Merge pull request #778 from excellentname/handle-sigchld

Handle SIGCHLD for exec/forkExec
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Alex 2020-08-07 13:33:27 +02:00 committed by GitHub
commit 5ebd3594e4
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2 changed files with 90 additions and 4 deletions

View File

@ -7,6 +7,9 @@
#include <array> #include <array>
extern std::mutex reap_mtx;
extern std::list<pid_t> reap;
namespace waybar::util::command { namespace waybar::util::command {
struct res { struct res {
@ -32,10 +35,11 @@ inline std::string read(FILE* fp) {
inline int close(FILE* fp, pid_t pid) { inline int close(FILE* fp, pid_t pid) {
int stat = -1; int stat = -1;
pid_t ret;
fclose(fp); fclose(fp);
do { do {
waitpid(pid, &stat, WCONTINUED | WUNTRACED); ret = waitpid(pid, &stat, WCONTINUED | WUNTRACED);
if (WIFEXITED(stat)) { if (WIFEXITED(stat)) {
spdlog::debug("Cmd exited with code {}", WEXITSTATUS(stat)); spdlog::debug("Cmd exited with code {}", WEXITSTATUS(stat));
@ -45,6 +49,8 @@ inline int close(FILE* fp, pid_t pid) {
spdlog::debug("Cmd stopped by {}", WSTOPSIG(stat)); spdlog::debug("Cmd stopped by {}", WSTOPSIG(stat));
} else if (WIFCONTINUED(stat)) { } else if (WIFCONTINUED(stat)) {
spdlog::debug("Cmd continued"); spdlog::debug("Cmd continued");
} else if (ret == -1) {
spdlog::debug("waitpid failed: {}", strerror(errno));
} else { } else {
break; break;
} }
@ -65,6 +71,12 @@ inline FILE* open(const std::string& cmd, int& pid) {
} }
if (!child_pid) { if (!child_pid) {
int err;
sigset_t mask;
sigfillset(&mask);
// Reset sigmask
err = pthread_sigmask(SIG_UNBLOCK, &mask, nullptr);
if (err != 0) spdlog::error("pthread_sigmask in open failed: {}", strerror(err));
::close(fd[0]); ::close(fd[0]);
dup2(fd[1], 1); dup2(fd[1], 1);
setpgid(child_pid, child_pid); setpgid(child_pid, child_pid);
@ -97,7 +109,7 @@ inline struct res execNoRead(const std::string& cmd) {
inline int32_t forkExec(const std::string& cmd) { inline int32_t forkExec(const std::string& cmd) {
if (cmd == "") return -1; if (cmd == "") return -1;
int32_t pid = fork(); pid_t pid = fork();
if (pid < 0) { if (pid < 0) {
spdlog::error("Unable to exec cmd {}, error {}", cmd.c_str(), strerror(errno)); spdlog::error("Unable to exec cmd {}, error {}", cmd.c_str(), strerror(errno));
@ -106,12 +118,20 @@ inline int32_t forkExec(const std::string& cmd) {
// Child executes the command // Child executes the command
if (!pid) { if (!pid) {
int err;
sigset_t mask;
sigfillset(&mask);
// Reset sigmask
err = pthread_sigmask(SIG_UNBLOCK, &mask, nullptr);
if (err != 0) spdlog::error("pthread_sigmask in forkExec failed: {}", strerror(err));
setpgid(pid, pid); setpgid(pid, pid);
signal(SIGCHLD, SIG_DFL);
execl("/bin/sh", "sh", "-c", cmd.c_str(), (char*)0); execl("/bin/sh", "sh", "-c", cmd.c_str(), (char*)0);
exit(0); exit(0);
} else { } else {
signal(SIGCHLD, SIG_IGN); reap_mtx.lock();
reap.push_back(pid);
reap_mtx.unlock();
spdlog::debug("Added child to reap list: {}", pid);
} }
return pid; return pid;

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@ -1,7 +1,72 @@
#include <csignal> #include <csignal>
#include <list>
#include <mutex>
#include <sys/types.h>
#include <sys/wait.h>
#include <spdlog/spdlog.h> #include <spdlog/spdlog.h>
#include "client.hpp" #include "client.hpp"
std::mutex reap_mtx;
std::list<pid_t> reap;
void* signalThread(void* args) {
int err, signum;
sigset_t mask;
sigemptyset(&mask);
sigaddset(&mask, SIGCHLD);
while (true) {
err = sigwait(&mask, &signum);
if (err != 0) {
spdlog::error("sigwait failed: {}", strerror(errno));
continue;
}
switch (signum) {
case SIGCHLD:
spdlog::debug("Received SIGCHLD in signalThread");
if (!reap.empty()) {
reap_mtx.lock();
for (auto it = reap.begin(); it != reap.end(); ++it) {
if (waitpid(*it, nullptr, WNOHANG) == *it) {
spdlog::debug("Reaped child with PID: {}", *it);
it = reap.erase(it);
}
}
reap_mtx.unlock();
}
break;
default:
spdlog::debug("Received signal with number {}, but not handling",
signum);
break;
}
}
}
void startSignalThread(void) {
int err;
sigset_t mask;
sigemptyset(&mask);
sigaddset(&mask, SIGCHLD);
// Block SIGCHLD so it can be handled by the signal thread
// Any threads created by this one (the main thread) should not
// modify their signal mask to unblock SIGCHLD
err = pthread_sigmask(SIG_BLOCK, &mask, nullptr);
if (err != 0) {
spdlog::error("pthread_sigmask failed in startSignalThread: {}", strerror(err));
exit(1);
}
pthread_t thread_id;
err = pthread_create(&thread_id, nullptr, signalThread, nullptr);
if (err != 0) {
spdlog::error("pthread_create failed in startSignalThread: {}", strerror(err));
exit(1);
}
}
int main(int argc, char* argv[]) { int main(int argc, char* argv[]) {
try { try {
auto client = waybar::Client::inst(); auto client = waybar::Client::inst();
@ -18,6 +83,7 @@ int main(int argc, char* argv[]) {
} }
}); });
} }
startSignalThread();
auto ret = client->main(argc, argv); auto ret = client->main(argc, argv);
delete client; delete client;