libbb/appletlib.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Utility routines.
   4  *
   5  * Copyright (C) tons of folks.  Tracking down who wrote what
   6  * isn't something I'm going to worry about...  If you wrote something
   7  * here, please feel free to acknowledge your work.
   8  *
   9  * Based in part on code from sash, Copyright (c) 1999 by David I. Bell
  10  * Permission has been granted to redistribute this code under GPL.
  11  *
  12  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  13  */
  14
  15 /* We are trying to not use printf, this benefits the case when selected
  16  * applets are really simple. Example:
  17  *
  18  * $ ./busybox
  19  * ...
  20  * Currently defined functions:
  21  *         basename, false, true
  22  *
  23  * $ size busybox
  24  *    text    data     bss     dec     hex filename
  25  *    4473      52      72    4597    11f5 busybox
  26  *
  27  * FEATURE_INSTALLER or FEATURE_SUID will still link printf routines in. :(
  28  */
  29 #include "busybox.h"
  30
  31 #if !(defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__NetBSD__) \
  32     || defined(__APPLE__) \
  33     )
  34 # include <malloc.h> /* for mallopt */
  35 #endif
  36
  37
  38 /* Declare <applet>_main() */
  39 #define PROTOTYPES
  40 #include "applets.h"
  41 #undef PROTOTYPES
  42
  43 /* Include generated applet names, pointers to <applet>_main, etc */
  44 #include "applet_tables.h"
  45 /* ...and if applet_tables generator says we have only one applet... */
  46 #ifdef SINGLE_APPLET_MAIN
  47 # undef ENABLE_FEATURE_INDIVIDUAL
  48 # define ENABLE_FEATURE_INDIVIDUAL 1
  49 # undef IF_FEATURE_INDIVIDUAL
  50 # define IF_FEATURE_INDIVIDUAL(...) __VA_ARGS__
  51 #endif
  52
  53 #include "usage_compressed.h"
  54
  55
  56 #if ENABLE_SHOW_USAGE && !ENABLE_FEATURE_COMPRESS_USAGE
  57 static const char usage_messages[] ALIGN1 = UNPACKED_USAGE;
  58 #else
  59 # define usage_messages 0
  60 #endif
  61
  62 #if ENABLE_FEATURE_COMPRESS_USAGE
  63
  64 static const char packed_usage[] ALIGN1 = { PACKED_USAGE };
  65 # include "bb_archive.h"
  66 static const char *unpack_usage_messages(void)
  67 {
  68         char *outbuf = NULL;
  69         bunzip_data *bd;
  70         int i;
  71
  72         i = start_bunzip(&bd,
  73                         /* src_fd: */ -1,
  74                         /* inbuf:  */ packed_usage,
  75                         /* len:    */ sizeof(packed_usage));
  76         /* read_bunzip can longjmp to start_bunzip, and ultimately
  77          * end up here with i != 0 on read data errors! Not trivial */
  78         if (!i) {
  79                 /* Cannot use xmalloc: will leak bd in NOFORK case! */
  80                 outbuf = malloc_or_warn(sizeof(UNPACKED_USAGE));
  81                 if (outbuf)
  82                         read_bunzip(bd, outbuf, sizeof(UNPACKED_USAGE));
  83         }
  84         dealloc_bunzip(bd);
  85         return outbuf;
  86 }
  87 # define dealloc_usage_messages(s) free(s)
  88
  89 #else
  90
  91 # define unpack_usage_messages() usage_messages
  92 # define dealloc_usage_messages(s) ((void)(s))
  93
  94 #endif /* FEATURE_COMPRESS_USAGE */
  95
  96
  97 void FAST_FUNC bb_show_usage(void)
  98 {
  99         if (ENABLE_SHOW_USAGE) {
 100 #ifdef SINGLE_APPLET_STR
 101                 /* Imagine that this applet is "true". Dont suck in printf! */
 102                 const char *usage_string = unpack_usage_messages();
 103
 104                 if (*usage_string == '\b') {
 105                         full_write2_str("No help available.\n\n");
 106                 } else {
 107                         full_write2_str("Usage: "SINGLE_APPLET_STR" ");
 108                         full_write2_str(usage_string);
 109                         full_write2_str("\n\n");
 110                 }
 111                 if (ENABLE_FEATURE_CLEAN_UP)
