source: trunk/kernel/syscalls/sys_open.c @ 23

Last change on this file since 23 was 23, checked in by alain, 5 years ago

Introduce syscalls.

File size: 3.4 KB
Line 
1/*
2 * sys_open.c - open a file.
3 *
4 * Author        Alain Greiner (2016,2017)
5 *
6 * Copyright (c) UPMC Sorbonne Universites
7 *
8 * This file is part of ALMOS-MKH.
9 *
10 * ALMOS-MKH is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; version 2.0 of the License.
13 *
14 * ALMOS-MKH is distributed in the hope that it will be useful, but
15 * WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
17 * General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with ALMOS-MKH; if not, write to the Free Software Foundation,
21 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
24#include <kernel_config.h>
25#include <hal_types.h>
26#include <hal_uspace.h>
27#include <errno.h>
28#include <thread.h>
29#include <printk.h>
30#include <vfs.h>
31#include <process.h>
32#include <remote_spinlock.h>
33#include <remote_rwlock.h>
34
35///////////////////////////////////
36int sys_open ( char     * pathname,
37               uint32_t   flags,
38               uint32_t   mode )
39{
40
41        error_t        error;
42        xptr_t         file_xp;                          // extended pointer on vfs_file_t
43        uint32_t       file_id;                          // file descriptor index
44    uint32_t       length;                           // pathname length (bytes)
45    char           kbuf[CONFIG_VFS_MAX_PATH_LENGTH];
46
47        thread_t     * this     = CURRENT_THREAD;
48        process_t    * process  = this->process;
49
50        if( pathname == NULL )
51        {
52        printk("\n[ERROR] in %s : pathname is NULL\n", __FUNCTION__ );
53                this->errno = EINVAL;
54                return -1;
55        }       
56
57    // check fd_array not full
58        if( process_fd_array_full() )
59        {
60        printk("\n[ERROR] in %s : file descriptor array full for process %x\n",
61               __FUNCTION__ , process->pid );
62                this->errno = ENFILE;
63        return -1;
64        }
65   
66    // get pathname length
67    length = hal_strlen_from_uspace( pathname );
68
69    if( length >= CONFIG_VFS_MAX_PATH_LENGTH )
70    {
71        printk("\n[ERROR] in %s : pathname too long\n", __FUNCTION__ );
72                this->errno = ENFILE;
73        return -1;
74    }
75 
76        // get pathname copy in kernel space
77    hal_copy_from_uspace( kbuf, pathname, length );
78
79    // get cluster and local pointer on reference process
80    xptr_t      ref_xp  = process->ref_xp;
81    process_t * ref_ptr = (process_t *)GET_PTR( ref_xp );
82    cxy_t       ref_cxy = GET_CXY( ref_xp );
83
84    // get extended pointer on cwd inode
85    xptr_t cwd_xp = hal_remote_lwd( XPTR( ref_cxy , &ref_ptr->vfs_cwd_xp ) );
86   
87    // get the cwd lock in read mode from reference process
88        remote_rwlock_rd_lock( XPTR( ref_cxy , &ref_ptr->cwd_lock ) );
89
90    // call the relevant VFS function
91        error = vfs_open( cwd_xp,
92                      kbuf,
93                      flags,
94                      mode,
95                      &file_xp,
96                      &file_id );
97
98    // release the cwd lock
99        remote_rwlock_rd_unlock( XPTR( ref_cxy , &ref_ptr->cwd_lock ) );
100
101        if( error )
102        {
103        printk("\n[ERROR] in %s : cannot create file descriptor\n", __FUNCTION__ );
104                this->errno = ENFILE;
105            return -1;
106        }
107
108    // update local fd_array
109    remote_spinlock_lock( XPTR( local_cxy , &process->fd_array.lock ) );
110        process->fd_array.array[file_id] = file_xp;
111    remote_spinlock_unlock( XPTR( local_cxy , &process->fd_array.lock ) );
112
113        return file_id;
114}
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