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 <stdio.h>
13 #include <string.h>
14 #if HAVE_UNISTD_H
15 #include <unistd.h>
16 #endif
17
18 #include "ext2_fs.h"
19 #include "ext2fs.h"
20 #include "ext2fsP.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
ext2fs_file_open2(ext2_filsys fs,ext2_ino_t ino,struct ext2_inode * inode,int flags,ext2_file_t * ret)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
ext2fs_file_open(ext2_filsys fs,ext2_ino_t ino,int flags,ext2_file_t * ret)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 */
ext2fs_file_get_fs(ext2_file_t file)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 */
ext2fs_file_get_inode(ext2_file_t file)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 */
ext2fs_file_get_inode_num(ext2_file_t file)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 */
ext2fs_file_flush(ext2_file_t file)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_blk64(fs->io, file->physblock, 1, file->buf);
146 if (retval)
147 return retval;
148
149 file->flags &= ~EXT2_FILE_BUF_DIRTY;
150
151 return retval;
152 }
153
154 /*
155 * This function synchronizes the file's block buffer and the current
156 * file position, possibly invalidating block buffer if necessary
157 */
sync_buffer_position(ext2_file_t file)158 static errcode_t sync_buffer_position(ext2_file_t file)
159 {
160 blk64_t b;
161 errcode_t retval;
162
163 b = file->pos / file->fs->blocksize;
164 if (b != file->blockno) {
165 retval = ext2fs_file_flush(file);
166 if (retval)
167 return retval;
168 file->flags &= ~EXT2_FILE_BUF_VALID;
169 }
170 file->blockno = b;
171 return 0;
172 }
173
174 /*
175 * This function loads the file's block buffer with valid data from
176 * the disk as necessary.
177 *
178 * If dontfill is true, then skip initializing the buffer since we're
179 * going to be replacing its entire contents anyway. If set, then the
180 * function basically only sets file->physblock and EXT2_FILE_BUF_VALID
181 */
182 #define DONTFILL 1
load_buffer(ext2_file_t file,int dontfill)183 static errcode_t load_buffer(ext2_file_t file, int dontfill)
184 {
185 ext2_filsys fs = file->fs;
186 errcode_t retval;
187
188 if (!(file->flags & EXT2_FILE_BUF_VALID)) {
189 retval = ext2fs_bmap2(fs, file->ino, &file->inode,
190 BMAP_BUFFER, 0, file->blockno, 0,
191 &file->physblock);
192 if (retval)
193 return retval;
194 if (!dontfill) {
195 if (file->physblock) {
196 retval = io_channel_read_blk64(fs->io,
197 file->physblock,
198 1, file->buf);
199 if (retval)
200 return retval;
201 } else
202 memset(file->buf, 0, fs->blocksize);
203 }
204 file->flags |= EXT2_FILE_BUF_VALID;
205 }
206 return 0;
207 }
208
209
ext2fs_file_close(ext2_file_t file)210 errcode_t ext2fs_file_close(ext2_file_t file)
211 {
212 errcode_t retval;
213
214 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
215
216 retval = ext2fs_file_flush(file);
217
218 if (file->buf)
219 ext2fs_free_mem(&file->buf);
220 ext2fs_free_mem(&file);
221
222 return retval;
223 }
224
225
ext2fs_file_read(ext2_file_t file,void * buf,unsigned int wanted,unsigned int * got)226 errcode_t ext2fs_file_read(ext2_file_t file, void *buf,
227 unsigned int wanted, unsigned int *got)
228 {
229 ext2_filsys fs;
230 errcode_t retval = 0;
231 unsigned int start, c, count = 0;
232 __u64 left;
233 char *ptr = (char *) buf;
234
235 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
236 fs = file->fs;
237
238 while ((file->pos < EXT2_I_SIZE(&file->inode)) && (wanted > 0)) {
239 retval = sync_buffer_position(file);
240 if (retval)
241 goto fail;
242 retval = load_buffer(file, 0);
243 if (retval)
244 goto fail;
245
246 start = file->pos % fs->blocksize;
247 c = fs->blocksize - start;
248 if (c > wanted)
249 c = wanted;
250 left = EXT2_I_SIZE(&file->inode) - file->pos ;
251 if (c > left)
252 c = left;
253
254 memcpy(ptr, file->buf+start, c);
255 file->pos += c;
256 ptr += c;
257 count += c;
258 wanted -= c;
259 }
260
261 fail:
262 if (got)
263 *got = count;
264 return retval;
265 }
266
267
ext2fs_file_write(ext2_file_t file,const void * buf,unsigned int nbytes,unsigned int * written)268 errcode_t ext2fs_file_write(ext2_file_t file, const void *buf,
269 unsigned int nbytes, unsigned int *written)
270 {
271 ext2_filsys fs;
272 errcode_t retval = 0;
273 unsigned int start, c, count = 0;
274 const char *ptr = (const char *) buf;
275
276 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
277 fs = file->fs;
278
279 if (!(file->flags & EXT2_FILE_WRITE))
280 return EXT2_ET_FILE_RO;
281
282 while (nbytes > 0) {
283 retval = sync_buffer_position(file);
284 if (retval)
285 goto fail;
286
287 start = file->pos % fs->blocksize;
288 c = fs->blocksize - start;
289 if (c > nbytes)
290 c = nbytes;
291
292 /*
293 * We only need to do a read-modify-update cycle if
294 * we're doing a partial write.
