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
  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(void FAST_FUNC (*setvar)(const char *name, const char *val),
  50         char       **argv,
  51         const char *ifs,
  52         int        read_flags,
  53         const char *opt_n,
  54         const char *opt_p,
  55         const char *opt_t,
  56         const char *opt_u
  57 )
  58 {
  59         unsigned err;
  60         unsigned end_ms; /* -t TIMEOUT */
  61         int fd; /* -u FD */
  62         int nchars; /* -n NUM */
  63         char **pp;
  64         char *buffer;
  65         struct termios tty, old_tty;
  66         const char *retval;
  67         int bufpos; /* need to be able to hold -1 */
  68         int startword;
  69         smallint backslash;
  70
  71         errno = err = 0;
  72
  73         pp = argv;
  74         while (*pp) {
  75                 if (!is_well_formed_var_name(*pp, '\0')) {
  76                         /* Mimic bash message */
  77                         bb_error_msg("read: '%s': not a valid identifier", *pp);
  78                         return (const char *)(uintptr_t)1;
  79                 }
  80                 pp++;
  81         }
  82
  83         nchars = 0; /* if != 0, -n is in effect */
  84         if (opt_n) {
  85                 nchars = bb_strtou(opt_n, NULL, 10);
  86                 if (nchars < 0 || errno)
  87                         return "invalid count";
  88                 /* note: "-n 0": off (bash 3.2 does this too) */
  89         }
  90         end_ms = 0;
  91         if (opt_t) {
  92                 end_ms = bb_strtou(opt_t, NULL, 10);
  93                 if (errno || end_ms > UINT_MAX / 2048)
  94                         return "invalid timeout";
  95                 end_ms *= 1000;
  96 #if 0 /* even bash has no -t N.NNN support */
  97                 ts.tv_sec = bb_strtou(opt_t, &p, 10);
  98                 ts.tv_usec = 0;
  99                 /* EINVAL means number is ok, but not terminated by NUL */
 100                 if (*p == '.' && errno == EINVAL) {
 101                         char *p2;
 102                         if (*++p) {
 103                                 int scale;
 104                                 ts.tv_usec = bb_strtou(p, &p2, 10);
 105                                 if (errno)
 106                                         return "invalid timeout";
 107                                 scale = p2 - p;
 108                                 /* normalize to usec */
 109                                 if (scale > 6)
 110                                         return "invalid timeout";
 111                                 while (scale++ < 6)
 112                                         ts.tv_usec *= 10;
 113                         }
 114                 } else if (ts.tv_sec < 0 || errno) {
 115                         return "invalid timeout";
 116                 }
 117                 if (!(ts.tv_sec | ts.tv_usec)) { /* both are 0? */
 118                         return "invalid timeout";
 119                 }
 120 #endif /* if 0 */
 121         }
 122         fd = STDIN_FILENO;
 123         if (opt_u) {
 124                 fd = bb_strtou(opt_u, NULL, 10);
 125                 if (fd < 0 || errno)
 126                         return "invalid file descriptor";
 127         }
 128
 129         if (opt_p && isatty(fd)) {
 130                 fputs(opt_p, stderr);
 131                 fflush_all();
 132         }
 133
 134         if (ifs == NULL)
 135                 ifs = defifs;
 136
 137         if (nchars || (read_flags & BUILTIN_READ_SILENT)) {
 138                 tcgetattr(fd, &tty);
 139                 old_tty = tty;
 140                 if (nchars) {
 141                         tty.c_lflag &= ~ICANON;
 142                         // Setting it to more than 1 breaks poll():
 143                         // it blocks even if there's data. !??
 144                         //tty.c_cc[VMIN] = nchars < 256 ? nchars : 255;
 145                         /* reads would block only if < 1 char is available */
 146                         tty.c_cc[VMIN] = 1;
 147                         /* no timeout (reads block forever) */
 148                         tty.c_cc[VTIME] = 0;
 149                 }
 150                 if (read_flags & BUILTIN_READ_SILENT) {
 151                         tty.c_lflag &= ~(ECHO | ECHOK | ECHONL);
 152                 }
 153                 /* This forces execution of "restoring" tcgetattr later */
 154                 read_flags |= BUILTIN_READ_SILENT;
 155                 /* if tcgetattr failed, tcsetattr will fail too.
 156                  * Ignoring, it's harmless. */
 157                 tcsetattr(fd, TCSANOW, &tty);
 158         }
 159
 160         retval = (const char *)(uintptr_t)0;
 161         startword = 1;
 162         backslash = 0;
 163         if (end_ms) /* NB: end_ms stays nonzero: */
 164                 end_ms = ((unsigned)monotonic_ms() + end_ms) | 1;
 165         buffer = NULL;
 166         bufpos = 0;
 167         do {
 168                 char c;
 169                 struct pollfd pfd[1];
 170                 int timeout;
 171
 172                 if ((bufpos & 0xff) == 0)
 173                         buffer = xrealloc(buffer, bufpos + 0x101);
 174
 175                 timeout = -1;
 176                 if (end_ms) {
 177                         timeout = end_ms - (unsigned)monotonic_ms();
 178                         if (timeout <= 0) { /* already late? */
 179                                 retval = (const char *)(uintptr_t)1;
 180                                 goto ret;
 181                         }
 182                 }
 183
 184                 /* We must poll even if timeout is -1:
 185                  * we want to be interrupted if signal arrives,
 186                  * regardless of SA_RESTART-ness of that signal!
 187                  */
 188                 errno = 0;
 189                 pfd[0].fd = fd;
 190                 pfd[0].events = POLLIN;
 191                 if (poll(pfd, 1, timeout) != 1) {
 192                         /* timed out, or EINTR */
 193                         err = errno;
 194                         retval = (const char *)(uintptr_t)1;
 195                         goto ret;
 196                 }
 197                 if (read(fd, &buffer[bufpos], 1) != 1) {
 198                         err = errno;
 199                         retval = (const char *)(uintptr_t)1;
 200                         break;
 201                 }
 202
 203                 c = buffer[bufpos];
 204                 if (c == '\0')
 205                         continue;
 206                 if (backslash) {
 207                         backslash = 0;
 208                         if (c != '\n')
 209                                 goto put;
 210                         continue;
 211                 }
 212                 if (!(read_flags & BUILTIN_READ_RAW) && c == '\\') {
 213                         backslash = 1;
 214                         continue;
 215                 }
 216                 if (c == '\n')
 217                         break;
 218
 219                 /* $IFS splitting. NOT done if we run "read"
 220                  * without variable names (bash compat).
 221                  * Thus, "read" and "read REPLY" are not the same.
 222                  */
 223                 if (argv[0]) {
 224 /* http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_05 */
 225                         const char *is_ifs = strchr(ifs, c);
 226                         if (startword && is_ifs) {
 227                                 if (isspace(c))
 228                                         continue;
 229                                 /* it is a non-space ifs char */
 230                                 startword--;
 231                                 if (startword == 1) /* first one? */
 232                                         continue; /* yes, it is not next word yet */
 233                         }
 234                         startword = 0;
 235                         if (argv[1] != NULL && is_ifs) {
 236                                 buffer[bufpos] = '\0';
 237                                 bufpos = 0;
 238                                 setvar(*argv, buffer);
 239                                 argv++;
 240                                 /* can we skip one non-space ifs char? (2: yes) */
 241                                 startword = isspace(c) ? 2 : 1;
 242                                 continue;
 243                         }
 244                 }
 245  put:
 246                 bufpos++;
 247         } while (--nchars);
 248
 249         if (argv[0]) {
 250                 /* Remove trailing space $IFS chars */
 251                 while (--bufpos >= 0 && isspace(buffer[bufpos]) && strchr(ifs, buffer[bufpos]) != NULL)
 252                         continue;
 253                 buffer[bufpos + 1] = '\0';
 254                 /* Use the remainder as a value for the next variable */
