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

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");
+		elog(ERROR, "could not seek to block %ld in temporary file", blknum);
-	if (BufFileRead(file, ptr, BLCKSZ) != BLCKSZ)
+	nread = BufFileRead(file, ptr, BLCKSZ);
-		elog(ERROR, "could not read temporary file: %m");
+	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");
+		elog(ERROR, "could not seek to block %ld in temporary file", blknum);
-	if (BufFileWrite(file, ptr, BLCKSZ) != BLCKSZ)
+	BufFileWrite(file, ptr, 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)));
-	}
 }

src/backend/executor/nodeHashjoin.c

@@ -820,7 +820,7 @@ 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,
@@ -850,7 +850,7 @@ 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;
@@ -872,7 +872,6 @@ ExecHashJoinSaveTuple(MinimalTuple tuple, uint32 hashvalue,
 					  BufFile **fileptr)
 {
 	BufFile    *file = *fileptr;
-	size_t		written;
 
 	if (file == NULL)
 	{
@@ -881,17 +880,8 @@ ExecHashJoinSaveTuple(MinimalTuple tuple, uint32 hashvalue,
 		*fileptr = file;
 	}
 
-	written = BufFileWrite(file, (void *) &hashvalue, sizeof(uint32));
+	BufFileWrite(file, (void *) &hashvalue, sizeof(uint32));
-	if (written != sizeof(uint32))
+	BufFileWrite(file, (void *) tuple, tuple->t_len);
-		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")));
 }
 
 /*
@@ -932,7 +922,8 @@ 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];
@@ -942,7 +933,8 @@ 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))));
 	return ExecStoreMinimalTuple(tuple, tupleSlot, true);
 }
 

src/backend/storage/file/buffile.c

@@ -93,8 +93,7 @@ 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);
-
 
 /*
  * Create a BufFile given the first underlying physical file.
@@ -247,7 +246,10 @@ BufFileLoadBuffer(BufFile *file)
 	if (file->curOffset != file->offsets[file->curFile])
 	{
 		if (FileSeek(thisfile, file->curOffset, SEEK_SET) != file->curOffset)
-			return;				/* seek failed, read nothing */
+			ereport(ERROR,
+					(errcode_for_file_access(),
+					 errmsg("could not seek in file \"%s\": %m",
+							FilePathName(thisfile))));
 		file->offsets[file->curFile] = file->curOffset;
 	}
 
@@ -256,7 +258,14 @@ BufFileLoadBuffer(BufFile *file)
 	 */
 	file->nbytes = FileRead(thisfile, file->buffer.data, sizeof(file->buffer));
 	if (file->nbytes < 0)
+	{
 		file->nbytes = 0;
+		ereport(ERROR,
+				(errcode_for_file_access(),
+				 errmsg("could not read file \"%s\": %m",
+						FilePathName(thisfile))));
+	}
+
 	file->offsets[file->curFile] += file->nbytes;
 	/* we choose not to advance curOffset here */
 
@@ -314,12 +323,19 @@ BufFileDumpBuffer(BufFile *file)
 		if (file->curOffset != file->offsets[file->curFile])
 		{
 			if (FileSeek(thisfile, file->curOffset, SEEK_SET) != file->curOffset)
-				return;			/* seek failed, give up */
+				ereport(ERROR,
+						(errcode_for_file_access(),
+						 errmsg("could not seek in file \"%s\": %m",
+								FilePathName(thisfile))));
 			file->offsets[file->curFile] = file->curOffset;
 		}
 		bytestowrite = FileWrite(thisfile, file->buffer.data + wpos, bytestowrite);
 		if (bytestowrite <= 0)
-			return;				/* failed to write */
+			ereport(ERROR,
+					(errcode_for_file_access(),
+					 errmsg("could not write to file \"%s\" : %m",
+							FilePathName(thisfile))));
+
 		file->offsets[file->curFile] += bytestowrite;
 		file->curOffset += bytestowrite;
 		wpos += bytestowrite;
@@ -352,7 +368,8 @@ 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)
@@ -360,12 +377,7 @@ BufFileRead(BufFile *file, void *ptr, size_t size)
 	size_t		nread = 0;
 	size_t		nthistime;
 
-	if (file->dirty)
+	BufFileFlush(file);
-	{
-		if (BufFileFlush(file) != 0)
-			return 0;			/* could not flush... */
-		Assert(!file->dirty);
-	}
 
 	while (size > 0)
 	{
@@ -399,7 +411,8 @@ 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)
@@ -413,11 +426,7 @@ 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? */
@@ -449,19 +458,15 @@ 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);
 }
 
