source: trunk/kernel/syscalls/sys_read.c @ 313

Last change on this file since 313 was 313, checked in by alain, 5 years ago

RSeveral modifs in the page-fault handling.

File size: 3.1 KB
Line 
1/*
2 * sys_read.c - read bytes from 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 <hal_special.h>
28#include <errno.h>
29#include <vfs.h>
30#include <vmm.h>
31#include <thread.h>
32#include <printk.h>
33#include <process.h>
34
35/* TODO: user page(s) need to be locked  [AG] */
36
37/////////////////////////////////
38int sys_read( uint32_t   file_id,
39              void     * buf,
40              uint32_t   count )
41{
42    error_t      error;
43    paddr_t      paddr;       // required for user space checking
44        xptr_t       file_xp;     // remote file extended pointer
45
46        thread_t  *  this    = CURRENT_THREAD;
47        process_t *  process = this->process;
48 
49    // check file_id argument
50        if( file_id >= CONFIG_PROCESS_FILE_MAX_NR )
51        {
52        printk("\n[ERROR] in %s : illegal file descriptor index = %d\n",
53               __FUNCTION__ , file_id );
54                this->errno = EBADFD;
55                return -1;
56        }
57
58    // check user buffer in user space
59    error = vmm_v2p_translate( false , buf , &paddr );
60
61    if ( error )
62    {
63        printk("\n[ERROR] in %s : user buffer unmapped = %x\n",
64               __FUNCTION__ , (intptr_t)buf );
65                this->errno = EINVAL;
66                return -1;
67    }
68
69    // get extended pointer on remote file descriptor
70    file_xp = process_fd_get_xptr( process , file_id );
71
72    if( file_xp == XPTR_NULL )
73    {
74        printk("\n[ERROR] in %s : undefined file descriptor index = %d\n",
75               __FUNCTION__ , file_id );
76        this->errno = EBADFD;
77        return -1;
78    }
79
80    // get file descriptor cluster and local pointer
81    vfs_file_t * file_ptr = (vfs_file_t *)GET_PTR( file_xp );
82    cxy_t        file_cxy = GET_CXY( file_xp );
83
84    // check file readable
85    uint32_t attr = hal_remote_lw( XPTR( file_cxy , &file_ptr->attr ) );
86    if( (attr & FD_ATTR_READ_ENABLE) == 0 )
87        {
88        printk("\n[ERROR] in %s : file %d not readable\n",
89               __FUNCTION__ , file_id );
90                this->errno = EBADFD;
91                return -1;
92        }
93   
94    // transfer count bytes directly from mapper to user buffer
95    error = vfs_user_move( true,               // to_buffer
96                           file_xp , 
97                           buf, 
98                           count );
99
100    if( error )
101    {
102        printk("\n[ERROR] in %s cannot read data from file %d\n",
103               __FUNCTION__ , file_id );
104        this->errno = error;
105        return -1;
106    }
107
108    hal_fence();
109
110        return 0;
111
112}  // end sys_read()
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