src/tools/tor_runner.c

   1 /* Copyright (c) 2001 Matej Pfajfar.
   2  * Copyright (c) 2001-2004, Roger Dingledine.
   3  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
   4  * Copyright (c) 2007-2021, The Tor Project, Inc. */
   5 /* See LICENSE for licensing information */
   6
   7 /**
   8  * @file tor_runner.c
   9  * @brief Experimental module to emulate tor_run_main() API with fork+exec
  10  *
  11  * The functions here are meant to allow the application developer to
  12  * use the tor_run_main() API without having to care whether Tor is
  13  * running in-process or out-of-process.  For in-process usage, the
  14  * developer can link Tor as a library and call tor_run_main(); for
  15  * out-of-process usage, the developer can link this library instead.
  16  *
  17  * This interface is EXPERIMENTAL; please let us know if you would like
  18  * to depend on it.  We don't know yet whether it will be reliable in
  19  * practice.
  20  */
  21
  22 /* NOTE: This module is supposed to work without the standard Tor utility
  23  * functions.  Don't add more dependencies!
  24  */
  25
  26 #include "feature/api/tor_api.h"
  27 #include "feature/api/tor_api_internal.h"
  28
  29 #include "orconfig.h"
  30 #ifdef HAVE_UNISTD_H
  31 #include <unistd.h>
  32 #endif
  33 #ifdef HAVE_SYS_WAIT_H
  34 #include <sys/wait.h>
  35 #endif
  36 #ifdef HAVE_SYS_SOCKET_H
  37 #include <sys/socket.h>
  38 #endif
  39 #include <stdlib.h>
  40 #include <string.h>
  41
  42 #ifndef __GNUC__
  43 #define __attribute__(x)
  44 #endif
  45
  46 static void child(const tor_main_configuration_t *cfg)
  47   __attribute__((noreturn));
  48
  49 const char *
  50 tor_api_get_provider_version(void)
  51 {
  52   return "libtorrunner " VERSION;
  53 }
  54
  55 int
  56 tor_run_main(const tor_main_configuration_t *cfg)
  57 {
  58   pid_t pid = fork();
  59   if (pid == 0) {
  60     child(cfg);
  61     exit(0); /* Unreachable */
  62   }
  63
  64   pid_t stopped_pid;
  65   int status = 0;
  66   do {
  67     stopped_pid = waitpid(pid, &status, 0);
  68   } while (stopped_pid == -1);
  69
  70   /* Note: these return values are not documented.  No return value is
  71    * documented! */
  72
  73   if (stopped_pid != pid) {
  74     return -99999;
  75   }
  76   if (WIFSTOPPED(status)) {
  77     return WEXITSTATUS(status);
  78   }
  79   if (WIFSIGNALED(status)) {
  80     return -WTERMSIG(status);
  81   }
  82
  83   return -999988;
  84 }
  85
  86 /* circumlocution to avoid getting warned about calling calloc instead of
  87  * tor_calloc. */
  88 #define real_calloc calloc
  89 #define real_free free
  90
  91 static void
  92 child(const tor_main_configuration_t *cfg)
  93 {
  94   /* XXXX Close unused file descriptors. */
  95
  96   char **args = real_calloc(cfg->argc + cfg->argc_owned+1, sizeof(char *));
  97   memcpy(args, cfg->argv, cfg->argc * sizeof(char *));
  98   if (cfg->argc_owned)
  99     memcpy(args + cfg->argc, cfg->argv_owned,
 100            cfg->argc_owned * sizeof(char *));
 101
 102   args[cfg->argc + cfg->argc_owned] = NULL;
 103
 104   int rv = execv(BINDIR "/tor", args);
 105
 106   if (rv < 0) {
 107     real_free(args);
 108     exit(254);
 109   } else {
 110     abort(); /* Unreachable */
 111   }
 112 }