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 95f2885c6196ac62ee2c2db43fd95fffa4e5e1df..232c64d30eee9fee6aa6ce45684c7e28a6ceb4b5 100644 (file)
--- 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
- *       $PostgreSQL: pgsql/src/backend/storage/file/buffile.c,v 1.22 2005/10/15 02:49:25 momjian Exp $
+ *       $PostgreSQL: pgsql/src/backend/storage/file/buffile.c,v 1.22.2.1 2007/06/01 23:43:23 tgl Exp $
  *
  * NOTES:
  *
@@ -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;