source: trunk/kernel/syscalls/sys_lseek.c @ 1

Last change on this file since 1 was 1, checked in by alain, 5 years ago

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File size: 1.6 KB
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1/*
2 * kern/sys_lseek.c - set the read/write offset of an opened file
3 *
4 * Copyright (c) 2008,2009,2010,2011,2012 Ghassan Almaless
5 * Copyright (c) 2011,2012 UPMC Sorbonne Universites
6 *
7 * This file is part of ALMOS-kernel.
8 *
9 * ALMOS-kernel is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; version 2.0 of the License.
12 *
13 * ALMOS-kernel is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16 * General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with ALMOS-kernel; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23#include <types.h>
24#include <vfs.h>
25#include <thread.h>
26#include <sys-vfs.h>
27#include <task.h>
28
29int sys_lseek (uint_t fd, off_t offset, int whence)
30{
31        error_t err = 0;
32        size_t new_offset;
33        struct thread_s *this;
34        struct task_s *task;
35        struct vfs_file_s *file;
36
37        file = NULL;
38        this = current_thread;
39        task = current_task;
40
41        /* FIXME: file may be closed in parallel
42         * of seek/read/write/mmap ..etc
43         * so file may be NULL or invalid */
44        if((fd >= CONFIG_TASK_FILE_MAX_NR) || (task_fd_lookup(task, fd, &file)))
45        {
46                this->info.errno = EBADFD;
47                return -1;
48        }
49
50        if((err = vfs_lseek(file, offset, whence, &new_offset)))
51        {
52                this->info.errno = (err < 0) ? -err : err;
53                return -1;
54        }
55 
56        return new_offset;
57}
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