mirror of https://github.com/vitalif/e2fsprogs
326 lines
6.3 KiB
C
326 lines
6.3 KiB
C
/*
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* fileio.c --- Simple file I/O routines
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*
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* Copyright (C) 1997 Theodore Ts'o.
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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 EXT2_FLAT_INCLUDES
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#include "ext2_fs.h"
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#else
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#include <linux/ext2_fs.h>
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#endif
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#include "ext2fs.h"
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struct ext2_file {
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errcode_t magic;
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ext2_filsys fs;
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ino_t ino;
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struct ext2_inode inode;
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int flags;
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ext2_off_t pos;
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blk_t blockno;
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blk_t physblock;
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char *buf;
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};
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errcode_t ext2fs_file_open(ext2_filsys fs, ino_t ino,
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int flags, ext2_file_t *ret)
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{
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ext2_file_t file;
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errcode_t retval;
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/*
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* Don't let caller create or open a file for writing if the
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* filesystem is read-only.
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*/
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if ((flags & (EXT2_FILE_WRITE | EXT2_FILE_CREATE)) &&
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!(fs->flags & EXT2_FLAG_RW))
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return EXT2_ET_RO_FILSYS;
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retval = ext2fs_get_mem(sizeof(struct ext2_file), (void **) &file);
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if (retval)
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return retval;
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memset(file, 0, sizeof(struct ext2_file));
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file->magic = EXT2_ET_MAGIC_EXT2_FILE;
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file->fs = fs;
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file->ino = ino;
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file->flags = flags & EXT2_FILE_MASK;
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retval = ext2fs_read_inode(fs, ino, &file->inode);
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if (retval)
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goto fail;
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retval = ext2fs_get_mem(fs->blocksize * 2, (void **) &file->buf);
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if (retval)
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goto fail;
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*ret = file;
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return 0;
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fail:
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if (file->buf)
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ext2fs_free_mem((void **) &file->buf);
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ext2fs_free_mem((void **) &file);
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return retval;
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}
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/*
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* This function returns the filesystem handle of a file from the structure
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*/
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ext2_filsys ext2fs_file_get_fs(ext2_file_t file)
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{
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if (file->magic != EXT2_ET_MAGIC_EXT2_FILE)
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return 0;
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return file->fs;
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}
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/*
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* This function flushes the dirty block buffer out to disk if
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* necessary.
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*/
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static errcode_t ext2fs_file_flush(ext2_file_t file)
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{
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errcode_t retval;
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EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
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if (!(file->flags & EXT2_FILE_BUF_VALID) ||
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!(file->flags & EXT2_FILE_BUF_DIRTY))
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return 0;
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/*
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* OK, the physical block hasn't been allocated yet.
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* Allocate it.
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*/
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if (!file->physblock) {
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retval = ext2fs_bmap(file->fs, file->ino, &file->inode,
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file->buf, BMAP_ALLOC,
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file->blockno, &file->physblock);
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if (retval)
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return retval;
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}
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retval = io_channel_write_blk(file->fs->io, file->physblock,
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1, file->buf);
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if (retval)
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return retval;
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file->flags &= ~EXT2_FILE_BUF_DIRTY;
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return retval;
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}
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errcode_t ext2fs_file_close(ext2_file_t file)
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{
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errcode_t retval;
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EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
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retval = ext2fs_file_flush(file);
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if (file->buf)
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ext2fs_free_mem((void **) &file->buf);
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ext2fs_free_mem((void **) &file);
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return retval;
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}
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errcode_t ext2fs_file_read(ext2_file_t file, void *buf,
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unsigned int wanted, unsigned int *got)
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{
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ext2_filsys fs;
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errcode_t retval;
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blk_t b, pb;
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unsigned int start, left, c, count = 0;
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char *ptr = (char *) buf;
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EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
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fs = file->fs;
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again:
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if (file->pos >= file->inode.i_size)
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goto done;
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b = file->pos / fs->blocksize;
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if (b != file->blockno) {
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retval = ext2fs_file_flush(file);
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if (retval)
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goto fail;
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file->flags &= ~EXT2_FILE_BUF_VALID;
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}
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file->blockno = b;
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if (!(file->flags & EXT2_FILE_BUF_VALID)) {
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retval = ext2fs_bmap(fs, file->ino, &file->inode,
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file->buf, 0, b, &pb);