295 */
296 retval = load_buffer(file, (c == fs->blocksize));
297 if (retval)
298 goto fail;
299
300 /*
301 * OK, the physical block hasn't been allocated yet.
302 * Allocate it.
303 */
304 if (!file->physblock) {
305 retval = ext2fs_bmap2(fs, file->ino, &file->inode,
306 BMAP_BUFFER,
307 file->ino ? BMAP_ALLOC : 0,
308 file->blockno, 0,
309 &file->physblock);
310 if (retval)
311 goto fail;
312 }
313
314 file->flags |= EXT2_FILE_BUF_DIRTY;
315 memcpy(file->buf+start, ptr, c);
316 file->pos += c;
317 ptr += c;
318 count += c;
319 nbytes -= c;
320 }
321
322 fail:
323 /* Update inode size */
324 if (count != 0 && EXT2_I_SIZE(&file->inode) < file->pos) {
325 errcode_t rc;
326
327 rc = ext2fs_file_set_size2(file, file->pos);
328 if (retval == 0)
329 retval = rc;
330 }
331
332 if (written)
333 *written = count;
334 return retval;
335 }
336
ext2fs_file_llseek(ext2_file_t file,__u64 offset,int whence,__u64 * ret_pos)337 errcode_t ext2fs_file_llseek(ext2_file_t file, __u64 offset,
338 int whence, __u64 *ret_pos)
339 {
340 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
341
342 if (whence == EXT2_SEEK_SET)
343 file->pos = offset;
344 else if (whence == EXT2_SEEK_CUR)
345 file->pos += offset;
346 else if (whence == EXT2_SEEK_END)
347 file->pos = EXT2_I_SIZE(&file->inode) + offset;
348 else
349 return EXT2_ET_INVALID_ARGUMENT;
350
351 if (ret_pos)
352 *ret_pos = file->pos;
353
354 return 0;
355 }
356
ext2fs_file_lseek(ext2_file_t file,ext2_off_t offset,int whence,ext2_off_t * ret_pos)357 errcode_t ext2fs_file_lseek(ext2_file_t file, ext2_off_t offset,
358 int whence, ext2_off_t *ret_pos)
359 {
360 __u64 loffset, ret_loffset;
361 errcode_t retval;
362
363 loffset = offset;
364 retval = ext2fs_file_llseek(file, loffset, whence, &ret_loffset);
365 if (ret_pos)
366 *ret_pos = (ext2_off_t) ret_loffset;
367 return retval;
368 }
369
370
371 /*
372 * This function returns the size of the file, according to the inode
373 */
ext2fs_file_get_lsize(ext2_file_t file,__u64 * ret_size)374 errcode_t ext2fs_file_get_lsize(ext2_file_t file, __u64 *ret_size)
375 {
376 if (file->magic != EXT2_ET_MAGIC_EXT2_FILE)
377 return EXT2_ET_MAGIC_EXT2_FILE;
378 *ret_size = EXT2_I_SIZE(&file->inode);
379 return 0;
380 }
381
382 /*
383 * This function returns the size of the file, according to the inode
384 */
ext2fs_file_get_size(ext2_file_t file)385 ext2_off_t ext2fs_file_get_size(ext2_file_t file)
386 {
387 __u64 size;
388
389 if (ext2fs_file_get_lsize(file, &size))
390 return 0;
391 if ((size >> 32) != 0)
392 return 0;
393 return size;
394 }
395
396 /* Zero the parts of the last block that are past EOF. */
ext2fs_file_zero_past_offset(ext2_file_t file,ext2_off64_t offset)397 static errcode_t ext2fs_file_zero_past_offset(ext2_file_t file,
398 ext2_off64_t offset)
399 {
400 ext2_filsys fs = file->fs;
401 char *b = NULL;
