/* Copyright (C) 1998, 1999 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Library General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License for more details. You should have received a copy of the GNU Library General Public License along with the GNU C Library; see the file COPYING.LIB. If not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #include #include #include #include #include #include #include extern void __libc_init_first (int argc, char **argv, char **envp); extern int _dl_starting_up; weak_extern (_dl_starting_up) extern int __libc_multiple_libcs; extern void *__libc_stack_end; /* Prototype for local function. */ static void check_standard_fds (void); int __libc_start_main (int (*main) (int, char **, char **), int argc, char **argv, void (*init) (void), void (*fini) (void), void (*rtld_fini) (void), void *stack_end) { #ifndef PIC /* The next variable is only here to work around a bug in gcc <= 2.7.2.2. If the address would be taken inside the expression the optimizer would try to be too smart and throws it away. Grrr. */ int *dummy_addr = &_dl_starting_up; __libc_multiple_libcs = dummy_addr && !_dl_starting_up; #endif /* Store the lowest stack address. */ __libc_stack_end = stack_end; /* Set the global _environ variable correctly. */ __environ = &argv[argc + 1]; /* Some security at this point. Prevent starting a SUID binary where the standard file descriptors are not opened. */ if (__libc_enable_secure) check_standard_fds (); /* Register the destructor of the dynamic linker if there is any. */ if (rtld_fini != NULL) atexit (rtld_fini); /* Call the initializer of the libc. */ #ifdef PIC if (_dl_debug_impcalls) _dl_debug_message (1, "\ninitialize libc\n\n", NULL); #endif __libc_init_first (argc, argv, __environ); /* Register the destructor of the program, if any. */ if (fini) atexit (fini); /* Call the initializer of the program, if any. */ #ifdef PIC if (_dl_debug_impcalls) _dl_debug_message (1, "\ninitialize program: ", argv[0], "\n\n", NULL); #endif if (init) (*init) (); #ifdef PIC if (_dl_debug_impcalls) _dl_debug_message (1, "\ntransferring control: ", argv[0], "\n\n", NULL); #endif exit ((*main) (argc, argv, __environ)); } /* Should other OSes (e.g., Hurd) have different versions which can be written in a better way? */ static void check_one_fd (int fd, int mode) { if (__libc_fcntl (fd, F_GETFD) == -1 && errno == EBADF) { /* Something is wrong with this descriptor, it's probably not opened. Open /dev/null so that the SUID program we are about to start does not accidently use this descriptor. */ int nullfd = __libc_open (_PATH_DEVNULL, mode); if (nullfd == -1) /* We cannot even given an error message here since it would run into the same problems. */ abort (); } } static void check_standard_fds (void) { /* Check all three standard file descriptors. */ check_one_fd (STDIN_FILENO, O_RDONLY); check_one_fd (STDOUT_FILENO, O_RDWR); check_one_fd (STDERR_FILENO, O_RDWR); }