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signal-util: add common implementation for propagating a signal

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i.e. let's add a common logic to be called from a signal handler to
raise the passed signal again.

Follow-up for: #25399
This commit is contained in:
Lennart Poettering
2022-11-16 18:54:29 +01:00
committed by Yu Watanabe
parent 58dad4d5e5
commit 128a11ea99
4 changed files with 26 additions and 10 deletions
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4
src/basic/sigbus.c
View File

@@ -10,6 +10,7 @@
#include "missing_syscall.h"
#include "process-util.h"
#include "sigbus.h"
#include "signal-util.h"
#define SIGBUS_QUEUE_MAX 64
@@ -102,8 +103,7 @@ static void sigbus_handler(int sn, siginfo_t *si, void *data) {
if (si->si_code != BUS_ADRERR || !si->si_addr) {
assert_se(sigaction(SIGBUS, &old_sigaction, NULL) == 0);
if (rt_tgsigqueueinfo(getpid_cached(), gettid(), SIGBUS, si) < 0)
(void) raise(SIGBUS);
propagate_signal(sn, si);
return;
}

18
src/basic/signal-util.c
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@@ -5,6 +5,7 @@
#include "errno-util.h"
#include "macro.h"
#include "missing_syscall.h"
#include "parse-util.h"
#include "signal-util.h"
#include "stdio-util.h"
@@ -282,3 +283,20 @@ int pop_pending_signal_internal(int sig, ...) {
return r; /* Returns the signal popped */
}
void propagate_signal(int sig, siginfo_t *siginfo) {
pid_t p;
/* To be called from a signal handler. Will raise the same signal again, in our process + in our threads.
*
* Note that we use raw_getpid() instead of getpid_cached(). We might have forked with raw_clone()
* earlier (see PID 1), and hence let's go to the raw syscall here. In particular as this is not
* performance sensitive code.
*
* Note that we use kill() rather than raise() as fallback, for similar reasons. */
p = raw_getpid();
if (rt_tgsigqueueinfo(p, gettid(), sig, siginfo) < 0)
assert_se(kill(p, sig) >= 0);
}

2
src/basic/signal-util.h
View File

@@ -65,3 +65,5 @@ int signal_is_blocked(int sig);
int pop_pending_signal_internal(int sig, ...);
#define pop_pending_signal(...) pop_pending_signal_internal(__VA_ARGS__, -1)
void propagate_signal(int sig, siginfo_t *siginfo);

12
src/core/crash-handler.c
View File

@@ -47,11 +47,10 @@ _noreturn_ static void crash(int sig, siginfo_t *siginfo, void *context) {
* memory allocation is not async-signal-safe anyway — see signal-safety(7) for details —, and thus
* is not permissible in signal handlers.) */
if (getpid_cached() != 1) {
if (getpid_cached() != 1)
/* Pass this on immediately, if this is not PID 1 */
if (rt_tgsigqueueinfo(getpid_cached(), gettid(), sig, siginfo) < 0)
(void) raise(sig);
} else if (!arg_dump_core)
propagate_signal(sig, siginfo);
else if (!arg_dump_core)
log_emergency("Caught <%s>, not dumping core.", signal_to_string(sig));
else {
sa = (struct sigaction) {
@@ -80,10 +79,7 @@ _noreturn_ static void crash(int sig, siginfo_t *siginfo, void *context) {
(void) chdir("/");
/* Raise the signal again */
pid = raw_getpid();
if (rt_tgsigqueueinfo(pid, gettid(), sig, siginfo) < 0)
(void) kill(pid, sig); /* raise() would kill the parent */
propagate_signal(sig, siginfo);
assert_not_reached();
_exit(EXIT_EXCEPTION);
} else {