diff options
Diffstat (limited to 'libc-top-half/musl/src/env/__libc_start_main.c')
-rw-r--r-- | libc-top-half/musl/src/env/__libc_start_main.c | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/libc-top-half/musl/src/env/__libc_start_main.c b/libc-top-half/musl/src/env/__libc_start_main.c new file mode 100644 index 0000000..c5b277b --- /dev/null +++ b/libc-top-half/musl/src/env/__libc_start_main.c @@ -0,0 +1,97 @@ +#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, + void (*init_dummy)(), void(*fini_dummy)(), void(*ldso_dummy)()) +{ + 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; +} |