From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 1 Jun 2007 23:43:23 +0000 (+0000)
Subject: Fix aboriginal bug in BufFileDumpBuffer that would cause it to write the
X-Git-Url: http://waps.l3s.uni-hannover.de/gitweb/?a=commitdiff_plain;h=35f4e0dcfcf7fee8290392e3dd688f09b8c7f55e;p=users%2Fbernd%2Fpostgres.git

Fix aboriginal bug in BufFileDumpBuffer that would cause it to write the
wrong data when dumping a bufferload that crosses a component-file boundary.
This probably has not been seen in the wild because (a) component files are
normally 1GB apiece and (b) non-block-aligned buffer usage is relatively
rare.  But it's fairly easy to reproduce a problem if one reduces RELSEG_SIZE
in a test build.  Kudos to Kurt Harriman for spotting the bug.
---

diff --git a/src/backend/storage/file/buffile.c b/src/backend/storage/file/buffile.c
index 3afe8a063f..8c4ef2f09c 100644
--- a/src/backend/storage/file/buffile.c
+++ b/src/backend/storage/file/buffile.c
@@ -291,7 +291,7 @@ BufFileDumpBuffer(BufFile *file)
 				return;			/* seek failed, give up */
 			file->offsets[file->curFile] = file->curOffset;
 		}
-		bytestowrite = FileWrite(thisfile, file->buffer, bytestowrite);
+		bytestowrite = FileWrite(thisfile, file->buffer + wpos, bytestowrite);
 		if (bytestowrite <= 0)
 			return;				/* failed to write */
 		file->offsets[file->curFile] += bytestowrite;