__uClibc_main.c 13 KB

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  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 <unistd.h>
  25. #include <asm/errno.h>
  26. #include <fcntl.h>
  27. #include <sys/stat.h>
  28. #include <sys/sysmacros.h>
  29. libc_hidden_proto(exit)
  30. #ifdef __UCLIBC_HAS_PROGRAM_INVOCATION_NAME__
  31. libc_hidden_proto(strrchr)
  32. #endif
  33. #ifndef __ARCH_HAS_NO_LDSO__
  34. libc_hidden_proto(memcpy)
  35. libc_hidden_proto(getgid)
  36. libc_hidden_proto(getuid)
  37. libc_hidden_proto(getegid)
  38. libc_hidden_proto(geteuid)
  39. libc_hidden_proto(fstat)
  40. libc_hidden_proto(abort)
  41. extern __typeof(open) __libc_open;
  42. libc_hidden_proto(__libc_open)
  43. extern __typeof(fcntl) __libc_fcntl;
  44. libc_hidden_proto(__libc_fcntl)
  45. #endif
  46. #ifndef SHARED
  47. void *__libc_stack_end=NULL;
  48. # ifdef __UCLIBC_HAS_SSP__
  49. # include <dl-osinfo.h>
  50. # ifndef THREAD_SET_STACK_GUARD
  51. /* Only exported for architectures that don't store the stack guard canary
  52. * in thread local area. */
  53. # include <stdint.h>
  54. uintptr_t stack_chk_guard;
  55. /* for gcc-4.1 non-TLS */
  56. uintptr_t __stack_chk_guard attribute_relro;
  57. /* for gcc-3.x + Etoh ssp */
  58. # ifdef __UCLIBC_HAS_SSP_COMPAT__
  59. # ifdef __HAVE_SHARED__
  60. strong_alias(__stack_chk_guard,__guard)
  61. # else
  62. uintptr_t __guard attribute_relro;
  63. # endif
  64. # endif
  65. # elif defined __UCLIBC_HAS_SSP_COMPAT__
  66. uintptr_t __guard attribute_relro;
  67. # endif
  68. # endif
  69. #endif /* !SHARED */
  70. /*
  71. * Prototypes.
  72. */
  73. extern void weak_function _stdio_init(void) attribute_hidden;
  74. extern int *weak_const_function __errno_location(void);
  75. extern int *weak_const_function __h_errno_location(void);
  76. #ifdef __UCLIBC_HAS_LOCALE__
  77. extern void weak_function _locale_init(void) attribute_hidden;
  78. #endif
  79. #ifdef __UCLIBC_HAS_THREADS__
  80. extern void weak_function __pthread_initialize_minimal(void);
  81. #endif
  82. /* If __UCLIBC_FORMAT_SHARED_FLAT__, all array initialisation and finalisation
  83. * is handled by the routines passed to __uClibc_main(). */
  84. #if defined (__UCLIBC_CTOR_DTOR__) && !defined (__UCLIBC_FORMAT_SHARED_FLAT__)
  85. extern void _dl_app_init_array(void);
  86. extern void _dl_app_fini_array(void);
  87. # ifndef SHARED
  88. /* These magic symbols are provided by the linker. */
  89. extern void (*__preinit_array_start []) (void) attribute_hidden;
  90. extern void (*__preinit_array_end []) (void) attribute_hidden;
  91. extern void (*__init_array_start []) (void) attribute_hidden;
  92. extern void (*__init_array_end []) (void) attribute_hidden;
  93. extern void (*__fini_array_start []) (void) attribute_hidden;
  94. extern void (*__fini_array_end []) (void) attribute_hidden;
  95. # endif
  96. #endif
  97. attribute_hidden const char *__uclibc_progname = "";
  98. #ifdef __UCLIBC_HAS_PROGRAM_INVOCATION_NAME__
  99. const char *program_invocation_short_name = "";
  100. const char *program_invocation_name = "";
  101. #endif
  102. #ifdef __UCLIBC_HAS___PROGNAME__
  103. weak_alias (program_invocation_short_name, __progname)
  104. weak_alias (program_invocation_name, __progname_full)
  105. #endif
  106. /*
  107. * Declare the __environ global variable and create a strong alias environ.
  108. * Note: Apparently we must initialize __environ to ensure that the strong
  109. * environ symbol is also included.
