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/*
* fileio.c --- Simple file I/O routines
*
* Copyright (C) 1997 Theodore Ts'o.
*
* %Begin-Header%
* This file may be redistributed under the terms of the GNU Public
* License.
* %End-Header%
*/
#include <stdio.h>
#include <string.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#if EXT2_FLAT_INCLUDES
#include "ext2_fs.h"
#else
#include <linux/ext2_fs.h>
#endif
#include "ext2fs.h"
struct ext2_file {
errcode_t magic;
ext2_filsys fs;
ino_t ino;
struct ext2_inode inode;
int flags;
ext2_off_t pos;
blk_t blockno;
blk_t physblock;
char *buf;
};
/*
* XXX Doesn't handle writing yet
*/
errcode_t ext2fs_file_open(ext2_filsys fs, ino_t ino,
int flags, ext2_file_t *ret)
{
ext2_file_t file;
errcode_t retval;
/*
* Don't let caller create or open a file for writing if the
* filesystem is read-only.
*/
if ((flags & (EXT2_FILE_WRITE | EXT2_FILE_CREATE)) &&
!(fs->flags & EXT2_FLAG_RW))
return EXT2_ET_RO_FILSYS;
retval = ext2fs_get_mem(sizeof(struct ext2_file), (void **) &file);
if (retval)
return retval;
memset(file, 0, sizeof(struct ext2_file));
file->magic = EXT2_ET_MAGIC_EXT2_FILE;
file->fs = fs;
file->ino = ino;
file->flags = flags & EXT2_FILE_MASK;
retval = ext2fs_read_inode(fs, ino, &file->inode);
if (retval)
goto fail;
retval = ext2fs_get_mem(fs->blocksize, (void **) &file->buf);
if (retval)
goto fail;
*ret = file;
return 0;
fail:
if (file->buf)
ext2fs_free_mem((void **) &file->buf);
ext2fs_free_mem((void **) &file);
return retval;
}
/*
* This function returns the filesystem handle of a file from the structure
*/
ext2_filsys ext2fs_file_get_fs(ext2_file_t file)
{
if (file->magic != EXT2_ET_MAGIC_EXT2_FILE)
return 0;
return file->fs;
}
/*
* This function flushes the dirty block buffer out to disk if
* necessary.
*/
static errcode_t ext2fs_file_flush(ext2_file_t file)
{
errcode_t retval;
EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
if (!(file->flags & EXT2_FILE_BUF_VALID) ||
!(file->flags & EXT2_FILE_BUF_DIRTY))
return 0;
/*
* OK, the physical block hasn't been allocated yet.
* Allocate it.
*/
if (!file->physblock) {
retval = ext2fs_bmap(file->fs, file->ino, &file->inode,
file->buf, BMAP_ALLOC,
file->blockno, &file->physblock);
if (retval)
return retval;
}
retval = io_channel_write_blk(file->fs->io, file->physblock,
1, file->buf);
if (retval)
return retval;
file->flags &= ~EXT2_FILE_BUF_DIRTY;
return retval;
}
errcode_t ext2fs_file_close(ext2_file_t file)
{
errcode_t retval;
EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
retval = ext2fs_file_flush(file);
if (file->buf)
ext2fs_free_mem((void **) &file->buf);
ext2fs_free_mem((void **) &file);
return retval;
}
errcode_t ext2fs_file_read(ext2_file_t file, void *buf,
unsigned int wanted, unsigned int *got)
{
ext2_filsys fs;
errcode_t retval;
blk_t b, pb;
unsigned int start, left, c, count = 0;
char *ptr = (char *) buf;
EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
fs = file->fs;
again:
if (file->pos >= file->inode.i_size)
goto done;
b = file->pos / fs->blocksize;
if (b != file->blockno) {
retval = ext2fs_file_flush(file);
if (retval)
goto fail;
file->flags &= ~EXT2_FILE_BUF_VALID;
}
file->blockno = b;
if (!(file->flags & EXT2_FILE_BUF_VALID)) {
retval = ext2fs_bmap(fs, file->ino, &file->inode,
file->buf, 0, b, &pb);
if (retval)
goto fail;
if (pb) {
file->physblock = pb;
retval = io_channel_read_blk(fs->io, pb, 1, file->buf);
if (retval)
goto fail;
} else {
file->physblock = 0;
memset(file->buf, 0, fs->blocksize);
}
file->flags |= EXT2_FILE_BUF_VALID;
}
start = file->pos % fs->blocksize;
c = fs->blocksize - start;
if (c > wanted)
c = wanted;
left = file->inode.i_size - file->pos ;
if (c > left)
c = left;
memcpy(ptr, file->buf+start, c);
file->pos += c;
ptr += c;
count += c;
wanted -= c;
if (wanted > 0)
goto again;
done:
if (got)
*got = count;
return 0;
fail:
if (count)
goto done;
return retval;
}
errcode_t ext2fs_file_write(ext2_file_t file, void *buf,
unsigned int nbytes, unsigned int *written)
{
ext2_filsys fs;
errcode_t retval;
blk_t b, pb;
unsigned int start, c, count = 0;
char *ptr = (char *) buf;
EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
fs = file->fs;
if (!(file->flags & EXT2_FILE_WRITE))
return EXT2_ET_FILE_RO;
again:
b = file->pos / fs->blocksize;
if (b != file->blockno) {
retval = ext2fs_file_flush(file);
if (retval)
goto fail;
file->flags &= ~EXT2_FILE_BUF_VALID;
}
file->blockno = b;
if (!(file->flags & EXT2_FILE_BUF_VALID)) {
retval = ext2fs_bmap(fs, file->ino, &file->inode,
file->buf, BMAP_ALLOC, b, &pb);
if (retval)
goto fail;
file->physblock = pb;
retval = io_channel_read_blk(fs->io, pb, 1, file->buf);
if (retval)
goto fail;
file->flags |= EXT2_FILE_BUF_VALID;
}
start = file->pos % fs->blocksize;
c = fs->blocksize - start;
if (c > nbytes)
c = nbytes;
file->flags |= EXT2_FILE_BUF_DIRTY;
memcpy(file->buf+start, ptr, c);
file->pos += c;
ptr += c;
count += c;
nbytes -= c;
if (nbytes > 0)
goto again;
done:
if (written)
*written = count;
return 0;
fail:
if (count)
goto done;
return retval;
}
errcode_t ext2fs_file_llseek(ext2_file_t file, ext2_off_t offset,
int whence, ext2_off_t *ret_pos)
{
EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
if (whence == EXT2_SEEK_SET)
file->pos = offset;
else if (whence == EXT2_SEEK_CUR)
file->pos += offset;
else if (whence == EXT2_SEEK_END)
file->pos = file->inode.i_size + offset;
else
return EXT2_ET_INVALID_ARGUMENT;
if (ret_pos)
*ret_pos = file->pos;
return 0;
}
/*
* This function returns the size of the file, according to the inode
*/
ext2_off_t ext2fs_file_get_size(ext2_file_t file)
{
if (file->magic != EXT2_ET_MAGIC_EXT2_FILE)
return 0;
return file->inode.i_size;
}
/*
* This function sets the size of the file, truncating it if necessary
*
* XXX still need to call truncate
*/
extern errcode_t ext2fs_file_set_size(ext2_file_t file, ext2_off_t size)
{
errcode_t retval;
EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
file->inode.i_size = size;
retval = ext2fs_write_inode(file->fs, file->ino, &file->inode);
if (retval)
return retval;
/*
* XXX truncate inode if necessary
*/
return 0;
}
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