postgres.git / summary / log / commit / refs
commit f53ed82b7feeb1eee7388a24aa792e1d1b33e650
Author: Michael Paquier <michael@paquier.xyz>
Date: Mon Jun 25 01:30:59 2018 +0000
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/transam/twophase.c | 23 +++++++++++++++++++++++
src/backend/access/transam/xlog.c | 7 +++++++
src/backend/replication/basebackup.c | 3 +++
src/bin/pg_basebackup/receivelog.c | 16 +++++++++++++++-
4 files changed, 48 insertions(+), 1 deletion(-)
diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c
index 4e0756059e8..94fd721517b 100644
--- a/src/backend/access/transam/twophase.c
+++ b/src/backend/access/transam/twophase.c
@@ -1237,12 +1237,17 @@ 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;
}
@@ -1269,12 +1274,17 @@ 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;
}
@@ -1562,14 +1572,24 @@ 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_crc32)) != sizeof(pg_crc32))
{
+ 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")));
@@ -1581,7 +1601,10 @@ 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 618d4273772..f788d70e5a3 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -2364,7 +2364,10 @@ 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)));
@@ -9777,8 +9780,10 @@ 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",
@@ -9789,8 +9794,10 @@ 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/replication/basebackup.c b/src/backend/replication/basebackup.c
index 587d7d61c2a..53a5bf6d41c 100644
--- a/src/backend/replication/basebackup.c
+++ b/src/backend/replication/basebackup.c
@@ -379,6 +379,8 @@ 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
@@ -386,6 +388,7 @@ 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/bin/pg_basebackup/receivelog.c b/src/bin/pg_basebackup/receivelog.c
index 49ae0a598ce..3e12d63530e 100644
--- a/src/bin/pg_basebackup/receivelog.c
+++ b/src/bin/pg_basebackup/receivelog.c
@@ -140,6 +140,9 @@ open_walfile(XLogRecPtr startpoint, uint32 timeline, char *basedir,
{
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));
@@ -382,7 +385,9 @@ writeTimeLineHistoryFile(char *basedir, TimeLineID tli, char *filename,
*/
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));
@@ -391,7 +396,10 @@ writeTimeLineHistoryFile(char *basedir, TimeLineID tli, char *filename,
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;
@@ -1125,6 +1133,12 @@ HandleCopyStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline,
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,
[parent: 0a140ab32f49]