Use consistent style for checking return from system calls

Use

    if (something() != 0)
        error ...

instead of just

    if (something)
        error ...

The latter is not incorrect, but it's a bit confusing and not the
common style.

Discussion: https://www.postgresql.org/message-id/flat/5de61b6b-8be9-7771-0048-860328efe027%402ndquadrant.com

contrib/pg_stat_statements/pg_stat_statements.c

@@ -1992,7 +1992,7 @@ qtext_load_file(Size *buffer_size)
 		return NULL;
 	}
 
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 		ereport(LOG,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m", PGSS_TEXT_FILE)));

src/backend/access/heap/rewriteheap.c

@@ -1202,7 +1202,7 @@ heap_xlog_logical_rewrite(XLogReaderState *r)
 				 errmsg("could not fsync file \"%s\": %m", path)));
 	pgstat_report_wait_end();
 
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m", path)));
@@ -1304,7 +1304,7 @@ CheckPointLogicalRewriteHeap(void)
 						 errmsg("could not fsync file \"%s\": %m", path)));
 			pgstat_report_wait_end();
 
-			if (CloseTransientFile(fd))
+			if (CloseTransientFile(fd) != 0)
 				ereport(ERROR,
 						(errcode_for_file_access(),
 						 errmsg("could not close file \"%s\": %m", path)));

src/backend/access/transam/slru.c

@@ -621,7 +621,7 @@ SimpleLruDoesPhysicalPageExist(SlruCtl ctl, int pageno)
 
 	result = endpos >= (off_t) (offset + BLCKSZ);
 
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 	{
 		slru_errcause = SLRU_CLOSE_FAILED;
 		slru_errno = errno;
@@ -697,7 +697,7 @@ SlruPhysicalReadPage(SlruCtl ctl, int pageno, int slotno)
 	}
 	pgstat_report_wait_end();
 
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 	{
 		slru_errcause = SLRU_CLOSE_FAILED;
 		slru_errno = errno;
@@ -869,7 +869,7 @@ SlruPhysicalWritePage(SlruCtl ctl, int pageno, int slotno, SlruFlush fdata)
 	if (!fdata)
 	{
 		pgstat_report_wait_start(WAIT_EVENT_SLRU_SYNC);
-		if (ctl->do_fsync && pg_fsync(fd))
+		if (ctl->do_fsync && pg_fsync(fd) != 0)
 		{
 			pgstat_report_wait_end();
 			slru_errcause = SLRU_FSYNC_FAILED;
@@ -879,7 +879,7 @@ SlruPhysicalWritePage(SlruCtl ctl, int pageno, int slotno, SlruFlush fdata)
 		}
 		pgstat_report_wait_end();
 
-		if (CloseTransientFile(fd))
+		if (CloseTransientFile(fd) != 0)
 		{
 			slru_errcause = SLRU_CLOSE_FAILED;
 			slru_errno = errno;
@@ -1146,7 +1146,7 @@ SimpleLruFlush(SlruCtl ctl, bool allow_redirtied)
 	for (i = 0; i < fdata.num_files; i++)
 	{
 		pgstat_report_wait_start(WAIT_EVENT_SLRU_FLUSH_SYNC);
-		if (ctl->do_fsync && pg_fsync(fdata.fd[i]))
+		if (ctl->do_fsync && pg_fsync(fdata.fd[i]) != 0)
 		{
 			slru_errcause = SLRU_FSYNC_FAILED;
 			slru_errno = errno;
@@ -1155,7 +1155,7 @@ SimpleLruFlush(SlruCtl ctl, bool allow_redirtied)
 		}
 		pgstat_report_wait_end();
 
-		if (CloseTransientFile(fdata.fd[i]))
+		if (CloseTransientFile(fdata.fd[i]) != 0)
 		{
 			slru_errcause = SLRU_CLOSE_FAILED;
 			slru_errno = errno;

src/backend/access/transam/timeline.c

@@ -371,7 +371,7 @@ writeTimeLineHistory(TimeLineID newTLI, TimeLineID parentTLI,
 			pgstat_report_wait_end();
 		}
 
-		if (CloseTransientFile(srcfd))
+		if (CloseTransientFile(srcfd) != 0)
 			ereport(ERROR,
 					(errcode_for_file_access(),
 					 errmsg("could not close file \"%s\": %m", path)));
@@ -415,7 +415,7 @@ writeTimeLineHistory(TimeLineID newTLI, TimeLineID parentTLI,
 				 errmsg("could not fsync file \"%s\": %m", tmppath)));
 	pgstat_report_wait_end();
 
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m", tmppath)));
@@ -493,7 +493,7 @@ writeTimeLineHistoryFile(TimeLineID tli, char *content, int size)
 				 errmsg("could not fsync file \"%s\": %m", tmppath)));
 	pgstat_report_wait_end();
 
