From: Savin Zlobec <savin@elatec.si>
To: Gratian Crisan <nelu@iv.ro>
Cc: ecos-discuss@ecos.sourceware.org
Subject: Re: [ECOS] fatfs lseek EOF bug
Date: Tue, 10 May 2005 12:30:00 -0000 [thread overview]
Message-ID: <428091CE.20300@elatec.si> (raw)
In-Reply-To: <200505101258.48354.nelu@iv.ro>
[-- Attachment #1: Type: text/plain, Size: 1509 bytes --]
Gratian Crisan wrote:
>Hi,
>
>please see my answers below:
>
>On Tuesday 10 May 2005 09:48, Savin Zlobec wrote:
>
>
>>Gratian Crisan wrote:
>>
>>
>>>Hi all,
>>>
>>>I think I've found a bug in the ecos FAT implementation for lseek
>>>function. (fatfs_fo_lseek).
>>>When calling the function like this 'lseek(fd, 0, SEEK_CUR)' to get the
>>>current file position and the postion is right at the end of the file the
>>>fat lseek function returns end of file error EEOF. I've looked at the
>>>other filesystems from ecos and did a test in linux and the correct
>>>behavior seems to be to return the current position of the end of file if
>>>the read/write pointer is at the end of file (equal with the file size).
>>>This bug occurs for example when creating a new file, writing some data in
>>>it and calling lseek(fd, 0, SEEK_CUR) to get the current file position.
>>>
>>>Suggestions?
>>>
[snip]
> See the file attached. The test is for an MMC driver but should be pretty
>straight forward to adapt (only the mount command should be changed).
>The test creates a file and writes blocks of data into it while printing the
>current file offset. In a new file after writing the first block, for which
>the value returned is 0, the value returned by lseek function is -1. The
>strange thing is that if you overwrite an existing file the lseek function
>correctly returns the current file offset (equal to EOF).
>
>
Found the BUG -- Please try the attached patch and let me know if it works.
savin
[-- Attachment #2: fatfs.diff --]
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Index: src/fatfs_supp.c
===================================================================
RCS file: /cvs/ecos/ecos/packages/fs/fat/current/src/fatfs_supp.c,v
retrieving revision 1.3
diff -u -r1.3 fatfs_supp.c
--- src/fatfs_supp.c 22 Oct 2004 14:10:23 -0000 1.3
+++ src/fatfs_supp.c 10 May 2005 10:43:14 -0000
@@ -1172,8 +1172,10 @@
// Err could be EEOF wich means that the given
// offset if out of given file (cluster chain)
- if (ENOERR == err)
- *pos = new_pos;
+ if (EEOF == err)
+ new_pos.cluster_pos = disk->cluster_size;
+
+ *pos = new_pos;
return err;
}
@@ -2056,11 +2058,18 @@
fatfs_data_pos_t *pos,
cyg_uint32 offset)
{
+ int err;
+
CYG_CHECK_DATA_PTRC(disk);
CYG_CHECK_DATA_PTRC(file);
CYG_CHECK_DATA_PTRC(pos);
- return get_position_from_off(disk, file->cluster, offset, pos, CO_NONE);
+ err = get_position_from_off(disk, file->cluster, offset, pos, CO_NONE);
+
+ if (EEOF == err && offset == file->size)
+ return ENOERR;
+ else
+ return err;
}
// -------------------------------------------------------------------------
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--
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next prev parent reply other threads:[~2005-05-10 10:51 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-05-09 11:25 Gratian Crisan
2005-05-10 10:51 ` Savin Zlobec
2005-05-10 12:05 ` Gratian Crisan
2005-05-10 12:30 ` Savin Zlobec [this message]
2005-05-10 13:00 ` Gratian Crisan
2005-05-11 9:32 ` Savin Zlobec
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