 112                         dealloc_usage_messages((char*)usage_string);
 113 #else
 114                 const char *p;
 115                 const char *usage_string = p = unpack_usage_messages();
 116                 int ap = find_applet_by_name(applet_name);
 117
 118                 if (ap < 0) /* never happens, paranoia */
 119                         xfunc_die();
 120                 while (ap) {
 121                         while (*p++) continue;
 122                         ap--;
 123                 }
 124                 full_write2_str(bb_banner);
 125                 full_write2_str(" multi-call binary.\n");
 126                 if (*p == '\b')
 127                         full_write2_str("\nNo help available.\n\n");
 128                 else {
 129                         full_write2_str("\nUsage: ");
 130                         full_write2_str(applet_name);
 131                         full_write2_str(" ");
 132                         full_write2_str(p);
 133                         full_write2_str("\n");
 134                 }
 135                 if (ENABLE_FEATURE_CLEAN_UP)
 136                         dealloc_usage_messages((char*)usage_string);
 137 #endif
 138         }
 139         xfunc_die();
 140 }
 141
 142 #if NUM_APPLETS > 8
 143 static int applet_name_compare(const void *name, const void *idx)
 144 {
 145         int i = (int)(ptrdiff_t)idx - 1;
 146         return strcmp(name, APPLET_NAME(i));
 147 }
 148 #endif
 149 int FAST_FUNC find_applet_by_name(const char *name)
 150 {
 151 #if NUM_APPLETS > 8
 152         /* Do a binary search to find the applet entry given the name. */
 153         const char *p;
 154         p = bsearch(name, (void*)(ptrdiff_t)1, ARRAY_SIZE(applet_main), 1, applet_name_compare);
 155         /*
 156          * if (!p) return -1;
 157          * ^^^^^^^^^^^^^^^^^^ the code below will do this if p == NULL :)
 158          */
 159         return (int)(ptrdiff_t)p - 1;
 160 #else
 161         /* A version which does not pull in bsearch */
 162         int i = 0;
 163         const char *p = applet_names;
 164         while (i < NUM_APPLETS) {
 165                 if (strcmp(name, p) == 0)
 166                         return i;
 167                 p += strlen(p) + 1;
 168                 i++;
 169         }
 170         return -1;
 171 #endif
 172 }
 173
 174
 175 void lbb_prepare(const char *applet
 176                 IF_FEATURE_INDIVIDUAL(, char **argv))
 177                                 MAIN_EXTERNALLY_VISIBLE;
 178 void lbb_prepare(const char *applet
 179                 IF_FEATURE_INDIVIDUAL(, char **argv))
 180 {
 181 #ifdef __GLIBC__
 182         (*(int **)&bb_errno) = __errno_location();
 183         barrier();
 184 #endif
 185         applet_name = applet;
 186
 187         if (ENABLE_LOCALE_SUPPORT)
 188                 setlocale(LC_ALL, "");
 189
 190 #if ENABLE_FEATURE_INDIVIDUAL
 191         /* Redundant for busybox (run_applet_and_exit covers that case)
 192          * but needed for "individual applet" mode */
 193         if (argv[1]
 194          && !argv[2]
 195          && strcmp(argv[1], "--help") == 0
 196          && !is_prefixed_with(applet, "busybox")
 197         ) {
 198                 /* Special case. POSIX says "test --help"
 199                  * should be no different from e.g. "test --foo".  */
 200                 if (!ENABLE_TEST || strcmp(applet_name, "test") != 0)
 201                         bb_show_usage();
 202         }
 203 #endif
 204 }
 205
 206 /* The code below can well be in applets/applets.c, as it is used only
 207  * for busybox binary, not "individual" binaries.
 208  * However, keeping it here and linking it into libbusybox.so
 209  * (together with remaining tiny applets/applets.o)
 210  * makes it possible to avoid --whole-archive at link time.
 211  * This makes (shared busybox) + libbusybox smaller.
 212  * (--gc-sections would be even better....)