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m", tmppath)));

src/backend/access/transam/twophase.c

@@ -1299,7 +1299,7 @@ ReadTwoPhaseFile(TransactionId xid, bool missing_ok)
 
 	pgstat_report_wait_end();
 
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m", path)));

src/backend/access/transam/xlog.c

@@ -3321,7 +3321,7 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent, bool use_lock)
 	}
 	pgstat_report_wait_end();
 
-	if (close(fd))
+	if (close(fd) != 0)
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m", tmppath)));
@@ -3489,12 +3489,12 @@ XLogFileCopy(XLogSegNo destsegno, TimeLineID srcTLI, XLogSegNo srcsegno,
 				 errmsg("could not fsync file \"%s\": %m", tmppath)));
 	pgstat_report_wait_end();
 
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m", tmppath)));
 
-	if (CloseTransientFile(srcfd))
+	if (CloseTransientFile(srcfd) != 0)
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m", path)));
@@ -3791,7 +3791,7 @@ XLogFileClose(void)
 		(void) posix_fadvise(openLogFile, 0, 0, POSIX_FADV_DONTNEED);
 #endif
 
-	if (close(openLogFile))
+	if (close(openLogFile) != 0)
 		ereport(PANIC,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m",
@@ -4566,7 +4566,7 @@ WriteControlFile(void)
 						XLOG_CONTROL_FILE)));
 	pgstat_report_wait_end();
 
-	if (close(fd))
+	if (close(fd) != 0)
 		ereport(PANIC,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m",
@@ -5225,7 +5225,7 @@ BootStrapXLOG(void)
 				 errmsg("could not fsync bootstrap write-ahead log file: %m")));
 	pgstat_report_wait_end();
 
-	if (close(openLogFile))
+	if (close(openLogFile) != 0)
 		ereport(PANIC,
 				(errcode_for_file_access(),
 				 errmsg("could not close bootstrap write-ahead log file: %m")));
@@ -5527,7 +5527,7 @@ exitArchiveRecovery(TimeLineID endTLI, XLogRecPtr endOfLog)
 
 		fd = XLogFileInit(startLogSegNo, &use_existent, true);
 
-		if (close(fd))
+		if (close(fd) != 0)
 			ereport(ERROR,
 					(errcode_for_file_access(),
 					 errmsg("could not close file \"%s\": %m",

src/backend/libpq/be-fsstubs.c

@@ -456,7 +456,7 @@ lo_import_internal(text *filename, Oid lobjOid)
 
 	inv_close(lobj);
 
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m",
@@ -529,7 +529,7 @@ be_lo_export(PG_FUNCTION_ARGS)
 							fnamebuf)));
 	}
 
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m",

src/backend/postmaster/postmaster.c

@@ -2520,7 +2520,7 @@ ClosePostmasterPorts(bool am_syslogger)
 	 * do this as early as possible, so that if postmaster dies, others won't
 	 * think that it's still running because we're holding the pipe open.
 	 */
-	if (close(postmaster_alive_fds[POSTMASTER_FD_OWN]))
+	if (close(postmaster_alive_fds[POSTMASTER_FD_OWN]) != 0)
 		ereport(FATAL,
 				(errcode_for_file_access(),
 				 errmsg_internal("could not close postmaster death monitoring pipe in child process: %m")));

src/backend/replication/logical/origin.c

@@ -650,7 +650,7 @@ CheckPointReplicationOrigin(void)
 						tmppath)));
 	}
 
-	if (CloseTransientFile(tmpfd))
+	if (CloseTransientFile(tmpfd) != 0)
 		ereport(PANIC,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m",
@@ -789,7 +789,7 @@ StartupReplicationOrigin(void)
 				 errmsg("replication slot checkpoint has wrong checksum %u, expected %u",
 						crc, file_crc)));
 
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 		ereport(PANIC,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m",

src/backend/replication/logical/reorderbuffer.c

@@ -3360,7 +3360,7 @@ ApplyLogicalMappingFile(HTAB *tuplecid_data, Oid relid, const char *fname)
 		}
 	}
 
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m", path)));

src/backend/replication/logical/snapbuild.c

@@ -1652,7 +1652,7 @@ SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn)
 	}
 	pgstat_report_wait_end();
 
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m", tmppath)));
@@ -1850,7 +1850,7 @@ SnapBuildRestore(SnapBuild *builder, XLogRecPtr lsn)
 	}
 	COMP_CRC32C(checksum, ondisk.builder.committed.xip, sz);
 
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m", path)));

src/backend/replication/slot.c

@@ -1315,7 +1315,7 @@ SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel)
 	}
 	pgstat_report_wait_end();
 
