378 lines
7.1 KiB
C
378 lines
7.1 KiB
C
/*
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* image.c --- writes out the critical parts of the filesystem as a
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* flat file.
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*
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* Copyright (C) 2000 Theodore Ts'o.
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*
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* Note: this uses the POSIX IO interfaces, unlike most of the other
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* functions in this library. So sue me.
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*
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* %Begin-Header%
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* This file may be redistributed under the terms of the GNU Public
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* License.
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* %End-Header%
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*/
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#include <stdio.h>
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#include <string.h>
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#if HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#if HAVE_ERRNO_H
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#include <errno.h>
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#endif
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#include <fcntl.h>
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#include <time.h>
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#if HAVE_SYS_STAT_H
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#include <sys/stat.h>
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#endif
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#if HAVE_SYS_TYPES_H
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#include <sys/types.h>
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#endif
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#include "ext2_fs.h"
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#include "ext2fs.h"
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#ifndef HAVE_TYPE_SSIZE_T
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typedef int ssize_t;
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#endif
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/*
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* This function returns 1 if the specified block is all zeros
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*/
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static int check_zero_block(char *buf, int blocksize)
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{
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char *cp = buf;
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int left = blocksize;
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while (left > 0) {
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if (*cp++)
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return 0;
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left--;
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}
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return 1;
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}
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/*
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* Write the inode table out as a single block.
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*/
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#define BUF_BLOCKS 32
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errcode_t ext2fs_image_inode_write(ext2_filsys fs, int fd, int flags)
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{
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unsigned int group, left, c, d;
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char *buf, *cp;
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blk_t blk;
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ssize_t actual;
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errcode_t retval;
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buf = xmalloc(fs->blocksize * BUF_BLOCKS);
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for (group = 0; group < fs->group_desc_count; group++) {
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blk = fs->group_desc[(unsigned)group].bg_inode_table;
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if (!blk)
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return EXT2_ET_MISSING_INODE_TABLE;
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left = fs->inode_blocks_per_group;
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while (left) {
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c = BUF_BLOCKS;
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if (c > left)
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c = left;
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retval = io_channel_read_blk(fs->io, blk, c, buf);
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if (retval)
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goto errout;
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cp = buf;
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while (c) {
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if (!(flags & IMAGER_FLAG_SPARSEWRITE)) {
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d = c;
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goto skip_sparse;
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}
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/* Skip zero blocks */
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if (check_zero_block(cp, fs->blocksize)) {
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c--;
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blk++;
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left--;
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cp += fs->blocksize;
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lseek(fd, fs->blocksize, SEEK_CUR);
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continue;
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}
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/* Find non-zero blocks */
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for (d=1; d < c; d++) {
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if (check_zero_block(cp + d*fs->blocksize, fs->blocksize))
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break;
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}
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skip_sparse:
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actual = write(fd, cp, fs->blocksize * d);
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if (actual == -1) {
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retval = errno;
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goto errout;
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}
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if (actual != (ssize_t) (fs->blocksize * d)) {
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retval = EXT2_ET_SHORT_WRITE;
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goto errout;
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}
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blk += d;
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left -= d;
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cp += fs->blocksize * d;
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c -= d;
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}
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}
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}
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retval = 0;
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errout:
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free(buf);
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return retval;
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}
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/*
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* Read in the inode table and stuff it into place
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*/
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errcode_t ext2fs_image_inode_read(ext2_filsys fs, int fd,
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int flags EXT2FS_ATTR((unused)))
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{
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unsigned int group, c, left;
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char *buf;
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blk_t blk;
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ssize_t actual;
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errcode_t retval;
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buf = xmalloc(fs->blocksize * BUF_BLOCKS);
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for (group = 0; group < fs->group_desc_count; group++) {
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blk = fs->group_desc[(unsigned)group].bg_inode_table;
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if (!blk) {
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retval = EXT2_ET_MISSING_INODE_TABLE;
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goto errout;
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}
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left = fs->inode_blocks_per_group;
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while (left) {
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c = BUF_BLOCKS;
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if (c > left)
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c = left;
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actual = read(fd, buf, fs->blocksize * c);
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if (actual == -1) {
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retval = errno;
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goto errout;
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}
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if (actual != (ssize_t) (fs->blocksize * c)) {
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retval = EXT2_ET_SHORT_READ;
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goto errout;
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}
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retval = io_channel_write_blk(fs->io, blk, c, buf);
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if (retval)
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goto errout;
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blk += c;
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left -= c;
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}
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}
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retval = ext2fs_flush_icache(fs);
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errout:
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free(buf);
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return retval;
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}
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/*
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* Write out superblock and group descriptors
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*/
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errcode_t ext2fs_image_super_write(ext2_filsys fs, int fd,
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int flags EXT2FS_ATTR((unused)))
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{
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char *buf, *cp;
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ssize_t actual;
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errcode_t retval;
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buf = xmalloc(fs->blocksize);
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/*
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* Write out the superblock
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*/
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memset(buf, 0, fs->blocksize);
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memcpy(buf, fs->super, SUPERBLOCK_SIZE);
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actual = write(fd, buf, fs->blocksize);
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if (actual == -1) {
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retval = errno;
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goto errout;
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}
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if (actual != (ssize_t) fs->blocksize) {
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retval = EXT2_ET_SHORT_WRITE;
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goto errout;
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}
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/*
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* Now write out the block group descriptors
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*/
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cp = (char *) fs->group_desc;
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actual = write(fd, cp, fs->blocksize * fs->desc_blocks);
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if (actual == -1) {
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retval = errno;
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goto errout;
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}
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if (actual != (ssize_t) (fs->blocksize * fs->desc_blocks)) {
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retval = EXT2_ET_SHORT_WRITE;
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goto errout;
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}
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retval = 0;
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errout:
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free(buf);
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return retval;
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}
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/*
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* Read the superblock and group descriptors and overwrite them.