 213  */
 214
 215 const char *applet_name;
 216 #if !BB_MMU
 217 bool re_execed;
 218 #endif
 219
 220
 221 /* If not built as a single-applet executable... */
 222 #if !defined(SINGLE_APPLET_MAIN)
 223
 224 IF_FEATURE_SUID(static uid_t ruid;)  /* real uid */
 225
 226 # if ENABLE_FEATURE_SUID_CONFIG
 227
 228 static struct suid_config_t {
 229         /* next ptr must be first: this struct needs to be llist-compatible */
 230         struct suid_config_t *m_next;
 231         struct bb_uidgid_t m_ugid;
 232         int m_applet;
 233         mode_t m_mode;
 234 } *suid_config;
 235
 236 static bool suid_cfg_readable;
 237
 238 /* check if u is member of group g */
 239 static int ingroup(uid_t u, gid_t g)
 240 {
 241         struct group *grp = getgrgid(g);
 242         if (grp) {
 243                 char **mem;
 244                 for (mem = grp->gr_mem; *mem; mem++) {
 245                         struct passwd *pwd = getpwnam(*mem);
 246                         if (pwd && (pwd->pw_uid == u))
 247                                 return 1;
 248                 }
 249         }
 250         return 0;
 251 }
 252
 253 /* libbb candidate */
 254 static char *get_trimmed_slice(char *s, char *e)
 255 {
 256         /* First, consider the value at e to be nul and back up until we
 257          * reach a non-space char.  Set the char after that (possibly at
 258          * the original e) to nul. */
 259         while (e-- > s) {
 260                 if (!isspace(*e)) {
 261                         break;
 262                 }
 263         }
 264         e[1] = '\0';
 265
 266         /* Next, advance past all leading space and return a ptr to the
 267          * first non-space char; possibly the terminating nul. */
 268         return skip_whitespace(s);
 269 }
 270
 271 static void parse_config_file(void)
 272 {
 273         /* Don't depend on the tools to combine strings. */
 274         static const char config_file[] ALIGN1 = "/etc/busybox.conf";
 275
 276         struct suid_config_t *sct_head;
 277         int applet_no;
 278         FILE *f;
 279         const char *errmsg;
 280         unsigned lc;
 281         smallint section;
 282         struct stat st;
 283
 284         ruid = getuid();
 285         if (ruid == 0) /* run by root - don't need to even read config file */
 286                 return;
 287
 288         if ((stat(config_file, &st) != 0)       /* No config file? */
 289          || !S_ISREG(st.st_mode)                /* Not a regular file? */
 290          || (st.st_uid != 0)                    /* Not owned by root? */
 291          || (st.st_mode & (S_IWGRP | S_IWOTH))  /* Writable by non-root? */
 292          || !(f = fopen_for_read(config_file))  /* Cannot open? */
 293         ) {
 294                 return;
 295         }
 296
 297         suid_cfg_readable = 1;
 298         sct_head = NULL;
 299         section = lc = 0;
 300
 301         while (1) {
 302                 char buffer[256];
 303                 char *s;
 304
 305                 if (!fgets(buffer, sizeof(buffer), f)) { /* Are we done? */
 306                         // Looks like bloat
 307                         //if (ferror(f)) {   /* Make sure it wasn't a read error. */
 308                         //      errmsg = "reading";
 309                         //      goto pe_label;
 310                         //}
 311                         fclose(f);
 312                         suid_config = sct_head; /* Success, so set the pointer. */
 313                         return;
 314                 }
 315
 316                 s = buffer;
 317                 lc++;                                   /* Got a (partial) line. */
 318
 319                 /* If a line is too long for our buffer, we consider it an error.
 320                  * The following test does mistreat one corner case though.
 321                  * If the final line of the file does not end with a newline and
 322                  * yet exactly fills the buffer, it will be treated as too long
 323                  * even though there isn't really a problem.  But it isn't really
 324                  * worth adding code to deal with such an unlikely situation, and
 325                  * we do err on the side of caution.  Besides, the line would be
 326                  * too long if it did end with a newline. */
 327                 if (!strchr(s, '\n') && !feof(f)) {
 328                         errmsg = "line too long";
 329                         goto pe_label;
 330                 }
 331
 332                 /* Trim leading and trailing whitespace, ignoring comments, and
 333                  * check if the resulting string is empty. */
 334                 s = get_trimmed_slice(s, strchrnul(s, '#'));
 335                 if (!*s) {
 336                         continue;
 337                 }
 338
 339                 /* Check for a section header. */
 340
 341                 if (*s == '[') {
 342                         /* Unlike the old code, we ignore leading and trailing
 343                          * whitespace for the section name.  We also require that
 344                          * there are no stray characters after the closing bracket. */
 345                         char *e = strchr(s, ']');
 346                         if (!e   /* Missing right bracket? */
 347                          || e[1] /* Trailing characters? */
 348                          || !*(s = get_trimmed_slice(s+1, e)) /* Missing name? */
 349                         ) {
 350                                 errmsg = "section header";
 351                                 goto pe_label;
 352                         }
 353                         /* Right now we only have one section so just check it.
