From c77c9a162a57ca140b922859b06cba6bcba3fb22 Mon Sep 17 00:00:00 2001 From: Egor Tensin Date: Mon, 15 May 2023 18:52:56 +0200 Subject: signal: refactoring, add comments in tcp_server, etc. --- src/server.c | 2 +- src/signal.c | 38 ++++++++++++++++++++++---------------- src/signal.h | 8 ++++---- src/tcp_server.c | 14 ++++++++++---- src/worker.c | 2 +- 5 files changed, 38 insertions(+), 26 deletions(-) (limited to 'src') diff --git a/src/server.c b/src/server.c index 67f9e17..3df1f7d 100644 --- a/src/server.c +++ b/src/server.c @@ -213,7 +213,7 @@ int server_create(struct server **_server, const struct settings *settings) struct storage_settings storage_settings; int ret = 0; - ret = signal_install_global_handler(); + ret = signal_handle_stop_signals(); if (ret < 0) return ret; diff --git a/src/signal.c b/src/signal.c index ecf45ca..0676e60 100644 --- a/src/signal.c +++ b/src/signal.c @@ -10,8 +10,11 @@ #include "log.h" #include +#include #include +static int stop_signals[] = {SIGINT, SIGTERM, SIGQUIT}; + volatile sig_atomic_t global_stop_flag = 0; static void set_global_stop_flag(UNUSED int signum) @@ -32,7 +35,7 @@ static int my_sigaction(int signo, const struct sigaction *act) return ret; } -int signal_install_global_handler(void) +int signal_handle_stop_signals(void) { int ret = 0; @@ -42,20 +45,17 @@ int signal_install_global_handler(void) /* Don't care about proper cleanup here; we exit the program if this * fails anyway. */ - ret = my_sigaction(SIGINT, &sa); - if (ret < 0) - return ret; - ret = my_sigaction(SIGQUIT, &sa); - if (ret < 0) - return ret; - ret = my_sigaction(SIGTERM, &sa); - if (ret < 0) - return ret; + + for (size_t i = 0; i < sizeof(stop_signals) / sizeof(stop_signals[0]); ++i) { + ret = my_sigaction(stop_signals[i], &sa); + if (ret < 0) + return ret; + } return ret; } -int signal_set(const sigset_t *new, sigset_t *old) +static int signal_set(const sigset_t *new, sigset_t *old) { int ret = 0; @@ -68,19 +68,25 @@ int signal_set(const sigset_t *new, sigset_t *old) return ret; } -int signal_block_parent(sigset_t *old) +int signal_block_all(sigset_t *old) { sigset_t new; sigfillset(&new); return signal_set(&new, old); } -int signal_block_child(void) +int signal_restore(const sigset_t *new) +{ + return signal_set(new, NULL); +} + +int signal_unblock_all_except_stop_signals(void) { sigset_t set; sigemptyset(&set); - sigaddset(&set, SIGINT); - sigaddset(&set, SIGQUIT); - sigaddset(&set, SIGTERM); + + for (size_t i = 0; i < sizeof(stop_signals) / sizeof(stop_signals[0]); ++i) + sigaddset(&set, stop_signals[i]); + return signal_set(&set, NULL); } diff --git a/src/signal.h b/src/signal.h index 88c9734..713c842 100644 --- a/src/signal.h +++ b/src/signal.h @@ -11,11 +11,11 @@ #include extern volatile sig_atomic_t global_stop_flag; -int signal_install_global_handler(void); +int signal_handle_stop_signals(void); -int signal_set(const sigset_t *new, sigset_t *old); +int signal_block_all(sigset_t *old); +int signal_restore(const sigset_t *new); -int signal_block_parent(sigset_t *old); -int signal_block_child(void); +int signal_unblock_all_except_stop_signals(void); #endif diff --git a/src/tcp_server.c b/src/tcp_server.c index d840414..dbf1146 100644 --- a/src/tcp_server.c +++ b/src/tcp_server.c @@ -60,7 +60,9 @@ static void *connection_thread(void *_ctx) struct child_context *ctx = (struct child_context *)_ctx; int ret = 0; - ret = signal_block_child(); + /* Let the child thread handle its signals except those that should be + * handled in the main thread. */ + ret = signal_unblock_all_except_stop_signals(); if (ret < 0) goto free_ctx; @@ -92,7 +94,10 @@ int tcp_server_accept(const struct tcp_server *server, tcp_server_conn_handler h goto free_ctx; ctx->fd = ret; - ret = signal_block_parent(&old_mask); + /* Block all signals (we'll unblock them later); the child thread will + * have all signals blocked initially. This allows the main thread to + * handle SIGINT/SIGTERM/etc. */ + ret = signal_block_all(&old_mask); if (ret < 0) goto close_conn; @@ -102,12 +107,13 @@ int tcp_server_accept(const struct tcp_server *server, tcp_server_conn_handler h goto restore_mask; } - signal_set(&old_mask, NULL); + /* Restore the previously-enabled signals for handling in the main thread. */ + signal_restore(&old_mask); return ret; restore_mask: - signal_set(&old_mask, NULL); + signal_restore(&old_mask); close_conn: log_errno_if(close(ctx->fd), "close"); diff --git a/src/worker.c b/src/worker.c index a316d7f..d085000 100644 --- a/src/worker.c +++ b/src/worker.c @@ -27,7 +27,7 @@ int worker_create(struct worker **_worker) { int ret = 0; - ret = signal_install_global_handler(); + ret = signal_handle_stop_signals(); if (ret < 0) return ret; -- cgit v1.2.3