]> git.ipfire.org Git - thirdparty/e2fsprogs.git/blob - lib/ext2fs/fileio.c
projects / thirdparty / e2fsprogs.git / blob
? search:


059bda2dc47ba517b6b2c194677a01a532e68fc4
[thirdparty/e2fsprogs.git] / lib / ext2fs / fileio.c
1 /*
2 * fileio.c --- Simple file I/O routines
3 *
4 * Copyright (C) 1997 Theodore Ts'o.
5 *
6 * %Begin-Header%
7 * This file may be redistributed under the terms of the GNU Library
8 * General Public License, version 2.
9 * %End-Header%
10 */
11
12 #include "config.h"
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
22 struct 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 blk64_t blockno;
30 blk64_t physblock;
31 char *buf;
32 };
33
34 #define BMAP_BUFFER (file->buf + fs->blocksize)
35
36 errcode_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_array(3, fs->blocksize, &file->buf);
70 if (retval)
71 goto fail;
72
73 *ret = file;
74 return 0;
75
76 fail:
77 if (file->buf)
78 ext2fs_free_mem(&file->buf);
79 ext2fs_free_mem(&file);
80 return retval;
81 }
82
83 errcode_t ext2fs_file_open(ext2_filsys fs, ext2_ino_t ino,
84 int flags, ext2_file_t *ret)
85 {
86 return ext2fs_file_open2(fs, ino, NULL, flags, ret);
87 }
88
89 /*
90 * This function returns the filesystem handle of a file from the structure
91 */
92 ext2_filsys ext2fs_file_get_fs(ext2_file_t file)
93 {
94 if (file->magic != EXT2_ET_MAGIC_EXT2_FILE)
95 return 0;
96 return file->fs;
97 }
98
99 /*
100 * This function returns the pointer to the inode of a file from the structure
101 */
102 struct ext2_inode *ext2fs_file_get_inode(ext2_file_t file)
103 {
104 if (file->magic != EXT2_ET_MAGIC_EXT2_FILE)
105 return NULL;
106 return &file->inode;
107 }
108
109 /* This function returns the inode number from the structure */
110 ext2_ino_t ext2fs_file_get_inode_num(ext2_file_t file)
111 {
112 if (file->magic != EXT2_ET_MAGIC_EXT2_FILE)
113 return 0;
114 return file->ino;
115 }
116
117 /*
118 * This function flushes the dirty block buffer out to disk if
119 * necessary.
120 */
121 errcode_t ext2fs_file_flush(ext2_file_t file)
122 {
123 errcode_t retval;
124 ext2_filsys fs;
125
126 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
127 fs = file->fs;
128
129 if (!(file->flags & EXT2_FILE_BUF_VALID) ||
130 !(file->flags & EXT2_FILE_BUF_DIRTY))
131 return 0;
132
133 /*
134 * OK, the physical block hasn't been allocated yet.
135 * Allocate it.
136 */
137 if (!file->physblock) {
138 retval = ext2fs_bmap2(fs, file->ino, &file->inode,
139 BMAP_BUFFER, file->ino ? BMAP_ALLOC : 0,
140 file->blockno, 0, &file->physblock);
141 if (retval)
142 return retval;
143 }
144
145 retval = io_channel_write_blk(fs->io, file->physblock,
146 1, file->buf);
147 if (retval)
148 return retval;
149
150 file->flags &= ~EXT2_FILE_BUF_DIRTY;
151
152 return retval;
153 }
154
155 /*
156 * This function synchronizes the file's block buffer and the current
157 * file position, possibly invalidating block buffer if necessary
158 */
159 static errcode_t sync_buffer_position(ext2_file_t file)
160 {
161 blk64_t b;
162 errcode_t retval;
163
164 b = file->pos / file->fs->blocksize;
165 if (b != file->blockno) {
166 retval = ext2fs_file_flush(file);
167 if (retval)
168 return retval;
169 file->flags &= ~EXT2_FILE_BUF_VALID;
170 }
171 file->blockno = b;
172 return 0;
173 }
174
175 /*
176 * This function loads the file's block buffer with valid data from
177 * the disk as necessary.