402 ext2_off64_t off = offset % fs->blocksize;
403 blk64_t blk;
404 int ret_flags;
405 errcode_t retval;
406
407 if (off == 0)
408 return 0;
409
410 retval = sync_buffer_position(file);
411 if (retval)
412 return retval;
413
414 /* Is there an initialized block at the end? */
415 retval = ext2fs_bmap2(fs, file->ino, NULL, NULL, 0,
416 offset / fs->blocksize, &ret_flags, &blk);
417 if (retval)
418 return retval;
419 if ((blk == 0) || (ret_flags & BMAP_RET_UNINIT))
420 return 0;
421
422 /* Zero to the end of the block */
423 retval = ext2fs_get_mem(fs->blocksize, &b);
424 if (retval)
425 return retval;
426
427 /* Read/zero/write block */
428 retval = io_channel_read_blk64(fs->io, blk, 1, b);
429 if (retval)
430 goto out;
431
432 memset(b + off, 0, fs->blocksize - off);
433
434 retval = io_channel_write_blk64(fs->io, blk, 1, b);
435 if (retval)
436 goto out;
437
438 out:
439 ext2fs_free_mem(&b);
440 return retval;
441 }
442
443 /*
444 * This function sets the size of the file, truncating it if necessary
445 *
446 */
ext2fs_file_set_size2(ext2_file_t file,ext2_off64_t size)447 errcode_t ext2fs_file_set_size2(ext2_file_t file, ext2_off64_t size)
448 {
449 ext2_off64_t old_size;
450 errcode_t retval;
451 blk64_t old_truncate, truncate_block;
452
453 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
454
455 if (size && ext2fs_file_block_offset_too_big(file->fs, &file->inode,
456 (size - 1) / file->fs->blocksize))
457 return EXT2_ET_FILE_TOO_BIG;
458 truncate_block = ((size + file->fs->blocksize - 1) >>
459 EXT2_BLOCK_SIZE_BITS(file->fs->super));
460 old_size = EXT2_I_SIZE(&file->inode);
461 old_truncate = ((old_size + file->fs->blocksize - 1) >>
462 EXT2_BLOCK_SIZE_BITS(file->fs->super));
463
464 /* If we're writing a large file, set the large_file flag */
465 if (LINUX_S_ISREG(file->inode.i_mode) &&
466 ext2fs_needs_large_file_feature(EXT2_I_SIZE(&file->inode)) &&
467 (!EXT2_HAS_RO_COMPAT_FEATURE(file->fs->super,
468 EXT2_FEATURE_RO_COMPAT_LARGE_FILE) ||
469 file->fs->super->s_rev_level == EXT2_GOOD_OLD_REV)) {
470 file->fs->super->s_feature_ro_compat |=
471 EXT2_FEATURE_RO_COMPAT_LARGE_FILE;
472 ext2fs_update_dynamic_rev(file->fs);
473 ext2fs_mark_super_dirty(file->fs);
474 }
475
476 file->inode.i_size = size & 0xffffffff;
477 file->inode.i_size_high = (size >> 32);
478 if (file->ino) {
479 retval = ext2fs_write_inode(file->fs, file->ino, &file->inode);
480 if (retval)
481 return retval;
482 }
483
484 retval = ext2fs_file_zero_past_offset(file, size);
485 if (retval)
486 return retval;
487
488 if (truncate_block >= old_truncate)
489 return 0;
490
491 return ext2fs_punch(file->fs, file->ino, &file->inode, 0,
492 truncate_block, ~0ULL);
493 }
494
ext2fs_file_set_size(ext2_file_t file,ext2_off_t size)495 errcode_t ext2fs_file_set_size(ext2_file_t file, ext2_off_t size)
496 {
497 return ext2fs_file_set_size2(file, size);
498 }
499