From 1661c40b9deb22408864e487c9f0579f54182399 Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Sat, 16 Jul 2022 10:59:52 +1200 Subject: [PATCH] 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 Reviewed-by: Tom Lane 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 c7e15c09a7..a5dbd662b2 100644 --- a/src/backend/storage/ipc/dsm_impl.c +++ b/src/backend/storage/ipc/dsm_impl.c @@ -50,6 +50,7 @@ #include "miscadmin.h" #include +#include #include #ifndef WIN32 #include @@ -63,7 +64,7 @@ #endif #include "common/file_perm.h" -#include "libpq/pqsignal.h" /* for PG_SETMASK macro */ +#include "libpq/pqsignal.h" #include "pgstat.h" #include "portability/mem.h" #include "storage/dsm_impl.h" @@ -345,6 +346,7 @@ 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 @@ -353,7 +355,7 @@ 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); /* Truncate (or extend) the file to the requested size. */ do @@ -394,7 +396,7 @@ 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; }