| #include <elf.h> |
| #include <poll.h> |
| #include <fcntl.h> |
| #include <signal.h> |
| #include <unistd.h> |
| #include "syscall.h" |
| #include "atomic.h" |
| #include "libc.h" |
| |
| static void dummy(void) {} |
| weak_alias(dummy, _init); |
| |
| extern weak hidden void (*const __init_array_start)(void), (*const __init_array_end)(void); |
| |
| static void dummy1(void *p) {} |
| weak_alias(dummy1, __init_ssp); |
| |
| #define AUX_CNT 38 |
| |
| #ifdef __GNUC__ |
| __attribute__((__noinline__)) |
| #endif |
| void __init_libc(char **envp, char *pn) |
| { |
| size_t i, *auxv, aux[AUX_CNT] = { 0 }; |
| __environ = envp; |
| for (i=0; envp[i]; i++); |
| libc.auxv = auxv = (void *)(envp+i+1); |
| for (i=0; auxv[i]; i+=2) if (auxv[i]<AUX_CNT) aux[auxv[i]] = auxv[i+1]; |
| __hwcap = aux[AT_HWCAP]; |
| if (aux[AT_SYSINFO]) __sysinfo = aux[AT_SYSINFO]; |
| libc.page_size = aux[AT_PAGESZ]; |
| |
| if (!pn) pn = (void*)aux[AT_EXECFN]; |
| if (!pn) pn = ""; |
| __progname = __progname_full = pn; |
| for (i=0; pn[i]; i++) if (pn[i]=='/') __progname = pn+i+1; |
| |
| __init_tls(aux); |
| __init_ssp((void *)aux[AT_RANDOM]); |
| |
| if (aux[AT_UID]==aux[AT_EUID] && aux[AT_GID]==aux[AT_EGID] |
| && !aux[AT_SECURE]) return; |
| |
| struct pollfd pfd[3] = { {.fd=0}, {.fd=1}, {.fd=2} }; |
| int r = |
| #ifdef SYS_poll |
| __syscall(SYS_poll, pfd, 3, 0); |
| #else |
| __syscall(SYS_ppoll, pfd, 3, &(struct timespec){0}, 0, _NSIG/8); |
| #endif |
| if (r<0) a_crash(); |
| for (i=0; i<3; i++) if (pfd[i].revents&POLLNVAL) |
| if (__sys_open("/dev/null", O_RDWR)<0) |
| a_crash(); |
| libc.secure = 1; |
| } |
| |
| static void libc_start_init(void) |
| { |
| _init(); |
| uintptr_t a = (uintptr_t)&__init_array_start; |
| for (; a<(uintptr_t)&__init_array_end; a+=sizeof(void(*)())) |
| (*(void (**)(void))a)(); |
| } |
| |
| weak_alias(libc_start_init, __libc_start_init); |
| |
| typedef int lsm2_fn(int (*)(int,char **,char **), int, char **); |
| static lsm2_fn libc_start_main_stage2; |
| |
| int __libc_start_main(int (*main)(int,char **,char **), int argc, char **argv) |
| { |
| char **envp = argv+argc+1; |
| |
| /* External linkage, and explicit noinline attribute if available, |
| * are used to prevent the stack frame used during init from |
| * persisting for the entire process lifetime. */ |
| __init_libc(envp, argv[0]); |
| |
| /* Barrier against hoisting application code or anything using ssp |
| * or thread pointer prior to its initialization above. */ |
| lsm2_fn *stage2 = libc_start_main_stage2; |
| __asm__ ( "" : "+r"(stage2) : : "memory" ); |
| return stage2(main, argc, argv); |
| } |
| |
| static int libc_start_main_stage2(int (*main)(int,char **,char **), int argc, char **argv) |
| { |
| char **envp = argv+argc+1; |
| __libc_start_init(); |
| |
| /* Pass control to the application */ |
| exit(main(argc, argv, envp)); |
| return 0; |
| } |