From 7fdf56b0a796f9e6f625c8fa236ece72b91b2270 Mon Sep 17 00:00:00 2001 From: Michael Paquier Date: Mon, 25 Jun 2018 11:20:50 +0900 Subject: Address set of issues with errno handling System calls mixed up in error code paths are causing two issues which several code paths have not correctly handled: 1) For write() calls, sometimes the system may return less bytes than what has been written without errno being set. Some paths were careful enough to consider that case, and assumed that errno should be set to ENOSPC, other calls missed that. 2) errno generated by a system call is overwritten by other system calls which may succeed once an error code path is taken, causing what is reported to the user to be incorrect. This patch uses the brute-force approach of correcting all those code paths. Some refactoring could happen in the future, but this is let as future work, which is not targeted for back-branches anyway. Author: Michael Paquier Reviewed-by: Ashutosh Sharma Discussion: https://postgr.es/m/20180622061535.GD5215@paquier.xyz --- src/backend/replication/logical/snapbuild.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) (limited to 'src/backend/replication/logical/snapbuild.c') diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 901e95ede4f..a2668765984 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -1583,7 +1583,12 @@ SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn) if ((write(fd, ondisk, needed_length)) != needed_length) { + int save_errno = errno; + CloseTransientFile(fd); + + /* if write didn't set errno, assume problem is no disk space */ + errno = save_errno ? save_errno : ENOSPC; ereport(ERROR, (errcode_for_file_access(), errmsg("could not write to file \"%s\": %m", tmppath))); @@ -1599,7 +1604,10 @@ SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn) */ if (pg_fsync(fd) != 0) { + int save_errno = errno; + CloseTransientFile(fd); + errno = save_errno; ereport(ERROR, (errcode_for_file_access(), errmsg("could not fsync file \"%s\": %m", tmppath))); @@ -1681,7 +1689,10 @@ SnapBuildRestore(SnapBuild *builder, XLogRecPtr lsn) readBytes = read(fd, &ondisk, SnapBuildOnDiskConstantSize); if (readBytes != SnapBuildOnDiskConstantSize) { + int save_errno = errno; + CloseTransientFile(fd); + errno = save_errno; ereport(ERROR, (errcode_for_file_access(), errmsg("could not read file \"%s\", read %d of %d: %m", @@ -1707,7 +1718,10 @@ SnapBuildRestore(SnapBuild *builder, XLogRecPtr lsn) readBytes = read(fd, &ondisk.builder, sizeof(SnapBuild)); if (readBytes != sizeof(SnapBuild)) { + int save_errno = errno; + CloseTransientFile(fd); + errno = save_errno; ereport(ERROR, (errcode_for_file_access(), errmsg("could not read file \"%s\", read %d of %d: %m", @@ -1722,7 +1736,10 @@ SnapBuildRestore(SnapBuild *builder, XLogRecPtr lsn) readBytes = read(fd, ondisk.builder.was_running.was_xip, sz); if (readBytes != sz) { + int save_errno = errno; + CloseTransientFile(fd); + errno = save_errno; ereport(ERROR, (errcode_for_file_access(), errmsg("could not read file \"%s\", read %d of %d: %m", @@ -1736,7 +1753,10 @@ SnapBuildRestore(SnapBuild *builder, XLogRecPtr lsn) readBytes = read(fd, ondisk.builder.committed.xip, sz); if (readBytes != sz) { + int save_errno = errno; + CloseTransientFile(fd); + errno = save_errno; ereport(ERROR, (errcode_for_file_access(), errmsg("could not read file \"%s\", read %d of %d: %m", -- cgit v1.2.3