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libc_ffat: enhance 'lseek()' support

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This patch adds support for the 'SEEK_CUR' and 'SEEK_END' values of the
'whence' argument of the 'lseek()' function..

Fixes #277.
This commit is contained in:
Christian Prochaska 2012-07-12 16:29:41 +02:00 committed by Norman Feske
parent e5bf7828d9
commit 0f8f87c3fe
1 changed files with 20 additions and 4 deletions
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24
libports/src/lib/libc_ffat/plugin.cc
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@ -32,6 +32,12 @@ namespace Ffat { extern "C" {
#include <ffat/ff.h>
} }
/*
* These macros are defined in later versions of the FatFs lib, but not in the
* one currently used for Genode.
*/
#define f_size(fp) ((fp)->fsize)
#define f_tell(fp) ((fp)->fptr)
static bool const verbose = false;
@ -373,16 +379,26 @@ class Plugin : public Libc::Plugin
{
using namespace Ffat;
if (whence != SEEK_SET) {
PERR("only SEEK_SET is supported by the ffat lib");
errno = EINVAL;
return (::off_t)-1;
switch(whence) {
case SEEK_CUR:
offset += f_tell(_get_ffat_file(fd));
break;
case SEEK_END:
offset += f_size(_get_ffat_file(fd));
break;
default:
break;
}
FRESULT res = f_lseek(_get_ffat_file(fd), offset);
switch(res) {
case FR_OK:
/* according to the FatFs documentation this can happen */
if (f_tell(_get_ffat_file(fd)) != offset) {
errno = EINVAL;
return -1;
}
return offset;
case FR_DISK_ERR:
case FR_INT_ERR: