__uClibc_main.c 13 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425
  1. /*
  2. * Copyright (C) Feb 2001 Manuel Novoa III
  3. * Copyright (C) 2000-2005 Erik Andersen <andersen@uclibc.org>
  4. *
  5. * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
  6. *
  7. * __uClibc_main is the routine to be called by all the arch-specific
  8. * versions of crt1.S in uClibc.
  9. *
  10. * It is meant to handle any special initialization needed by the library
  11. * such as setting the global variable(s) __environ (environ) and
  12. * initializing the stdio package. Using weak symbols, the latter is
  13. * avoided in the static library case.
  14. */
  15. #define _ERRNO_H
  16. #include <features.h>
  17. #include <unistd.h>
  18. #include <stdlib.h>
  19. #include <string.h>
  20. #include <elf.h>
  21. #include <link.h>
  22. #include <bits/uClibc_page.h>
  23. #include <paths.h>
  24. #include <asm/errno.h>
  25. #include <fcntl.h>
  26. #include <sys/stat.h>
  27. #include <sys/sysmacros.h>
  28. libc_hidden_proto(exit)
  29. #ifdef __UCLIBC_HAS_PROGRAM_INVOCATION_NAME__
  30. /* Experimentally off - libc_hidden_proto(strrchr) */
  31. #endif
  32. #ifndef __ARCH_HAS_NO_LDSO__
  33. /* Experimentally off - libc_hidden_proto(memcpy) */
  34. libc_hidden_proto(getgid)
  35. libc_hidden_proto(getuid)
  36. libc_hidden_proto(getegid)
  37. libc_hidden_proto(geteuid)
  38. libc_hidden_proto(fstat)
  39. libc_hidden_proto(abort)
  40. extern __typeof(open) __libc_open;
  41. libc_hidden_proto(__libc_open)
  42. extern __typeof(fcntl) __libc_fcntl;
  43. libc_hidden_proto(__libc_fcntl)
  44. #endif
  45. #ifndef SHARED
  46. void *__libc_stack_end=NULL;
  47. # ifdef __UCLIBC_HAS_SSP__
  48. # include <dl-osinfo.h>
  49. # ifndef THREAD_SET_STACK_GUARD
  50. /* Only exported for architectures that don't store the stack guard canary
  51. * in thread local area. */
  52. # include <stdint.h>
  53. uintptr_t stack_chk_guard;
  54. /* for gcc-4.1 non-TLS */
  55. uintptr_t __stack_chk_guard attribute_relro;
  56. /* for gcc-3.x + Etoh ssp */
  57. # ifdef __UCLIBC_HAS_SSP_COMPAT__
  58. # ifdef __HAVE_SHARED__
  59. strong_alias(__stack_chk_guard,__guard)
  60. # else
  61. uintptr_t __guard attribute_relro;
  62. # endif
  63. # endif
  64. # elif defined __UCLIBC_HAS_SSP_COMPAT__
  65. uintptr_t __guard attribute_relro;
  66. # endif
  67. # endif
  68. #endif /* !SHARED */
  69. /*
  70. * Prototypes.
  71. */
  72. extern void weak_function _stdio_init(void) attribute_hidden;
  73. extern int *weak_const_function __errno_location(void);
  74. extern int *weak_const_function __h_errno_location(void);
  75. #ifdef __UCLIBC_HAS_LOCALE__
  76. extern void weak_function _locale_init(void) attribute_hidden;
  77. #endif
  78. #ifdef __UCLIBC_HAS_THREADS__
  79. extern void weak_function __pthread_initialize_minimal(void);
  80. #endif
  81. /* If __UCLIBC_FORMAT_SHARED_FLAT__, all array initialisation and finalisation
  82. * is handled by the routines passed to __uClibc_main(). */
  83. #if defined (__UCLIBC_CTOR_DTOR__) && !defined (__UCLIBC_FORMAT_SHARED_FLAT__)
  84. extern void _dl_app_init_array(void);
  85. extern void _dl_app_fini_array(void);
  86. # ifndef SHARED
  87. /* These magic symbols are provided by the linker. */
  88. extern void (*__preinit_array_start []) (void) attribute_hidden;
  89. extern void (*__preinit_array_end []) (void) attribute_hidden;
  90. extern void (*__init_array_start []) (void) attribute_hidden;
  91. extern void (*__init_array_end []) (void) attribute_hidden;
  92. extern void (*__fini_array_start []) (void) attribute_hidden;
  93. extern void (*__fini_array_end []) (void) attribute_hidden;
  94. # endif
  95. #endif
  96. attribute_hidden const char *__uclibc_progname = "";
  97. #ifdef __UCLIBC_HAS_PROGRAM_INVOCATION_NAME__
  98. const char *program_invocation_short_name = "";
  99. const char *program_invocation_name = "";
  100. #endif
  101. #ifdef __UCLIBC_HAS___PROGNAME__
  102. weak_alias (program_invocation_short_name, __progname)
  103. weak_alias (program_invocation_name, __progname_full)
  104. #endif
  105. /*
  106. * Declare the __environ global variable and create a strong alias environ.
