[3320] | 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * image.c --- writes out the critical parts of the filesystem as a
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| 4 | * flat file.
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| 5 | *
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| 6 | * Copyright (C) 2000 Theodore Ts'o.
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| 7 | *
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| 8 | * Note: this uses the POSIX IO interfaces, unlike most of the other
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| 9 | * functions in this library. So sue me.
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| 10 | *
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| 11 | * %Begin-Header%
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| 12 | * This file may be redistributed under the terms of the GNU Public
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| 13 | * License.
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| 14 | * %End-Header%
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| 15 | */
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| 16 |
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| 17 | #include <stdio.h>
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| 18 | #include <string.h>
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| 19 | #if HAVE_UNISTD_H
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| 20 | #include <unistd.h>
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| 21 | #endif
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| 22 | #if HAVE_ERRNO_H
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| 23 | #include <errno.h>
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| 24 | #endif
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| 25 | #include <fcntl.h>
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| 26 | #include <time.h>
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| 27 | #if HAVE_SYS_STAT_H
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| 28 | #include <sys/stat.h>
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| 29 | #endif
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| 30 | #if HAVE_SYS_TYPES_H
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| 31 | #include <sys/types.h>
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| 32 | #endif
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| 33 |
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| 34 | #include "ext2_fs.h"
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| 35 | #include "ext2fs.h"
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| 36 |
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| 37 | #ifndef HAVE_TYPE_SSIZE_T
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| 38 | typedef int ssize_t;
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| 39 | #endif
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| 40 |
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| 41 | /*
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| 42 | * This function returns 1 if the specified block is all zeros
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| 43 | */
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| 44 | static int check_zero_block(char *buf, int blocksize)
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| 45 | {
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| 46 | char *cp = buf;
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| 47 | int left = blocksize;
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| 48 |
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| 49 | while (left > 0) {
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| 50 | if (*cp++)
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| 51 | return 0;
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| 52 | left--;
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| 53 | }
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| 54 | return 1;
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| 55 | }
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| 56 |
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| 57 | /*
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| 58 | * Write the inode table out as a single block.
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| 59 | */
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| 60 | #define BUF_BLOCKS 32
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| 61 |
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| 62 | errcode_t ext2fs_image_inode_write(ext2_filsys fs, int fd, int flags)
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| 63 | {
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| 64 | unsigned int group, left, c, d;
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| 65 | char *buf, *cp;
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| 66 | blk_t blk;
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| 67 | ssize_t actual;
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| 68 | errcode_t retval;
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| 69 |
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| 70 | buf = xmalloc(fs->blocksize * BUF_BLOCKS);
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| 71 |
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| 72 | for (group = 0; group < fs->group_desc_count; group++) {
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| 73 | blk = fs->group_desc[(unsigned)group].bg_inode_table;
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| 74 | if (!blk)
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| 75 | return EXT2_ET_MISSING_INODE_TABLE;
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| 76 | left = fs->inode_blocks_per_group;
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| 77 | while (left) {
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| 78 | c = BUF_BLOCKS;
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| 79 | if (c > left)
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| 80 | c = left;
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| 81 | retval = io_channel_read_blk(fs->io, blk, c, buf);
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| 82 | if (retval)
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| 83 | goto errout;
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| 84 | cp = buf;
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| 85 | while (c) {
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| 86 | if (!(flags & IMAGER_FLAG_SPARSEWRITE)) {
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| 87 | d = c;
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| 88 | goto skip_sparse;
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| 89 | }
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| 90 | /* Skip zero blocks */
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| 91 | if (check_zero_block(cp, fs->blocksize)) {
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| 92 | c--;
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| 93 | blk++;
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| 94 | left--;
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| 95 | cp += fs->blocksize;
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| 96 | lseek(fd, fs->blocksize, SEEK_CUR);
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| 97 | continue;
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| 98 | }
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| 99 | /* Find non-zero blocks */
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| 100 | for (d=1; d < c; d++) {
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| 101 | if (check_zero_block(cp + d*fs->blocksize, fs->blocksize))
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| 102 | break;
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| 103 | }
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| 104 | skip_sparse:
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| 105 | actual = write(fd, cp, fs->blocksize * d);
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| 106 | if (actual == -1) {
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| 107 | retval = errno;
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| 108 | goto errout;
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| 109 | }
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| 110 | if (actual != (ssize_t) (fs->blocksize * d)) {
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| 111 | retval = EXT2_ET_SHORT_WRITE;
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| 112 | goto errout;
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| 113 | }
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| 114 | blk += d;
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| 115 | left -= d;
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| 116 | cp += fs->blocksize * d;
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| 117 | c -= d;
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| 118 | }
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| 119 | }
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| 120 | }
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| 121 | retval = 0;
