1/*
2 * rw_bitmaps.c --- routines to read and write the  inode and block bitmaps.
3 *
4 * Copyright (C) 1993, 1994, 1994, 1996 Theodore Ts'o.
5 *
6 * %Begin-Header%
7 * This file may be redistributed under the terms of the GNU Public
8 * License.
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#include <fcntl.h>
18#include <time.h>
19#ifdef HAVE_SYS_STAT_H
20#include <sys/stat.h>
21#endif
22#ifdef HAVE_SYS_TYPES_H
23#include <sys/types.h>
24#endif
25
26#include "ext2_fs.h"
27#include "ext2fs.h"
28#include "e2image.h"
29
30#if defined(__powerpc__) && defined(EXT2FS_ENABLE_SWAPFS)
31/*
32 * On the PowerPC, the big-endian variant of the ext2 filesystem
33 * has its bitmaps stored as 32-bit words with bit 0 as the LSB
34 * of each word.  Thus a bitmap with only bit 0 set would be, as
35 * a string of bytes, 00 00 00 01 00 ...
36 * To cope with this, we byte-reverse each word of a bitmap if
37 * we have a big-endian filesystem, that is, if we are *not*
38 * byte-swapping other word-sized numbers.
39 */
40#define EXT2_BIG_ENDIAN_BITMAPS
41#endif
42
43#ifdef EXT2_BIG_ENDIAN_BITMAPS
44static void ext2fs_swap_bitmap(ext2_filsys fs, char *bitmap, int nbytes)
45{
46	__u32 *p = (__u32 *) bitmap;
47	int n;
48
49	for (n = nbytes / sizeof(__u32); n > 0; --n, ++p)
50		*p = ext2fs_swab32(*p);
51}
52#endif
53
54static errcode_t write_bitmaps(ext2_filsys fs, int do_inode, int do_block)
55{
56	dgrp_t 		i;
57	unsigned int	j;
58	int		block_nbytes, inode_nbytes;
59	unsigned int	nbits;
60	errcode_t	retval;
61	char 		*block_bitmap, *inode_bitmap;
62	char 		*block_buf, *inode_buf;
63	int		lazy_flag = 0;
64	blk_t		blk;
65
66	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
67
68	if (!(fs->flags & EXT2_FLAG_RW))
69		return EXT2_ET_RO_FILSYS;
70	if (EXT2_HAS_COMPAT_FEATURE(fs->super,
71				    EXT2_FEATURE_COMPAT_LAZY_BG))
72		lazy_flag = 1;
73	inode_nbytes = block_nbytes = 0;
74	block_bitmap = inode_bitmap = 0;
75	if (do_block) {
76		block_bitmap = fs->block_map->bitmap;
77		block_nbytes = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
78		retval = ext2fs_get_mem(fs->blocksize, &block_buf);
79		if (retval)
80			return retval;
81		memset(block_buf, 0xff, fs->blocksize);
82	}
83	if (do_inode) {
84		inode_bitmap = fs->inode_map->bitmap;
85		inode_nbytes = (size_t)
86			((EXT2_INODES_PER_GROUP(fs->super)+7) / 8);
87		retval = ext2fs_get_mem(fs->blocksize, &inode_buf);
88		if (retval)
89			return retval;
90		memset(inode_buf, 0xff, fs->blocksize);
91	}
92
93	for (i = 0; i < fs->group_desc_count; i++) {
94		if (!block_bitmap || !do_block)
95			goto skip_block_bitmap;
96
97		if (lazy_flag && fs->group_desc[i].bg_flags &
98		    EXT2_BG_BLOCK_UNINIT)
99			goto skip_this_block_bitmap;
100
101		memcpy(block_buf, block_bitmap, block_nbytes);
102		if (i == fs->group_desc_count - 1) {
103			/* Force bitmap padding for the last group */
104			nbits = ((fs->super->s_blocks_count
105				  - fs->super->s_first_data_block)
106				 % EXT2_BLOCKS_PER_GROUP(fs->super));
107			if (nbits)
108				for (j = nbits; j < fs->blocksize * 8; j++)
