Code review for 64-bit-large-object patch.

Fix broken-on-bigendian-machines byte-swapping functions, add missed update
of alternate regression expected file, improve error reporting, remove some
unnecessary code, sync testlo64.c with current testlo.c (it seems to have
been cloned from a very old copy of that), assorted cosmetic improvements.

3 files changed, 73 insertions, 63 deletions

diff --git a/src/backend/libpq/be-fsstubs.c b/src/backend/libpq/be-fsstubs.c
index 4bc81ba9f4d..c4ac1a650f5 100644
--- a/src/backend/libpq/be-fsstubs.c
+++ b/src/backend/libpq/be-fsstubs.c
@@ -39,7 +39,6 @@
 #include "postgres.h"
 
 #include <fcntl.h>
-#include <limits.h>
 #include <sys/stat.h>
 #include <unistd.h>
 
@@ -57,7 +56,9 @@
  */
 bool		lo_compat_privileges;
 
-/*#define FSDB 1*/
+/* define this to enable debug logging */
+/* #define FSDB 1 */
+/* chunk size for lo_import/lo_export transfers */
 #define BUFSIZE			8192
 
 /*
@@ -210,7 +211,6 @@ lo_write(int fd, const char *buf, int len)
 	return status;
 }
 
-
 Datum
 lo_lseek(PG_FUNCTION_ARGS)
 {
@@ -226,42 +226,31 @@ lo_lseek(PG_FUNCTION_ARGS)
 
 	status = inv_seek(cookies[fd], offset, whence);
 
-	if (INT_MAX < status)
-	{
+	/* guard against result overflow */
+	if (status != (int32) status)
 		ereport(ERROR,
-				(errcode(ERRCODE_BLOB_OFFSET_OVERFLOW),
-				 errmsg("offset overflow: %d", fd)));
-		PG_RETURN_INT32(-1);
-	}
+				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
+				 errmsg("lo_lseek result out of range for large-object descriptor %d",
+						fd)));
 
-	PG_RETURN_INT32(status);
+	PG_RETURN_INT32((int32) status);
 }
 
-
 Datum
 lo_lseek64(PG_FUNCTION_ARGS)
 {
 	int32		fd = PG_GETARG_INT32(0);
 	int64		offset = PG_GETARG_INT64(1);
 	int32		whence = PG_GETARG_INT32(2);
-	MemoryContext currentContext;
-	int64			status;
+	int64		status;
 
 	if (fd < 0 || fd >= cookies_size || cookies[fd] == NULL)
-	{
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_OBJECT),
 				 errmsg("invalid large-object descriptor: %d", fd)));
-		PG_RETURN_INT64(-1);
-	}
-
-	Assert(fscxt != NULL);
-	currentContext = MemoryContextSwitchTo(fscxt);
 
 	status = inv_seek(cookies[fd], offset, whence);
 
-	MemoryContextSwitchTo(currentContext);
-
 	PG_RETURN_INT64(status);
 }
 
@@ -301,7 +290,7 @@ Datum
 lo_tell(PG_FUNCTION_ARGS)
 {
 	int32		fd = PG_GETARG_INT32(0);
-	int64		offset = 0;
+	int64		offset;
 
 	if (fd < 0 || fd >= cookies_size || cookies[fd] == NULL)
 		ereport(ERROR,
@@ -310,37 +299,30 @@ lo_tell(PG_FUNCTION_ARGS)
 
 	offset = inv_tell(cookies[fd]);
 
-	if (INT_MAX < offset)
-	{
+	/* guard against result overflow */
+	if (offset != (int32) offset)
 		ereport(ERROR,
-				(errcode(ERRCODE_BLOB_OFFSET_OVERFLOW),
-				 errmsg("offset overflow: %d", fd)));
-		PG_RETURN_INT32(-1);
-	}
+				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
+				 errmsg("lo_tell result out of range for large-object descriptor %d",
+						fd)));
 
-	PG_RETURN_INT32(offset);
+	PG_RETURN_INT32((int32) offset);
 }
 
-
 Datum
 lo_tell64(PG_FUNCTION_ARGS)
 {
 	int32		fd = PG_GETARG_INT32(0);
+	int64		offset;
 
 	if (fd < 0 || fd >= cookies_size || cookies[fd] == NULL)
-	{
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_OBJECT),
 				 errmsg("invalid large-object descriptor: %d", fd)));
-		PG_RETURN_INT64(-1);
-	}
 
-	/*
-	 * We assume we do not need to switch contexts for inv_tell. That is
-	 * true for now, but is probably more than this module ought to
-	 * assume...
-	 */
-	PG_RETURN_INT64(inv_tell(cookies[fd]));
+	offset = inv_tell(cookies[fd]);
+
+	PG_RETURN_INT64(offset);
 }
 
 Datum
diff --git a/src/backend/storage/large_object/inv_api.c b/src/backend/storage/large_object/inv_api.c
index 3f5688b939b..5dd17823c23 100644
--- a/src/backend/storage/large_object/inv_api.c
+++ b/src/backend/storage/large_object/inv_api.c
@@ -30,6 +30,8 @@
  */
 #include "postgres.h"
 
