[OpenBIOS] [PATCH] grubfs: don't try to read a file beyond its end

[Aurelien Jarno]

Yaboot relies on the read function from openbios to stop reading at the
end of a file. This patch makes sure to not read beyond the end of the
file. This fixes the boot of debian-installer using a CD-ROM.
    
Signed-off-by: Aurelien Jarno <aurelien at aurel32.net>

diff --git a/fs/grubfs/grubfs_fs.c b/fs/grubfs/grubfs_fs.c
index f172b75..588d677 100644
--- a/fs/grubfs/grubfs_fs.c
+++ b/fs/grubfs/grubfs_fs.c
@@ -161,6 +161,9 @@ grubfs_file_read( file_desc_t *fd, void *buf, size_t count )
 	filepos=file->pos;
 	filemax=file->len;
 
+	if (count > filemax - filepos)
+		count = filemax - filepos;
+
 	ret=curfs->fsys->read_func(buf, count);
 
 	file->pos=filepos;

-- 
  .''`.  Aurelien Jarno	            | GPG: 1024D/F1BCDB73
 : :' :  Debian developer           | Electrical Engineer
 `. `'   aurel32 at debian.org         | aurelien at aurel32.net
   `-    people.debian.org/~aurel32 | www.aurel32.net