 354                          * If more sections are added in the future, please don't
 355                          * resort to cascading ifs with multiple strcasecmp calls.
 356                          * That kind of bloated code is all too common.  A loop
 357                          * and a string table would be a better choice unless the
 358                          * number of sections is very small. */
 359                         if (strcasecmp(s, "SUID") == 0) {
 360                                 section = 1;
 361                                 continue;
 362                         }
 363                         section = -1;   /* Unknown section so set to skip. */
 364                         continue;
 365                 }
 366
 367                 /* Process sections. */
 368
 369                 if (section == 1) {             /* SUID */
 370                         /* Since we trimmed leading and trailing space above, we're
 371                          * now looking for strings of the form
 372                          *    <key>[::space::]*=[::space::]*<value>
 373                          * where both key and value could contain inner whitespace. */
 374
 375                         /* First get the key (an applet name in our case). */
 376                         char *e = strchr(s, '=');
 377                         if (e) {
 378                                 s = get_trimmed_slice(s, e);
 379                         }
 380                         if (!e || !*s) {        /* Missing '=' or empty key. */
 381                                 errmsg = "keyword";
 382                                 goto pe_label;
 383                         }
 384
 385                         /* Ok, we have an applet name.  Process the rhs if this
 386                          * applet is currently built in and ignore it otherwise.
 387                          * Note: this can hide config file bugs which only pop
 388                          * up when the busybox configuration is changed. */
 389                         applet_no = find_applet_by_name(s);
 390                         if (applet_no >= 0) {
 391                                 unsigned i;
 392                                 struct suid_config_t *sct;
 393
 394                                 /* Note: We currently don't check for duplicates!
 395                                  * The last config line for each applet will be the
 396                                  * one used since we insert at the head of the list.
 397                                  * I suppose this could be considered a feature. */
 398                                 sct = xzalloc(sizeof(*sct));
 399                                 sct->m_applet = applet_no;
 400                                 /*sct->m_mode = 0;*/
 401                                 sct->m_next = sct_head;
 402                                 sct_head = sct;
 403
 404                                 /* Get the specified mode. */
 405
 406                                 e = skip_whitespace(e+1);
 407
 408                                 for (i = 0; i < 3; i++) {
 409                                         /* There are 4 chars for each of user/group/other.
 410                                          * "x-xx" instead of "x-" are to make
 411                                          * "idx > 3" check catch invalid chars.
 412                                          */
 413                                         static const char mode_chars[] ALIGN1 = "Ssx-" "Ssx-" "x-xx";
 414                                         static const unsigned short mode_mask[] ALIGN2 = {
 415                                                 S_ISUID, S_ISUID|S_IXUSR, S_IXUSR, 0, /* Ssx- */
 416                                                 S_ISGID, S_ISGID|S_IXGRP, S_IXGRP, 0, /* Ssx- */
 417                                                                           S_IXOTH, 0  /*   x- */
 418                                         };
 419                                         const char *q = strchrnul(mode_chars + 4*i, *e);
 420                                         unsigned idx = q - (mode_chars + 4*i);
 421                                         if (idx > 3) {
 422                                                 errmsg = "mode";
 423                                                 goto pe_label;
 424                                         }
 425                                         sct->m_mode |= mode_mask[q - mode_chars];
 426                                         e++;
 427                                 }
 428
 429                                 /* Now get the user/group info. */
 430
 431                                 s = skip_whitespace(e);
 432                                 /* Default is 0.0, else parse USER.GROUP: */
 433                                 if (*s) {
 434                                         /* We require whitespace between mode and USER.GROUP */
 435                                         if ((s == e) || !(e = strchr(s, '.'))) {
 436                                                 errmsg = "uid.gid";
 437                                                 goto pe_label;
 438                                         }
 439                                         *e = ':'; /* get_uidgid needs USER:GROUP syntax */
 440                                         if (get_uidgid(&sct->m_ugid, s) == 0) {
 441                                                 errmsg = "unknown user/group";
 442                                                 goto pe_label;
 443                                         }
 444                                 }
 445                         }
 446                         continue;
 447                 }
 448
 449                 /* Unknown sections are ignored. */
 450
 451                 /* Encountering configuration lines prior to seeing a
 452                  * section header is treated as an error.  This is how
 453                  * the old code worked, but it may not be desirable.
