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

2 files changed, 38 insertions, 37 deletions

diff --git a/src/backend/utils/sort/logtape.c b/src/backend/utils/sort/logtape.c
index 774520752f0..7396b15f5ac 100644
--- a/src/backend/utils/sort/logtape.c
+++ b/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 ||
-		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);
 }
 
 /*
@@ -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 ||
-		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)));
 }
 
 /*
diff --git a/src/backend/utils/sort/tuplestore.c b/src/backend/utils/sort/tuplestore.c
index 1347fc4520a..c77d3f85fe3 100644
--- a/src/backend/utils/sort/tuplestore.c
+++ b/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,
-					 sizeof(tuplen)) != sizeof(tuplen))
-		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")));
+	BufFileWrite(state->myfile, (void *) &tuplen, sizeof(tuplen));
+	BufFileWrite(state->myfile, (void *) tupbody, tupbodylen);
 	if (state->backward)		/* need trailing length word? */
-		if (BufFileWrite(state->myfile, (void *) &tuplen,
-						 sizeof(tuplen)) != sizeof(tuplen))
-			ereport(ERROR,
-					(errcode_for_file_access(),
-				errmsg("could not write to tuplestore temporary file: %m")));
+		BufFileWrite(state->myfile, (void *) &tuplen, sizeof(tuplen));
 
 	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,
-					tupbodylen) != (size_t) tupbodylen)
+	nread = BufFileRead(state->myfile, (void *) tupbody, 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;
 }