From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 1 Jun 2007 23:43:34 +0000 (+0000)
Subject: Fix aboriginal bug in BufFileDumpBuffer that would cause it to write the
X-Git-Tag: REL7_4_18~28
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=20c031eb8a9e9d0e74159d8d1d0dd1f77c3db648;p=thirdparty%2Fpostgresql.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 45ee4b0326a..957d033efd0 100644
--- a/src/backend/storage/file/buffile.c
+++ b/src/backend/storage/file/buffile.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/file/buffile.c,v 1.18 2003/08/04 02:40:03 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/file/buffile.c,v 1.18.4.1 2007/06/01 23:43:34 tgl Exp $
  *
  * NOTES:
  *
@@ -292,7 +292,7 @@ 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;