 /*
@@ -470,6 +475,7 @@ BufFileFlush(BufFile *file)
  * Like fseek(), except that target position needs two values in order to
  * work when logical filesize exceeds maximum value representable by long.
  * We do not support relative seeks across more than LONG_MAX, 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.
@@ -527,8 +533,7 @@ 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)
+	BufFileFlush(file);
-		return EOF;
 
 	/*
 	 * At this point and no sooner, check for seek past last segment. The

src/backend/utils/sort/logtape.c

@@ -202,12 +202,12 @@ static void ltsDumpBuffer(LogicalTapeSet *lts, LogicalTape *lt);
 static void
 ltsWriteBlock(LogicalTapeSet *lts, long blocknum, void *buffer)
 {
-	if (BufFileSeekBlock(lts->pfile, blocknum) != 0 ||
+	if (BufFileSeekBlock(lts->pfile, blocknum) != 0)
-		BufFileWrite(lts->pfile, buffer, BLCKSZ) != BLCKSZ)
 		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);
 }
 
 /*
@@ -219,12 +219,19 @@ ltsWriteBlock(LogicalTapeSet *lts, long blocknum, void *buffer)
 static void
 ltsReadBlock(LogicalTapeSet *lts, long blocknum, void *buffer)
 {
-	if (BufFileSeekBlock(lts->pfile, blocknum) != 0 ||
+	size_t		nread;
-		BufFileRead(lts->pfile, buffer, BLCKSZ) != BLCKSZ)
+
+	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/tuplestore.c

@@ -512,7 +512,7 @@ tuplestore_select_read_pointer(Tuplestorestate *state, int ptr)
 								SEEK_SET) != 0)
 					ereport(ERROR,
 							(errcode_for_file_access(),
-							 errmsg("could not seek in tuplestore temporary file: %m")));
+							 errmsg("could not seek in tuplestore temporary file")));
 			}
 			else
 			{
@@ -522,7 +522,7 @@ tuplestore_select_read_pointer(Tuplestorestate *state, int ptr)
 								SEEK_SET) != 0)
 					ereport(ERROR,
 							(errcode_for_file_access(),
-							 errmsg("could not seek in tuplestore temporary file: %m")));
+							 errmsg("could not seek in tuplestore temporary file")));
 			}
 			break;
 		default:
@@ -849,7 +849,7 @@ tuplestore_puttuple_common(Tuplestorestate *state, void *tuple)
 							SEEK_SET) != 0)
 				ereport(ERROR,
 						(errcode_for_file_access(),
-				 errmsg("could not seek in tuplestore temporary file: %m")));
+				 errmsg("could not seek in tuplestore temporary file")));
 			state->status = TSS_WRITEFILE;
 
 			/*
@@ -953,7 +953,7 @@ tuplestore_gettuple(Tuplestorestate *state, bool forward,
 								SEEK_SET) != 0)
 					ereport(ERROR,
 							(errcode_for_file_access(),
-							 errmsg("could not seek in tuplestore temporary file: %m")));
+							 errmsg("could not seek in tuplestore temporary file")));
 			state->status = TSS_READFILE;
 			/* FALL THRU into READFILE case */
 
@@ -1017,7 +1017,7 @@ tuplestore_gettuple(Tuplestorestate *state, bool forward,
 									SEEK_CUR) != 0)
 						ereport(ERROR,
 								(errcode_for_file_access(),
-								 errmsg("could not seek in tuplestore temporary file: %m")));
+								 errmsg("could not seek in tuplestore temporary file")));
 					Assert(!state->truncated);
 					return NULL;
 				}
@@ -1034,7 +1034,7 @@ tuplestore_gettuple(Tuplestorestate *state, bool forward,
 							SEEK_CUR) != 0)
 				ereport(ERROR,
 						(errcode_for_file_access(),
-				 errmsg("could not seek in tuplestore temporary file: %m")));
+				 errmsg("could not seek in tuplestore temporary file")));
 			tup = READTUP(state, tuplen);
 			return tup;
 
