BufFileSeek's behavior at segment boundaries wasn't what

logfile.c wanted ... seems easier to fix BufFileSeek.

diff --git a/src/backend/storage/file/buffile.c b/src/backend/storage/file/buffile.c
index 452e3a187dfdd612c01b4accb8e42e719aa93f99..2dafe08c5d99515216818cf416d2ba6119e38373 100644 (file)
--- a/src/backend/storage/file/buffile.c
+++ b/src/backend/storage/file/buffile.c
@@ -6,7 +6,7 @@
  * Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/storage/file/buffile.c,v 1.2 1999/10/16 19:49:26 tgl Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/storage/file/buffile.c,v 1.3 1999/10/19 02:34:45 tgl Exp $
  *
  * NOTES:
  *
@@ -434,8 +434,7 @@ BufFileSeek(BufFile *file, int fileno, long offset, int whence)
        switch (whence)
        {
                case SEEK_SET:
-                       if (fileno < 0 || fileno >= file->numFiles ||
-                               offset < 0)
+                       if (fileno < 0)
                                return EOF;
                        newFile = fileno;
                        newOffset = offset;
@@ -443,7 +442,7 @@ BufFileSeek(BufFile *file, int fileno, long offset, int whence)
                case SEEK_CUR:
                        /*
                         * Relative seek considers only the signed offset, ignoring fileno.
-                        * Note that large offsets (> 1 gig) risk overflow.
+                        * Note that large offsets (> 1 gig) risk overflow in this add...
                         */
                        newFile = file->curFile;
                        newOffset = (file->curOffset + file->pos) + offset;
@@ -463,15 +462,6 @@ BufFileSeek(BufFile *file, int fileno, long offset, int whence)
                        return EOF;
                newOffset += MAX_PHYSICAL_FILESIZE;
        }
-       if (file->isTemp)
-       {
-               while (newOffset > MAX_PHYSICAL_FILESIZE)
-               {
-                       if (++newFile >= file->numFiles)
-                               return EOF;
-                       newOffset -= MAX_PHYSICAL_FILESIZE;
-               }
-       }
        if (newFile == file->curFile &&
                newOffset >= file->curOffset &&
                newOffset <= file->curOffset + file->nbytes)
@@ -488,6 +478,29 @@ BufFileSeek(BufFile *file, int fileno, long offset, int whence)
        /* Otherwise, must reposition buffer, so flush any dirty data */
        if (BufFileFlush(file) != 0)
                return EOF;
+       /*
+        * At this point and no sooner, check for seek past last segment.
+        * The above flush could have created a new segment, so
+        * checking sooner would not work (at least not with this code).
+        */
+       if (file->isTemp)
+       {
+               /* convert seek to "start of next seg" to "end of last seg" */
+               if (newFile == file->numFiles && newOffset == 0)
+               {
+                       newFile--;
+                       newOffset = MAX_PHYSICAL_FILESIZE;
+               }
+               while (newOffset > MAX_PHYSICAL_FILESIZE)
+               {
+                       if (++newFile >= file->numFiles)
+                               return EOF;
+                       newOffset -= MAX_PHYSICAL_FILESIZE;
+               }
+       }
+       if (newFile >= file->numFiles)
+               return EOF;
+       /* Seek is OK! */
        file->curFile = newFile;
        file->curOffset = newOffset;
        file->pos = 0;