rw_bitmaps.c revision 9f8046fc6dfc13eee2f5c363214e60b533872cac 
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#ifdef __powerpc__
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
44void 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
54errcode_t ext2fs_write_inode_bitmap(ext2_filsys fs)
55{
56	dgrp_t 		i;
57	size_t		nbytes;
58	errcode_t	retval;
59	char * inode_bitmap = fs->inode_map->bitmap;
60	char * bitmap_block = NULL;
61	blk_t		blk;
62
63	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
64
65	if (!(fs->flags & EXT2_FLAG_RW))
66		return EXT2_ET_RO_FILSYS;
67	if (!inode_bitmap)
68		return 0;
69	nbytes = (size_t) ((EXT2_INODES_PER_GROUP(fs->super)+7) / 8);
70
71	retval = ext2fs_get_mem(fs->blocksize, (void **) &bitmap_block);
72	if (retval)
73		return retval;
74	memset(bitmap_block, 0xff, fs->blocksize);
75	for (i = 0; i < fs->group_desc_count; i++) {
76		memcpy(bitmap_block, inode_bitmap, nbytes);
77		blk = fs->group_desc[i].bg_inode_bitmap;
78		if (blk) {
79#ifdef EXT2_BIG_ENDIAN_BITMAPS
80			if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
81			      (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)))
82				ext2fs_swap_bitmap(fs, bitmap_block, nbytes);
83#endif
84			retval = io_channel_write_blk(fs->io, blk, 1,
85						      bitmap_block);
86			if (retval)
87				return EXT2_ET_INODE_BITMAP_WRITE;
88		}
89		inode_bitmap += nbytes;
90	}
91	fs->flags |= EXT2_FLAG_CHANGED;
92	fs->flags &= ~EXT2_FLAG_IB_DIRTY;
93	ext2fs_free_mem((void **) &bitmap_block);
94	return 0;
95}
96
97errcode_t ext2fs_write_block_bitmap (ext2_filsys fs)
98{
99	dgrp_t 		i;
100	int		j;
101	int		nbytes;
102	int		nbits;
103	errcode_t	retval;
104	char * block_bitmap = fs->block_map->bitmap;
105	char * bitmap_block = NULL;
106	blk_t		blk;
107
108	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
109
110	if (!(fs->flags & EXT2_FLAG_RW))
111		return EXT2_ET_RO_FILSYS;
112	if (!block_bitmap)
113		return 0;
114	nbytes = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
115	retval = ext2fs_get_mem(fs->blocksize, (void **) &bitmap_block);
116	if (retval)
117		return retval;
118	memset(bitmap_block, 0xff, fs->blocksize);
119	for (i = 0; i < fs->group_desc_count; i++) {
120		memcpy(bitmap_block, block_bitmap, nbytes);
121		if (i == fs->group_desc_count - 1) {
122			/* Force bitmap padding for the last group */
123			nbits = (int) ((fs->super->s_blocks_count
124					- fs->super->s_first_data_block)
125				       % EXT2_BLOCKS_PER_GROUP(fs->super));
126			if (nbits)
127				for (j = nbits; j < fs->blocksize * 8; j++)
128					ext2fs_set_bit(j, bitmap_block);
129		}
130		blk = fs->group_desc[i].bg_block_bitmap;
131		if (blk) {
132#ifdef EXT2_BIG_ENDIAN_BITMAPS
133			if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
134			      (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)))
135				ext2fs_swap_bitmap(fs, bitmap_block, nbytes);
136#endif
137			retval = io_channel_write_blk(fs->io, blk, 1,
138						      bitmap_block);
139			if (retval)
140				return EXT2_ET_BLOCK_BITMAP_WRITE;
141		}
142		block_bitmap += nbytes;
143	}
144	fs->flags |= EXT2_FLAG_CHANGED;
145	fs->flags &= ~EXT2_FLAG_BB_DIRTY;
146	ext2fs_free_mem((void **) &bitmap_block);
147	return 0;
148}
149
150static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block)
151{
152	dgrp_t i;
153	char *block_bitmap = 0, *inode_bitmap = 0;
154	char *buf;
155	errcode_t retval;
156	int block_nbytes = (int) EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
157	int inode_nbytes = (int) EXT2_INODES_PER_GROUP(fs->super) / 8;
158	blk_t	blk;
159
160	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
161
162	fs->write_bitmaps = ext2fs_write_bitmaps;
163
164	retval = ext2fs_get_mem(strlen(fs->device_name) + 80, (void **) &buf);
165	if (retval)
