56 lines
2.3 KiB
C
56 lines
2.3 KiB
C
// Copyright 2014 The Chromium Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style license that can be
|
|
// found in the LICENSE file.
|
|
#include <dlfcn.h>
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
#include <sys/prctl.h>
|
|
#include <unistd.h>
|
|
// This is a wrapper to run position independent executables on Android ICS,
|
|
// where the linker doesn't support PIE. This requires the PIE binaries to be
|
|
// built with CFLAGS +=-fvisibility=default -fPIE, and LDFLAGS += -rdynamic -pie
|
|
// such that the main() symbol remains exported and can be dlsym-ed.
|
|
#define ERR_PREFIX "[PIE Loader] "
|
|
typedef int (*main_t)(int, char**);
|
|
int main(int argc, char** argv) {
|
|
if (argc < 2) {
|
|
printf("Usage: %s path_to_pie_executable [args]\n", argv[0]);
|
|
return -1;
|
|
}
|
|
// Shift left the argv[]. argv is what /proc/PID/cmdline prints out. In turn
|
|
// cmdline is what Android "ps" prints out. In turn "ps" is what many scripts
|
|
// look for to decide which processes to kill / killall.
|
|
int i;
|
|
char* next_argv_start = argv[0];
|
|
for (i = 1; i < argc; ++i) {
|
|
const size_t argv_len = strlen(argv[i]) + 1;
|
|
memcpy(argv[i - 1], argv[i], argv_len);
|
|
next_argv_start += argv_len;
|
|
argv[i] = next_argv_start;
|
|
}
|
|
argv[argc - 1] = NULL; // The last argv must be a NULL ptr.
|
|
// Set also the proc name accordingly (/proc/PID/comm).
|
|
prctl(PR_SET_NAME, (long) argv[0]);
|
|
// dlopen should not fail, unless:
|
|
// - The target binary does not exists:
|
|
// - The dependent .so libs cannot be loaded.
|
|
// In both cases, just bail out with an explicit error message.
|
|
void* handle = dlopen(argv[0], RTLD_NOW);
|
|
if (handle == NULL) {
|
|
printf(ERR_PREFIX "dlopen() failed: %s.\n", dlerror());
|
|
return -1;
|
|
}
|
|
main_t pie_main = (main_t) dlsym(handle, "main");
|
|
if (pie_main) {
|
|
return pie_main(argc - 1, argv);
|
|
}
|
|
// If we reached this point dlsym failed, very likely because the target
|
|
// binary has not been compiled with the proper CFLAGS / LDFLAGS.
|
|
// At this point the most sensible thing to do is running that normally
|
|
// via exec and hope that the target binary wasn't a PIE.
|
|
execv(argv[0], argv);
|
|
// exevc is supposed to never return, unless it fails.
|
|
printf(ERR_PREFIX "Both dlsym() and the execv() fallback failed.\n");
|
|
perror("execv");
|
|
return -1;
|
|
}
|