178 *
179 * If dontfill is true, then skip initializing the buffer since we're
180 * going to be replacing its entire contents anyway. If set, then the
181 * function basically only sets file->physblock and EXT2_FILE_BUF_VALID
182 */
183 #define DONTFILL 1
184 static errcode_t load_buffer(ext2_file_t file, int dontfill)
185 {
186 ext2_filsys fs = file->fs;
187 errcode_t retval;
188
189 if (!(file->flags & EXT2_FILE_BUF_VALID)) {
190 retval = ext2fs_bmap2(fs, file->ino, &file->inode,
191 BMAP_BUFFER, 0, file->blockno, 0,
192 &file->physblock);
193 if (retval)
194 return retval;
195 if (!dontfill) {
196 if (file->physblock) {
197 retval = io_channel_read_blk(fs->io,
198 file->physblock,
199 1, file->buf);
200 if (retval)
201 return retval;
202 } else
203 memset(file->buf, 0, fs->blocksize);
204 }
205 file->flags |= EXT2_FILE_BUF_VALID;
206 }
207 return 0;
208 }
209
210
211 errcode_t ext2fs_file_close(ext2_file_t file)
212 {
213 errcode_t retval;
214
215 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
216
217 retval = ext2fs_file_flush(file);
218
219 if (file->buf)
220 ext2fs_free_mem(&file->buf);
221 ext2fs_free_mem(&file);
222
223 return retval;
224 }
225
226
227 errcode_t ext2fs_file_read(ext2_file_t file, void *buf,
228 unsigned int wanted, unsigned int *got)
229 {
230 ext2_filsys fs;
231 errcode_t retval = 0;
232 unsigned int start, c, count = 0;
233 __u64 left;
234 char *ptr = (char *) buf;
235
236 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
237 fs = file->fs;
238
239 while ((file->pos < EXT2_I_SIZE(&file->inode)) && (wanted > 0)) {
240 retval = sync_buffer_position(file);
241 if (retval)
242 goto fail;
243 retval = load_buffer(file, 0);
244 if (retval)
245 goto fail;
246
247 start = file->pos % fs->blocksize;
248 c = fs->blocksize - start;
249 if (c > wanted)
250 c = wanted;
251 left = EXT2_I_SIZE(&file->inode) - file->pos ;
252 if (c > left)
253 c = left;
254
255 memcpy(ptr, file->buf+start, c);
256 file->pos += c;
257 ptr += c;
258 count += c;
259 wanted -= c;
260 }
261
262 fail:
263 if (got)
264 *got = count;
265 return retval;
266 }
267
268
269 errcode_t ext2fs_file_write(ext2_file_t file, const void *buf,
270 unsigned int nbytes, unsigned int *written)
271 {
272 ext2_filsys fs;
273 errcode_t retval = 0;
274 unsigned int start, c, count = 0;
275 const char *ptr = (const char *) buf;
276
277 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
278 fs = file->fs;
279
280 if (!(file->flags & EXT2_FILE_WRITE))
281 return EXT2_ET_FILE_RO;
282
283 while (nbytes > 0) {
284 retval = sync_buffer_position(file);
285 if (retval)
286 goto fail;
287
288 start = file->pos % fs->blocksize;
289 c = fs->blocksize - start;
290 if (c > nbytes)
291 c = nbytes;
292
293 /*
294 * We only need to do a read-modify-update cycle if
295 * we're doing a partial write.
