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Address set of issues with errno handling

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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
This commit is contained in:
Michael Paquier 2018-06-25 11:20:50 +09:00
parent 037768cf75
commit 7fdf56b0a7
10 changed files with 98 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
src/backend/access/heap/rewriteheap.c
View File

@ -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

23
src/backend/access/transam/twophase.c
View File

@ -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")));

7
src/backend/access/transam/xlog.c
View File

@ -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",

4
src/backend/access/transam/xlogutils.c
View File

@ -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",

3
src/backend/replication/basebackup.c
View File

@ -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)));

15
src/backend/replication/logical/origin.c
View File

@ -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",

4
src/backend/replication/logical/reorderbuffer.c
View File

@ -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",

20
src/backend/replication/logical/snapbuild.c
View File

@ -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",

7
src/backend/replication/slot.c
View File

@ -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",

13
src/bin/pg_basebackup/receivelog.c
View File

@ -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,