1 //===-- Launcher.cpp --------------------------------------------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 10 //---------------------------------------------------------------------- 11 // Darwin launch helper 12 // 13 // This program was written to allow programs to be launched in a new 14 // Terminal.app window and have the application be stopped for debugging 15 // at the program entry point. 16 // 17 // Although it uses posix_spawn(), it uses Darwin specific posix spawn 18 // attribute flags to accomplish its task. It uses an "exec only" flag 19 // which avoids forking this process, and it uses a "stop at entry" 20 // flag to stop the program at the entry point. 21 // 22 // Since it uses darwin specific flags this code should not be compiled 23 // on other systems. 24 //---------------------------------------------------------------------- 25 #if defined (__APPLE__) 26 27 #include <getopt.h> 28 #include <mach/machine.h> 29 #include <spawn.h> 30 #include <stdio.h> 31 #include <stdlib.h> 32 #include <string.h> 33 #include <sys/types.h> 34 #include <sys/socket.h> 35 #include <sys/un.h> 36 37 #include <string> 38 39 #ifndef _POSIX_SPAWN_DISABLE_ASLR 40 #define _POSIX_SPAWN_DISABLE_ASLR 0x0100 41 #endif 42 43 #define streq(a,b) strcmp(a,b) == 0 44 45 static struct option g_long_options[] = 46 { 47 { "arch", required_argument, NULL, 'a' }, 48 { "disable-aslr", no_argument, NULL, 'd' }, 49 { "no-env", no_argument, NULL, 'e' }, 50 { "help", no_argument, NULL, 'h' }, 51 { "setsid", no_argument, NULL, 's' }, 52 { "unix-socket", required_argument, NULL, 'u' }, 53 { NULL, 0, NULL, 0 } 54 }; 55 56 static void 57 usage() 58 { 59 puts ( 60 "NAME\n" 61 " darwin-debug -- posix spawn a process that is stopped at the entry point\n" 62 " for debugging.\n" 63 "\n" 64 "SYNOPSIS\n" 65 " darwin-debug --unix-socket=<SOCKET> [--arch=<ARCH>] [--disable-aslr] [--no-env] [--setsid] [--help] -- <PROGRAM> [<PROGRAM-ARG> <PROGRAM-ARG> ....]\n" 66 "\n" 67 "DESCRIPTION\n" 68 " darwin-debug will exec itself into a child process <PROGRAM> that is\n" 69 " halted for debugging. It does this by using posix_spawn() along with\n" 70 " darwin specific posix_spawn flags that allows exec only (no fork), and\n" 71 " stop at the program entry point. Any program arguments <PROGRAM-ARG> are\n" 72 " passed on to the exec as the arguments for the new process. The current\n" 73 " environment will be passed to the new process unless the \"--no-env\"\n" 74 " option is used. A unix socket must be supplied using the\n" 75 " --unix-socket=<SOCKET> option so the calling program can handshake with\n" 76 " this process and get its process id.\n" 77 "\n" 78 "EXAMPLE\n" 79 " darwin-debug --arch=i386 -- /bin/ls -al /tmp\n" 80 ); 81 exit (1); 82 } 83 84 static void 85 exit_with_errno (int err, const char *prefix) 86 { 87 if (err) 88 { 89 fprintf (stderr, 90 "%s%s", 91 prefix ? prefix : "", 92 strerror(err)); 93 exit (err); 94 } 95 } 96 97 pid_t 98 posix_spawn_for_debug (char *const *argv, char *const *envp, cpu_type_t cpu_type, int disable_aslr) 99 { 100 pid_t pid = 0; 101 102 const char *path = argv[0]; 103 104 posix_spawnattr_t attr; 105 106 exit_with_errno (::posix_spawnattr_init (&attr), "::posix_spawnattr_init (&attr) error: "); 107 108 // Here we are using a darwin specific feature that allows us to exec only 109 // since we want this program to turn into the program we want to debug, 110 // and also have the new program start suspended (right at __dyld_start) 111 // so we can debug it 112 short flags = POSIX_SPAWN_START_SUSPENDED | POSIX_SPAWN_SETEXEC; 113 114 // Disable ASLR if we were asked to 115 if (disable_aslr) 116 flags |= _POSIX_SPAWN_DISABLE_ASLR; 117 118 // Set the flags we just made into our posix spawn attributes 119 exit_with_errno (::posix_spawnattr_setflags (&attr, flags), "::posix_spawnattr_setflags (&attr, flags) error: "); 120 121 122 // Another darwin specific thing here where we can select the architecture 123 // of the binary we want to re-exec as. 124 if (cpu_type != 0) 125 { 126 size_t ocount = 0; 127 exit_with_errno (::posix_spawnattr_setbinpref_np (&attr, 1, &cpu_type, &ocount), "posix_spawnattr_setbinpref_np () error: "); 128 } 129 130 exit_with_errno (::posix_spawnp (&pid, path, NULL, &attr, (char * const*)argv, (char * const*)envp), "posix_spawn() error: "); 131 132 // This code will only be reached if the posix_spawn exec failed... 