Fix buffile.c error handling.

Convert buffile.c error handling to use ereport.  This fixes cases where
I/O errors were indistinguishable from EOF or not reported.  Also remove
"%m" from error messages where errno would be bogus.  While we're
modifying those strings, add block numbers and short read byte counts
where appropriate.

Back-patch to all supported releases.

Reported-by: Amit Khandekar <amitdkhan.pg@gmail.com>
Reviewed-by: Melanie Plageman <melanieplageman@gmail.com>
Reviewed-by: Alvaro Herrera <alvherre@2ndquadrant.com>
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Reviewed-by: Ibrar Ahmed <ibrar.ahmad@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/CA%2BhUKGJE04G%3D8TLK0DLypT_27D9dR8F1RQgNp0jK6qR0tZGWOw%40mail.gmail.com

Author: macdice

src/backend/access/gist/gistbuildbuffers.c

@@ -757,26 +757,20 @@ gistRelocateBuildBuffersOnSplit(GISTBuildBuffers *gfbb, GISTSTATE *giststate,
 static void
 ReadTempFileBlock(BufFile *file, long blknum, void *ptr)
 {
+	size_t		nread;
+
 	if (BufFileSeekBlock(file, blknum) != 0)
-		elog(ERROR, "could not seek temporary file: %m");
-	if (BufFileRead(file, ptr, BLCKSZ) != BLCKSZ)
-		elog(ERROR, "could not read temporary file: %m");
+		elog(ERROR, "could not seek to block %ld in temporary file", blknum);
+	nread = BufFileRead(file, ptr, BLCKSZ);
+	if (nread != BLCKSZ)
+		elog(ERROR, "could not read temporary file: read only %zu of %zu bytes",
+			 nread, (size_t) BLCKSZ);
 }
 
 static void
 WriteTempFileBlock(BufFile *file, long blknum, void *ptr)
 {
 	if (BufFileSeekBlock(file, blknum) != 0)
-		elog(ERROR, "could not seek temporary file: %m");
-	if (BufFileWrite(file, ptr, BLCKSZ) != BLCKSZ)
-	{
-		/*
-		 * the other errors in Read/WriteTempFileBlock shouldn't happen, but
-		 * an error at write can easily happen if you run out of disk space.
-		 */
-		ereport(ERROR,
-				(errcode_for_file_access(),
-				 errmsg("could not write block %ld of temporary file: %m",
-						blknum)));
-	}
+		elog(ERROR, "could not seek to block %ld in temporary file", blknum);
+	BufFileWrite(file, ptr, BLCKSZ);
 }

src/backend/executor/nodeHashjoin.c

@@ -1043,7 +1043,7 @@ ExecHashJoinNewBatch(HashJoinState *hjstate)
 		if (BufFileSeek(innerFile, 0, 0L, SEEK_SET))
 			ereport(ERROR,
 					(errcode_for_file_access(),
-					 errmsg("could not rewind hash-join temporary file: %m")));
+					 errmsg("could not rewind hash-join temporary file")));
 
 		while ((slot = ExecHashJoinGetSavedTuple(hjstate,
 												 innerFile,
@@ -1073,7 +1073,7 @@ ExecHashJoinNewBatch(HashJoinState *hjstate)
 		if (BufFileSeek(hashtable->outerBatchFile[curbatch], 0, 0L, SEEK_SET))
 			ereport(ERROR,
 					(errcode_for_file_access(),
-					 errmsg("could not rewind hash-join temporary file: %m")));
+					 errmsg("could not rewind hash-join temporary file")));
 	}
 
 	return true;
@@ -1219,7 +1219,6 @@ ExecHashJoinSaveTuple(MinimalTuple tuple, uint32 hashvalue,
 					  BufFile **fileptr)
 {
 	BufFile    *file = *fileptr;
-	size_t		written;
 
 	if (file == NULL)
 	{
@@ -1228,17 +1227,8 @@ ExecHashJoinSaveTuple(MinimalTuple tuple, uint32 hashvalue,
 		*fileptr = file;
 	}
 
