source: trunk/kernel/syscalls/sys_read.c @ 124

Last change on this file since 124 was 124, checked in by max@…, 5 years ago

rename hal_wbflush->hal_fence

File size: 3.7 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;
44    char         kbuf[CONFIG_VFS_KBUF_SIZE];
45
46        xptr_t       file_xp;     // remote file extended pointer
47    uint32_t     nbytes;      // number of bytes in one iteration
48
49        thread_t  *  this    = CURRENT_THREAD;
50        process_t *  process = this->process;
51 
52    // check file_id argument
53        if( file_id >= CONFIG_PROCESS_FILE_MAX_NR )
54        {
55        printk("\n[ERROR] in %s : illegal file descriptor index = %d\n",
56               __FUNCTION__ , file_id );
57                this->errno = EBADFD;
58                return -1;
59        }
60
61    // check user buffer in user space
62    error = vmm_v2p_translate( false , buf , &paddr );
63
64    if ( error )
65    {
66        printk("\n[ERROR] in %s : user buffer unmapped = %x\n",
67               __FUNCTION__ , (intptr_t)buf );
68                this->errno = EINVAL;
69                return -1;
70    }
71
72    // get extended pointer on remote file descriptor
73    file_xp = process_fd_get_xptr( process , file_id );
74
75    if( file_xp == XPTR_NULL )
76    {
77        printk("\n[ERROR] in %s : undefined file descriptor index = %d\n",
78               __FUNCTION__ , file_id );
79        this->errno = EBADFD;
80        return -1;
81    }
82
83    // get file descriptor cluster and local pointer
84    vfs_file_t * file_ptr = (vfs_file_t *)GET_PTR( file_xp );
85    cxy_t        file_cxy = GET_CXY( file_xp );
86
87    // check file readable
88    uint32_t attr = hal_remote_lw( XPTR( file_cxy , &file_ptr->attr ) );
89    if( (attr & FD_ATTR_READ_ENABLE) == 0 )
90        {
91        printk("\n[ERROR] in %s : file %d not readable\n",
92               __FUNCTION__ , file_id );
93                this->errno = EBADFD;
94                return -1;
95        }
96   
97    // transfer at most CONFIG_VFS_KBUF_SIZE bytes per iteration
98    while( count )
99    {
100        if( count <= CONFIG_VFS_KBUF_SIZE ) 
101        {
102            nbytes = count;
103            count  = 0;
104        }
105        else
106        {
107            nbytes = CONFIG_VFS_KBUF_SIZE;
108            count  = count - CONFIG_VFS_KBUF_SIZE;
109        }
110
111        // transfer nbytes to kernel buffer
112        error = vfs_move( true,               // read => (to_buffer = true)
113                          file_xp , 
114                          kbuf , 
115                          nbytes );
116
117        if( error )
118        {
119            printk("\n[ERROR] in %s cannot read data from file %d\n",
120                   __FUNCTION__ , file_id );
121            this->errno = error;
122            return -1;
123        }
124
125        // copy kernel buffer to user space
126        hal_copy_to_uspace( buf , kbuf , nbytes );
127    }
128
129    hal_fence();
130
131        return 0;
132
133}  // end sys_read()
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