source: MondoRescue/branches/2.2.5/mindi-busybox/e2fsprogs/old_e2fsprogs/ext2fs/fileio.c@ 1765

Last change on this file since 1765 was 1765, checked in by Bruno Cornec, 16 years ago

Update to busybox 1.7.2
  • Property svn:eol-style set to native
File size: 7.7 KB
Line 
1/* vi: set sw=4 ts=4: */
2/*
3 * fileio.c --- Simple file I/O routines
4 *
5 * Copyright (C) 1997 Theodore Ts'o.
6 *
7 * %Begin-Header%
8 * This file may be redistributed under the terms of the GNU Public
9 * License.
10 * %End-Header%
11 */
12
13#include <stdio.h>
14#include <string.h>
15#if HAVE_UNISTD_H
16#include <unistd.h>
17#endif
18
19#include "ext2_fs.h"
20#include "ext2fs.h"
21
22struct ext2_file {
23 errcode_t magic;
24 ext2_filsys fs;
25 ext2_ino_t ino;
26 struct ext2_inode inode;
27 int flags;
28 __u64 pos;
29 blk_t blockno;
30 blk_t physblock;
31 char *buf;
32};
33
34#define BMAP_BUFFER (file->buf + fs->blocksize)
35
36errcode_t ext2fs_file_open2(ext2_filsys fs, ext2_ino_t ino,
37 struct ext2_inode *inode,
38 int flags, ext2_file_t *ret)
39{
40 ext2_file_t file;
41 errcode_t retval;
42
43 /*
44 * Don't let caller create or open a file for writing if the
45 * filesystem is read-only.
46 */
47 if ((flags & (EXT2_FILE_WRITE | EXT2_FILE_CREATE)) &&
48 !(fs->flags & EXT2_FLAG_RW))
49 return EXT2_ET_RO_FILSYS;
50
51 retval = ext2fs_get_mem(sizeof(struct ext2_file), &file);
52 if (retval)
53 return retval;
54
55 memset(file, 0, sizeof(struct ext2_file));
56 file->magic = EXT2_ET_MAGIC_EXT2_FILE;
57 file->fs = fs;
58 file->ino = ino;
59 file->flags = flags & EXT2_FILE_MASK;
60
61 if (inode) {
62 memcpy(&file->inode, inode, sizeof(struct ext2_inode));
63 } else {
64 retval = ext2fs_read_inode(fs, ino, &file->inode);
65 if (retval)
66 goto fail;
67 }
68
69 retval = ext2fs_get_mem(fs->blocksize * 3, &file->buf);
70 if (retval)
71 goto fail;
72
73 *ret = file;
74 return 0;
75
76fail:
77 ext2fs_free_mem(&file->buf);
78 ext2fs_free_mem(&file);
79 return retval;
80}
81
82errcode_t ext2fs_file_open(ext2_filsys fs, ext2_ino_t ino,
83 int flags, ext2_file_t *ret)
84{
85 return ext2fs_file_open2(fs, ino, NULL, flags, ret);
86}
87
88/*
89 * This function returns the filesystem handle of a file from the structure
90 */
91ext2_filsys ext2fs_file_get_fs(ext2_file_t file)
92{
93 if (file->magic != EXT2_ET_MAGIC_EXT2_FILE)
94 return 0;
95 return file->fs;
96}
97
98/*
99 * This function flushes the dirty block buffer out to disk if
100 * necessary.
101 */
102errcode_t ext2fs_file_flush(ext2_file_t file)
103{
104 errcode_t retval;
105 ext2_filsys fs;
106
107 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
108 fs = file->fs;
109
110 if (!(file->flags & EXT2_FILE_BUF_VALID) ||
111 !(file->flags & EXT2_FILE_BUF_DIRTY))
112 return 0;
113
114 /*
115 * OK, the physical block hasn't been allocated yet.
116 * Allocate it.
117 */
118 if (!file->physblock) {
119 retval = ext2fs_bmap(fs, file->ino, &file->inode,
120 BMAP_BUFFER, file->ino ? BMAP_ALLOC : 0,
121 file->blockno, &file->physblock);
122 if (retval)
123 return retval;
124 }
125
126 retval = io_channel_write_blk(fs->io, file->physblock,
127 1, file->buf);
128 if (retval)
129 return retval;
130
131 file->flags &= ~EXT2_FILE_BUF_DIRTY;
132
133 return retval;
134}
135
136/*
137 * This function synchronizes the file's block buffer and the current
138 * file position, possibly invalidating block buffer if necessary
139 */
140static errcode_t sync_buffer_position(ext2_file_t file)
141{
142 blk_t b;
143 errcode_t retval;
144
145 b = file->pos / file->fs->blocksize;
146 if (b != file->blockno) {
147 retval = ext2fs_file_flush(file);
148 if (retval)
149 return retval;
150 file->flags &= ~EXT2_FILE_BUF_VALID;
151 }
152 file->blockno = b;
153 return 0;
154}
155
156/*
157 * This function loads the file's block buffer with valid data from
158 * the disk as necessary.
