Prevent overflow for block number in buffile.c

michaelpq · pull[bot] · commit 6fc0d99cb18e · 2024-01-24T15:43:36.000Z
As coded, the start block calculated by BufFileAppend() would overflow once more than 16k files are used with a default block size. This issue existed before b1e5c9f, but there's no reason not to be clean about it. Per report from Coverity, with a fix suggested by Tom Lane.
diff --git a/src/backend/storage/file/buffile.c b/src/backend/storage/file/buffile.c
@@ -904,7 +904,7 @@ BufFileSize(BufFile *file)
 int64
 BufFileAppend(BufFile *target, BufFile *source)
 {
-	int64		startBlock = target->numFiles * BUFFILE_SEG_SIZE;
+	int64		startBlock = (int64) target->numFiles * BUFFILE_SEG_SIZE;
 	int			newNumFiles = target->numFiles + source->numFiles;
 	int			i;
 

Original file line number	Diff line number	Diff line change
`@@ -904,7 +904,7 @@ BufFileSize(BufFile *file)`
`904`	`904`	`int64`
`905`	`905`	`BufFileAppend(BufFile target, BufFile source)`
`906`	`906`	`{`
`907`		`- int64 startBlock = target->numFiles * BUFFILE_SEG_SIZE;`
	`907`	`+ int64 startBlock = (int64) target->numFiles * BUFFILE_SEG_SIZE;`
`908`	`908`	`int newNumFiles = target->numFiles + source->numFiles;`
`909`	`909`	`int i;`
`910`	`910`