@@ -1236,7 +1236,7 @@ tuplestore_rescan(Tuplestorestate *state)
 			if (BufFileSeek(state->myfile, 0, 0L, SEEK_SET) != 0)
 				ereport(ERROR,
 						(errcode_for_file_access(),
-				 errmsg("could not seek in tuplestore temporary file: %m")));
+				 errmsg("could not seek in tuplestore temporary file")));
 			break;
 		default:
 			elog(ERROR, "invalid tuplestore state");
@@ -1301,7 +1301,7 @@ tuplestore_copy_read_pointer(Tuplestorestate *state,
 									SEEK_SET) != 0)
 						ereport(ERROR,
 								(errcode_for_file_access(),
-								 errmsg("could not seek in tuplestore temporary file: %m")));
+								 errmsg("could not seek in tuplestore temporary file")));
 				}
 				else
 				{
@@ -1310,7 +1310,7 @@ tuplestore_copy_read_pointer(Tuplestorestate *state,
 									SEEK_SET) != 0)
 						ereport(ERROR,
 								(errcode_for_file_access(),
-								 errmsg("could not seek in tuplestore temporary file: %m")));
+								 errmsg("could not seek in tuplestore temporary file")));
 				}
 			}
 			else if (srcptr == state->activeptr)
@@ -1457,7 +1457,8 @@ getlen(Tuplestorestate *state, bool eofOK)
 	if (nbytes != 0 || !eofOK)
 		ereport(ERROR,
 				(errcode_for_file_access(),
-			   errmsg("could not read from tuplestore temporary file: %m")));
+			   errmsg("could not read from tuplestore temporary file: read only %zu of %zu bytes",
+						nbytes, sizeof(len))));
 	return 0;
 }
 
@@ -1494,22 +1495,10 @@ writetup_heap(Tuplestorestate *state, void *tup)
 	/* total on-disk footprint: */
 	unsigned int tuplen = tupbodylen + sizeof(int);
 
-	if (BufFileWrite(state->myfile, (void *) &tuplen,
+	BufFileWrite(state->myfile, (void *) &tuplen, sizeof(tuplen));
-					 sizeof(tuplen)) != sizeof(tuplen))
+	BufFileWrite(state->myfile, (void *) tupbody, tupbodylen);
-		ereport(ERROR,
-				(errcode_for_file_access(),
-				 errmsg("could not write to tuplestore temporary file: %m")));
-	if (BufFileWrite(state->myfile, (void *) tupbody,
-					 tupbodylen) != (size_t) tupbodylen)
-		ereport(ERROR,
-				(errcode_for_file_access(),
-				 errmsg("could not write to tuplestore temporary file: %m")));
 	if (state->backward)		/* need trailing length word? */
-		if (BufFileWrite(state->myfile, (void *) &tuplen,
+		BufFileWrite(state->myfile, (void *) &tuplen, sizeof(tuplen));
-						 sizeof(tuplen)) != sizeof(tuplen))
-			ereport(ERROR,
-					(errcode_for_file_access(),
-				errmsg("could not write to tuplestore temporary file: %m")));
 
 	FREEMEM(state, GetMemoryChunkSpace(tuple));
 	heap_free_minimal_tuple(tuple);
@@ -1522,20 +1511,25 @@ readtup_heap(Tuplestorestate *state, unsigned int len)
 	unsigned int tuplen = tupbodylen + MINIMAL_TUPLE_DATA_OFFSET;
 	MinimalTuple tuple = (MinimalTuple) palloc(tuplen);
 	char	   *tupbody = (char *) tuple + MINIMAL_TUPLE_DATA_OFFSET;
+	size_t		nread;
 
 	USEMEM(state, GetMemoryChunkSpace(tuple));
 	/* read in the tuple proper */
 	tuple->t_len = tuplen;
-	if (BufFileRead(state->myfile, (void *) tupbody,
+	nread = BufFileRead(state->myfile, (void *) tupbody, tupbodylen);
-					tupbodylen) != (size_t) tupbodylen)
+	if (nread != (size_t) tupbodylen)
 		ereport(ERROR,
 				(errcode_for_file_access(),
-			   errmsg("could not read from tuplestore temporary file: %m")));
+			   errmsg("could not read from tuplestore temporary file: read only %zu of %zu bytes",
+						nread, (size_t) tupbodylen)));
 	if (state->backward)		/* need trailing length word? */
-		if (BufFileRead(state->myfile, (void *) &tuplen,
+	{
-						sizeof(tuplen)) != sizeof(tuplen))
+		nread = BufFileRead(state->myfile, (void *) &tuplen, sizeof(tuplen));
+		if (nread != sizeof(tuplen))
 			ereport(ERROR,
 					(errcode_for_file_access(),
-			   errmsg("could not read from tuplestore temporary file: %m")));
+			   errmsg("could not read from tuplestore temporary file: read only %zu of %zu bytes",
+							nread, sizeof(tuplen))));
+	}
 	return (void *) tuple;
 }