133 ::posix_spawnattr_destroy (&attr); 134 135 return pid; 136 } 137 138 139 int main (int argc, char *const *argv, char *const *envp, const char **apple) 140 { 141 const char *program_name = strrchr(apple[0], '/'); 142 143 if (program_name) 144 program_name++; // Skip the last slash.. 145 else 146 program_name = apple[0]; 147 148 #if defined (DEBUG_LLDB_LAUNCHER) 149 printf("%s called with:\n", program_name); 150 for (int i=0; i<argc; ++i) 151 printf("argv[%u] = '%s'\n", i, argv[i]); 152 #endif 153 154 cpu_type_t cpu_type = 0; 155 bool show_usage = false; 156 char ch; 157 int disable_aslr = 0; // By default we disable ASLR 158 int pass_env = 1; 159 std::string unix_socket_name; 160 while ((ch = getopt_long(argc, argv, "a:dehsu:?", g_long_options, NULL)) != -1) 161 { 162 switch (ch) 163 { 164 case 0: 165 break; 166 167 case 'a': // "-a i386" or "--arch=i386" 168 if (optarg) 169 { 170 if (streq (optarg, "i386")) 171 cpu_type = CPU_TYPE_I386; 172 else if (streq (optarg, "x86_64")) 173 cpu_type = CPU_TYPE_X86_64; 174 else if (strstr (optarg, "arm") == optarg) 175 cpu_type = CPU_TYPE_ARM; 176 else 177 { 178 ::fprintf (stderr, "error: unsupported cpu type '%s'\n", optarg); 179 ::exit (1); 180 } 181 } 182 break; 183 184 case 'd': 185 disable_aslr = 1; 186 break; 187 188 case 'e': 189 pass_env = 0; 190 break; 191 192 case 's': 193 // Create a new session to avoid having control-C presses kill our current 194 // terminal session when this program is launched from a .command file 195 ::setsid(); 196 break; 197 198 case 'u': 199 unix_socket_name.assign (optarg); 200 break; 201 202 case 'h': 203 case '?': 204 default: 205 show_usage = true; 206 break; 207 } 208 } 209 argc -= optind; 210 argv += optind; 211 212 if (show_usage || argc <= 0 || unix_socket_name.empty()) 213 usage(); 214 215 #if defined (DEBUG_LLDB_LAUNCHER) 216 printf ("\n%s post options:\n", program_name); 217 for (int i=0; i<argc; ++i) 218 printf ("argv[%u] = '%s'\n", i, argv[i]); 219 #endif 220 221 // Open the socket that was passed in as an argument 222 struct sockaddr_un saddr_un; 223 int s = ::socket (AF_UNIX, SOCK_STREAM, 0); 224 if (s < 0) 225 { 226 perror("error: socket (AF_UNIX, SOCK_STREAM, 0)"); 227 exit(1); 228 } 229 230 saddr_un.sun_family = AF_UNIX; 231 ::strncpy(saddr_un.sun_path, unix_socket_name.c_str(), sizeof(saddr_un.sun_path) - 1); 232 saddr_un.sun_path[sizeof(saddr_un.sun_path) - 1] = '\0'; 233 saddr_un.sun_len = SUN_LEN (&saddr_un); 234 235 if (::connect (s, (struct sockaddr *)&saddr_un, SUN_LEN (&saddr_un)) < 0) 236 { 237 perror("error: connect (socket, &saddr_un, saddr_un_len)"); 238 exit(1); 239 } 240 241 // We were able to connect to the socket, now write our PID so whomever 242 // launched us will know this process's ID 243 char pid_str[64]; 244 const int pid_str_len = ::snprintf (pid_str, sizeof(pid_str), "%i", ::getpid()); 245 const int bytes_sent = ::send (s, pid_str, pid_str_len, 0); 246 247 if (pid_str_len != bytes_sent) 248 { 249 perror("error: send (s, pid_str, pid_str_len, 0)"); 250 exit (1); 251 } 252 253 // We are done with the socket 254 close (s); 255 256 // Now we posix spawn to exec this process into the inferior that we want 257 // to debug. 258 posix_spawn_for_debug (argv, 259 pass_env ? envp : NULL, 260 cpu_type, 261 disable_aslr); 262 263 return 0; 264 } 265 266 #endif // #if defined (__APPLE__) 267 268