-	written = BufFileWrite(file, (void *) &hashvalue, sizeof(uint32));
-	if (written != sizeof(uint32))
-		ereport(ERROR,
-				(errcode_for_file_access(),
-				 errmsg("could not write to hash-join temporary file: %m")));
-
-	written = BufFileWrite(file, (void *) tuple, tuple->t_len);
-	if (written != tuple->t_len)
-		ereport(ERROR,
-				(errcode_for_file_access(),
-				 errmsg("could not write to hash-join temporary file: %m")));
+	BufFileWrite(file, (void *) &hashvalue, sizeof(uint32));
+	BufFileWrite(file, (void *) tuple, tuple->t_len);
 }
 
 /*
@@ -1279,7 +1269,8 @@ ExecHashJoinGetSavedTuple(HashJoinState *hjstate,
 	if (nread != sizeof(header))
 		ereport(ERROR,
 				(errcode_for_file_access(),
-				 errmsg("could not read from hash-join temporary file: %m")));
+				 errmsg("could not read from hash-join temporary file: read only %zu of %zu bytes",
+						nread, sizeof(header))));
 	*hashvalue = header[0];
 	tuple = (MinimalTuple) palloc(header[1]);
 	tuple->t_len = header[1];
@@ -1289,7 +1280,8 @@ ExecHashJoinGetSavedTuple(HashJoinState *hjstate,
 	if (nread != header[1] - sizeof(uint32))
 		ereport(ERROR,
 				(errcode_for_file_access(),
-				 errmsg("could not read from hash-join temporary file: %m")));
+				 errmsg("could not read from hash-join temporary file: read only %zu of %zu bytes",
+						nread, header[1] - sizeof(uint32))));
 	ExecForceStoreMinimalTuple(tuple, tupleSlot, true);
 	return tupleSlot;
 }

src/backend/replication/backup_manifest.c

@@ -319,7 +319,7 @@ SendBackupManifest(backup_manifest_info *manifest)
 	if (BufFileSeek(manifest->buffile, 0, 0L, SEEK_SET))
 		ereport(ERROR,
 				(errcode_for_file_access(),
-				 errmsg("could not rewind temporary file: %m")));
+				 errmsg("could not rewind temporary file")));
 
 	/* Send CopyOutResponse message */
 	pq_beginmessage(&protobuf, 'H');
@@ -365,15 +365,10 @@ static void
 AppendStringToManifest(backup_manifest_info *manifest, char *s)
 {
 	int			len = strlen(s);
-	size_t		written;
 
 	Assert(manifest != NULL);
 	if (manifest->still_checksumming)
 		pg_sha256_update(&manifest->manifest_ctx, (uint8 *) s, len);
-	written = BufFileWrite(manifest->buffile, s, len);
-	if (written != len)
-		ereport(ERROR,
-				(errcode_for_file_access(),
-				 errmsg("could not write to temporary file: %m")));
+	BufFileWrite(manifest->buffile, s, len);
 	manifest->manifest_size += len;
 }

src/backend/storage/file/buffile.c

@@ -99,7 +99,7 @@ static BufFile *makeBufFile(File firstfile);
 static void extendBufFile(BufFile *file);
 static void BufFileLoadBuffer(BufFile *file);
 static void BufFileDumpBuffer(BufFile *file);
-static int	BufFileFlush(BufFile *file);
+static void BufFileFlush(BufFile *file);
 static File MakeNewSharedSegment(BufFile *file, int segment);
 