 454                  * We may want to simply ignore such lines in case they
 455                  * are used in some future version of busybox. */
 456                 if (!section) {
 457                         errmsg = "keyword outside section";
 458                         goto pe_label;
 459                 }
 460         } /* while (1) */
 461
 462  pe_label:
 463         fclose(f);
 464         bb_error_msg("parse error in %s, line %u: %s", config_file, lc, errmsg);
 465
 466         /* Release any allocated memory before returning. */
 467         llist_free((llist_t*)sct_head, NULL);
 468 }
 469 # else
 470 static inline void parse_config_file(void)
 471 {
 472         IF_FEATURE_SUID(ruid = getuid();)
 473 }
 474 # endif /* FEATURE_SUID_CONFIG */
 475
 476
 477 # if ENABLE_FEATURE_SUID
 478 static void check_suid(int applet_no)
 479 {
 480         gid_t rgid;  /* real gid */
 481
 482         if (ruid == 0) /* set by parse_config_file() */
 483                 return; /* run by root - no need to check more */
 484         rgid = getgid();
 485
 486 #  if ENABLE_FEATURE_SUID_CONFIG
 487         if (suid_cfg_readable) {
 488                 uid_t uid;
 489                 struct suid_config_t *sct;
 490                 mode_t m;
 491
 492                 for (sct = suid_config; sct; sct = sct->m_next) {
 493                         if (sct->m_applet == applet_no)
 494                                 goto found;
 495                 }
 496                 goto check_need_suid;
 497  found:
 498                 /* Is this user allowed to run this applet? */
 499                 m = sct->m_mode;
 500                 if (sct->m_ugid.uid == ruid)
 501                         /* same uid */
 502                         m >>= 6;
 503                 else if ((sct->m_ugid.gid == rgid) || ingroup(ruid, sct->m_ugid.gid))
 504                         /* same group / in group */
 505                         m >>= 3;
 506                 if (!(m & S_IXOTH)) /* is x bit not set? */
 507                         bb_error_msg_and_die("you have no permission to run this applet");
 508
 509                 /* We set effective AND saved ids. If saved-id is not set
 510                  * like we do below, seteuid(0) can still later succeed! */
 511
 512                 /* Are we directed to change gid
 513                  * (APPLET = *s* USER.GROUP or APPLET = *S* USER.GROUP)?
 514                  */
 515                 if (sct->m_mode & S_ISGID)
 516                         rgid = sct->m_ugid.gid;
 517                 /* else: we will set egid = rgid, thus dropping sgid effect */
 518                 if (setresgid(-1, rgid, rgid))
 519                         bb_perror_msg_and_die("setresgid");
 520
 521                 /* Are we directed to change uid
 522                  * (APPLET = s** USER.GROUP or APPLET = S** USER.GROUP)?
