs(opt_p, stderr);
 132                 fflush_all();
 133         }
 134
 135         if (ifs == NULL)
 136                 ifs = defifs;
 137
 138         if (nchars || (read_flags & BUILTIN_READ_SILENT)) {
 139                 tcgetattr(fd, &tty);
 140                 old_tty = tty;
 141                 if (nchars) {
 142                         tty.c_lflag &= ~ICANON;
 143                         // Setting it to more than 1 breaks poll():
 144                         // it blocks even if there's data. !??
 145                         //tty.c_cc[VMIN] = nchars < 256 ? nchars : 255;
 146                         /* reads will block only if < 1 char is available */
 147                         tty.c_cc[VMIN] = 1;
 148                         /* no timeout (reads block forever) */
 149                         tty.c_cc[VTIME] = 0;
 150                 }
 151                 if (read_flags & BUILTIN_READ_SILENT) {
 152                         tty.c_lflag &= ~(ECHO | ECHOK | ECHONL);
 153                 }
 154                 /* This forces execution of "restoring" tcgetattr later */
 155                 read_flags |= BUILTIN_READ_SILENT;
 156                 /* if tcgetattr failed, tcsetattr will fail too.
 157                  * Ignoring, it's harmless. */
 158                 tcsetattr(fd, TCSANOW, &tty);
 159         }
 160
 161         retval = (const char *)(uintptr_t)0;
 162         startword = 1;
 163         backslash = 0;
 164         if (end_ms) /* NB: end_ms stays nonzero: */
 165                 end_ms = ((unsigned)monotonic_ms() + end_ms) | 1;
 166         buffer = NULL;
 167         bufpos = 0;
 168         do {
 169                 char c;
 170                 struct pollfd pfd[1];
 171                 int timeout;
 172
 173                 if ((bufpos & 0xff) == 0)
 174                         buffer = xrealloc(buffer, bufpos + 0x101);
 175
 176                 timeout = -1;
 177                 if (end_ms) {
 178                         timeout = end_ms - (unsigned)monotonic_ms();
 179                         if (timeout <= 0) { /* already late? */
 180                                 retval = (const char *)(uintptr_t)1;
 181                                 goto ret;
 182                         }
 183                 }
 184
 185                 /* We must poll even if timeout is -1:
 186                  * we want to be interrupted if signal arrives,
 187                  * regardless of SA_RESTART-ness of that signal!
 188                  */
 189                 errno = 0;
 190                 pfd[0].fd = fd;
 191                 pfd[0].events = POLLIN;
 192                 if (poll(pfd, 1, timeout) != 1) {
 193                         /* timed out, or EINTR */
 194                         err = errno;
 195                         retval = (const char *)(uintptr_t)1;
 196                         goto ret;
 197                 }
 198                 if (read(fd, &buffer[bufpos], 1) != 1) {
 199                         err = errno;
 200                         retval = (const char *)(uintptr_t)1;
 201                         break;
 202                 }
 203
 204                 c = buffer[bufpos];
 205                 if (c == '\0')
 206                         continue;
 207                 if (!(read_flags & BUILTIN_READ_RAW)) {
 208                         if (backslash) {
 209                                 backslash = 0;
 210                                 if (c != '\n')
 211                                         goto put;
 212                                 continue;
 213                         }
 214                         if (c == '\\') {
 215                                 backslash = 1;
 216                                 continue;
 217                         }
 218                 }
 219                 if (c == '\n')
 220                         break;
 221
 222                 /* $IFS splitting. NOT done if we run "read"
 223                  * without variable names (bash compat).
 224                  * Thus, "read" and "read REPLY" are not the same.