  107. * Note: Apparently we must initialize __environ to ensure that the strong
  108. * environ symbol is also included.
  109. */
  110. char **__environ = 0;
  111. weak_alias(__environ, environ)
  112. /* TODO: don't export __pagesize; we cant now because libpthread uses it */
  113. size_t __pagesize = 0;
  114. #ifndef O_NOFOLLOW
  115. # define O_NOFOLLOW 0
  116. #endif
  117. #ifndef __ARCH_HAS_NO_LDSO__
  118. static void __check_one_fd(int fd, int mode)
  119. {
  120. /* Check if the specified fd is already open */
  121. if (__libc_fcntl(fd, F_GETFD) == -1)
  122. {
  123. /* The descriptor is probably not open, so try to use /dev/null */
  124. int nullfd = __libc_open(_PATH_DEVNULL, mode);
  125. /* /dev/null is major=1 minor=3. Make absolutely certain
  126. * that is in fact the device that we have opened and not
  127. * some other wierd file... */
  128. if (nullfd!=fd)
  129. {
  130. abort();
  131. }
  132. }
  133. }
  134. static int __check_suid(void)
  135. {
  136. uid_t uid, euid;
  137. gid_t gid, egid;
  138. uid = getuid();
  139. euid = geteuid();
  140. if (uid != euid)
  141. return 1;
  142. gid = getgid();
  143. egid = getegid();
  144. if (gid != egid)
  145. return 1;
  146. return 0; /* we are not suid */
  147. }
  148. #endif
  149. /* __uClibc_init completely initialize uClibc so it is ready to use.
  150. *
  151. * On ELF systems (with a dynamic loader) this function must be called
  152. * from the dynamic loader (see TIS and ELF Specification), so that
  153. * constructors of shared libraries (which depend on libc) can use all
  154. * the libc code without restriction. For this we link the shared
  155. * version of the uClibc with -init __uClibc_init so DT_INIT for
  156. * uClibc is the address of __uClibc_init
  157. *
  158. * In all other cases we call it from the main stub
  159. * __uClibc_main.
  160. */
  161. extern void __uClibc_init(void);
  162. libc_hidden_proto(__uClibc_init)
  163. void __uClibc_init(void)
  164. {
  165. static smallint been_there_done_that;
  166. if (been_there_done_that)
  167. return;
  168. been_there_done_that++;
  169. /* Setup an initial value. This may not be perfect, but is
  170. * better than malloc using __pagesize=0 for atexit, ctors, etc. */
  171. __pagesize = PAGE_SIZE;
  172. #ifdef __UCLIBC_HAS_THREADS__
  173. /* Before we start initializing uClibc we have to call
  174. * __pthread_initialize_minimal so we can use pthread_locks
  175. * whenever they are needed.
  176. */
  177. if (likely(__pthread_initialize_minimal!=NULL))
  178. __pthread_initialize_minimal();
  179. #endif
  180. #ifndef SHARED
  181. # ifdef __UCLIBC_HAS_SSP__
  182. /* Set up the stack checker's canary. */
  183. stack_chk_guard = _dl_setup_stack_chk_guard();
  184. # ifdef THREAD_SET_STACK_GUARD
  185. THREAD_SET_STACK_GUARD (stack_chk_guard);
  186. # ifdef __UCLIBC_HAS_SSP_COMPAT__
  187. __guard = stack_chk_guard;
  188. # endif
  189. # else
  190. __stack_chk_guard = stack_chk_guard;
  191. # if !defined __HAVE_SHARED__ && defined __UCLIBC_HAS_SSP_COMPAT__
  192. __guard = stack_chk_guard;
  193. # endif
  194. # endif
  195. # endif
  196. #endif
  197. #ifdef __UCLIBC_HAS_LOCALE__
  198. /* Initialize the global locale structure. */
  199. if (likely(_locale_init!=NULL))
  200. _locale_init();
  201. #endif
  202. /*
  203. * Initialize stdio here. In the static library case, this will
  204. * be bypassed if not needed because of the weak alias above.