166		return retval;
167	if (do_block) {
168		if (fs->block_map)
169			ext2fs_free_block_bitmap(fs->block_map);
170		sprintf(buf, "block bitmap for %s", fs->device_name);
171		retval = ext2fs_allocate_block_bitmap(fs, buf, &fs->block_map);
172		if (retval)
173			goto cleanup;
174		block_bitmap = fs->block_map->bitmap;
175	}
176	if (do_inode) {
177		if (fs->inode_map)
178			ext2fs_free_inode_bitmap(fs->inode_map);
179		sprintf(buf, "inode bitmap for %s", fs->device_name);
180		retval = ext2fs_allocate_inode_bitmap(fs, buf, &fs->inode_map);
181		if (retval)
182			goto cleanup;
183		inode_bitmap = fs->inode_map->bitmap;
184	}
185	ext2fs_free_mem((void **) &buf);
186
187	if (fs->flags & EXT2_FLAG_IMAGE_FILE) {
188		if (inode_bitmap) {
189			blk = (fs->image_header->offset_inodemap /
190			       fs->blocksize);
191			retval = io_channel_read_blk(fs->io, blk,
192			     -(inode_nbytes * fs->group_desc_count),
193			     inode_bitmap);
194			if (retval)
195				goto cleanup;
196		}
197		if (block_bitmap) {
198			blk = (fs->image_header->offset_blockmap /
199			       fs->blocksize);
200			retval = io_channel_read_blk(fs->io, blk,
201			     -(block_nbytes * fs->group_desc_count),
202			     block_bitmap);
203			if (retval)
204				goto cleanup;
205		}
206		return 0;
207	}
208
209	for (i = 0; i < fs->group_desc_count; i++) {
210		if (block_bitmap) {
211			blk = fs->group_desc[i].bg_block_bitmap;
212			if (blk) {
213				retval = io_channel_read_blk(fs->io, blk,
214					     -block_nbytes, block_bitmap);
215				if (retval) {
216					retval = EXT2_ET_BLOCK_BITMAP_READ;
217					goto cleanup;
218				}
219#ifdef EXT2_BIG_ENDIAN_BITMAPS
220				if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
221				      (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
222					ext2fs_swap_bitmap(fs, block_bitmap, block_nbytes);
223#endif
224			} else
225				memset(block_bitmap, 0, block_nbytes);
226			block_bitmap += block_nbytes;
227		}
228		if (inode_bitmap) {
229			blk = fs->group_desc[i].bg_inode_bitmap;
230			if (blk) {
231				retval = io_channel_read_blk(fs->io, blk,
232					     -inode_nbytes, inode_bitmap);
233				if (retval) {
234					retval = EXT2_ET_INODE_BITMAP_READ;
235					goto cleanup;
236				}
237#ifdef EXT2_BIG_ENDIAN_BITMAPS
238				if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
239				      (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
240					ext2fs_swap_bitmap(fs, inode_bitmap, inode_nbytes);
241#endif
242			} else
243				memset(inode_bitmap, 0, inode_nbytes);
244			inode_bitmap += inode_nbytes;
245		}
246	}
247	return 0;
248
249cleanup:
250	if (do_block) {
251		ext2fs_free_mem((void **) &fs->block_map);
252		fs->block_map = 0;
253	}
254	if (do_inode) {
255		ext2fs_free_mem((void **) &fs->inode_map);
256		fs->inode_map = 0;
257	}
258	if (buf)
259		ext2fs_free_mem((void **) &buf);
260	return retval;
261}
262
263errcode_t ext2fs_read_inode_bitmap (ext2_filsys fs)
264{
265	return read_bitmaps(fs, 1, 0);
266}
267
268errcode_t ext2fs_read_block_bitmap(ext2_filsys fs)
269{
270	return read_bitmaps(fs, 0, 1);
271}
272
273errcode_t ext2fs_read_bitmaps(ext2_filsys fs)
274{
275
276	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
277
278	if (fs->inode_map && fs->block_map)
279		return 0;
280
281	return read_bitmaps(fs, !fs->inode_map, !fs->block_map);
282}
283
284errcode_t ext2fs_write_bitmaps(ext2_filsys fs)
285{
286	errcode_t	retval;
287
288	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
289
290	if (fs->block_map && ext2fs_test_bb_dirty(fs)) {
291		retval = ext2fs_write_block_bitmap(fs);
292		if (retval)
293			return retval;
294	}
295	if (fs->inode_map && ext2fs_test_ib_dirty(fs)) {
296		retval = ext2fs_write_inode_bitmap(fs);
297		if (retval)
298			return retval;
299	}
300	return 0;
301}
302
303