 255                 setvar(*argv, buffer);
 256                 /* Set the rest to "" */
 257                 while (*++argv)
 258                         setvar(*argv, "");
 259         } else {
 260                 /* Note: no $IFS removal */
 261                 buffer[bufpos] = '\0';
 262                 setvar("REPLY", buffer);
 263         }
 264
 265  ret:
 266         free(buffer);
 267         if (read_flags & BUILTIN_READ_SILENT)
 268                 tcsetattr(fd, TCSANOW, &old_tty);
 269
 270         errno = err;
 271         return retval;
 272 }
 273
 274 /* ulimit builtin */
 275
 276 struct limits {
 277         uint8_t cmd;            /* RLIMIT_xxx fit into it */
 278         uint8_t factor_shift;   /* shift by to get rlim_{cur,max} values */
 279         char option;
 280         const char *name;
 281 };
 282
 283 static const struct limits limits_tbl[] = {
 284 #ifdef RLIMIT_FSIZE
 285         { RLIMIT_FSIZE,         9,      'f',    "file size (blocks)" },
 286 #endif
 287 #ifdef RLIMIT_CPU
 288         { RLIMIT_CPU,           0,      't',    "cpu time (seconds)" },
 289 #endif
 290 #ifdef RLIMIT_DATA
 291         { RLIMIT_DATA,          10,     'd',    "data seg size (kb)" },
 292 #endif
 293 #ifdef RLIMIT_STACK
 294         { RLIMIT_STACK,         10,     's',    "stack size (kb)" },
 295 #endif
 296 #ifdef RLIMIT_CORE
 297         { RLIMIT_CORE,          9,      'c',    "core file size (blocks)" },
 298 #endif
 299 #ifdef RLIMIT_RSS
 300         { RLIMIT_RSS,           10,     'm',    "resident set size (kb)" },
 301 #endif
 302 #ifdef RLIMIT_MEMLOCK
 303         { RLIMIT_MEMLOCK,       10,     'l',    "locked memory (kb)" },
 304 #endif
 305 #ifdef RLIMIT_NPROC
 306         { RLIMIT_NPROC,         0,      'p',    "processes" },
 307 #endif
 308 #ifdef RLIMIT_NOFILE
 309         { RLIMIT_NOFILE,        0,      'n',    "file descriptors" },
 310 #endif
 311 #ifdef RLIMIT_AS
 312         { RLIMIT_AS,            10,     'v',    "address space (kb)" },
 313 #endif
 314 #ifdef RLIMIT_LOCKS
 315         { RLIMIT_LOCKS,         0,      'w',    "locks" },
 316 #endif
 317 #ifdef RLIMIT_NICE
 318         { RLIMIT_NICE,          0,      'e',    "scheduling priority" },
 319 #endif
 320 #ifdef RLIMIT_RTPRIO
 321         { RLIMIT_RTPRIO,        0,      'r',    "real-time priority" },
 322 #endif
 323 };
 324
 325 enum {
 326         OPT_hard = (1 << 0),
 327         OPT_soft = (1 << 1),
 328 };
 329
 330 /* "-": treat args as parameters of option with ASCII code 1 */
 331 static const char ulimit_opt_string[] = "-HSa"
 332 #ifdef RLIMIT_FSIZE
 333                         "f::"
 334 #endif
 335 #ifdef RLIMIT_CPU
 336                         "t::"
 337 #endif
 338 #ifdef RLIMIT_DATA
 339                         "d::"
 340 #endif
 341 #ifdef RLIMIT_STACK
 342                         "s::"
 343 #endif
 344 #ifdef RLIMIT_CORE
 345                         "c::"
 346 #endif
 347 #ifdef RLIMIT_RSS
 348                         "m::"
 349 #endif
 350 #ifdef RLIMIT_MEMLOCK
 351                         "l::"
 352 #endif
 353 #ifdef RLIMIT_NPROC
 354                         "p::"
 355 #endif
 356 #ifdef RLIMIT_NOFILE
 357                         "n::"
 358 #endif
 359 #ifdef RLIMIT_AS
 360                         "v::"
 361 #endif
 362 #ifdef RLIMIT_LOCKS
 363                         "w::"
 364 #endif
 365 #ifdef RLIMIT_NICE
 366                         "e::"
 367 #endif
 368 #ifdef RLIMIT_RTPRIO
 369                         "r::"
 370 #endif
 371                         ;
 372
 373 static void printlim(unsigned opts, const struct rlimit *limit,
 374                         const struct limits *l)
 375 {
 376         rlim_t val;
 377
 378         val = limit->rlim_max;
 379         if (!(opts & OPT_hard))
 380                 val = limit->rlim_cur;
 381
 382         if (val == RLIM_INFINITY)
 383                 printf("unlimited\n");
 384         else {
 385                 val >>= l->factor_shift;
 386                 printf("%llu\n", (long long) val);
 387         }
 388 }
 389
 390 int FAST_FUNC
 391 shell_builtin_ulimit(char **argv)
 392 {
 393         unsigned opts;
 394         unsigned argc;
 395
 396         /* We can't use getopt32: need to handle commands like
 397          * ulimit 123 -c2 -l 456
 398          */
 399
 400         /* In case getopt was already called:
 401          * reset the libc getopt() function, which keeps internal state.