  205. * Thus we get a nice size savings because the stdio functions
  206. * won't be pulled into the final static binary unless used.
  207. */
  208. if (likely(_stdio_init != NULL))
  209. _stdio_init();
  210. }
  211. libc_hidden_def(__uClibc_init)
  212. #ifdef __UCLIBC_CTOR_DTOR__
  213. void attribute_hidden (*__app_fini)(void) = NULL;
  214. #endif
  215. void attribute_hidden (*__rtld_fini)(void) = NULL;
  216. extern void __uClibc_fini(void);
  217. libc_hidden_proto(__uClibc_fini)
  218. void __uClibc_fini(void)
  219. {
  220. #ifdef __UCLIBC_CTOR_DTOR__
  221. /* If __UCLIBC_FORMAT_SHARED_FLAT__, all array finalisation is handled
  222. * by __app_fini. */
  223. # ifdef SHARED
  224. _dl_app_fini_array();
  225. # elif !defined (__UCLIBC_FORMAT_SHARED_FLAT__)
  226. size_t i = __fini_array_end - __fini_array_start;
  227. while (i-- > 0)
  228. (*__fini_array_start [i]) ();
  229. # endif
  230. if (__app_fini != NULL)
  231. (__app_fini)();
  232. #endif
  233. if (__rtld_fini != NULL)
  234. (__rtld_fini)();
  235. }
  236. libc_hidden_def(__uClibc_fini)
  237. /* __uClibc_main is the new main stub for uClibc. This function is
  238. * called from crt1 (version 0.9.28 or newer), after ALL shared libraries
  239. * are initialized, just before we call the application's main function.
  240. */
  241. void __uClibc_main(int (*main)(int, char **, char **), int argc,
  242. char **argv, void (*app_init)(void), void (*app_fini)(void),
  243. void (*rtld_fini)(void), void *stack_end) attribute_noreturn;
  244. void __uClibc_main(int (*main)(int, char **, char **), int argc,
  245. char **argv, void (*app_init)(void), void (*app_fini)(void),
  246. void (*rtld_fini)(void), void *stack_end)
  247. {
  248. #ifndef __ARCH_HAS_NO_LDSO__
  249. unsigned long *aux_dat;
  250. ElfW(auxv_t) auxvt[AT_EGID + 1];
  251. #endif
  252. #ifndef SHARED
  253. __libc_stack_end = stack_end;
  254. #endif
  255. __rtld_fini = rtld_fini;
  256. /* The environment begins right after argv. */
  257. __environ = &argv[argc + 1];
  258. /* If the first thing after argv is the arguments
  259. * the the environment is empty. */
  260. if ((char *) __environ == *argv) {
  261. /* Make __environ point to the NULL at argv[argc] */
  262. __environ = &argv[argc];
  263. }
  264. #ifndef __ARCH_HAS_NO_LDSO__
  265. /* Pull stuff from the ELF header when possible */
  266. memset(auxvt, 0x00, sizeof(auxvt));
  267. aux_dat = (unsigned long*)__environ;
  268. while (*aux_dat) {
  269. aux_dat++;
  270. }
  271. aux_dat++;
  272. while (*aux_dat) {
  273. ElfW(auxv_t) *auxv_entry = (ElfW(auxv_t) *) aux_dat;
  274. if (auxv_entry->a_type <= AT_EGID) {
  275. memcpy(&(auxvt[auxv_entry->a_type]), auxv_entry, sizeof(ElfW(auxv_t)));
  276. }
  277. aux_dat += 2;
  278. }
  279. #endif
  280. /* We need to initialize uClibc. If we are dynamically linked this
  281. * may have already been completed by the shared lib loader. We call
  282. * __uClibc_init() regardless, to be sure the right thing happens. */
  283. __uClibc_init();
  284. #ifndef __ARCH_HAS_NO_LDSO__
  285. /* Make certain getpagesize() gives the correct answer */
  286. __pagesize = (auxvt[AT_PAGESZ].a_un.a_val)? auxvt[AT_PAGESZ].a_un.a_val : PAGE_SIZE;
  287. /* Prevent starting SUID binaries where the stdin. stdout, and
  288. * stderr file descriptors are not already opened. */
  289. if ((auxvt[AT_UID].a_un.a_val == (size_t)-1 && __check_suid()) ||
  290. (auxvt[AT_UID].a_un.a_val != (size_t)-1 &&
  291. (auxvt[AT_UID].a_un.a_val != auxvt[AT_EUID].a_un.a_val ||
  292. auxvt[AT_GID].a_un.a_val != auxvt[AT_EGID].a_un.a_val)))