296 */
297 retval = load_buffer(file, (c == fs->blocksize));
298 if (retval)
299 goto fail;
300
301 file->flags |= EXT2_FILE_BUF_DIRTY;
302 memcpy(file->buf+start, ptr, c);
303 file->pos += c;
304 ptr += c;
305 count += c;
306 nbytes -= c;
307 }
308
309 fail:
310 /* Update inode size */
311 if (count != 0 && EXT2_I_SIZE(&file->inode) < file->pos) {
312 errcode_t rc;
313
314 rc = ext2fs_file_set_size2(file, file->pos);
315 if (retval == 0)
316 retval = rc;
317 }
318
319 if (written)
320 *written = count;
321 return retval;
322 }
323
324 errcode_t ext2fs_file_llseek(ext2_file_t file, __u64 offset,
325 int whence, __u64 *ret_pos)
326 {
327 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
328
329 if (whence == EXT2_SEEK_SET)
330 file->pos = offset;
331 else if (whence == EXT2_SEEK_CUR)
332 file->pos += offset;
333 else if (whence == EXT2_SEEK_END)
334 file->pos = EXT2_I_SIZE(&file->inode) + offset;
335 else
336 return EXT2_ET_INVALID_ARGUMENT;
337
338 if (ret_pos)
339 *ret_pos = file->pos;
340
341 return 0;
342 }
343
344 errcode_t ext2fs_file_lseek(ext2_file_t file, ext2_off_t offset,
345 int whence, ext2_off_t *ret_pos)
346 {
347 __u64 loffset, ret_loffset;
348 errcode_t retval;
349
350 loffset = offset;
351 retval = ext2fs_file_llseek(file, loffset, whence, &ret_loffset);
352 if (ret_pos)
353 *ret_pos = (ext2_off_t) ret_loffset;
354 return retval;
355 }
356
357
358 /*
359 * This function returns the size of the file, according to the inode
360 */
361 errcode_t ext2fs_file_get_lsize(ext2_file_t file, __u64 *ret_size)
362 {
363 if (file->magic != EXT2_ET_MAGIC_EXT2_FILE)
364 return EXT2_ET_MAGIC_EXT2_FILE;
365 *ret_size = EXT2_I_SIZE(&file->inode);
366 return 0;
367 }
368
369 /*
370 * This function returns the size of the file, according to the inode
371 */
372 ext2_off_t ext2fs_file_get_size(ext2_file_t file)
373 {
374 __u64 size;
375
376 if (ext2fs_file_get_lsize(file, &size))
377 return 0;
378 if ((size >> 32) != 0)
379 return 0;
380 return size;
381 }
382
383 /*
384 * This function sets the size of the file, truncating it if necessary
385 *
386 */
387 errcode_t ext2fs_file_set_size2(ext2_file_t file, ext2_off64_t size)
388 {
389 ext2_off64_t old_size;
390 errcode_t retval;
391 blk64_t old_truncate, truncate_block;
392
393 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
394
395 truncate_block = ((size + file->fs->blocksize - 1) >>
396 EXT2_BLOCK_SIZE_BITS(file->fs->super)) + 1;
397 old_size = EXT2_I_SIZE(&file->inode);
398 old_truncate = ((old_size + file->fs->blocksize - 1) >>
399 EXT2_BLOCK_SIZE_BITS(file->fs->super)) + 1;
400
401 /* If we're writing a large file, set the large_file flag */
402 if (LINUX_S_ISREG(file->inode.i_mode) &&
403 EXT2_I_SIZE(&file->inode) > 0x7FFFFFFULL &&
404 (!EXT2_HAS_RO_COMPAT_FEATURE(file->fs->super,
405 EXT2_FEATURE_RO_COMPAT_LARGE_FILE) ||
406 file->fs->super->s_rev_level == EXT2_GOOD_OLD_REV)) {
407 file->fs->super->s_feature_ro_compat |=
408 EXT2_FEATURE_RO_COMPAT_LARGE_FILE;
409 ext2fs_update_dynamic_rev(file->fs);
410 ext2fs_mark_super_dirty(file->fs);
411 }
412
413 file->inode.i_size = size & 0xffffffff;
414 file->inode.i_size_high = (size >> 32);
415 if (file->ino) {
416 retval = ext2fs_write_inode(file->fs, file->ino, &file->inode);
417 if (retval)
418 return retval;
419 }
420
421 if (truncate_block >= old_truncate)
422 return 0;
423
424 return ext2fs_punch(file->fs, file->ino, &file->inode, 0,
425 truncate_block, ~0ULL);
426 }
427
428 errcode_t ext2fs_file_set_size(ext2_file_t file, ext2_off_t size)
429 {
430 return ext2fs_file_set_size2(file, size);
431 }
Unnamed repository; edit this file 'description' to name the repository.