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| 122 |
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| 123 | errout:
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| 124 | free(buf);
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| 125 | return retval;
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| 126 | }
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| 127 |
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| 128 | /*
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| 129 | * Read in the inode table and stuff it into place
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| 130 | */
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| 131 | errcode_t ext2fs_image_inode_read(ext2_filsys fs, int fd,
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| 132 | int flags EXT2FS_ATTR((unused)))
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| 133 | {
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| 134 | unsigned int group, c, left;
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| 135 | char *buf;
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| 136 | blk_t blk;
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| 137 | ssize_t actual;
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| 138 | errcode_t retval;
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| 139 |
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| 140 | buf = xmalloc(fs->blocksize * BUF_BLOCKS);
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| 141 |
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| 142 | for (group = 0; group < fs->group_desc_count; group++) {
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| 143 | blk = fs->group_desc[(unsigned)group].bg_inode_table;
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| 144 | if (!blk) {
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| 145 | retval = EXT2_ET_MISSING_INODE_TABLE;
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| 146 | goto errout;
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| 147 | }
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| 148 | left = fs->inode_blocks_per_group;
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| 149 | while (left) {
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| 150 | c = BUF_BLOCKS;
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| 151 | if (c > left)
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| 152 | c = left;
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| 153 | actual = read(fd, buf, fs->blocksize * c);
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| 154 | if (actual == -1) {
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| 155 | retval = errno;
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| 156 | goto errout;
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| 157 | }
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| 158 | if (actual != (ssize_t) (fs->blocksize * c)) {
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| 159 | retval = EXT2_ET_SHORT_READ;
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| 160 | goto errout;
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| 161 | }
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| 162 | retval = io_channel_write_blk(fs->io, blk, c, buf);
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| 163 | if (retval)
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| 164 | goto errout;
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| 165 |
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| 166 | blk += c;
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| 167 | left -= c;
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| 168 | }
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| 169 | }
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| 170 | retval = ext2fs_flush_icache(fs);
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| 171 |
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| 172 | errout:
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| 173 | free(buf);
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| 174 | return retval;
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| 175 | }
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| 176 |
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| 177 | /*
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| 178 | * Write out superblock and group descriptors
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| 179 | */
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| 180 | errcode_t ext2fs_image_super_write(ext2_filsys fs, int fd,
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| 181 | int flags EXT2FS_ATTR((unused)))
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| 182 | {
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| 183 | char *buf, *cp;
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| 184 | ssize_t actual;
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| 185 | errcode_t retval;
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| 186 |
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| 187 | buf = xmalloc(fs->blocksize);
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| 188 |
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| 189 | /*
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| 190 | * Write out the superblock
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| 191 | */
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| 192 | memset(buf, 0, fs->blocksize);
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| 193 | memcpy(buf, fs->super, SUPERBLOCK_SIZE);
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| 194 | actual = write(fd, buf, fs->blocksize);
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| 195 | if (actual == -1) {
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| 196 | retval = errno;
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| 197 | goto errout;
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| 198 | }
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| 199 | if (actual != (ssize_t) fs->blocksize) {
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| 200 | retval = EXT2_ET_SHORT_WRITE;
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| 201 | goto errout;
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| 202 | }
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| 203 |
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| 204 | /*
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| 205 | * Now write out the block group descriptors
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| 206 | */
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| 207 | cp = (char *) fs->group_desc;
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| 208 | actual = write(fd, cp, fs->blocksize * fs->desc_blocks);
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| 209 | if (actual == -1) {
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| 210 | retval = errno;
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| 211 | goto errout;
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| 212 | }
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| 213 | if (actual != (ssize_t) (fs->blocksize * fs->desc_blocks)) {
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| 214 | retval = EXT2_ET_SHORT_WRITE;
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| 215 | goto errout;
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| 216 | }
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| 217 |
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| 218 | retval = 0;
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| 219 |
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| 220 | errout:
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| 221 | free(buf);
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| 222 | return retval;
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| 223 | }
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| 224 |
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| 225 | /*
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| 226 | * Read the superblock and group descriptors and overwrite them.
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| 227 | */
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| 228 | errcode_t ext2fs_image_super_read(ext2_filsys fs, int fd,
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| 229 | int flags EXT2FS_ATTR((unused)))
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| 230 | {
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| 231 | char *buf;
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| 232 | ssize_t actual, size;
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| 233 | errcode_t retval;
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| 234 |
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| 235 | size = fs->blocksize * (fs->group_desc_count + 1);
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| 236 | buf = xmalloc(size);
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| 237 |
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| 238 | /*
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| 239 | * Read it all in.