  293. {
  294. __check_one_fd (STDIN_FILENO, O_RDONLY | O_NOFOLLOW);
  295. __check_one_fd (STDOUT_FILENO, O_RDWR | O_NOFOLLOW);
  296. __check_one_fd (STDERR_FILENO, O_RDWR | O_NOFOLLOW);
  297. }
  298. #endif
  299. __uclibc_progname = *argv;
  300. #ifdef __UCLIBC_HAS_PROGRAM_INVOCATION_NAME__
  301. if (*argv != NULL) {
  302. program_invocation_name = *argv;
  303. program_invocation_short_name = strrchr(*argv, '/');
  304. if (program_invocation_short_name != NULL)
  305. ++program_invocation_short_name;
  306. else
  307. program_invocation_short_name = program_invocation_name;
  308. }
  309. #endif
  310. #ifdef __UCLIBC_CTOR_DTOR__
  311. /* Arrange for the application's dtors to run before we exit. */
  312. __app_fini = app_fini;
  313. /* If __UCLIBC_FORMAT_SHARED_FLAT__, all array initialisation is handled
  314. * by __app_init. */
  315. # if !defined (SHARED) && !defined (__UCLIBC_FORMAT_SHARED_FLAT__)
  316. /* For dynamically linked executables the preinit array is executed by
  317. the dynamic linker (before initializing any shared object).
  318. For static executables, preinit happens rights before init. */
  319. {
  320. const size_t size = __preinit_array_end - __preinit_array_start;
  321. size_t i;
  322. for (i = 0; i < size; i++)
  323. (*__preinit_array_start [i]) ();
  324. }
  325. # endif
  326. /* Run all the application's ctors now. */
  327. if (app_init!=NULL) {
  328. app_init();
  329. }
  330. /* If __UCLIBC_FORMAT_SHARED_FLAT__, all array initialisation is handled
  331. * by __app_init. */
  332. # ifdef SHARED
  333. _dl_app_init_array();
  334. # elif !defined (__UCLIBC_FORMAT_SHARED_FLAT__)
  335. {
  336. const size_t size = __init_array_end - __init_array_start;
  337. size_t i;
  338. for (i = 0; i < size; i++)
  339. (*__init_array_start [i]) ();
  340. }
  341. # endif
  342. #endif
  343. /* Note: It is possible that any initialization done above could
  344. * have resulted in errno being set nonzero, so set it to 0 before
  345. * we call main.
  346. */
  347. if (likely(__errno_location!=NULL))
  348. *(__errno_location()) = 0;
  349. /* Set h_errno to 0 as well */
  350. if (likely(__h_errno_location!=NULL))
  351. *(__h_errno_location()) = 0;
  352. /*
  353. * Finally, invoke application's main and then exit.
  354. */
  355. exit(main(argc, argv, __environ));
  356. }
  357. #if defined(__UCLIBC_HAS_THREADS__) && !defined(SHARED)
  358. /* Weaks for internal library use only.
  359. *
  360. * We need to define weaks here to cover all the pthread functions that
  361. * libc itself will use so that we aren't forced to link libc against
  362. * libpthread. This file is only used in libc.a and since we have
  363. * weaks here, they will be automatically overridden by libpthread.a
  364. * if it gets linked in.
  365. */
  366. static int __pthread_return_0 (void) { return 0; }
  367. static void __pthread_return_void (void) { return; }
  368. weak_alias (__pthread_return_0, __pthread_mutex_init)
  369. weak_alias (__pthread_return_0, __pthread_mutex_lock)
  370. weak_alias (__pthread_return_0, __pthread_mutex_trylock)
  371. weak_alias (__pthread_return_0, __pthread_mutex_unlock)
  372. weak_alias (__pthread_return_void, _pthread_cleanup_push_defer)
  373. weak_alias (__pthread_return_void, _pthread_cleanup_pop_restore)
  374. # ifdef __UCLIBC_HAS_THREADS_NATIVE__
  375. weak_alias (__pthread_return_0, __pthread_mutexattr_init)
  376. weak_alias (__pthread_return_0, __pthread_mutexattr_destroy)
  377. weak_alias (__pthread_return_0, __pthread_mutexattr_settype)
  378. # endif
  379. #endif