Linux debugging

Check our new training course

Linux debugging, tracing, profiling & perf. analysis

Check our new training course
with Creative Commons CC-BY-SA
lecture and lab materials

Bootlin logo

Elixir Cross Referencer

#include <elf.h>
#include <poll.h>
#include <fcntl.h>
#include <signal.h>
#include "syscall.h"
#include "atomic.h"
#include "libc.h"

void __init_tls(size_t *);

#ifndef SHARED
static void dummy() {}
weak_alias(dummy, _init);
extern void (*const __init_array_start)() __attribute__((weak));
extern void (*const __init_array_end)() __attribute__((weak));

static void dummy1(void *p) {}
weak_alias(dummy1, __init_ssp);

#define AUX_CNT 38

extern size_t __hwcap, __sysinfo;
extern char *__progname, *__progname_full;

#ifndef SHARED
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];
	__sysinfo = aux[AT_SYSINFO];
	libc.page_size = aux[AT_PAGESZ];

	if (pn) {
		__progname = __progname_full = pn;
		for (i=0; pn[i]; i++) if (pn[i]=='/') __progname = pn+i+1;

	__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} };
#ifdef SYS_poll
	__syscall(SYS_poll, pfd, 3, 0);
	__syscall(SYS_ppoll, pfd, 3, &(struct timespec){0}, 0, _NSIG/8);
	for (i=0; i<3; i++) if (pfd[i].revents&POLLNVAL)
		if (__sys_open("/dev/null", O_RDWR)<0)
			a_crash(); = 1;

int __libc_start_main(int (*main)(int,char **,char **), int argc, char **argv)
	char **envp = argv+argc+1;

#ifndef SHARED
	__init_libc(envp, argv[0]);
	uintptr_t a = (uintptr_t)&__init_array_start;
	for (; a<(uintptr_t)&__init_array_end; a+=sizeof(void(*)()))
		(*(void (**)())a)();

	/* Pass control to the application */
	exit(main(argc, argv, envp));
	return 0;