+#include <limits.h>
+
 #include "access/genam.h"
 #include "access/heapam.h"
 #include "access/sysattr.h"
@@ -264,7 +266,10 @@ inv_open(Oid lobjId, int flags, MemoryContext mcxt)
 		retval->flags = IFS_RDLOCK;
 	}
 	else
-		elog(ERROR, "invalid flags: %d", flags);
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("invalid flags for opening a large object: %d",
+						flags)));
 
 	/* Can't use LargeObjectExists here because it always uses SnapshotNow */
 	if (!myLargeObjectExists(lobjId, retval->snapshot))
@@ -381,34 +386,45 @@ inv_getsize(LargeObjectDesc *obj_desc)
 int64
 inv_seek(LargeObjectDesc *obj_desc, int64 offset, int whence)
 {
+	int64		newoffset;
+
 	Assert(PointerIsValid(obj_desc));
 
+	/*
+	 * Note: overflow in the additions is possible, but since we will reject
+	 * negative results, we don't need any extra test for that.
+	 */
 	switch (whence)
 	{
 		case SEEK_SET:
-			if (offset < 0 || offset >= MAX_LARGE_OBJECT_SIZE)
-				elog(ERROR, "invalid seek offset: " INT64_FORMAT, offset);
-			obj_desc->offset = offset;
+			newoffset = offset;
 			break;
 		case SEEK_CUR:
-			if ((offset + obj_desc->offset) < 0 ||
-			   (offset + obj_desc->offset) >= MAX_LARGE_OBJECT_SIZE)
-				elog(ERROR, "invalid seek offset: " INT64_FORMAT, offset);
-			obj_desc->offset += offset;
+			newoffset = obj_desc->offset + offset;
 			break;
 		case SEEK_END:
-			{
-				int64		pos = inv_getsize(obj_desc) + offset;
-
-				if (pos < 0 || pos >= MAX_LARGE_OBJECT_SIZE)
-					elog(ERROR, "invalid seek offset: " INT64_FORMAT, offset);
-				obj_desc->offset = pos;
-			}
+			newoffset = inv_getsize(obj_desc) + offset;
 			break;
 		default:
-			elog(ERROR, "invalid whence: %d", whence);
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					 errmsg("invalid whence setting: %d", whence)));
+			newoffset = 0;		/* keep compiler quiet */
+			break;
 	}
-	return obj_desc->offset;
+
+	/*
+	 * use errmsg_internal here because we don't want to expose INT64_FORMAT
+	 * in translatable strings; doing better is not worth the trouble
+	 */
+	if (newoffset < 0 || newoffset > MAX_LARGE_OBJECT_SIZE)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg_internal("invalid large object seek target: " INT64_FORMAT,
+								 newoffset)));
+
+	obj_desc->offset = newoffset;
+	return newoffset;
 }
 
 int64
@@ -438,9 +454,6 @@ inv_read(LargeObjectDesc *obj_desc, char *buf, int nbytes)
 	if (nbytes <= 0)
 		return 0;
 
-	if ((nbytes + obj_desc->offset) > MAX_LARGE_OBJECT_SIZE)
-		elog(ERROR, "invalid read request size: %d", nbytes);
-
 	open_lo_relation();
 
 	ScanKeyInit(&skey[0],
@@ -559,13 +572,18 @@ inv_write(LargeObjectDesc *obj_desc, const char *buf, int nbytes)
 	if (!LargeObjectExists(obj_desc->id))
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_OBJECT),
-			   errmsg("large object %u was already dropped", obj_desc->id)));
+				 errmsg("large object %u was already dropped",
+						obj_desc->id)));
 
 	if (nbytes <= 0)
 		return 0;
 
+	/* this addition can't overflow because nbytes is only int32 */
 	if ((nbytes + obj_desc->offset) > MAX_LARGE_OBJECT_SIZE)
-		elog(ERROR, "invalid write request size: %d", nbytes);
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("invalid large object write request size: %d",
+						nbytes)));
 
 	open_lo_relation();
 
@@ -759,7 +777,18 @@ inv_truncate(LargeObjectDesc *obj_desc, int64 len)
 	if (!LargeObjectExists(obj_desc->id))
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_OBJECT),
-			   errmsg("large object %u was already dropped", obj_desc->id)));
+				 errmsg("large object %u was already dropped",
+						obj_desc->id)));
+
+	/*
+	 * use errmsg_internal here because we don't want to expose INT64_FORMAT
+	 * in translatable strings; doing better is not worth the trouble
+	 */
+	if (len < 0 || len > MAX_LARGE_OBJECT_SIZE)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg_internal("invalid large object truncation target: " INT64_FORMAT,
+								 len)));
 
 	open_lo_relation();
 
diff --git a/src/backend/utils/errcodes.txt b/src/backend/utils/errcodes.txt
index db8ab53af26..3e041649563 100644
--- a/src/backend/utils/errcodes.txt
+++ b/src/backend/utils/errcodes.txt
@@ -199,7 +199,6 @@ Section: Class 22 - Data Exception
 2200N    E    ERRCODE_INVALID_XML_CONTENT                                    invalid_xml_content
 2200S    E    ERRCODE_INVALID_XML_COMMENT                                    invalid_xml_comment
 2200T    E    ERRCODE_INVALID_XML_PROCESSING_INSTRUCTION                     invalid_xml_processing_instruction
-22P07    E    ERRCODE_BLOB_OFFSET_OVERFLOW                                   blob_offset_overflow
 
 Section: Class 23 - Integrity Constraint Violation