postgres.git / summary / log / commit / refs

commit    3b8d23a3e14f05890f1f306902cd4b992beeee71
Author:   Thomas Munro <tmunro@postgresql.org>
Date:     Fri Jul 15 22:59:52 2022 +0000
First released in: 16.0, 10.22, 11.17, 12.12, 13.8, 14.5, 15.0

    Make dsm_impl_posix_resize more future-proof.
    
    Commit 4518c798 blocks signals for a short region of code, but it
    assumed that whatever called it had the signal mask set to UnBlockSig on
    entry.  That may be true today (or may even not be, in extensions in the
    wild), but it would be better not to make that assumption.  We should
    save-and-restore the caller's signal mask.
    
    The PG_SETMASK() portability macro couldn't be used for that, which is
    why it wasn't done before.  But... considering that commit a65e0864
    established back in 9.6 that supported POSIX systems have sigprocmask(),
    and that this is POSIX-only code, there is no reason not to use standard
    sigprocmask() directly to achieve that.
    
    Back-patch to all supported releases, like 4518c798 and 80845b7c.
    
    Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
    Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
    Discussion: https://postgr.es/m/CA%2BhUKGKx6Biq7_UuV0kn9DW%2B8QWcpJC1qwhizdtD9tN-fn0H0g%40mail.gmail.com


 src/backend/storage/ipc/dsm_impl.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/backend/storage/ipc/dsm_impl.c b/src/backend/storage/ipc/dsm_impl.c
index 0247d13a913..69c6df75b48 100644
--- a/src/backend/storage/ipc/dsm_impl.c
+++ b/src/backend/storage/ipc/dsm_impl.c
@@ -49,6 +49,7 @@
 #include "postgres.h"
 
 #include <fcntl.h>
+#include <signal.h>
 #include <unistd.h>
 #ifndef WIN32
 #include <sys/mman.h>
@@ -62,7 +63,7 @@
 #endif
 
 #include "common/file_perm.h"
-#include "libpq/pqsignal.h"		/* for PG_SETMASK macro */
+#include "libpq/pqsignal.h"
 #include "miscadmin.h"
 #include "pgstat.h"
 #include "portability/mem.h"
@@ -355,6 +356,7 @@ dsm_impl_posix_resize(int fd, off_t size)
 {
 	int			rc;
 	int			save_errno;
+	sigset_t	save_sigmask;
 
 	/*
 	 * Block all blockable signals, except SIGQUIT.  posix_fallocate() can run
@@ -363,7 +365,7 @@ dsm_impl_posix_resize(int fd, off_t size)
 	 * conflicts), the retry loop might never succeed.
 	 */
 	if (IsUnderPostmaster)
-		PG_SETMASK(&BlockSig);
+		sigprocmask(SIG_SETMASK, &BlockSig, &save_sigmask);
 
 	pgstat_report_wait_start(WAIT_EVENT_DSM_ALLOCATE);
 #if defined(HAVE_POSIX_FALLOCATE) && defined(__linux__)
@@ -402,7 +404,7 @@ dsm_impl_posix_resize(int fd, off_t size)
 	if (IsUnderPostmaster)
 	{
 		save_errno = errno;
-		PG_SETMASK(&UnBlockSig);
+		sigprocmask(SIG_SETMASK, &save_sigmask, NULL);
 		errno = save_errno;
 	}
 


[parent: 3a0e385048ad]