109					ext2fs_set_bit(j, block_buf);
110		}
111		blk = fs->group_desc[i].bg_block_bitmap;
112		if (blk) {
113#ifdef EXT2_BIG_ENDIAN_BITMAPS
114			if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
115			      (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)))
116				ext2fs_swap_bitmap(fs, block_buf,
117						   block_nbytes);
118#endif
119			retval = io_channel_write_blk(fs->io, blk, 1,
120						      block_buf);
121			if (retval)
122				return EXT2_ET_BLOCK_BITMAP_WRITE;
123		}
124	skip_this_block_bitmap:
125		block_bitmap += block_nbytes;
126	skip_block_bitmap:
127
128		if (!inode_bitmap || !do_inode)
129			continue;
130
131		if (lazy_flag && fs->group_desc[i].bg_flags &
132		    EXT2_BG_INODE_UNINIT)
133			goto skip_this_inode_bitmap;
134
135		memcpy(inode_buf, inode_bitmap, inode_nbytes);
136		blk = fs->group_desc[i].bg_inode_bitmap;
137		if (blk) {
138#ifdef EXT2_BIG_ENDIAN_BITMAPS
139			if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
140			      (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)))
141				ext2fs_swap_bitmap(fs, inode_buf,
142						   inode_nbytes);
143#endif
144			retval = io_channel_write_blk(fs->io, blk, 1,
145						      inode_buf);
146			if (retval)
147				return EXT2_ET_INODE_BITMAP_WRITE;
148		}
149	skip_this_inode_bitmap:
150		inode_bitmap += inode_nbytes;
151
152	}
153	if (do_block) {
154		fs->flags &= ~EXT2_FLAG_BB_DIRTY;
155		ext2fs_free_mem(&block_buf);
156	}
157	if (do_inode) {
158		fs->flags &= ~EXT2_FLAG_IB_DIRTY;
159		ext2fs_free_mem(&inode_buf);
160	}
161	return 0;
162}
163
164static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block)
165{
166	dgrp_t i;
167	char *block_bitmap = 0, *inode_bitmap = 0;
168	char *buf;
169	errcode_t retval;
170	int block_nbytes = (int) EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
171	int inode_nbytes = (int) EXT2_INODES_PER_GROUP(fs->super) / 8;
172	int lazy_flag = 0;
173	blk_t	blk;
174
175	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
176
177	fs->write_bitmaps = ext2fs_write_bitmaps;
178
179	if (EXT2_HAS_COMPAT_FEATURE(fs->super,
180				    EXT2_FEATURE_COMPAT_LAZY_BG))
181		lazy_flag = 1;
182
183	retval = ext2fs_get_mem(strlen(fs->device_name) + 80, &buf);
184	if (retval)
185		return retval;
186	if (do_block) {
187		if (fs->block_map)
188			ext2fs_free_block_bitmap(fs->block_map);
189		sprintf(buf, "block bitmap for %s", fs->device_name);
190		retval = ext2fs_allocate_block_bitmap(fs, buf, &fs->block_map);
191		if (retval)
192			goto cleanup;
193		block_bitmap = fs->block_map->bitmap;
194	}
195	if (do_inode) {
196		if (fs->inode_map)
197			ext2fs_free_inode_bitmap(fs->inode_map);
198		sprintf(buf, "inode bitmap for %s", fs->device_name);
199		retval = ext2fs_allocate_inode_bitmap(fs, buf, &fs->inode_map);
200		if (retval)
201			goto cleanup;
202		inode_bitmap = fs->inode_map->bitmap;
203	}
204	ext2fs_free_mem(&buf);
205
206	if (fs->flags & EXT2_FLAG_IMAGE_FILE) {
207		if (inode_bitmap) {
208			blk = (fs->image_header->offset_inodemap /
209			       fs->blocksize);
210			retval = io_channel_read_blk(fs->image_io, blk,
