[AD] pack_ferror() - differences between platforms

[Ben Davis <bnd25@xxxxxxxxxx>]

Hi

I was about to post a bug report - pack_ferror() wasn't being set on Linux - 
but it seems to be more of a quirk than a bug. With DJGPP, pack_ferror() will 
return nonzero if the end of the file has been reached (incidentally I was 
using a compressed file). With Linux, pack_ferror() will not. While I was 
looking for a possible cause for the bug, it occurred to me that this was 
what pack_feof() was for.

I tested with Allegro 4.0.0 on DJGPP and Allegro 4.1.x CVS on Linux. Just to 
make sure, I tried Allegro 4.0.0 on Linux, and it behaved the same as Allegro 
4.1.x CVS on Linux. So this really does appear to be a platform issue, not a 
version issue.

(By the way, I still have Allegro 4.0.0 on my laptop because I hardly ever 
use the laptop any more and it's not worth the trouble of upgrading :)

Anyhow, I believe it should be documented in pack_ferror()'s description that 
EOF may not be considered an error - or the library should be fixed so that 
it either always is or always isn't considered an error.

I've attached three patches - don't apply more than one of them. They are as 
follows:

allegro._tx.diff
  Updates the docs to indicate that the return value of pack_ferror() is
  undefined after you try to read beyond the end of the file.

file.inl.eofiserror.diff
  Modifies packfile_ferror() to return nonzero if either PACKFILE_FLAG_EOF or
  PACKFILE_FLAG_ERROR is set in the PACKFILE struct.

file.inl.eofnoterror.hacky.diff
  Modifies packfile_ferror() to return nonzero only if PACKFILE_FLAG_ERROR is
  set _and_ PACKFILE_FLAG_EOF is clear. This is hacky, as a valid error
  condition may accidentally be missed...

I've also attached an archive of these files, in case your e-mail clients 
mess them up :)

Ben

Attachment: diffs.tar.gz
Description: GNU Zip compressed data

--- include/allegro/inline/file.inl.old	Sun Jan 19 13:35:50 2003
+++ include/allegro/inline/file.inl	Sun Jan 19 13:40:25 2003
@@ -51,7 +51,7 @@
 
 AL_INLINE(int, pack_ferror, (PACKFILE *f),
 {
-   return (f->flags & PACKFILE_FLAG_ERROR);
+   return ((f->flags & (PACKFILE_FLAG_ERROR | PACKFILE_FLAG_EOF)) == PACKFILE_FLAG_ERROR);
 })
 
 #ifdef __cplusplus

--- include/allegro/inline/file.inl.old	Sun Jan 19 13:35:50 2003
+++ include/allegro/inline/file.inl	Sun Jan 19 13:35:55 2003
@@ -51,7 +51,7 @@
 
 AL_INLINE(int, pack_ferror, (PACKFILE *f),
 {
-   return (f->flags & PACKFILE_FLAG_ERROR);
+   return (f->flags & (PACKFILE_FLAG_ERROR | PACKFILE_FLAG_EOF));
 })
 
 #ifdef __cplusplus

--- docs/src/allegro._tx.old	Sun Jan 19 13:26:35 2003
+++ docs/src/allegro._tx	Sun Jan 19 13:33:31 2003
@@ -6321,6 +6321,10 @@
    DOS/Windows. If you do not want either of these things to happen,
    use pack_fwrite() and/or pack_putc() instead.
 </ul>
+   Please note that the return value of pack_ferror() after you try to read 
+   beyond the end of the file is undefined. If you wish to detect premature 
+   end of file, you should check both pack_ferror() and pack_feof().
+
 @@PACKFILE *@pack_fopen_chunk(PACKFILE *f, int pack);
 @xref pack_fclose_chunk, pack_fopen
    Opens a sub-chunk of a file. Chunks are primarily intended for use by the