159 *
160 * If dontfill is true, then skip initializing the buffer since we're
161 * going to be replacing its entire contents anyway. If set, then the
162 * function basically only sets file->physblock and EXT2_FILE_BUF_VALID
163 */
164#define DONTFILL 1
165static errcode_t load_buffer(ext2_file_t file, int dontfill)
166{
167 ext2_filsys fs = file->fs;
168 errcode_t retval;
169
170 if (!(file->flags & EXT2_FILE_BUF_VALID)) {
171 retval = ext2fs_bmap(fs, file->ino, &file->inode,
172 BMAP_BUFFER, 0, file->blockno,
173 &file->physblock);
174 if (retval)
175 return retval;
176 if (!dontfill) {
177 if (file->physblock) {
178 retval = io_channel_read_blk(fs->io,
179 file->physblock,
180 1, file->buf);
181 if (retval)
182 return retval;
183 } else
184 memset(file->buf, 0, fs->blocksize);
185 }
186 file->flags |= EXT2_FILE_BUF_VALID;
187 }
188 return 0;
189}
190
191
192errcode_t ext2fs_file_close(ext2_file_t file)
193{
194 errcode_t retval;
195
196 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
197
198 retval = ext2fs_file_flush(file);
199
200 ext2fs_free_mem(&file->buf);
201 ext2fs_free_mem(&file);
202
203 return retval;
204}
205
206
207errcode_t ext2fs_file_read(ext2_file_t file, void *buf,
208 unsigned int wanted, unsigned int *got)
209{
210 ext2_filsys fs;
211 errcode_t retval = 0;
212 unsigned int start, c, count = 0;
213 __u64 left;
214 char *ptr = (char *) buf;
215
216 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
217 fs = file->fs;
218
219 while ((file->pos < EXT2_I_SIZE(&file->inode)) && (wanted > 0)) {
220 retval = sync_buffer_position(file);
221 if (retval)
222 goto fail;
223 retval = load_buffer(file, 0);
224 if (retval)
225 goto fail;
226
227 start = file->pos % fs->blocksize;
228 c = fs->blocksize - start;
229 if (c > wanted)
230 c = wanted;
231 left = EXT2_I_SIZE(&file->inode) - file->pos;
232 if (c > left)
233 c = left;
234
235 memcpy(ptr, file->buf+start, c);
236 file->pos += c;
237 ptr += c;
238 count += c;
239 wanted -= c;
240 }
241
242fail:
243 if (got)
244 *got = count;
245 return retval;
246}
247
248
249errcode_t ext2fs_file_write(ext2_file_t file, const void *buf,
250 unsigned int nbytes, unsigned int *written)
251{
252 ext2_filsys fs;
253 errcode_t retval = 0;
254 unsigned int start, c, count = 0;
255 const char *ptr = (const char *) buf;
256
257 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
258 fs = file->fs;
259
260 if (!(file->flags & EXT2_FILE_WRITE))
261 return EXT2_ET_FILE_RO;
262
263 while (nbytes > 0) {
264 retval = sync_buffer_position(file);
265 if (retval)
266 goto fail;
267
268 start = file->pos % fs->blocksize;
269 c = fs->blocksize - start;
270 if (c > nbytes)
271 c = nbytes;
272
273 /*
274 * We only need to do a read-modify-update cycle if
275 * we're doing a partial write.
276 */
277 retval = load_buffer(file, (c == fs->blocksize));
278 if (retval)
279 goto fail;
280
281 file->flags |= EXT2_FILE_BUF_DIRTY;
282 memcpy(file->buf+start, ptr, c);
283 file->pos += c;
284 ptr += c;
285 count += c;
286 nbytes -= c;
287 }
288
289fail:
290 if (written)
291 *written = count;
292 return retval;
293}
294
295errcode_t ext2fs_file_llseek(ext2_file_t file, __u64 offset,
296 int whence, __u64 *ret_pos)
297{
298 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
299
300 if (whence == EXT2_SEEK_SET)
301 file->pos = offset;
302 else if (whence == EXT2_SEEK_CUR)
303 file->pos += offset;
304 else if (whence == EXT2_SEEK_END)
305 file->pos = EXT2_I_SIZE(&file->inode) + offset;
306 else
307 return EXT2_ET_INVALID_ARGUMENT;
308
309 if (ret_pos)
310 *ret_pos = file->pos;
311
312 return 0;
313}
314
315errcode_t ext2fs_file_lseek(ext2_file_t file, ext2_off_t offset,
316 int whence, ext2_off_t *ret_pos)
317{
318 __u64 loffset, ret_loffset;
319 errcode_t retval;
320
321 loffset = offset;
322 retval = ext2fs_file_llseek(file, loffset, whence, &ret_loffset);
323 if (ret_pos)
324 *ret_pos = (ext2_off_t) ret_loffset;
325 return retval;
326}
327
328
329/*
330 * This function returns the size of the file, according to the inode
331 */
332errcode_t ext2fs_file_get_lsize(ext2_file_t file, __u64 *ret_size)
333{
334 if (file->magic != EXT2_ET_MAGIC_EXT2_FILE)
335 return EXT2_ET_MAGIC_EXT2_FILE;
336 *ret_size = EXT2_I_SIZE(&file->inode);
337 return 0;
338}
339
340/*
341 * This function returns the size of the file, according to the inode
342 */
343ext2_off_t ext2fs_file_get_size(ext2_file_t file)
344{
345 __u64 size;
346
347 if (ext2fs_file_get_lsize(file, &size))
348 return 0;
349 if ((size >> 32) != 0)
350 return 0;
351 return size;
352}
353
354/*
355 * This function sets the size of the file, truncating it if necessary
356 *
357 * XXX still need to call truncate
358 */
359errcode_t ext2fs_file_set_size(ext2_file_t file, ext2_off_t size)
360{
361 errcode_t retval;
362 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
363
364 file->inode.i_size = size;
365 file->inode.i_size_high = 0;
366 if (file->ino) {
367 retval = ext2fs_write_inode(file->fs, file->ino, &file->inode);
368 if (retval)
369 return retval;
370 }
371
372 /*
373 * XXX truncate inode if necessary
374 */
375
376 return 0;
377}
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