  110. */
  111. char **__environ = 0;
  112. weak_alias(__environ, environ)
  113. /* TODO: don't export __pagesize; we cant now because libpthread uses it */
  114. size_t __pagesize = 0;
  115. #ifndef O_NOFOLLOW
  116. # define O_NOFOLLOW 0
  117. #endif
  118. #ifndef __ARCH_HAS_NO_LDSO__
  119. static void __check_one_fd(int fd, int mode)
  120. {
  121. /* Check if the specified fd is already open */
  122. if (unlikely(__libc_fcntl(fd, F_GETFD)==-1 && *(__errno_location())==EBADF))
  123. {
  124. /* The descriptor is probably not open, so try to use /dev/null */
  125. struct stat st;
  126. int nullfd = __libc_open(_PATH_DEVNULL, mode);
  127. /* /dev/null is major=1 minor=3. Make absolutely certain
  128. * that is in fact the device that we have opened and not
  129. * some other wierd file... */
  130. if ( (nullfd!=fd) || fstat(fd, &st) || !S_ISCHR(st.st_mode) ||
  131. (st.st_rdev != makedev(1, 3)))
  132. {
  133. abort();
  134. }
  135. }
  136. }
  137. static int __check_suid(void)
  138. {
  139. uid_t uid, euid;
  140. gid_t gid, egid;
  141. uid = getuid();
  142. euid = geteuid();
  143. gid = getgid();
  144. egid = getegid();
  145. if(uid == euid && gid == egid) {
  146. return 0;
  147. }
  148. return 1;
  149. }
  150. #endif
  151. /* __uClibc_init completely initialize uClibc so it is ready to use.
  152. *
  153. * On ELF systems (with a dynamic loader) this function must be called
  154. * from the dynamic loader (see TIS and ELF Specification), so that
  155. * constructors of shared libraries (which depend on libc) can use all
  156. * the libc code without restriction. For this we link the shared
  157. * version of the uClibc with -init __uClibc_init so DT_INIT for
  158. * uClibc is the address of __uClibc_init
  159. *
  160. * In all other cases we call it from the main stub
  161. * __uClibc_main.
  162. */
  163. extern void __uClibc_init(void);
  164. libc_hidden_proto(__uClibc_init)
  165. void __uClibc_init(void)
  166. {
  167. static int been_there_done_that = 0;
  168. if (been_there_done_that)
  169. return;
  170. been_there_done_that++;
  171. /* Setup an initial value. This may not be perfect, but is
  172. * better than malloc using __pagesize=0 for atexit, ctors, etc. */
  173. __pagesize = PAGE_SIZE;
  174. #ifdef __UCLIBC_HAS_THREADS__
  175. /* Before we start initializing uClibc we have to call
  176. * __pthread_initialize_minimal so we can use pthread_locks
  177. * whenever they are needed.
  178. */
  179. if (likely(__pthread_initialize_minimal!=NULL))
  180. __pthread_initialize_minimal();
  181. #endif
  182. #ifndef SHARED
  183. # ifdef __UCLIBC_HAS_SSP__
  184. /* Set up the stack checker's canary. */
  185. stack_chk_guard = _dl_setup_stack_chk_guard();
  186. # ifdef THREAD_SET_STACK_GUARD
  187. THREAD_SET_STACK_GUARD (stack_chk_guard);
  188. # ifdef __UCLIBC_HAS_SSP_COMPAT__
  189. __guard = stack_chk_guard;
  190. # endif
  191. # else
  192. __stack_chk_guard = stack_chk_guard;
  193. # if !defined __HAVE_SHARED__ && defined __UCLIBC_HAS_SSP_COMPAT__
  194. __guard = stack_chk_guard;
  195. # endif
  196. # endif
  197. # endif
  198. #endif
  199. #ifdef __UCLIBC_HAS_LOCALE__
  200. /* Initialize the global locale structure. */
  201. if (likely(_locale_init!=NULL))
  202. _locale_init();
  203. #endif
  204. /*
  205. * Initialize stdio here. In the static library case, this will
  206. * be bypassed if not needed because of the weak alias above.
  207. * Thus we get a nice size savings because the stdio functions
  208. * won't be pulled into the final static binary unless used.