 225                  */
 226                 if (argv[0]) {
 227 /* http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_05 */
 228                         const char *is_ifs = strchr(ifs, c);
 229                         if (startword && is_ifs) {
 230                                 if (isspace(c))
 231                                         continue;
 232                                 /* it is a non-space ifs char */
 233                                 startword--;
 234                                 if (startword == 1) /* first one? */
 235                                         continue; /* yes, it is not next word yet */
 236                         }
 237                         startword = 0;
 238                         if (argv[1] != NULL && is_ifs) {
 239                                 buffer[bufpos] = '\0';
 240                                 bufpos = 0;
 241                                 setvar(*argv, buffer);
 242                                 argv++;
 243                                 /* can we skip one non-space ifs char? (2: yes) */
 244                                 startword = isspace(c) ? 2 : 1;
 245                                 continue;
 246                         }
 247                 }
 248  put:
 249                 bufpos++;
 250         } while (--nchars);
 251
 252         if (argv[0]) {
 253                 /* Remove trailing space $IFS chars */
 254                 while (--bufpos >= 0 && isspace(buffer[bufpos]) && strchr(ifs, buffer[bufpos]) != NULL)
 255                         continue;
 256                 buffer[bufpos + 1] = '\0';
 257                 /* Use the remainder as a value for the next variable */
 258                 setvar(*argv, buffer);
 259                 /* Set the rest to "" */
 260                 while (*++argv)
 261                         setvar(*argv, "");
 262         } else {
 263                 /* Note: no $IFS removal */
 264                 buffer[bufpos] = '\0';
 265                 setvar("REPLY", buffer);
 266         }
 267
 268  ret:
 269         free(buffer);
 270         if (read_flags & BUILTIN_READ_SILENT)
 271                 tcsetattr(fd, TCSANOW, &old_tty);
 272
 273         errno = err;
 274         return retval;
 275 }
 276
 277 /* ulimit builtin */
 278
 279 struct limits {
 280         uint8_t cmd;            /* RLIMIT_xxx fit into it */
 281         uint8_t factor_shift;   /* shift by to get rlim_{cur,max} values */
 282         char option;
 283         const char *name;
 284 };
 285
 286 static const struct limits limits_tbl[] = {
 287 #ifdef RLIMIT_FSIZE
 288         { RLIMIT_FSIZE,         9,      'f',    "file size (blocks)" },
 289 #endif
 290 #ifdef RLIMIT_CPU
 291         { RLIMIT_CPU,           0,      't',    "cpu time (seconds)" },
 292 #endif
 293 #ifdef RLIMIT_DATA
 294         { RLIMIT_DATA,          10,     'd',    "data seg size (kb)" },
 295 #endif
 296 #ifdef RLIMIT_STACK
 297         { RLIMIT_STACK,         10,     's',    "stack size (kb)" },
 298 #endif
 299 #ifdef RLIMIT_CORE
 300         { RLIMIT_CORE,          9,      'c',    "core file size (blocks)" },
 301 #endif
 302 #ifdef RLIMIT_RSS
 303         { RLIMIT_RSS,           10,     'm',    "resident set size (kb)" },
 304 #endif
 305 #ifdef RLIMIT_MEMLOCK
 306         { RLIMIT_MEMLOCK,       10,     'l',    "locked memory (kb)" },
 307 #endif
 308 #ifdef RLIMIT_NPROC
 309         { RLIMIT_NPROC,         0,      'p',    "processes" },
 310 #endif
 311 #ifdef RLIMIT_NOFILE
 312         { RLIMIT_NOFILE,        0,      'n',    "file descriptors" },
 313 #endif
 314 #ifdef RLIMIT_AS
 315         { RLIMIT_AS,            10,     'v',    "address space (kb)" },
 316 #endif
 317 #ifdef RLIMIT_LOCKS
 318         { RLIMIT_LOCKS,         0,      'w',    "locks" },
 319 #endif
 320 #ifdef RLIMIT_NICE
 321         { RLIMIT_NICE,          0,      'e',    "scheduling priority" },
 322 #endif
 323 #ifdef RLIMIT_RTPRIO
 324         { RLIMIT_RTPRIO,        0,      'r',    "real-time priority" },
 325 #endif
 326 };
 327
 328 enum {
 329         OPT_hard = (1 << 0),
 330         OPT_soft = (1 << 1),
 331 };
 332
 333 /* "-": treat args as parameters of option with ASCII code 1 */
 334 static const char ulimit_opt_string[] ALIGN1 = "-HSa"
 335 #ifdef RLIMIT_FSIZE
 336                         "f::"
 337 #endif
 338 #ifdef RLIMIT_CPU
 339                         "t::"
 340 #endif
 341 #ifdef RLIMIT_DATA
 342                         "d::"
 343 #endif
 344 #ifdef RLIMIT_STACK
 345                         "s::"
 346 #endif
 347 #ifdef RLIMIT_CORE
 348                         "c::"
 349 #endif
 350 #ifdef RLIMIT_RSS
 351                         "m::"
 352 #endif
 353 #ifdef RLIMIT_MEMLOCK
 354                         "l::"
 355 #endif
 356 #ifdef RLIMIT_NPROC
 357                         "p::"
 358 #endif
 359 #ifdef RLIMIT_NOFILE
 360                         "n::"
 361 #endif
 362 #ifdef RLIMIT_AS
 363                         "v::"
 364 #endif
 365 #ifdef RLIMIT_LOCKS
 366                         "w::"
 367 #endif
 368 #ifdef RLIMIT_NICE
 369                         "e::"
 370 #endif
 371 #ifdef RLIMIT_RTPRIO
 372                         "r::"
 373 #endif
 374                         ;
 375
 376 static void printlim(unsigned opts, const struct rlimit *limit,
 377                         const struct limits *l)
 378 {
 379         rlim_t val;
 380
 381         val = limit->rlim_max;
 382         if (!(opts & OPT_hard))
 383                 val = limit->rlim_cur;
 384
 385         if (val == RLIM_INFINITY)
 386                 puts("unlimited");
 387         else {
 388                 val >>= l->factor_shift;
 389                 printf("%llu\n", (long long) val);
 390         }
 391 }
 392
 393 int FAST_FUNC
 394 shell_builtin_ulimit(char **argv)
 395 {
 396         unsigned opts;
 397         unsigned argc;
 398
 399         /* We can't use getopt32: need to handle commands like
 400          * ulimit 123 -c2 -l 456
 401          */
 402
 403         /* In case getopt was already called:
 404          * reset the libc getopt() function, which keeps internal state.
