/* vi: set sw=4 ts=4: *//* * 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#include "ext2_fs.h"#include "ext2fs.h"struct ext2_file {	errcode_t		magic;	ext2_filsys		fs;	ext2_ino_t		ino;	struct ext2_inode	inode;	int			flags;	__u64			pos;	blk_t			blockno;	blk_t			physblock;	char			*buf;};#define BMAP_BUFFER (file->buf + fs->blocksize)errcode_t ext2fs_file_open2(ext2_filsys fs, ext2_ino_t ino,			    struct ext2_inode *inode,			    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), &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;	if (inode) {		memcpy(&file->inode, inode, sizeof(struct ext2_inode));	} else {		retval = ext2fs_read_inode(fs, ino, &file->inode);		if (retval)			goto fail;	}	retval = ext2fs_get_mem(fs->blocksize * 3, &file->buf);	if (retval)		goto fail;	*ret = file;	return 0;fail:	ext2fs_free_mem(&file->buf);	ext2fs_free_mem(&file);	return retval;}errcode_t ext2fs_file_open(ext2_filsys fs, ext2_ino_t ino,			   int flags, ext2_file_t *ret){	return ext2fs_file_open2(fs, ino, NULL, flags, ret);}/* * 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. */errcode_t ext2fs_file_flush(ext2_file_t file){	errcode_t	retval;	ext2_filsys fs;	EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);	fs = file->fs;	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(fs, file->ino, &file->inode,				     BMAP_BUFFER, file->ino ? BMAP_ALLOC : 0,				     file->blockno, &file->physblock);		if (retval)			return retval;	}	retval = io_channel_write_blk(fs->io, file->physblock,				      1, file->buf);	if (retval)		return retval;	file->flags &= ~EXT2_FILE_BUF_DIRTY;	return retval;}/* * This function synchronizes the file's block buffer and the current * file position, possibly invalidating block buffer if necessary */static errcode_t sync_buffer_position(ext2_file_t file){	blk_t	b;	errcode_t	retval;	b = file->pos / file->fs->blocksize;	if (b != file->blockno) {		retval = ext2fs_file_flush(file);		if (retval)			return retval;		file->flags &= ~EXT2_FILE_BUF_VALID;	}	file->blockno = b;	return 0;}/* * This function loads the file's block buffer with valid data from * the disk as necessary. * * If dontfill is true, then skip initializing the buffer since we're * going to be replacing its entire contents anyway.  If set, then the * function basically only sets file->physblock and EXT2_FILE_BUF_VALID */#define DONTFILL 1static errcode_t load_buffer(ext2_file_t file, int dontfill){	ext2_filsys	fs = file->fs;	errcode_t	retval;	if (!(file->flags & EXT2_FILE_BUF_VALID)) {		retval = ext2fs_bmap(fs, file->ino, &file->inode,				     BMAP_BUFFER, 0, file->blockno,				     &file->physblock);		if (retval)			return retval;		if (!dontfill) {			if (file->physblock) {				retval = io_channel_read_blk(fs->io,							     file->physblock,							     1, file->buf);				if (retval)					return retval;			} else				memset(file->buf, 0, fs->blocksize);		}		file->flags |= EXT2_FILE_BUF_VALID;	}	return 0;}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);	ext2fs_free_mem(&file->buf);	ext2fs_free_mem(&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 = 0;	unsigned int	start, c, count = 0;	__u64		left;	char		*ptr = (char *) buf;	EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);	fs = file->fs;	while ((file->pos < EXT2_I_SIZE(&file->inode)) && (wanted > 0)) {		retval = sync_buffer_position(file);		if (retval)			goto fail;		retval = load_buffer(file, 0);		if (retval)			goto fail;		start = file->pos % fs->blocksize;		c = fs->blocksize - start;		if (c > wanted)			c = wanted;		left = EXT2_I_SIZE(&file->inode) - file->pos;		if (c > left)			c = left;		memcpy(ptr, file->buf+start, c);		file->pos += c;		ptr += c;		count += c;		wanted -= c;	}fail:	if (got)		*got = count;	return retval;}errcode_t ext2fs_file_write(ext2_file_t file, const void *buf,			    unsigned int nbytes, unsigned int *written){	ext2_filsys	fs;	errcode_t	retval = 0;	unsigned int	start, c, count = 0;	const char	*ptr = (const 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;	while (nbytes > 0) {		retval = sync_buffer_position(file);		if (retval)			goto fail;		start = file->pos % fs->blocksize;		c = fs->blocksize - start;		if (c > nbytes)			c = nbytes;		/*		 * We only need to do a read-modify-update cycle if		 * we're doing a partial write.		 */		retval = load_buffer(file, (c == fs->blocksize));		if (retval)			goto fail;		file->flags |= EXT2_FILE_BUF_DIRTY;		memcpy(file->buf+start, ptr, c);		file->pos += c;		ptr += c;		count += c;		nbytes -= c;	}fail:	if (written)		*written = count;	return retval;}errcode_t ext2fs_file_llseek(ext2_file_t file, __u64 offset,			    int whence, __u64 *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 = EXT2_I_SIZE(&file->inode) + offset;	else		return EXT2_ET_INVALID_ARGUMENT;	if (ret_pos)		*ret_pos = file->pos;	return 0;}errcode_t ext2fs_file_lseek(ext2_file_t file, ext2_off_t offset,			    int whence, ext2_off_t *ret_pos){	__u64		loffset, ret_loffset;	errcode_t	retval;	loffset = offset;	retval = ext2fs_file_llseek(file, loffset, whence, &ret_loffset);	if (ret_pos)		*ret_pos = (ext2_off_t) ret_loffset;	return retval;}/* * This function returns the size of the file, according to the inode */errcode_t ext2fs_file_get_lsize(ext2_file_t file, __u64 *ret_size){	if (file->magic != EXT2_ET_MAGIC_EXT2_FILE)		return EXT2_ET_MAGIC_EXT2_FILE;	*ret_size = EXT2_I_SIZE(&file->inode);	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){	__u64	size;	if (ext2fs_file_get_lsize(file, &size))		return 0;	if ((size >> 32) != 0)		return 0;	return size;}/* * This function sets the size of the file, truncating it if necessary * * XXX still need to call truncate */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;	file->inode.i_size_high = 0;	if (file->ino) {		retval = ext2fs_write_inode(file->fs, file->ino, &file->inode);		if (retval)			return retval;	}	/*	 * XXX truncate inode if necessary	 */	return 0;}