  209. */
  210. if (likely(_stdio_init != NULL))
  211. _stdio_init();
  212. }
  213. libc_hidden_def(__uClibc_init)
  214. #ifdef __UCLIBC_CTOR_DTOR__
  215. void attribute_hidden (*__app_fini)(void) = NULL;
  216. #endif
  217. void attribute_hidden (*__rtld_fini)(void) = NULL;
  218. extern void __uClibc_fini(void);
  219. libc_hidden_proto(__uClibc_fini)
  220. void __uClibc_fini(void)
  221. {
  222. #ifdef __UCLIBC_CTOR_DTOR__
  223. /* If __UCLIBC_FORMAT_SHARED_FLAT__, all array finalisation is handled
  224. * by __app_fini. */
  225. # ifdef SHARED
  226. _dl_app_fini_array();
  227. # elif !defined (__UCLIBC_FORMAT_SHARED_FLAT__)
  228. size_t i = __fini_array_end - __fini_array_start;
  229. while (i-- > 0)
  230. (*__fini_array_start [i]) ();
  231. # endif
  232. if (__app_fini != NULL)
  233. (__app_fini)();
  234. #endif
  235. if (__rtld_fini != NULL)
  236. (__rtld_fini)();
  237. }
  238. libc_hidden_def(__uClibc_fini)
  239. /* __uClibc_main is the new main stub for uClibc. This function is
  240. * called from crt1 (version 0.9.28 or newer), after ALL shared libraries
  241. * are initialized, just before we call the application's main function.
  242. */
  243. void __uClibc_main(int (*main)(int, char **, char **), int argc,
  244. char **argv, void (*app_init)(void), void (*app_fini)(void),
  245. void (*rtld_fini)(void), void *stack_end) attribute_noreturn;
  246. void __uClibc_main(int (*main)(int, char **, char **), int argc,
  247. char **argv, void (*app_init)(void), void (*app_fini)(void),
  248. void (*rtld_fini)(void), void *stack_end)
  249. {
  250. #ifndef __ARCH_HAS_NO_LDSO__
  251. unsigned long *aux_dat;
  252. ElfW(auxv_t) auxvt[AT_EGID + 1];
  253. #endif
  254. #ifndef SHARED
  255. __libc_stack_end = stack_end;
  256. #endif
  257. __rtld_fini = rtld_fini;
  258. /* The environment begins right after argv. */
  259. __environ = &argv[argc + 1];
  260. /* If the first thing after argv is the arguments
  261. * the the environment is empty. */
  262. if ((char *) __environ == *argv) {
  263. /* Make __environ point to the NULL at argv[argc] */
  264. __environ = &argv[argc];
  265. }
  266. #ifndef __ARCH_HAS_NO_LDSO__
  267. /* Pull stuff from the ELF header when possible */
  268. memset(auxvt, 0x00, sizeof(auxvt));
  269. aux_dat = (unsigned long*)__environ;
  270. while (*aux_dat) {
  271. aux_dat++;
  272. }
  273. aux_dat++;
  274. while (*aux_dat) {
  275. ElfW(auxv_t) *auxv_entry = (ElfW(auxv_t) *) aux_dat;
  276. if (auxv_entry->a_type <= AT_EGID) {
  277. memcpy(&(auxvt[auxv_entry->a_type]), auxv_entry, sizeof(ElfW(auxv_t)));
  278. }
  279. aux_dat += 2;
  280. }
  281. #endif
  282. /* We need to initialize uClibc. If we are dynamically linked this
  283. * may have already been completed by the shared lib loader. We call
  284. * __uClibc_init() regardless, to be sure the right thing happens. */
  285. __uClibc_init();
  286. #ifndef __ARCH_HAS_NO_LDSO__
  287. /* Make certain getpagesize() gives the correct answer */
  288. __pagesize = (auxvt[AT_PAGESZ].a_un.a_val)? auxvt[AT_PAGESZ].a_un.a_val : PAGE_SIZE;
  289. /* Prevent starting SUID binaries where the stdin. stdout, and
  290. * stderr file descriptors are not already opened. */
  291. if ((auxvt[AT_UID].a_un.a_val == (size_t)-1 && __check_suid()) ||
  292. (auxvt[AT_UID].a_un.a_val != (size_t)-1 &&
  293. (auxvt[AT_UID].a_un.a_val != auxvt[AT_EUID].a_un.a_val ||
  294. auxvt[AT_GID].a_un.a_val != auxvt[AT_EGID].a_un.a_val)))
  295. {
  296. __check_one_fd (STDIN_FILENO, O_RDONLY | O_NOFOLLOW);
  297. __check_one_fd (STDOUT_FILENO, O_RDWR | O_NOFOLLOW);
  298. __check_one_fd (STDERR_FILENO, O_RDWR | O_NOFOLLOW);
  299. }
  300. #endif
  301. __uclibc_progname = *argv;
  302. #ifdef __UCLIBC_HAS_PROGRAM_INVOCATION_NAME__
  303. program_invocation_name = *argv;
  304. program_invocation_short_name = strrchr(*argv, '/');
  305. if (program_invocation_short_name != NULL)
  306. ++program_invocation_short_name;
  307. else
  308. program_invocation_short_name = program_invocation_name;
  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