From 7fdf56b0a796f9e6f625c8fa236ece72b91b2270 Mon Sep 17 00:00:00 2001 From: Michael Paquier Date: Mon, 25 Jun 2018 11:20:50 +0900 Subject: [PATCH] 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/access/heap/rewriteheap.c | 5 ++++ src/backend/access/transam/twophase.c | 23 +++++++++++++++++++ src/backend/access/transam/xlog.c | 7 ++++++ src/backend/access/transam/xlogutils.c | 4 ++++ src/backend/replication/basebackup.c | 3 +++ src/backend/replication/logical/origin.c | 15 ++++++++++++ .../replication/logical/reorderbuffer.c | 4 +++- src/backend/replication/logical/snapbuild.c | 20 ++++++++++++++++ src/backend/replication/slot.c | 7 +++++- src/bin/pg_basebackup/receivelog.c | 13 ++++++++++- 10 files changed, 98 insertions(+), 3 deletions(-) diff --git a/src/backend/access/heap/rewriteheap.c b/src/backend/access/heap/rewriteheap.c index 170e77dd84..e628c9bd89 100644 --- a/src/backend/access/heap/rewriteheap.c +++ b/src/backend/access/heap/rewriteheap.c @@ -1163,9 +1163,14 @@ heap_xlog_logical_rewrite(XLogReaderState *r) /* write out tail end of mapping file (again) */ if (write(fd, data, len) != len) + { + /* if write didn't set errno, assume problem is no disk space */ + if (errno == 0) + errno = ENOSPC; ereport(ERROR, (errcode_for_file_access(), errmsg("could not write to file \"%s\": %m", path))); + } /* * Now fsync all previously written data. We could improve things and only diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c index cdd0091a5f..c7cde25f83 100644 --- a/src/backend/access/transam/twophase.c +++ b/src/backend/access/transam/twophase.c @@ -1171,12 +1171,17 @@ ReadTwoPhaseFile(TransactionId xid, bool give_warnings) */ if (fstat(fd, &stat)) { + int save_errno = errno; + CloseTransientFile(fd); if (give_warnings) + { + errno = save_errno; ereport(WARNING, (errcode_for_file_access(), errmsg("could not stat two-phase state file \"%s\": %m", path))); + } return NULL; } @@ -1203,12 +1208,17 @@ ReadTwoPhaseFile(TransactionId xid, bool give_warnings) if (read(fd, buf, stat.st_size) != stat.st_size) { + int save_errno = errno; + CloseTransientFile(fd); if (give_warnings) + { + errno = save_errno; ereport(WARNING, (errcode_for_file_access(), errmsg("could not read two-phase state file \"%s\": %m", path))); + } pfree(buf); return NULL; } @@ -1550,14 +1560,24 @@ RecreateTwoPhaseFile(TransactionId xid, void *content, int len) /* Write content and CRC */ if (write(fd, content, len) != len) { + 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 two-phase state file: %m"))); } if (write(fd, &statefile_crc, sizeof(pg_crc32c)) != sizeof(pg_crc32c)) { + 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 two-phase state file: %m"))); @@ -1569,7 +1589,10 @@ RecreateTwoPhaseFile(TransactionId xid, void *content, int len) */ if (pg_fsync(fd) != 0) { + int save_errno = errno; + CloseTransientFile(fd); + errno = save_errno; ereport(ERROR, (errcode_for_file_access(), errmsg("could not fsync two-phase state file: %m"))); diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 98abc4961f..248ea9a976 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -3087,7 +3087,10 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent, bool use_lock) if (pg_fsync(fd) != 0) { + int save_errno = errno; + close(fd); + errno = save_errno; ereport(ERROR, (errcode_for_file_access(), errmsg("could not fsync file \"%s\": %m", tmppath))); @@ -11255,8 +11258,10 @@ retry: if (lseek(readFile, (off_t) readOff, SEEK_SET) < 0) { char fname[MAXFNAMELEN]; + int save_errno = errno; XLogFileName(fname, curFileTLI, readSegNo); + errno = save_errno; ereport(emode_for_corrupt_record(emode, targetPagePtr + reqLen), (errcode_for_file_access(), errmsg("could not seek in log segment %s to offset %u: %m", @@ -11267,8 +11272,10 @@ retry: if (read(readFile, readBuf, XLOG_BLCKSZ) != XLOG_BLCKSZ) { char fname[MAXFNAMELEN]; + int save_errno = errno; XLogFileName(fname, curFileTLI, readSegNo); + errno = save_errno; ereport(emode_for_corrupt_record(emode, targetPagePtr + reqLen), (errcode_for_file_access(), errmsg("could not read from log segment %s, offset %u: %m", diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c index 51a8e8ddb2..a82ccd4569 100644 --- a/src/backend/access/transam/xlogutils.c +++ b/src/backend/access/transam/xlogutils.c @@ -710,9 +710,11 @@ XLogRead(char *buf, TimeLineID tli, XLogRecPtr startptr, Size count) if (lseek(sendFile, (off_t) startoff, SEEK_SET) < 0) { char path[MAXPGPATH]; + int save_errno = errno; XLogFilePath(path, tli, sendSegNo); + errno = save_errno; ereport(ERROR, (errcode_for_file_access(), errmsg("could not seek in log segment %s to offset %u: %m", @@ -731,9 +733,11 @@ XLogRead(char *buf, TimeLineID tli, XLogRecPtr startptr, Size count) if (readbytes <= 0) { char path[MAXPGPATH]; + int save_errno = errno; XLogFilePath(path, tli, sendSegNo); + errno = save_errno; ereport(ERROR, (errcode_for_file_access(), errmsg("could not read from log segment %s, offset %u, length %lu: %m", diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c