 /*
@@ -434,7 +434,14 @@ BufFileLoadBuffer(BufFile *file)
 							file->curOffset,
 							WAIT_EVENT_BUFFILE_READ);
 	if (file->nbytes < 0)
+	{
 		file->nbytes = 0;
+		ereport(ERROR,
+				(errcode_for_file_access(),
+				 errmsg("could not read file \"%s\": %m",
+						FilePathName(thisfile))));
+	}
+
 	/* we choose not to advance curOffset here */
 
 	if (file->nbytes > 0)
@@ -490,7 +497,10 @@ BufFileDumpBuffer(BufFile *file)
 								 file->curOffset,
 								 WAIT_EVENT_BUFFILE_WRITE);
 		if (bytestowrite <= 0)
-			return;				/* failed to write */
+			ereport(ERROR,
+					(errcode_for_file_access(),
+					 errmsg("could not write to file \"%s\" : %m",
+							FilePathName(thisfile))));
 		file->curOffset += bytestowrite;
 		wpos += bytestowrite;
 
@@ -522,20 +532,16 @@ BufFileDumpBuffer(BufFile *file)
 /*
  * BufFileRead
  *
- * Like fread() except we assume 1-byte element size.
+ * Like fread() except we assume 1-byte element size and report I/O errors via
+ * ereport().
  */
 size_t
 BufFileRead(BufFile *file, void *ptr, size_t size)
 {
 	size_t		nread = 0;
 	size_t		nthistime;
 
-	if (file->dirty)
-	{
-		if (BufFileFlush(file) != 0)
-			return 0;			/* could not flush... */
-		Assert(!file->dirty);
-	}
+	BufFileFlush(file);
 
 	while (size > 0)
 	{
@@ -569,7 +575,8 @@ BufFileRead(BufFile *file, void *ptr, size_t size)
 /*
  * BufFileWrite
  *
- * Like fwrite() except we assume 1-byte element size.
+ * Like fwrite() except we assume 1-byte element size and report errors via
+ * ereport().
  */
 size_t
 BufFileWrite(BufFile *file, void *ptr, size_t size)
@@ -585,11 +592,7 @@ BufFileWrite(BufFile *file, void *ptr, size_t size)
 		{
 			/* Buffer full, dump it out */
 			if (file->dirty)
-			{
 				BufFileDumpBuffer(file);
-				if (file->dirty)
-					break;		/* I/O error */
-			}
 			else
 			{
 				/* Hmm, went directly from reading to writing? */
@@ -621,19 +624,15 @@ BufFileWrite(BufFile *file, void *ptr, size_t size)
 /*
  * BufFileFlush
  *
- * Like fflush()
+ * Like fflush(), except that I/O errors are reported with ereport().
  */
-static int
+static void
 BufFileFlush(BufFile *file)
 {
 	if (file->dirty)
-	{
 		BufFileDumpBuffer(file);
-		if (file->dirty)
-			return EOF;
-	}
 
-	return 0;
+	Assert(!file->dirty);
 }
 
 /*
@@ -642,6 +641,7 @@ BufFileFlush(BufFile *file)
  * Like fseek(), except that target position needs two values in order to
  * work when logical filesize exceeds maximum value representable by off_t.
  * We do not support relative seeks across more than that, however.
+ * I/O errors are reported by ereport().
  *
  * Result is 0 if OK, EOF if not.  Logical position is not moved if an
  * impossible seek is attempted.
@@ -699,8 +699,7 @@ BufFileSeek(BufFile *file, int fileno, off_t offset, int whence)
 		return 0;
 	}
 	/* Otherwise, must reposition buffer, so flush any dirty data */
-	if (BufFileFlush(file) != 0)
-		return EOF;
+	BufFileFlush(file);
 
 	/*
 	 * At this point and no sooner, check for seek past last segment. The

src/backend/utils/sort/logtape.c

@@ -262,12 +262,12 @@ ltsWriteBlock(LogicalTapeSet *lts, long blocknum, void *buffer)
 	}
 
 	/* Write the requested block */
-	if (BufFileSeekBlock(lts->pfile, blocknum) != 0 ||
-		BufFileWrite(lts->pfile, buffer, BLCKSZ) != BLCKSZ)
+	if (BufFileSeekBlock(lts->pfile, blocknum) != 0)
 		ereport(ERROR,
 				(errcode_for_file_access(),
-				 errmsg("could not write block %ld of temporary file: %m",
+				 errmsg("could not seek to block %ld of temporary file",
 						blocknum)));
+	BufFileWrite(lts->pfile, buffer, BLCKSZ);
 
