Rev 2404 | Go to most recent revision | Details | Compare with Previous | Last modification | View Log | RSS feed
Rev | Author | Line No. | Line |
---|---|---|---|
2404 | konopa | 1 | /* |
2 | * Copyright (c) 1987,1997, Prentice Hall |
||
3 | * All rights reserved. |
||
4 | * |
||
5 | * Redistribution and use of the MINIX operating system in source and |
||
6 | * binary forms, with or without modification, are permitted provided |
||
7 | * that the following conditions are met: |
||
8 | |||
9 | * - Redistributions of source code must retain the above copyright |
||
10 | * notice, this list of conditions and the following disclaimer. |
||
11 | |||
12 | * - Redistributions in binary form must reproduce the above |
||
13 | * copyright notice, this list of conditions and the following |
||
14 | * disclaimer in the documentation and/or other materials provided |
||
15 | * with the distribution. |
||
16 | |||
17 | * - Neither the name of Prentice Hall nor the names of the software |
||
18 | * authors or contributors may be used to endorse or promote |
||
19 | * products derived from this software without specific prior |
||
20 | * written permission. |
||
21 | |||
22 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS, AUTHORS, AND |
||
23 | * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, |
||
24 | * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF |
||
25 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
||
26 | * IN NO EVENT SHALL PRENTICE HALL OR ANY AUTHORS OR CONTRIBUTORS BE |
||
27 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
||
28 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
||
29 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR |
||
30 | * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
||
31 | * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE |
||
32 | * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, |
||
33 | * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
||
34 | */ |
||
2435 | jelen | 35 | |
36 | /** @addtogroup FileSystemImpl |
||
37 | * @{ |
||
38 | */ |
||
2404 | konopa | 39 | |
2435 | jelen | 40 | /** |
41 | * @file open.c |
||
42 | * @brief This file contains the procedures for opening, closing, and seeking on files. |
||
2374 | konopa | 43 | */ |
44 | |||
45 | #include "fs.h" |
||
46 | #include "block.h" |
||
47 | #include "file.h" |
||
48 | #include "fproc.h" |
||
49 | #include "inode.h" |
||
50 | #include "param.h" |
||
51 | |||
2435 | jelen | 52 | /** |
53 | * Perform the OPEN system call |
||
54 | */ |
||
2374 | konopa | 55 | int do_open() |
56 | { |
||
57 | |||
58 | /* Perform the open(file_name) system call */ |
||
59 | |||
60 | int r; |
||
61 | register inode_t *rip; |
||
62 | filp_t *fil_ptr; |
||
63 | |||
64 | |||
65 | r = fetch_name(file_name, strlen(file_name)+1); |
||
66 | if (r != OK) |
||
67 | return err_code; /* name was bad */ |
||
68 | |||
69 | /* See if file descriptor and filp slots are available. */ |
||
70 | if ( (r = get_fd(0, &fd, &fil_ptr)) != OK) |
||
71 | return r; |
||
72 | |||
73 | /* Scan path name. */ |
||
74 | if ( (rip = eat_path(user_path)) == NIL_INODE) |
||
75 | return err_code; |
||
76 | |||
77 | /* Claim the file descriptor and filp slot and fill them in. */ |
||
78 | fp->fp_filp[fd] = fil_ptr; |
||
79 | fil_ptr->filp_count = 1; |
||
80 | fil_ptr->filp_ino = rip; |
||
81 | fil_ptr->filp_flags = R_BIT; |
||
82 | |||
83 | return fd; |
||
84 | } |
||
85 | |||
2435 | jelen | 86 | /** |
87 | * Perform the CLOSE system call |
||
88 | */ |
||
2374 | konopa | 89 | int do_close() |
90 | { |
||
91 | |||
92 | /* Perform the close(fd) system call. */ |
||
93 | |||
94 | register filp_t *rfilp; |
||
95 | register inode_t *rip; |
||
96 | |||
97 | |||
98 | /* First locate the inode that belongs to the file descriptor */ |
||
99 | if ( (rfilp = get_filp(fd)) == NIL_FILP) |
||
100 | return err_code; |
||
101 | |||
102 | rip = rfilp->filp_ino; /* 'rip' points to the inode */ |
||
103 | |||
104 | if (--rfilp->filp_count == 0) { |
||
105 | put_inode(rip); |
||
106 | } |
||
107 | |||
108 | fp->fp_filp[fd] = NIL_FILP; |
||
109 | |||
110 | return OK; |
||
111 | } |
||
112 | |||
2435 | jelen | 113 | /** |
114 | * Perform the SEEK system call |
||
115 | */ |
||
2374 | konopa | 116 | int do_lseek() |
117 | { |
||
118 | |||
119 | /* Perform the seek(ls_fd, offset, whence) system call. */ |
||
120 | |||
121 | register filp_t *rfilp; |
||
122 | register offset_t pos, new_pos; |
||
123 | |||
124 | |||
125 | /* Check to see if the file descriptor is valid. */ |
||
126 | if ( (rfilp = get_filp(fd)) == NIL_FILP) |
||
127 | return err_code; |
||
128 | |||
129 | |||
130 | /* The value of 'whence' determines the start position to use. */ |
||
131 | switch(whence) { |
||
132 | case 0: pos = 0; |
||
133 | break; |
||
134 | case 1: pos = rfilp->filp_pos; |
||
135 | break; |
||
136 | case 2: pos = rfilp->filp_ino->i_size; |
||
137 | break; |
||
138 | default: return FS_EINVAL; |
||
139 | } |
||
140 | |||
141 | /* Check for overflow. */ |
||
142 | if (((long)offset > 0) && ((long)(pos + offset) < (long)pos)) |
||
143 | return FS_EINVAL; |
||
144 | if (((long)offset < 0) && ((long)(pos + offset) > (long)pos)) |
||
145 | return FS_EINVAL; |
||
146 | |||
147 | new_pos = pos + offset; |
||
148 | |||
149 | /* Check for setting behind the end. */ |
||
150 | if ((new_pos) > rfilp->filp_ino->i_size) { |
||
151 | pos = rfilp->filp_ino->i_size; |
||
152 | } |
||
153 | else if (new_pos < 0) { |
||
154 | pos = 0; |
||
155 | } |
||
156 | else { |
||
157 | pos = new_pos; |
||
158 | } |
||
159 | rfilp->filp_pos = pos; |
||
160 | |||
161 | return pos; |
||
162 | } |
||
163 | |||
2435 | jelen | 164 | /** |
165 | * } |
||
166 | */ |
||
167 |