commit f8344c2d28be2489c8abadd694b5b96fe18efc02 Author: Nick Mathewson nickm@torproject.org Date: Thu Apr 10 11:06:10 2014 -0400
Use waitpid code to learn when a controlled process dies
This lets us avoid sending SIGTERM to something that has already died, since we realize it has already died, and is a fix for the unix version of #8746. --- src/common/util.c | 46 +++++++++++++++++++++++++++++++++++++++++++--- src/common/util.h | 9 ++++++++- 2 files changed, 51 insertions(+), 4 deletions(-)
diff --git a/src/common/util.c b/src/common/util.c index 56235aa..0a14101 100644 --- a/src/common/util.c +++ b/src/common/util.c @@ -26,6 +26,7 @@ #include "address.h" #include "sandbox.h" #include "backtrace.h" +#include "util_process.h"
#ifdef _WIN32 #include <io.h> @@ -3642,7 +3643,10 @@ tor_terminate_process(process_handle_t *process_handle) return 0; } #else /* Unix */ - return kill(process_handle->pid, SIGTERM); + if (process_handle->waitpid_cb) { + /* We haven't got a waitpid yet, so we can just kill off the process. */ + return kill(process_handle->pid, SIGTERM); + } #endif
return -1; @@ -3691,6 +3695,23 @@ process_handle_new(void) return out; }
+#ifndef _WIN32 +/** Invoked when a process that we've launched via tor_spawn_background() has + * been found to have terminated. + */ +static void +process_handle_waitpid_cb(int status, void *arg) +{ + process_handle_t *process_handle = arg; + + process_handle->waitpid_exit_status = status; + clear_waitpid_callback(process_handle->waitpid_cb); + if (process_handle->status == PROCESS_STATUS_RUNNING) + process_handle->status = PROCESS_STATUS_NOTRUNNING; + process_handle->waitpid_cb = 0; +} +#endif + /** * @name child-process states * @@ -4007,6 +4028,10 @@ tor_spawn_background(const char *const filename, const char **argv, strerror(errno)); }
+ process_handle->waitpid_cb = set_waitpid_callback(pid, + process_handle_waitpid_cb, + process_handle); + process_handle->stderr_pipe = stderr_pipe[0]; retval = close(stderr_pipe[1]);
@@ -4071,6 +4096,8 @@ tor_process_handle_destroy,(process_handle_t *process_handle,
if (process_handle->stderr_handle) fclose(process_handle->stderr_handle); + + clear_waitpid_callback(process_handle->waitpid_cb); #endif
memset(process_handle, 0x0f, sizeof(process_handle_t)); @@ -4088,7 +4115,7 @@ tor_process_handle_destroy,(process_handle_t *process_handle, * probably not work in Tor, because waitpid() is called in main.c to reap any * terminated child processes.*/ int -tor_get_exit_code(const process_handle_t *process_handle, +tor_get_exit_code(process_handle_t *process_handle, int block, int *exit_code) { #ifdef _WIN32 @@ -4128,7 +4155,20 @@ tor_get_exit_code(const process_handle_t *process_handle, int stat_loc; int retval;
- retval = waitpid(process_handle->pid, &stat_loc, block?0:WNOHANG); + if (process_handle->waitpid_cb) { + /* We haven't processed a SIGCHLD yet. */ + retval = waitpid(process_handle->pid, &stat_loc, block?0:WNOHANG); + if (retval == process_handle->pid) { + clear_waitpid_callback(process_handle->waitpid_cb); + process_handle->waitpid_cb = NULL; + process_handle->waitpid_exit_status = stat_loc; + } + } else { + /* We already got a SIGCHLD for this process, and handled it. */ + retval = process_handle->pid; + stat_loc = process_handle->waitpid_exit_status; + } + if (!block && 0 == retval) { /* Process has not exited */ return PROCESS_EXIT_RUNNING; diff --git a/src/common/util.h b/src/common/util.h index 18dc206..97367a9 100644 --- a/src/common/util.h +++ b/src/common/util.h @@ -446,6 +446,7 @@ void set_environment_variable_in_smartlist(struct smartlist_t *env_vars, #define PROCESS_STATUS_ERROR -1
#ifdef UTIL_PRIVATE +struct waitpid_callback_t; /** Structure to represent the state of a process with which Tor is * communicating. The contents of this structure are private to util.c */ struct process_handle_t { @@ -461,6 +462,12 @@ struct process_handle_t { FILE *stdout_handle; FILE *stderr_handle; pid_t pid; + /** If the process has not given us a SIGCHLD yet, this has the + * waitpid_callback_t that gets invoked once it has. Otherwise this + * contains NULL. */ + struct waitpid_callback_t *waitpid_cb; + /** The exit status reported by waitpid. */ + int waitpid_exit_status; #endif // _WIN32 }; #endif @@ -469,7 +476,7 @@ struct process_handle_t { #define PROCESS_EXIT_RUNNING 1 #define PROCESS_EXIT_EXITED 0 #define PROCESS_EXIT_ERROR -1 -int tor_get_exit_code(const process_handle_t *process_handle, +int tor_get_exit_code(process_handle_t *process_handle, int block, int *exit_code); int tor_split_lines(struct smartlist_t *sl, char *buf, int len); #ifdef _WIN32