 523                  */
 524                 uid = ruid;
 525                 if (sct->m_mode & S_ISUID)
 526                         uid = sct->m_ugid.uid;
 527                 /* else: we will set euid = ruid, thus dropping suid effect */
 528                 if (setresuid(-1, uid, uid))
 529                         bb_perror_msg_and_die("setresuid");
 530
 531                 goto ret;
 532         }
 533 #   if !ENABLE_FEATURE_SUID_CONFIG_QUIET
 534         {
 535                 static bool onetime = 0;
 536
 537                 if (!onetime) {
 538                         onetime = 1;
 539                         bb_error_msg("using fallback suid method");
 540                 }
 541         }
 542 #   endif
 543  check_need_suid:
 544 #  endif
 545         if (APPLET_SUID(applet_no) == BB_SUID_REQUIRE) {
 546                 /* Real uid is not 0. If euid isn't 0 too, suid bit
 547                  * is most probably not set on our executable */
 548                 if (geteuid())
 549                         bb_error_msg_and_die("must be suid to work properly");
 550         } else if (APPLET_SUID(applet_no) == BB_SUID_DROP) {
 551                 xsetgid(rgid);  /* drop all privileges */
 552                 xsetuid(ruid);
 553         }
 554 #  if ENABLE_FEATURE_SUID_CONFIG
 555  ret: ;
 556         llist_free((llist_t*)suid_config, NULL);
 557 #  endif
 558 }
 559 # else
 560 #  define check_suid(x) ((void)0)
 561 # endif /* FEATURE_SUID */
 562
 563
 564 # if ENABLE_FEATURE_INSTALLER
 565 static const char usr_bin [] ALIGN1 = "/usr/bin/";
 566 static const char usr_sbin[] ALIGN1 = "/usr/sbin/";
 567 static const char *const install_dir[] = {
 568         &usr_bin [8], /* "/" */
 569         &usr_bin [4], /* "/bin/" */
 570         &usr_sbin[4]  /* "/sbin/" */
 571 #  if !ENABLE_INSTALL_NO_USR
 572         ,usr_bin
 573         ,usr_sbin
 574 #  endif
 575 };
 576
 577 /* create (sym)links for each applet */
 578 static void install_links(const char *busybox, int use_symbolic_links,
 579                 char *custom_install_dir)
 580 {
 581         /* directory table
 582          * this should be consistent w/ the enum,
 583          * busybox.h::bb_install_loc_t, or else... */
 584         int (*lf)(const char *, const char *);
 585         char *fpc;
 586         unsigned i;
 587         int rc;
 588
 589         lf = link;
 590         if (use_symbolic_links)
 591                 lf = symlink;
 592
 593         for (i = 0; i < ARRAY_SIZE(applet_main); i++) {
 594                 fpc = concat_path_file(
 595                                 custom_install_dir ? custom_install_dir : install_dir[APPLET_INSTALL_LOC(i)],
 596                                 APPLET_NAME(i));
 597                 // debug: bb_error_msg("%slinking %s to busybox",
 598                 //              use_symbolic_links ? "sym" : "", fpc);
 599                 rc = lf(busybox, fpc);
 600                 if (rc != 0 && errno != EEXIST) {
 601                         bb_simple_perror_msg(fpc);
 602                 }
 603                 free(fpc);
 604         }
 605 }
 606 # else
 607 static void install_links(const char *busybox UNUSED_PARAM,
 608                 int use_symbolic_links UNUSED_PARAM,
 609                 char *custom_install_dir UNUSED_PARAM)
 610 {
 611 }
 612 # endif
 613
 614 /* If we were called as "busybox..." */
 615 static int busybox_main(char **argv)
 616 {
 617         if (!argv[1]) {
 618                 /* Called without arguments */
 619                 const char *a;
 620                 int col;
 621                 unsigned output_width;
 622  help:
 623                 output_width = 80;
 624                 if (ENABLE_FEATURE_AUTOWIDTH) {
 625                         /* Obtain the terminal width */
 626                         output_width = get_terminal_width(2);
 627                 }
 628
 629                 dup2(1, 2);
 630                 full_write2_str(bb_banner); /* reuse const string */
 631                 full_write2_str(" multi-call binary.\n"); /* reuse */
 632                 full_write2_str(
 633                         "BusyBox is copyrighted by many authors between 1998-2015.\n"
 634                         "Licensed under GPLv2. See source distribution for detailed\n"
 635                         "copyright notices.\n"
 636                         "\n"
 637                         "Usage: busybox [function [arguments]...]\n"
 638                         "   or: busybox --list"IF_FEATURE_INSTALLER("[-full]")"\n"
 639                         IF_FEATURE_INSTALLER(
 640                         "   or: busybox --install [-s] [DIR]\n"
 641                         )
 642                         "   or: function [arguments]...\n"
 643                         "\n"
 644                         IF_NOT_FEATURE_SH_STANDALONE(
 645                         "\tBusyBox is a multi-call binary that combines many common Unix\n"
 646                         "\tutilities into a single executable.  Most people will create a\n"
 647                         "\tlink to busybox for each function they wish to use and BusyBox\n"
