Prevent overflow for block number in buffile.c

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 b1e5c9fa9ac4, 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
index 2ca37832331c49d5fcd2c8b4a77b0f03db0e26c9..73e9aca9d215fc72dc7329aa0ddd7fc079e00e32 100644 (file)
--- 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;