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
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	blk64_t			blockno;
30	blk64_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_array(3, fs->blocksize, &file->buf);
70	if (retval)
71		goto fail;
72
73	*ret = file;
74	return 0;
75
76fail:
77	if (file->buf)
78		ext2fs_free_mem(&file->buf);
79	ext2fs_free_mem(&file);
80	return retval;
81}
82
83errcode_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 */
92ext2_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 */
102struct 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 */
110ext2_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 */
121errcode_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 */
158static 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
183static 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
210errcode_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
226errcode_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
261fail:
262	if (got)
263		*got = count;
264	return retval;
265}
266
267
268errcode_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
322fail:
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
337errcode_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
357errcode_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 */
374errcode_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 */
385ext2_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. */
397static 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
438out:
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 */
447errcode_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
495errcode_t ext2fs_file_set_size(ext2_file_t file, ext2_off_t size)
496{
497	return ext2fs_file_set_size2(file, size);
498}
499