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| 240 | */
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| 241 | actual = read(fd, buf, size);
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| 242 | if (actual == -1) {
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| 243 | retval = errno;
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| 244 | goto errout;
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| 245 | }
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| 246 | if (actual != size) {
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| 247 | retval = EXT2_ET_SHORT_READ;
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| 248 | goto errout;
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| 249 | }
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| 250 |
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| 251 | /*
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| 252 | * Now copy in the superblock and group descriptors
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| 253 | */
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| 254 | memcpy(fs->super, buf, SUPERBLOCK_SIZE);
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| 255 |
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| 256 | memcpy(fs->group_desc, buf + fs->blocksize,
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| 257 | fs->blocksize * fs->group_desc_count);
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| 258 |
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| 259 | retval = 0;
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| 260 |
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| 261 | errout:
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| 262 | free(buf);
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| 263 | return retval;
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| 264 | }
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| 265 |
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| 266 | /*
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| 267 | * Write the block/inode bitmaps.
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| 268 | */
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| 269 | errcode_t ext2fs_image_bitmap_write(ext2_filsys fs, int fd, int flags)
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| 270 | {
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| 271 | char *ptr;
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| 272 | int c, size;
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| 273 | char zero_buf[1024];
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| 274 | ssize_t actual;
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| 275 | errcode_t retval;
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| 276 |
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| 277 | if (flags & IMAGER_FLAG_INODEMAP) {
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| 278 | if (!fs->inode_map) {
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| 279 | retval = ext2fs_read_inode_bitmap(fs);
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| 280 | if (retval)
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| 281 | return retval;
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| 282 | }
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| 283 | ptr = fs->inode_map->bitmap;
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| 284 | size = (EXT2_INODES_PER_GROUP(fs->super) / 8);
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| 285 | } else {
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| 286 | if (!fs->block_map) {
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| 287 | retval = ext2fs_read_block_bitmap(fs);
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| 288 | if (retval)
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| 289 | return retval;
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| 290 | }
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| 291 | ptr = fs->block_map->bitmap;
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| 292 | size = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
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| 293 | }
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| 294 | size = size * fs->group_desc_count;
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| 295 |
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| 296 | actual = write(fd, ptr, size);
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| 297 | if (actual == -1) {
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| 298 | retval = errno;
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| 299 | goto errout;
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| 300 | }
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| 301 | if (actual != size) {
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| 302 | retval = EXT2_ET_SHORT_WRITE;
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| 303 | goto errout;
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| 304 | }
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| 305 | size = size % fs->blocksize;
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| 306 | memset(zero_buf, 0, sizeof(zero_buf));
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| 307 | if (size) {
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| 308 | size = fs->blocksize - size;
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| 309 | while (size) {
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| 310 | c = size;
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| 311 | if (c > (int) sizeof(zero_buf))
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| 312 | c = sizeof(zero_buf);
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| 313 | actual = write(fd, zero_buf, c);
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| 314 | if (actual == -1) {
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| 315 | retval = errno;
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| 316 | goto errout;
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| 317 | }
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| 318 | if (actual != c) {
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| 319 | retval = EXT2_ET_SHORT_WRITE;
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| 320 | goto errout;
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| 321 | }
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| 322 | size -= c;
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| 323 | }
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| 324 | }
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| 325 | retval = 0;
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| 326 | errout:
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| 327 | return retval;
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| 328 | }
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| 329 |
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| 330 |
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| 331 | /*
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| 332 | * Read the block/inode bitmaps.
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| 333 | */
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| 334 | errcode_t ext2fs_image_bitmap_read(ext2_filsys fs, int fd, int flags)
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| 335 | {
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| 336 | char *ptr, *buf = NULL;
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| 337 | int size;
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| 338 | ssize_t actual;
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| 339 | errcode_t retval;
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| 340 |
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| 341 | if (flags & IMAGER_FLAG_INODEMAP) {
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| 342 | if (!fs->inode_map) {
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| 343 | retval = ext2fs_read_inode_bitmap(fs);
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| 344 | if (retval)
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| 345 | return retval;
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| 346 | }
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| 347 | ptr = fs->inode_map->bitmap;
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| 348 | size = (EXT2_INODES_PER_GROUP(fs->super) / 8);
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| 349 | } else {
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| 350 | if (!fs->block_map) {
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| 351 | retval = ext2fs_read_block_bitmap(fs);
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| 352 | if (retval)
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| 353 | return retval;
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| 354 | }
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| 355 | ptr = fs->block_map->bitmap;
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| 356 | size = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
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| 357 | }
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| 358 | size = size * fs->group_desc_count;
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| 359 |
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| 360 | buf = xmalloc(size);
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| 361 |
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| 362 | actual = read(fd, buf, size);
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| 363 | if (actual == -1) {
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| 364 | retval = errno;
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| 365 | goto errout;
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| 366 | }
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| 367 | if (actual != size) {
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| 368 | retval = EXT2_ET_SHORT_WRITE;
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| 369 | goto errout;
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| 370 | }
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| 371 | memcpy(ptr, buf, size);
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| 372 |
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| 373 | retval = 0;
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| 374 | errout:
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| 375 | free(buf);
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| 376 | return retval;
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| 377 | }
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