211			     -(inode_nbytes * fs->group_desc_count),
212			     inode_bitmap);
213			if (retval)
214				goto cleanup;
215		}
216		if (block_bitmap) {
217			blk = (fs->image_header->offset_blockmap /
218			       fs->blocksize);
219			retval = io_channel_read_blk(fs->image_io, blk,
220			     -(block_nbytes * fs->group_desc_count),
221			     block_bitmap);
222			if (retval)
223				goto cleanup;
224		}
225		return 0;
226	}
227
228	for (i = 0; i < fs->group_desc_count; i++) {
229		if (block_bitmap) {
230			blk = fs->group_desc[i].bg_block_bitmap;
231			if (lazy_flag && fs->group_desc[i].bg_flags &
232			    EXT2_BG_BLOCK_UNINIT)
233				blk = 0;
234			if (blk) {
235				retval = io_channel_read_blk(fs->io, blk,
236					     -block_nbytes, block_bitmap);
237				if (retval) {
238					retval = EXT2_ET_BLOCK_BITMAP_READ;
239					goto cleanup;
240				}
241#ifdef EXT2_BIG_ENDIAN_BITMAPS
242				if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
243				      (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
244					ext2fs_swap_bitmap(fs, block_bitmap, block_nbytes);
245#endif
246			} else
247				memset(block_bitmap, 0xff, block_nbytes);
248			block_bitmap += block_nbytes;
249		}
250		if (inode_bitmap) {
251			blk = fs->group_desc[i].bg_inode_bitmap;
252			if (lazy_flag && fs->group_desc[i].bg_flags &
253			    EXT2_BG_INODE_UNINIT)
254				blk = 0;
255			if (blk) {
256				retval = io_channel_read_blk(fs->io, blk,
257					     -inode_nbytes, inode_bitmap);
258				if (retval) {
259					retval = EXT2_ET_INODE_BITMAP_READ;
260					goto cleanup;
261				}
262#ifdef EXT2_BIG_ENDIAN_BITMAPS
263				if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
264				      (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
265					ext2fs_swap_bitmap(fs, inode_bitmap, inode_nbytes);
266#endif
267			} else
268				memset(inode_bitmap, 0xff, inode_nbytes);
269			inode_bitmap += inode_nbytes;
270		}
271	}
272	return 0;
273
274cleanup:
275	if (do_block) {
276		ext2fs_free_mem(&fs->block_map);
277		fs->block_map = 0;
278	}
279	if (do_inode) {
280		ext2fs_free_mem(&fs->inode_map);
281		fs->inode_map = 0;
282	}
283	if (buf)
284		ext2fs_free_mem(&buf);
285	return retval;
286}
287
288errcode_t ext2fs_read_inode_bitmap(ext2_filsys fs)
289{
290	return read_bitmaps(fs, 1, 0);
291}
292
293errcode_t ext2fs_read_block_bitmap(ext2_filsys fs)
294{
295	return read_bitmaps(fs, 0, 1);
296}
297
298errcode_t ext2fs_write_inode_bitmap(ext2_filsys fs)
299{
300	return write_bitmaps(fs, 1, 0);
301}
302
303errcode_t ext2fs_write_block_bitmap (ext2_filsys fs)
304{
305	return write_bitmaps(fs, 0, 1);
306}
307
308errcode_t ext2fs_read_bitmaps(ext2_filsys fs)
309{
310	if (fs->inode_map && fs->block_map)
311		return 0;
312
313	return read_bitmaps(fs, !fs->inode_map, !fs->block_map);
314}
315
316errcode_t ext2fs_write_bitmaps(ext2_filsys fs)
317{
318	int do_inode = fs->inode_map && ext2fs_test_ib_dirty(fs);
319	int do_block = fs->block_map && ext2fs_test_bb_dirty(fs);
320
321	if (!do_inode && !do_block)
322		return 0;
323
324	return write_bitmaps(fs, do_inode, do_block);
325}
326