From 47a34ece26a093102675e0a2dfc42c8182b98257 Mon Sep 17 00:00:00 2001 From: Matthias Schiffer Date: Fri, 23 May 2014 02:37:02 +0200 Subject: Revert "Fix waitpid race condition" This reverts commit 47d84679d6fe71f56d3a013578007dff92ff72db. --- src/fastd.c | 1 + src/shell.c | 57 ++++++++++++++++++++++----------------------------------- 2 files changed, 23 insertions(+), 35 deletions(-) (limited to 'src') diff --git a/src/fastd.c b/src/fastd.c index aabcaba..789b3a6 100644 --- a/src/fastd.c +++ b/src/fastd.c @@ -75,6 +75,7 @@ static void on_sigusr1(int signo UNUSED) { } static void on_sigchld(int signo UNUSED) { + while (waitpid(-1, NULL, WNOHANG) > 0) {} } static void init_signals(void) { diff --git a/src/shell.c b/src/shell.c index 8542bf9..9d03fbc 100644 --- a/src/shell.c +++ b/src/shell.c @@ -29,7 +29,6 @@ #include #include -#include typedef struct shell_env_entry { @@ -104,15 +103,18 @@ static void shell_command_setenv(pid_t pid, const fastd_shell_env_t *env) { } } -static bool shell_command_do_exec(const fastd_shell_command_t *command, const fastd_shell_env_t *env, pid_t *pid) { +static bool shell_command_do_exec(const fastd_shell_command_t *command, const fastd_shell_env_t *env, pid_t *pid_ret) { pid_t parent = getpid(); - *pid = fork(); - if (*pid < 0) { + pid_t pid = fork(); + if (pid < 0) { pr_error_errno("shell_command_do_exec: fork"); return false; } - else if (*pid > 0) { + else if (pid > 0) { + if (pid_ret) + *pid_ret = pid; + return true; } @@ -125,6 +127,12 @@ static bool shell_command_do_exec(const fastd_shell_command_t *command, const fa shell_command_setenv(parent, env); + /* unblock SIGCHLD */ + sigset_t set; + sigemptyset(&set); + sigaddset(&set, SIGCHLD); + pthread_sigmask(SIG_UNBLOCK, &set, NULL); + execl("/bin/sh", "sh", "-c", command->command, (char*)NULL); _exit(127); } @@ -133,6 +141,12 @@ bool fastd_shell_command_exec_sync(const fastd_shell_command_t *command, const f if (!fastd_shell_command_isset(command)) return true; + /* block SIGCHLD */ + sigset_t set, oldset; + sigemptyset(&set); + sigaddset(&set, SIGCHLD); + pthread_sigmask(SIG_BLOCK, &set, &oldset); + pid_t pid; if (!shell_command_do_exec(command, env, &pid)) return false; @@ -140,6 +154,8 @@ bool fastd_shell_command_exec_sync(const fastd_shell_command_t *command, const f int status; pid_t err = waitpid(pid, &status, 0); + pthread_sigmask(SIG_SETMASK, &oldset, NULL); + if (err <= 0) { pr_error_errno("fastd_shell_command_exec_sync: waitpid"); return false; @@ -158,35 +174,6 @@ bool fastd_shell_command_exec_sync(const fastd_shell_command_t *command, const f return true; } -static void * reap_child(void *arg) { - pid_t *pid = arg; - - pid_t err = waitpid(*pid, NULL, 0); - - pr_debug("child process %u finished", (unsigned)*pid); - - if (err <= 0) - pr_error_errno("reap_child: waitpid"); - - free(pid); - - return NULL; -} - -static void shell_command_exec_async(const fastd_shell_command_t *command, const fastd_shell_env_t *env) { - pid_t *pid = malloc(sizeof(*pid)); - if (!shell_command_do_exec(command, env, pid)) - return; - - pthread_t thread; - if ((errno = pthread_create(&thread, NULL, reap_child, pid)) != 0) { - pr_error_errno("unable to create reaper thread"); - free(pid); - return; - } - - pthread_detach(thread); -} void fastd_shell_command_exec(const fastd_shell_command_t *command, const fastd_shell_env_t *env) { if (!fastd_shell_command_isset(command)) @@ -195,5 +182,5 @@ void fastd_shell_command_exec(const fastd_shell_command_t *command, const fastd_ if (command->sync) fastd_shell_command_exec_sync(command, env, NULL); else - shell_command_exec_async(command, env); + shell_command_do_exec(command, env, NULL); } -- cgit v1.2.3