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*/
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errcode_t ext2fs_image_super_read(ext2_filsys fs, int fd,
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int flags EXT2FS_ATTR((unused)))
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{
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char *buf;
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ssize_t actual, size;
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errcode_t retval;
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size = fs->blocksize * (fs->group_desc_count + 1);
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buf = xmalloc(size);
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/*
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* Read it all in.
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*/
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actual = read(fd, buf, size);
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if (actual == -1) {
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retval = errno;
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goto errout;
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}
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if (actual != size) {
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retval = EXT2_ET_SHORT_READ;
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goto errout;
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}
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/*
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* Now copy in the superblock and group descriptors
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*/
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memcpy(fs->super, buf, SUPERBLOCK_SIZE);
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memcpy(fs->group_desc, buf + fs->blocksize,
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fs->blocksize * fs->group_desc_count);
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retval = 0;
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errout:
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free(buf);
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return retval;
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}
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/*
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* Write the block/inode bitmaps.
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*/
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errcode_t ext2fs_image_bitmap_write(ext2_filsys fs, int fd, int flags)
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{
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char *ptr;
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int c, size;
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char zero_buf[1024];
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ssize_t actual;
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errcode_t retval;
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if (flags & IMAGER_FLAG_INODEMAP) {
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if (!fs->inode_map) {
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retval = ext2fs_read_inode_bitmap(fs);
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if (retval)
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return retval;
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}
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ptr = fs->inode_map->bitmap;
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size = (EXT2_INODES_PER_GROUP(fs->super) / 8);
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} else {
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if (!fs->block_map) {
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retval = ext2fs_read_block_bitmap(fs);
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if (retval)
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return retval;
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}
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ptr = fs->block_map->bitmap;
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size = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
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}
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size = size * fs->group_desc_count;
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actual = write(fd, ptr, size);
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if (actual == -1) {
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retval = errno;
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goto errout;
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}
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if (actual != size) {
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retval = EXT2_ET_SHORT_WRITE;
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goto errout;
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}
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size = size % fs->blocksize;
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memset(zero_buf, 0, sizeof(zero_buf));
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if (size) {
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size = fs->blocksize - size;
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while (size) {
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c = size;
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if (c > (int) sizeof(zero_buf))
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c = sizeof(zero_buf);
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actual = write(fd, zero_buf, c);
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if (actual == -1) {
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retval = errno;
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goto errout;
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}
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if (actual != c) {
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retval = EXT2_ET_SHORT_WRITE;
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goto errout;
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}
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size -= c;
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}
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}
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retval = 0;
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errout:
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return (retval);
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}
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/*
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* Read the block/inode bitmaps.
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*/
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errcode_t ext2fs_image_bitmap_read(ext2_filsys fs, int fd, int flags)
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{
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char *ptr, *buf = 0;
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int size;
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ssize_t actual;
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errcode_t retval;
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if (flags & IMAGER_FLAG_INODEMAP) {
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if (!fs->inode_map) {
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retval = ext2fs_read_inode_bitmap(fs);
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if (retval)
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return retval;
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}
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ptr = fs->inode_map->bitmap;
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size = (EXT2_INODES_PER_GROUP(fs->super) / 8);
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} else {
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if (!fs->block_map) {
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retval = ext2fs_read_block_bitmap(fs);
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if (retval)
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return retval;
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}
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ptr = fs->block_map->bitmap;
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size = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
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}
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size = size * fs->group_desc_count;
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buf = xmalloc(size);
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actual = read(fd, buf, size);
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if (actual == -1) {
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retval = errno;
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goto errout;
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}
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if (actual != size) {
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retval = EXT2_ET_SHORT_WRITE;
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goto errout;
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}
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memcpy(ptr, buf, size);
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retval = 0;
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errout:
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if (buf)
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free(buf);
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return (retval);
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}
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