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Code Releases Activity

signal: workaround sigint handler flaw

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This commit is contained in:
Heinz Mauelshagen 2017-04-07 17:07:45 +02:00
parent ef3e1013aa
commit 53b62d950a
1 changed files with 21 additions and 12 deletions
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33
lib/misc/lvm-signal.c
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@ -22,7 +22,7 @@
static sigset_t _oldset; static sigset_t _oldset;
static int _signals_blocked = 0; static int _signals_blocked = 0;
static volatile sig_atomic_t _sigint_caught = 0; static volatile sig_atomic_t _sigint_caught = 0;
static volatile sig_atomic_t _handler_installed; static volatile sig_atomic_t _handler_installed = 0;
/* Support 3 level nesting, increase if needed more */ /* Support 3 level nesting, increase if needed more */
#define MAX_SIGINTS 3 #define MAX_SIGINTS 3
@ -34,7 +34,26 @@ static void _catch_sigint(int unused __attribute__((unused)))
_sigint_caught = 1; _sigint_caught = 1;
} }
static void _register_sigint_caught(struct sigaction *old_handler)
{
struct sigaction handler;
/* Grab old sigaction for SIGINT: shall not fail. */
if (sigaction(SIGINT, NULL, &handler))
log_sys_debug("sigaction", "SIGINT");
handler.sa_flags &= ~SA_RESTART; /* Clear restart flag */
handler.sa_handler = _catch_sigint;
/* Override the signal handler: shall not fail. */
if (sigaction(SIGINT, &handler, old_handler))
log_sys_debug("sigaction", "SIGINT");
}
int sigint_caught(void) { int sigint_caught(void) {
printf("%s[%u] CALLED\n", __func__, __LINE__);
_register_sigint_caught(NULL);
if (_sigint_caught) if (_sigint_caught)
log_error("Interrupted..."); log_error("Interrupted...");
@ -58,7 +77,6 @@ void sigint_clear(void)
void sigint_allow(void) void sigint_allow(void)
{ {
struct sigaction handler;
sigset_t sigs; sigset_t sigs;
if (memlock_count_daemon()) if (memlock_count_daemon())
@ -70,16 +88,7 @@ void sigint_allow(void)
if (++_handler_installed >= MAX_SIGINTS) if (++_handler_installed >= MAX_SIGINTS)
return; return;
/* Grab old sigaction for SIGINT: shall not fail. */ _register_sigint_caught(&_oldhandler[_handler_installed - 1]);
if (sigaction(SIGINT, NULL, &handler))
log_sys_debug("sigaction", "SIGINT");
handler.sa_flags &= ~SA_RESTART; /* Clear restart flag */
handler.sa_handler = _catch_sigint;
/* Override the signal handler: shall not fail. */
if (sigaction(SIGINT, &handler, &_oldhandler[_handler_installed - 1]))
log_sys_debug("sigaction", "SIGINT");
/* Unmask SIGINT. Remember to mask it again on restore. */ /* Unmask SIGINT. Remember to mask it again on restore. */
if (sigprocmask(0, NULL, &sigs)) if (sigprocmask(0, NULL, &sigs))