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[ext2fs] initial ext2fs support
This commit is contained in:
Pete Batard
parent
f4d70345af
commit
cda716c1ff
87 changed files with 29093 additions and 130 deletions
615
src/ext2fs/fileio.c
Normal file
615
src/ext2fs/fileio.c
Normal file
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@ -0,0 +1,615 @@
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/*
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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 Library
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* General Public License, version 2.
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* %End-Header%
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*/
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#include "config.h"
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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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#include "ext2_fs.h"
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#include "ext2fs.h"
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#include "ext2fsP.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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ext2_ino_t ino;
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struct ext2_inode inode;
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int flags;
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__u64 pos;
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blk64_t blockno;
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blk64_t physblock;
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char *buf;
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};
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#define BMAP_BUFFER (file->buf + fs->blocksize)
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errcode_t ext2fs_file_open2(ext2_filsys fs, ext2_ino_t ino,
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struct ext2_inode *inode,
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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), &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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if (inode) {
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memcpy(&file->inode, inode, sizeof(struct ext2_inode));
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} else {
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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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}
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retval = ext2fs_get_array(3, fs->blocksize, &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(&file->buf);
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ext2fs_free_mem(&file);
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return retval;
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}
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errcode_t ext2fs_file_open(ext2_filsys fs, ext2_ino_t ino,
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int flags, ext2_file_t *ret)
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{
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return ext2fs_file_open2(fs, ino, NULL, flags, ret);
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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 returns the pointer to the inode of a file from the structure
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*/
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struct ext2_inode *ext2fs_file_get_inode(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 NULL;
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return &file->inode;
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}
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/* This function returns the inode number from the structure */
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ext2_ino_t ext2fs_file_get_inode_num(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->ino;
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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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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_filsys fs;
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int ret_flags;
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blk64_t dontcare;
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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_BUF_VALID) ||
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!(file->flags & EXT2_FILE_BUF_DIRTY))
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return 0;
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/* Is this an uninit block? */
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if (file->physblock && file->inode.i_flags & EXT4_EXTENTS_FL) {
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retval = ext2fs_bmap2(fs, file->ino, &file->inode, BMAP_BUFFER,
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0, file->blockno, &ret_flags, &dontcare);
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if (retval)
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return retval;
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if (ret_flags & BMAP_RET_UNINIT) {
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retval = ext2fs_bmap2(fs, file->ino, &file->inode,
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BMAP_BUFFER, BMAP_SET,
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file->blockno, 0,
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&file->physblock);
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if (retval)
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return retval;
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}
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}
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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_bmap2(fs, file->ino, &file->inode,
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BMAP_BUFFER, file->ino ? BMAP_ALLOC : 0,
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file->blockno, 0, &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_blk64(fs->io, file->physblock, 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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/*
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* This function synchronizes the file's block buffer and the current
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* file position, possibly invalidating block buffer if necessary
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*/
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static errcode_t sync_buffer_position(ext2_file_t file)
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{
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blk64_t b;
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errcode_t retval;
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b = file->pos / file->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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return retval;
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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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return 0;
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}
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/*
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* This function loads the file's block buffer with valid data from
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* the disk as necessary.
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*
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* If dontfill is true, then skip initializing the buffer since we're
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* going to be replacing its entire contents anyway. If set, then the
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* function basically only sets file->physblock and EXT2_FILE_BUF_VALID
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*/
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#define DONTFILL 1
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static errcode_t load_buffer(ext2_file_t file, int dontfill)
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{
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ext2_filsys fs = file->fs;
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errcode_t retval;
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int ret_flags;
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if (!(file->flags & EXT2_FILE_BUF_VALID)) {
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retval = ext2fs_bmap2(fs, file->ino, &file->inode,
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BMAP_BUFFER, 0, file->blockno, &ret_flags,
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&file->physblock);
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if (retval)
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return retval;
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if (!dontfill) {
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if (file->physblock &&
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!(ret_flags & BMAP_RET_UNINIT)) {
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retval = io_channel_read_blk64(fs->io,
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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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} else
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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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return 0;
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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(&file->buf);
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ext2fs_free_mem(&file);
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return retval;
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}
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static errcode_t
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ext2fs_file_read_inline_data(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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unsigned int count = 0;
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size_t size;
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fs = file->fs;
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retval = ext2fs_inline_data_get(fs, file->ino, &file->inode,
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file->buf, &size);
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if (retval)
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return retval;
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if (file->pos >= size)
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goto out;
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count = size - file->pos;
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if (count > wanted)
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count = wanted;
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memcpy(buf, file->buf + file->pos, count);
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file->pos += count;