 	/* Update nBlocksWritten, if we extended the file */
 	if (blocknum == lts->nBlocksWritten)
@@ -283,12 +283,19 @@ ltsWriteBlock(LogicalTapeSet *lts, long blocknum, void *buffer)
 static void
 ltsReadBlock(LogicalTapeSet *lts, long blocknum, void *buffer)
 {
-	if (BufFileSeekBlock(lts->pfile, blocknum) != 0 ||
-		BufFileRead(lts->pfile, buffer, BLCKSZ) != BLCKSZ)
+	size_t		nread;
+
+	if (BufFileSeekBlock(lts->pfile, blocknum) != 0)
 		ereport(ERROR,
 				(errcode_for_file_access(),
-				 errmsg("could not read block %ld of temporary file: %m",
+				 errmsg("could not seek to block %ld of temporary file",
 						blocknum)));
+	nread = BufFileRead(lts->pfile, buffer, BLCKSZ);
+	if (nread != BLCKSZ)
+		ereport(ERROR,
+				(errcode_for_file_access(),
+				 errmsg("could not read block %ld of temporary file: read only %zu of %zu bytes",
+						blocknum, nread, (size_t) BLCKSZ)));
 }
 
 /*

src/backend/utils/sort/sharedtuplestore.c

@@ -196,14 +196,9 @@ static void
 sts_flush_chunk(SharedTuplestoreAccessor *accessor)
 {
 	size_t		size;
-	size_t		written;
 
 	size = STS_CHUNK_PAGES * BLCKSZ;
-	written = BufFileWrite(accessor->write_file, accessor->write_chunk, size);
-	if (written != size)
-		ereport(ERROR,
-				(errcode_for_file_access(),
-				 errmsg("could not write to temporary file: %m")));
+	BufFileWrite(accessor->write_file, accessor->write_chunk, size);
 	memset(accessor->write_chunk, 0, size);
 	accessor->write_pointer = &accessor->write_chunk->data[0];
 	accessor->sts->participants[accessor->participant].npages +=
@@ -555,6 +550,7 @@ sts_parallel_scan_next(SharedTuplestoreAccessor *accessor, void *meta_data)
 		if (!eof)
 		{
 			SharedTuplestoreChunk chunk_header;
+			size_t		nread;
 
 			/* Make sure we have the file open. */
 			if (accessor->read_file == NULL)
@@ -570,14 +566,15 @@ sts_parallel_scan_next(SharedTuplestoreAccessor *accessor, void *meta_data)
 			if (BufFileSeekBlock(accessor->read_file, read_page) != 0)
 				ereport(ERROR,
 						(errcode_for_file_access(),
-						 errmsg("could not read from shared tuplestore temporary file"),
-						 errdetail_internal("Could not seek to next block.")));
-			if (BufFileRead(accessor->read_file, &chunk_header,
-							STS_CHUNK_HEADER_SIZE) != STS_CHUNK_HEADER_SIZE)
+						 errmsg("could not seek block %u in shared tuplestore temporary file",
+								read_page)));
+			nread = BufFileRead(accessor->read_file, &chunk_header,
+								STS_CHUNK_HEADER_SIZE);
+			if (nread != STS_CHUNK_HEADER_SIZE)
 				ereport(ERROR,
 						(errcode_for_file_access(),
-						 errmsg("could not read from shared tuplestore temporary file"),
-						 errdetail_internal("Short read while reading chunk header.")));
+						 errmsg("could not read from shared tuplestore temporary file: read only %zu of %zu bytes",
+								nread, STS_CHUNK_HEADER_SIZE)));
 
 			/*
 			 * If this is an overflow chunk, we skip it and any following