index 53be5d55e4..73a56cbf16 100644 --- a/src/backend/replication/basebackup.c +++ b/src/backend/replication/basebackup.c @@ -392,6 +392,8 @@ perform_base_backup(basebackup_options *opt, DIR *tblspcdir) fp = AllocateFile(pathbuf, "rb"); if (fp == NULL) { + int save_errno = errno; + /* * Most likely reason for this is that the file was already * removed by a checkpoint, so check for that to get a better @@ -399,6 +401,7 @@ perform_base_backup(basebackup_options *opt, DIR *tblspcdir) */ CheckXLogRemoved(segno, tli); + errno = save_errno; ereport(ERROR, (errcode_for_file_access(), errmsg("could not open file \"%s\": %m", pathbuf))); diff --git a/src/backend/replication/logical/origin.c b/src/backend/replication/logical/origin.c index 4bd754df94..c281734fd5 100644 --- a/src/backend/replication/logical/origin.c +++ b/src/backend/replication/logical/origin.c @@ -549,7 +549,12 @@ CheckPointReplicationOrigin(void) /* write magic */ if ((write(tmpfd, &magic, sizeof(magic))) != sizeof(magic)) { + int save_errno = errno; + CloseTransientFile(tmpfd); + + /* if write didn't set errno, assume problem is no disk space */ + errno = save_errno ? save_errno : ENOSPC; ereport(PANIC, (errcode_for_file_access(), errmsg("could not write to file \"%s\": %m", @@ -588,7 +593,12 @@ CheckPointReplicationOrigin(void) if ((write(tmpfd, &disk_state, sizeof(disk_state))) != sizeof(disk_state)) { + int save_errno = errno; + CloseTransientFile(tmpfd); + + /* if write didn't set errno, assume problem is no disk space */ + errno = save_errno ? save_errno : ENOSPC; ereport(PANIC, (errcode_for_file_access(), errmsg("could not write to file \"%s\": %m", @@ -604,7 +614,12 @@ CheckPointReplicationOrigin(void) FIN_CRC32C(crc); if ((write(tmpfd, &crc, sizeof(crc))) != sizeof(crc)) { + int save_errno = errno; + CloseTransientFile(tmpfd); + + /* if write didn't set errno, assume problem is no disk space */ + errno = save_errno ? save_errno : ENOSPC; ereport(PANIC, (errcode_for_file_access(), errmsg("could not write to file \"%s\": %m", diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c index 93f373c9ef..6ed5fc405b 100644 --- a/src/backend/replication/logical/reorderbuffer.c +++ b/src/backend/replication/logical/reorderbuffer.c @@ -2352,7 +2352,9 @@ ReorderBufferSerializeChange(ReorderBuffer *rb, ReorderBufferTXN *txn, int save_errno = errno; CloseTransientFile(fd); - errno = save_errno; + + /* 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 data file for XID %u: %m", diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 901e95ede4..a266876598 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", diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c index ca0b8c65c6..59b0d84622 100644 --- a/src/backend/replication/slot.c +++ b/src/backend/replication/slot.c @@ -1085,7 +1085,9 @@ SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel) int save_errno = errno; CloseTransientFile(fd); - errno = save_errno; + + /* if write didn't set errno, assume problem is no disk space */ + errno = save_errno ? save_errno : ENOSPC; ereport(elevel, (errcode_for_file_access(), errmsg("could not write to file \"%s\": %m", @@ -1184,7 +1186,10 @@ RestoreSlotFromDisk(const char *name) */ if (pg_fsync(fd) != 0) { + int save_errno = errno; + CloseTransientFile(fd); + errno = save_errno; ereport(PANIC, (errcode_for_file_access(), errmsg("could not fsync file \"%s\": %m", diff --git a/src/bin/pg_basebackup/receivelog.c b/src/bin/pg_basebackup/receivelog.c index 3a921ebf2d..c9fb4198b0 100644 --- a/src/bin/pg_basebackup/receivelog.c +++ b/src/bin/pg_basebackup/receivelog.c @@ -149,6 +149,9 @@ open_walfile(StreamCtl *stream, XLogRecPtr startpoint) { if (write(f, zerobuf, XLOG_BLCKSZ) != XLOG_BLCKSZ) { + /* if write didn't set errno, assume problem is no disk space */ + if (errno == 0) + errno = ENOSPC; fprintf(stderr, _("%s: could not pad transaction log file \"%s\": %s\n"), progname, fn, strerror(errno)); @@ -334,7 +337,9 @@ writeTimeLineHistoryFile(StreamCtl *stream, char *filename, char *content) */ close(fd); unlink(tmppath); - errno = save_errno; + + /* if write didn't set errno, assume problem is no disk space */ + errno = save_errno ? save_errno : ENOSPC; fprintf(stderr, _("%s: could not write timeline history file \"%s\": %s\n"), progname, tmppath, strerror(errno)); @@ -343,7 +348,10 @@ writeTimeLineHistoryFile(StreamCtl *stream, char *filename, char *content) if (fsync(fd) != 0) { + int save_errno = errno; + close(fd); + errno = save_errno; fprintf(stderr, _("%s: could not fsync file \"%s\": %s\n"), progname, tmppath, strerror(errno)); return false; @@ -1185,6 +1193,9 @@ ProcessXLogDataMsg(PGconn *conn, StreamCtl *stream, char *copybuf, int len, copybuf + hdr_len + bytes_written, bytes_to_write) != bytes_to_write) { + /* if write didn't set errno, assume problem is no disk space */ + if (errno == 0) + errno = ENOSPC; fprintf(stderr, _("%s: could not write %u bytes to WAL file \"%s\": %s\n"), progname, bytes_to_write, current_walfile_name,