In pg_restore's dump_lo_buf(), work a little harder on error handling.

tglsfdc · tglsfdc · commit 929c69aa1970 · 2020-10-18T12:26:02.000-04:00
Failure to write data to a large object during restore led to an ugly and uninformative error message. To add insult to injury, it then fatal'd out, where other SQL-level errors usually result in pressing on. Report the underlying error condition, rather than just giving not-very- useful byte counts, and use warn_or_exit_horribly() so as to adhere to pg_restore's general policy about whether to continue or not. Also recognize that lo_write() returns int not size_t. Per report from Justin Pryzby, though I didn't use his patch. Given the lack of comparable complaints, I'm not sure this is worth back-patching. Discussion: https://postgr.es/m/20201018010232.GF9241@telsasoft.com
diff --git a/src/bin/pg_dump/pg_backup_archiver.c b/src/bin/pg_dump/pg_backup_archiver.c
@@ -1637,16 +1637,17 @@ dump_lo_buf(ArchiveHandle *AH)
 {
 	if (AH->connection)
 	{
-		size_t		res;
+		int			res;
 
 		res = lo_write(AH->connection, AH->loFd, AH->lo_buf, AH->lo_buf_used);
-		pg_log_debug(ngettext("wrote %lu byte of large object data (result = %lu)",
-							  "wrote %lu bytes of large object data (result = %lu)",
+		pg_log_debug(ngettext("wrote %zu byte of large object data (result = %d)",
+							  "wrote %zu bytes of large object data (result = %d)",
 							  AH->lo_buf_used),
-					 (unsigned long) AH->lo_buf_used, (unsigned long) res);
+					 AH->lo_buf_used, res);
+		/* We assume there are no short writes, only errors */
 		if (res != AH->lo_buf_used)
-			fatal("could not write to large object (result: %lu, expected: %lu)",
-				  (unsigned long) res, (unsigned long) AH->lo_buf_used);
+			warn_or_exit_horribly(AH, "could not write to large object: %s",
+								  PQerrorMessage(AH->connection));
 	}
 	else
 	{

Original file line number	Diff line number	Diff line change
`@@ -1637,16 +1637,17 @@ dump_lo_buf(ArchiveHandle *AH)`
`1637`	`1637`	`{`
`1638`	`1638`	`if (AH->connection)`
`1639`	`1639`	`{`
`1640`		`- size_t res;`
	`1640`	`+ int res;`
`1641`	`1641`
`1642`	`1642`	`res = lo_write(AH->connection, AH->loFd, AH->lo_buf, AH->lo_buf_used);`
`1643`		`- pg_log_debug(ngettext("wrote %lu byte of large object data (result = %lu)",`
`1644`		`- "wrote %lu bytes of large object data (result = %lu)",`
	`1643`	`+ pg_log_debug(ngettext("wrote %zu byte of large object data (result = %d)",`
	`1644`	`+ "wrote %zu bytes of large object data (result = %d)",`
`1645`	`1645`	`AH->lo_buf_used),`
`1646`		`- (unsigned long) AH->lo_buf_used, (unsigned long) res);`
	`1646`	`+ AH->lo_buf_used, res);`
	`1647`	`+ /* We assume there are no short writes, only errors */`
`1647`	`1648`	`if (res != AH->lo_buf_used)`
`1648`		`- fatal("could not write to large object (result: %lu, expected: %lu)",`
`1649`		`- (unsigned long) res, (unsigned long) AH->lo_buf_used);`
	`1649`	`+ warn_or_exit_horribly(AH, "could not write to large object: %s",`
	`1650`	`+ PQerrorMessage(AH->connection));`
`1650`	`1651`	`}`
`1651`	`1652`	`else`
`1652`	`1653`	`{`