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if (retval)
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goto fail;
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if (pb) {
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file->physblock = pb;
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retval = io_channel_read_blk(fs->io, pb, 1, file->buf);
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if (retval)
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goto fail;
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} else {
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file->physblock = 0;
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memset(file->buf, 0, fs->blocksize);
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}
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file->flags |= EXT2_FILE_BUF_VALID;
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}
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start = file->pos % fs->blocksize;
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c = fs->blocksize - start;
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if (c > wanted)
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c = wanted;
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left = file->inode.i_size - file->pos ;
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if (c > left)
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c = left;
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memcpy(ptr, file->buf+start, c);
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file->pos += c;
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ptr += c;
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count += c;
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wanted -= c;
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if (wanted > 0)
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goto again;
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done:
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if (got)
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*got = count;
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return 0;
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fail:
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if (count)
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goto done;
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return retval;
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}
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errcode_t ext2fs_file_write(ext2_file_t file, void *buf,
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unsigned int nbytes, unsigned int *written)
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{
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ext2_filsys fs;
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errcode_t retval;
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blk_t b, pb;
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unsigned int start, c, count = 0;
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char *ptr = (char *) buf;
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EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
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fs = file->fs;
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if (!(file->flags & EXT2_FILE_WRITE))
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return EXT2_ET_FILE_RO;
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again:
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b = file->pos / fs->blocksize;
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if (b != file->blockno) {
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retval = ext2fs_file_flush(file);
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if (retval)
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goto fail;
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file->flags &= ~EXT2_FILE_BUF_VALID;
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}
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file->blockno = b;
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if (!(file->flags & EXT2_FILE_BUF_VALID)) {
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retval = ext2fs_bmap(fs, file->ino, &file->inode,
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file->buf, BMAP_ALLOC, b, &pb);
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if (retval)
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goto fail;
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file->physblock = pb;
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retval = io_channel_read_blk(fs->io, pb, 1, file->buf);
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if (retval)
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goto fail;
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file->flags |= EXT2_FILE_BUF_VALID;
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}
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start = file->pos % fs->blocksize;
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c = fs->blocksize - start;
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if (c > nbytes)
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c = nbytes;
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file->flags |= EXT2_FILE_BUF_DIRTY;
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memcpy(file->buf+start, ptr, c);
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file->pos += c;
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ptr += c;
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count += c;
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nbytes -= c;
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if (nbytes > 0)
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goto again;
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done:
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if (written)
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*written = count;
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return 0;
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fail:
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if (count)
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goto done;
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return retval;
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}
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errcode_t ext2fs_file_lseek(ext2_file_t file, ext2_off_t offset,
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int whence, ext2_off_t *ret_pos)
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{
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EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
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if (whence == EXT2_SEEK_SET)
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file->pos = offset;
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else if (whence == EXT2_SEEK_CUR)
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file->pos += offset;
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else if (whence == EXT2_SEEK_END)
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file->pos = file->inode.i_size + offset;
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else
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return EXT2_ET_INVALID_ARGUMENT;
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if (ret_pos)
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*ret_pos = file->pos;
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return 0;
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}
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/*
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* This function returns the size of the file, according to the inode
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*/
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ext2_off_t ext2fs_file_get_size(ext2_file_t file)
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{
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if (file->magic != EXT2_ET_MAGIC_EXT2_FILE)
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return 0;
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return file->inode.i_size;
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}
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/*
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* This function sets the size of the file, truncating it if necessary
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*
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* XXX still need to call truncate
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*/
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errcode_t ext2fs_file_set_size(ext2_file_t file, ext2_off_t size)
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{
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errcode_t retval;
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EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
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file->inode.i_size = size;
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retval = ext2fs_write_inode(file->fs, file->ino, &file->inode);
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if (retval)
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return retval;
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/*
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* XXX truncate inode if necessary
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*/
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return 0;
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}
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