 648                         "\twill act like whatever it was invoked as.\n"
 649                         )
 650                         IF_FEATURE_SH_STANDALONE(
 651                         "\tBusyBox is a multi-call binary that combines many common Unix\n"
 652                         "\tutilities into a single executable.  The shell in this build\n"
 653                         "\tis configured to run built-in utilities without $PATH search.\n"
 654                         "\tYou don't need to install a link to busybox for each utility.\n"
 655                         "\tTo run external program, use full path (/sbin/ip instead of ip).\n"
 656                         )
 657                         "\n"
 658                         "Currently defined functions:\n"
 659                 );
 660                 col = 0;
 661                 a = applet_names;
 662                 /* prevent last comma to be in the very last pos */
 663                 output_width--;
 664                 while (*a) {
 665                         int len2 = strlen(a) + 2;
 666                         if (col >= (int)output_width - len2) {
 667                                 full_write2_str(",\n");
 668                                 col = 0;
 669                         }
 670                         if (col == 0) {
 671                                 col = 6;
 672                                 full_write2_str("\t");
 673                         } else {
 674                                 full_write2_str(", ");
 675                         }
 676                         full_write2_str(a);
 677                         col += len2;
 678                         a += len2 - 1;
 679                 }
 680                 full_write2_str("\n\n");
 681                 return 0;
 682         }
 683
 684         if (is_prefixed_with(argv[1], "--list")) {
 685                 unsigned i = 0;
 686                 const char *a = applet_names;
 687                 dup2(1, 2);
 688                 while (*a) {
 689 # if ENABLE_FEATURE_INSTALLER
 690                         if (argv[1][6]) /* --list-full? */
 691                                 full_write2_str(install_dir[APPLET_INSTALL_LOC(i)] + 1);
 692 # endif
 693                         full_write2_str(a);
 694                         full_write2_str("\n");
 695                         i++;
 696                         a += strlen(a) + 1;
 697                 }
 698                 return 0;
 699         }
 700
 701         if (ENABLE_FEATURE_INSTALLER && strcmp(argv[1], "--install") == 0) {
 702                 int use_symbolic_links;
 703                 const char *busybox;
 704
 705                 busybox = xmalloc_readlink(bb_busybox_exec_path);
 706                 if (!busybox) {
 707                         /* bb_busybox_exec_path is usually "/proc/self/exe".
 708                          * In chroot, readlink("/proc/self/exe") usually fails.
 709                          * In such case, better use argv[0] as symlink target
 710                          * if it is a full path name.
 711                          */
 712                         if (argv[0][0] != '/')
 713                                 bb_error_msg_and_die("'%s' is not an absolute path", argv[0]);
 714                         busybox = argv[0];
 715                 }
 716                 /* busybox --install [-s] [DIR]:
 717                  * -s: make symlinks
 718                  * DIR: directory to install links to
 719                  */
 720                 use_symbolic_links = (argv[2] && strcmp(argv[2], "-s") == 0 && ++argv);
 721                 install_links(busybox, use_symbolic_links, argv[2]);
 722                 return 0;
 723         }
 724
 725         if (strcmp(argv[1], "--help") == 0) {
 726                 /* "busybox --help [<applet>]" */
 727                 if (!argv[2])
 728                         goto help;
 729                 /* convert to "<applet> --help" */
 730                 argv[0] = argv[2];
 731                 argv[2] = NULL;
 732         } else {
 733                 /* "busybox <applet> arg1 arg2 ..." */
 734                 argv++;
 735         }
 736         /* We support "busybox /a/path/to/applet args..." too. Allows for
 737          * "#!/bin/busybox"-style wrappers */
 738         applet_name = bb_get_last_path_component_nostrip(argv[0]);
 739         run_applet_and_exit(applet_name, argv);
 740
 741         /*bb_error_msg_and_die("applet not found"); - sucks in printf */
 742         full_write2_str(applet_name);
 743         full_write2_str(": applet not found\n");
 744         /* POSIX: "If a command is not found, the exit status shall be 127" */
 745         exit(127);
 746 }
 747
 748 void FAST_FUNC run_applet_no_and_exit(int applet_no, char **argv)
 749 {
 750         int argc = 1;
 751
 752         while (argv[argc])
 753                 argc++;
 754
 755         /* Reinit some shared global data */
 756         xfunc_error_retval = EXIT_FAILURE;
 757         applet_name = APPLET_NAME(applet_no);
 758
 759         /* Special case. POSIX says "test --help"
 760          * should be no different from e.g. "test --foo".