 405          */
 406         GETOPT_RESET();
 407
 408         argc = string_array_len(argv);
 409
 410         opts = 0;
 411         while (1) {
 412                 struct rlimit limit;
 413                 const struct limits *l;
 414                 int opt_char = getopt(argc, argv, ulimit_opt_string);
 415
 416                 if (opt_char == -1)
 417                         break;
 418                 if (opt_char == 'H') {
 419                         opts |= OPT_hard;
 420                         continue;
 421                 }
 422                 if (opt_char == 'S') {
 423                         opts |= OPT_soft;
 424                         continue;
 425                 }
 426
 427                 if (opt_char == 'a') {
 428                         for (l = limits_tbl; l != &limits_tbl[ARRAY_SIZE(limits_tbl)]; l++) {
 429                                 getrlimit(l->cmd, &limit);
 430                                 printf("-%c: %-30s ", l->option, l->name);
 431                                 printlim(opts, &limit, l);
 432                         }
 433                         continue;
 434                 }
 435
 436                 if (opt_char == 1)
 437                         opt_char = 'f';
 438                 for (l = limits_tbl; l != &limits_tbl[ARRAY_SIZE(limits_tbl)]; l++) {
 439                         if (opt_char == l->option) {
 440                                 char *val_str;
 441
 442                                 getrlimit(l->cmd, &limit);
 443
 444                                 val_str = optarg;
 445                                 if (!val_str && argv[optind] && argv[optind][0] != '-')
 446                                         val_str = argv[optind++]; /* ++ skips NN in "-c NN" case */
 447                                 if (val_str) {
 448                                         rlim_t val;
 449
 450                                         if (strcmp(val_str, "unlimited") == 0)
 451                                                 val = RLIM_INFINITY;
 452                                         else {
 453                                                 if (sizeof(val) == sizeof(int))
 454                                                         val = bb_strtou(val_str, NULL, 10);
 455                                                 else if (sizeof(val) == sizeof(long))
 456                                                         val = bb_strtoul(val_str, NULL, 10);
 457                                                 else
 458                                                         val = bb_strtoull(val_str, NULL, 10);
 459                                                 if (errno) {
 460                                                         bb_error_msg("invalid number '%s'", val_str);
 461                                                         return EXIT_FAILURE;
 462                                                 }
 463                                                 val <<= l->factor_shift;
 464                                         }
 465 //bb_error_msg("opt %c val_str:'%s' val:%lld", opt_char, val_str, (long long)val);
 466                                         /* from man bash: "If neither -H nor -S
 467                                          * is specified, both the soft and hard
 468                                          * limits are set. */
 469                                         if (!opts)
 470                                                 opts = OPT_hard + OPT_soft;
 471                                         if (opts & OPT_hard)
 472                                                 limit.rlim_max = val;
 473                                         if (opts & OPT_soft)
 474                                                 limit.rlim_cur = val;
 475 //bb_error_msg("setrlimit(%d, %lld, %lld)", l->cmd, (long long)limit.rlim_cur, (long long)limit.rlim_max);
 476                                         if (setrlimit(l->cmd, &limit) < 0) {
 477                                                 bb_perror_msg("error setting limit");
 478                                                 return EXIT_FAILURE;
 479                                         }
 480                                 } else {
 481                                         printlim(opts, &limit, l);
 482                                 }
 483                                 break;
 484                         }
 485                 } /* for (every possible opt) */
 486
 487                 if (l == &limits_tbl[ARRAY_SIZE(limits_tbl)]) {
 488                         /* bad option. getopt already complained. */
 489                         break;
 490                 }
 491         } /* while (there are options) */
 492
 493         return 0;
 494 }