1#include <elf.h>
2#include <fcntl.h>
3#include <stdio.h>
4#include <stdlib.h>
5#include <sys/stat.h>
6#include <sys/types.h>
7#include <unistd.h>
8
9#include <string>
10
11void usage(const char* me) {
12  static const char* usage_s = "Usage:\n"
13    "  %s /system/bin/app_process <args>\n"
14    "or, better:\n"
15    "  setprop wrap.<nicename> %s\n";
16  fprintf(stderr, usage_s, me, me);
17  exit(1);
18}
19
20void env_prepend(const char* name, const char* value, const char* delim) {
21  const char* value_old = getenv(name);
22  std::string value_new = value;
23  if (value_old) {
24    value_new += delim;
25    value_new += value_old;
26  }
27  setenv(name, value_new.c_str(), 1);
28}
29
30bool elf_is_64bit(const char* path) {
31  int fd = open(path, O_RDONLY);
32  if (fd == -1) return false;
33
34  const size_t kBufSize = EI_CLASS + 1;
35  char buf[kBufSize];
36  ssize_t sz = read(fd, buf, kBufSize);
37  if (sz != kBufSize) {
38    close(fd);
39    return false;
40  }
41
42  if (buf[EI_MAG0] != ELFMAG0 || buf[EI_MAG1] != ELFMAG1 ||
43      buf[EI_MAG2] != ELFMAG2 || buf[EI_MAG3] != ELFMAG3)
44    return false;
45
46  bool is_64bit = buf[EI_CLASS] == ELFCLASS64;
47  close(fd);
48  return is_64bit;
49}
50
51int main(int argc, char** argv) {
52  if (argc < 2) {
53    usage(argv[0]);
54  }
55  char** args = new char*[argc];
56  // If we are wrapping app_process, replace it with app_process_asan.
57  // TODO(eugenis): rewrite to <dirname>/asan/<basename>, if exists?
58  if (strcmp(argv[1], "/system/bin/app_process") == 0) {
59    args[0] = (char*)"/system/bin/asan/app_process";
60  } else if (strcmp(argv[1], "/system/bin/app_process32") == 0) {
61    args[0] = (char*)"/system/bin/asan/app_process32";
62  } else if (strcmp(argv[1], "/system/bin/app_process64") == 0) {
63    args[0] = (char*)"/system/bin/asan/app_process64";
64  } else {
65    args[0] = argv[1];
66  }
67
68  for (int i = 1; i < argc - 1; ++i)
69    args[i] = argv[i + 1];
70  args[argc - 1] = 0;
71
72  if (elf_is_64bit(args[0])) {
73    env_prepend("LD_LIBRARY_PATH", "/system/lib64/asan:/system/lib64", ":");
74  } else {
75    env_prepend("LD_LIBRARY_PATH", "/system/lib/asan:/system/lib", ":");
76  }
77  env_prepend("ASAN_OPTIONS", "allow_user_segv_handler=1", ",");
78
79  printf("ASAN_OPTIONS: %s\n", getenv("ASAN_OPTIONS"));
80  printf("LD_LIBRARY_PATH: %s\n", getenv("LD_LIBRARY_PATH"));
81  for (int i = 0; i < argc - 1; ++i)
82    printf("argv[%d] = %s\n", i, args[i]);
83
84  execv(args[0], args);
85}
86