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Replace signal handler with signal handling thread

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This commit is contained in:
excellentname 2020-07-25 21:02:59 +10:00
parent 246f7bf555
commit c3359dec1b
2 changed files with 72 additions and 20 deletions
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22
include/util/command.hpp
View File

@ -7,7 +7,7 @@
#include <array>
extern sig_atomic_t is_inserting_pid;
extern std::mutex reap_mtx;
extern std::list<pid_t> reap;
namespace waybar::util::command {
@ -71,6 +71,12 @@ inline FILE* open(const std::string& cmd, int& 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]);
dup2(fd[1], 1);
setpgid(child_pid, child_pid);
@ -103,7 +109,7 @@ inline struct res execNoRead(const std::string& cmd) {
inline int32_t forkExec(const std::string& cmd) {
if (cmd == "") return -1;
int32_t pid = fork();
pid_t pid = fork();
if (pid < 0) {
spdlog::error("Unable to exec cmd {}, error {}", cmd.c_str(), strerror(errno));
@ -112,14 +118,20 @@ inline int32_t forkExec(const std::string& cmd) {
// Child executes the command
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);
signal(SIGCHLD, SIG_DFL);
execl("/bin/sh", "sh", "-c", cmd.c_str(), (char*)0);
exit(0);
} else {
is_inserting_pid = true;
reap_mtx.lock();
reap.push_back(pid);
is_inserting_pid = false;
reap_mtx.unlock();
spdlog::debug("Added child to reap list: {}", pid);
}
return pid;

70
src/main.cpp
View File

@ -1,30 +1,70 @@
#include <csignal>
#include <list>
#include <mutex>
#include <sys/types.h>
#include <sys/wait.h>
#include <spdlog/spdlog.h>
#include "client.hpp"
sig_atomic_t is_inserting_pid = false;
std::mutex reap_mtx;
std::list<pid_t> reap;
static void handler(int sig) {
int saved_errno = errno;
if (!is_inserting_pid) {
for (auto it = reap.begin(); it != reap.end(); ++it) {
if (waitpid(*it, nullptr, WNOHANG) == *it) {
it = reap.erase(it);
}
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;
}
}
errno = saved_errno;
}
inline void installSigChldHandler(void) {
struct sigaction sa;
sigemptyset(&sa.sa_mask);
sa.sa_handler = handler;
sigaction(SIGCHLD, &sa, nullptr);
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[]) {
@ -43,7 +83,7 @@ int main(int argc, char* argv[]) {
}
});
}
installSigChldHandler();
startSignalThread();
auto ret = client->main(argc, argv);
delete client;