 761          * Thus for "test", we skip --help check.
 762          * "true" and "false" are also special.
 763          */
 764         if (1
 765 #if defined APPLET_NO_test
 766          && applet_no != APPLET_NO_test
 767 #endif
 768 #if defined APPLET_NO_true
 769          && applet_no != APPLET_NO_true
 770 #endif
 771 #if defined APPLET_NO_false
 772          && applet_no != APPLET_NO_false
 773 #endif
 774         ) {
 775                 if (argc == 2 && strcmp(argv[1], "--help") == 0) {
 776                         /* Make "foo --help" exit with 0: */
 777                         xfunc_error_retval = 0;
 778                         bb_show_usage();
 779                 }
 780         }
 781         if (ENABLE_FEATURE_SUID)
 782                 check_suid(applet_no);
 783         exit(applet_main[applet_no](argc, argv));
 784 }
 785
 786 void FAST_FUNC run_applet_and_exit(const char *name, char **argv)
 787 {
 788         int applet = find_applet_by_name(name);
 789         if (applet >= 0)
 790                 run_applet_no_and_exit(applet, argv);
 791         if (is_prefixed_with(name, "busybox"))
 792                 exit(busybox_main(argv));
 793 }
 794
 795 #endif /* !defined(SINGLE_APPLET_MAIN) */
 796
 797
 798
 799 #if ENABLE_BUILD_LIBBUSYBOX
 800 int lbb_main(char **argv)
 801 #else
 802 int main(int argc UNUSED_PARAM, char **argv)
 803 #endif
 804 {
 805         /* Tweak malloc for reduced memory consumption */
 806 #ifdef M_TRIM_THRESHOLD
 807         /* M_TRIM_THRESHOLD is the maximum amount of freed top-most memory
 808          * to keep before releasing to the OS
 809          * Default is way too big: 256k
 810          */
 811         mallopt(M_TRIM_THRESHOLD, 8 * 1024);
 812 #endif
 813 #ifdef M_MMAP_THRESHOLD
 814         /* M_MMAP_THRESHOLD is the request size threshold for using mmap()
 815          * Default is too big: 256k
 816          */
 817         mallopt(M_MMAP_THRESHOLD, 32 * 1024 - 256);
 818 #endif
 819
 820 #if !BB_MMU
 821         /* NOMMU re-exec trick sets high-order bit in first byte of name */
 822         if (argv[0][0] & 0x80) {
 823                 re_execed = 1;
 824                 argv[0][0] &= 0x7f;
 825         }
 826 #endif
 827
 828 #if defined(SINGLE_APPLET_MAIN)
 829         /* Only one applet is selected in .config */
 830         if (argv[1] && is_prefixed_with(argv[0], "busybox")) {
 831                 /* "busybox <applet> <params>" should still work as expected */
 832                 argv++;
 833         }
 834         /* applet_names in this case is just "applet\0\0" */
 835         lbb_prepare(applet_names IF_FEATURE_INDIVIDUAL(, argv));
 836         return SINGLE_APPLET_MAIN(argc, argv);
 837 #else
 838         lbb_prepare("busybox" IF_FEATURE_INDIVIDUAL(, argv));
 839
 840         applet_name = argv[0];
 841         if (applet_name[0] == '-')
 842                 applet_name++;
 843         applet_name = bb_basename(applet_name);
 844
 845         parse_config_file(); /* ...maybe, if FEATURE_SUID_CONFIG */
 846
 847         run_applet_and_exit(applet_name, argv);
 848
 849         /*bb_error_msg_and_die("applet not found"); - sucks in printf */
 850         full_write2_str(applet_name);
 851         full_write2_str(": applet not found\n");
 852         /* POSIX: "If a command is not found, the exit status shall be 127" */
 853         exit(127);
 854 #endif
 855 }