/*
 * Restore original one from SHC obfuscated/compiled binary.
 *  - bushi.csk@gmail
 *
 * $ gcc -Os -Wall -shared -fPIC -pthread -ldl -nostdlib -s -o unshc.so unshc.c
 * $ LD_PRELOAD=./unshc.so ./test.sh.x
 */
#define _GNU_SOURCE
#include <stdio.h>
#include <dlfcn.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <pthread.h>

#pragma GCC visibility push(hidden)

#define __init       __attribute__((constructor))
#define __visible    __attribute__((visibility("default")))

static void autolock_unlock(pthread_mutex_t **mutex) { pthread_mutex_unlock(*mutex); }
#define __autounlock __attribute__((cleanup(autolock_unlock)))

#define __name_autolock(_name) autolock_ ##_name

#define AUTOLOCK_LOCK(_name) \
	__autounlock pthread_mutex_t *l_##_name = &__name_autolock(_name); \
	pthread_mutex_lock(l_##_name);

#define H_SYM(_ret, _func, _arg...) \
static pthread_mutex_t __name_autolock(_func) = PTHREAD_MUTEX_INITIALIZER; \
static _ret (*org_ ##_func)(_arg); \
static void __init hook_ ##_func(void) \
  { org_ ##_func = dlsym(RTLD_NEXT, #_func); } \
_ret __visible _func(_arg)

#define H_ORG(_func) org_ ## _func

/* against with shc-3.9.3 */
H_SYM(int, execvp, const char *f, char *const *arg)
{
  AUTOLOCK_LOCK(execvp);

  if (3[arg] && !strcmp(3[arg], getenv("_")) && getenv("unshc")) {
    const char *p = 2[arg];
    for (; ' ' == 0[p]; p++);
    write(fileno(stdout), p, strlen(p));
    exit(1);
  }
  putenv("unshc="__FILE__);

  return H_ORG(execvp(f, arg));
}