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 	{
 		ereport(elevel,
 				(errcode_for_file_access(),
@@ -1472,7 +1472,7 @@ RestoreSlotFromDisk(const char *name)
 							path, readBytes, (Size) cp.length)));
 	}
 
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 		ereport(PANIC,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m", path)));

src/backend/replication/walsender.c

@@ -522,7 +522,7 @@ SendTimeLineHistory(TimeLineHistoryCmd *cmd)
 		bytesleft -= nread;
 	}
 
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m", path)));

src/backend/storage/file/copydir.c

@@ -212,12 +212,12 @@ copy_file(char *fromfile, char *tofile)
 	if (offset > flush_offset)
 		pg_flush_data(dstfd, flush_offset, offset - flush_offset);
 
-	if (CloseTransientFile(dstfd))
+	if (CloseTransientFile(dstfd) != 0)
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m", tofile)));
 
-	if (CloseTransientFile(srcfd))
+	if (CloseTransientFile(srcfd) != 0)
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m", fromfile)));

src/backend/storage/file/fd.c

@@ -647,7 +647,7 @@ durable_rename(const char *oldfile, const char *newfile, int elevel)
 			return -1;
 		}
 
-		if (CloseTransientFile(fd))
+		if (CloseTransientFile(fd) != 0)
 		{
 			ereport(elevel,
 					(errcode_for_file_access(),
@@ -1047,7 +1047,7 @@ LruDelete(File file)
 	 * Close the file.  We aren't expecting this to fail; if it does, better
 	 * to leak the FD than to mess up our internal state.
 	 */
-	if (close(vfdP->fd))
+	if (close(vfdP->fd) != 0)
 		elog(vfdP->fdstate & FD_TEMP_FILE_LIMIT ? LOG : data_sync_elevel(LOG),
 			 "could not close file \"%s\": %m", vfdP->fileName);
 	vfdP->fd = VFD_CLOSED;
@@ -1724,7 +1724,7 @@ FileClose(File file)
 	if (!FileIsNotOpen(file))
 	{
 		/* close the file */
-		if (close(vfdP->fd))
+		if (close(vfdP->fd) != 0)
 		{
 			/*
 			 * We may need to panic on failure to close non-temporary files;
@@ -3302,7 +3302,7 @@ pre_sync_fname(const char *fname, bool isdir, int elevel)
 	 */
 	pg_flush_data(fd, 0, 0);
 
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 		ereport(elevel,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m", fname)));
@@ -3404,7 +3404,7 @@ fsync_fname_ext(const char *fname, bool isdir, bool ignore_perm, int elevel)
 		return -1;
 	}
 
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 	{
 		ereport(elevel,
 				(errcode_for_file_access(),

src/backend/storage/ipc/dsm_impl.c

@@ -917,7 +917,7 @@ dsm_impl_mmap(dsm_op op, dsm_handle handle, Size request_size,
 	*mapped_address = address;
 	*mapped_size = request_size;
 
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 	{
 		ereport(elevel,
 				(errcode_for_file_access(),

src/backend/utils/cache/relmapper.c

@@ -747,7 +747,7 @@ load_relmap_file(bool shared)
 	}
 	pgstat_report_wait_end();
 
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 		ereport(FATAL,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m",
@@ -886,7 +886,7 @@ write_relmap_file(bool shared, RelMapFile *newmap,
 						mapfilename)));
 	pgstat_report_wait_end();
 
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m",

src/common/controldata_utils.c

@@ -106,13 +106,13 @@ get_controlfile(const char *DataDir, bool *crc_ok_p)
 	}
 
 #ifndef FRONTEND
-	if (CloseTransientFile(fd))
+	if (CloseTransientFile(fd) != 0)
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("could not close file \"%s\": %m",
 						ControlFilePath)));
 #else
-	if (close(fd))
+	if (close(fd) != 0)
 	{
 		pg_log_fatal("could not close file \"%s\": %m", ControlFilePath);
 		exit(EXIT_FAILURE);
@@ -248,7 +248,7 @@ update_controlfile(const char *DataDir,
 #endif
 	}
 
-	if (close(fd) < 0)
+	if (close(fd) != 0)
 	{
 #ifndef FRONTEND
 		ereport(PANIC,

src/interfaces/libpq/fe-lobj.c

@@ -853,7 +853,7 @@ lo_export(PGconn *conn, Oid lobjId, const char *filename)
 	}
 
 	/* if we already failed, don't overwrite that msg with a close error */
-	if (close(fd) && result >= 0)
+	if (close(fd) != 0 && result >= 0)
 	{
 		printfPQExpBuffer(&conn->errorMessage,
 						  libpq_gettext("could not write to file \"%s\": %s\n"),