 402          */
 403 #ifdef __GLIBC__
 404         optind = 0;
 405 #else /* BSD style */
 406         optind = 1;
 407         /* optreset = 1; */
 408 #endif
 409         /* optarg = NULL; opterr = 0; optopt = 0; - do we need this?? */
 410
 411         argc = 1;
 412         while (argv[argc])
 413                 argc++;
 414
 415         opts = 0;
 416         while (1) {
 417                 struct rlimit limit;
 418                 const struct limits *l;
 419                 int opt_char = getopt(argc, argv, ulimit_opt_string);
 420
 421                 if (opt_char == -1)
 422                         break;
 423                 if (opt_char == 'H') {
 424                         opts |= OPT_hard;
 425                         continue;
 426                 }
 427                 if (opt_char == 'S') {
 428                         opts |= OPT_soft;
 429                         continue;
 430                 }
 431
 432                 if (opt_char == 'a') {
 433                         for (l = limits_tbl; l != &limits_tbl[ARRAY_SIZE(limits_tbl)]; l++) {
 434                                 getrlimit(l->cmd, &limit);
 435                                 printf("-%c: %-30s ", l->option, l->name);
 436                                 printlim(opts, &limit, l);
 437                         }
 438                         continue;
 439                 }
 440
 441                 if (opt_char == 1)
 442                         opt_char = 'f';
 443                 for (l = limits_tbl; l != &limits_tbl[ARRAY_SIZE(limits_tbl)]; l++) {
 444                         if (opt_char == l->option) {
 445                                 char *val_str;
 446
 447                                 getrlimit(l->cmd, &limit);
 448
 449                                 val_str = optarg;
 450                                 if (!val_str && argv[optind] && argv[optind][0] != '-')
 451                                         val_str = argv[optind++]; /* ++ skips NN in "-c NN" case */
 452                                 if (val_str) {
 453                                         rlim_t val;
 454
 455                                         if (strcmp(val_str, "unlimited") == 0)
 456                                                 val = RLIM_INFINITY;
 457                                         else {
 458                                                 if (sizeof(val) == sizeof(int))
 459                                                         val = bb_strtou(val_str, NULL, 10);
 460                                                 else if (sizeof(val) == sizeof(long))
 461                                                         val = bb_strtoul(val_str, NULL, 10);
 462                                                 else
 463                                                         val = bb_strtoull(val_str, NULL, 10);
 464                                                 if (errno) {
 465                                                         bb_error_msg("invalid number '%s'", val_str);
 466                                                         return EXIT_FAILURE;
 467                                                 }
 468                                                 val <<= l->factor_shift;
 469                                         }
 470 //bb_error_msg("opt %c val_str:'%s' val:%lld", opt_char, val_str, (long long)val);
 471                                         /* from man bash: "If neither -H nor -S
 472                                          * is specified, both the soft and hard
 473                                          * limits are set. */
 474                                         if (!opts)
 475                                                 opts = OPT_hard + OPT_soft;
 476                                         if (opts & OPT_hard)
 477                                                 limit.rlim_max = val;
 478                                         if (opts & OPT_soft)
 479                                                 limit.rlim_cur = val;
 480 //bb_error_msg("setrlimit(%d, %lld, %lld)", l->cmd, (long long)limit.rlim_cur, (long long)limit.rlim_max);
 481                                         if (setrlimit(l->cmd, &limit) < 0) {
 482                                                 bb_perror_msg("error setting limit");
 483                                                 return EXIT_FAILURE;
 484                                         }
 485                                 } else {
 486                                         printlim(opts, &limit, l);
 487                                 }
 488                                 break;
 489                         }
 490                 } /* for (every possible opt) */
 491
 492                 if (l == &limits_tbl[ARRAY_SIZE(limits_tbl)]) {
 493                         /* bad option. getopt already complained. */
 494                         break;
 495                 }
 496
 497         } /* while (there are options) */
 498
 499         return 0;
 500 }