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buf = (char *) buf + count;
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out:
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if (got)
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*got = count;
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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 = 0;
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unsigned int start, c, count = 0;
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__u64 left;
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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 an inode has inline data, things get complicated. */
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if (file->inode.i_flags & EXT4_INLINE_DATA_FL)
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return ext2fs_file_read_inline_data(file, buf, wanted, got);
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while ((file->pos < EXT2_I_SIZE(&file->inode)) && (wanted > 0)) {
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retval = sync_buffer_position(file);
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if (retval)
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goto fail;
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retval = load_buffer(file, 0);
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if (retval)
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goto fail;
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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 = EXT2_I_SIZE(&file->inode) - 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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}
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fail:
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if (got)
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*got = count;
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return retval;
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}
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static errcode_t
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ext2fs_file_write_inline_data(ext2_file_t file, const 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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unsigned int count = 0;
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size_t size;
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fs = file->fs;
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retval = ext2fs_inline_data_get(fs, file->ino, &file->inode,
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file->buf, &size);
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if (retval)
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return retval;
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if (file->pos < size) {
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count = nbytes - file->pos;
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memcpy(file->buf + file->pos, buf, count);
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retval = ext2fs_inline_data_set(fs, file->ino, &file->inode,
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file->buf, count);
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if (retval == EXT2_ET_INLINE_DATA_NO_SPACE)
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goto expand;
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if (retval)
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return retval;
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file->pos += count;
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/* Update inode size */
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if (count != 0 && EXT2_I_SIZE(&file->inode) < file->pos) {
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errcode_t rc;
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rc = ext2fs_file_set_size2(file, file->pos);
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if (retval == 0)
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retval = rc;
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}
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if (written)
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*written = count;
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return 0;
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}
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expand:
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retval = ext2fs_inline_data_expand(fs, file->ino);
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if (retval)
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return retval;
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/*
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* reload inode and return no space error
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*
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* XXX: file->inode could be copied from the outside
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* in ext2fs_file_open2(). We have no way to modify
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* the outside inode.
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*/
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retval = ext2fs_read_inode(fs, file->ino, &file->inode);
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if (retval)
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return retval;
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return EXT2_ET_INLINE_DATA_NO_SPACE;
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}
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errcode_t ext2fs_file_write(ext2_file_t file, const 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 = 0;
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unsigned int start, c, count = 0;
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const char *ptr = (const 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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/* If an inode has inline data, things get complicated. */
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if (file->inode.i_flags & EXT4_INLINE_DATA_FL) {
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retval = ext2fs_file_write_inline_data(file, buf, nbytes,
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written);
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if (retval != EXT2_ET_INLINE_DATA_NO_SPACE)
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return retval;
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/* fall through to read data from the block */
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retval = 0;
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}
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while (nbytes > 0) {
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retval = sync_buffer_position(file);
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if (retval)
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goto fail;
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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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/*
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* We only need to do a read-modify-update cycle if
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* we're doing a partial write.
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*/
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retval = load_buffer(file, (c == fs->blocksize));
|
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if (retval)
|
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goto fail;
|
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|
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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_bmap2(fs, file->ino, &file->inode,
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BMAP_BUFFER,
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file->ino ? BMAP_ALLOC : 0,
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file->blockno, 0,
|
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&file->physblock);
|
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if (retval)
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goto fail;
|
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}
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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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}
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|
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fail:
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/* Update inode size */
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if (count != 0 && EXT2_I_SIZE(&file->inode) < file->pos) {
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errcode_t rc;
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rc = ext2fs_file_set_size2(file, file->pos);
|
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if (retval == 0)
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retval = rc;
|
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}
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|
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if (written)
|
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*written = count;
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return retval;
|
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}
|
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|
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errcode_t ext2fs_file_llseek(ext2_file_t file, __u64 offset,
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int whence, __u64 *ret_pos)
|
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{
|
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EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
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|
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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 = EXT2_I_SIZE(&file->inode) + offset;
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else
|
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return EXT2_ET_INVALID_ARGUMENT;
|
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|
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if (ret_pos)
|
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*ret_pos = file->pos;
|
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|
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return 0;
|
||||
}
|
||||
|
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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)
|
||||
{
|
||||
__u64 loffset, ret_loffset = 0;
|
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errcode_t retval;
|
||||
|
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loffset = offset;
|
||||
retval = ext2fs_file_llseek(file, loffset, whence, &ret_loffset);
|
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if (ret_pos)
|
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*ret_pos = (ext2_off_t) ret_loffset;
|
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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;
|
||||
}
|
||||
|
||||
/* Zero the parts of the last block that are past EOF. */
|
||||
static errcode_t ext2fs_file_zero_past_offset(ext2_file_t file,
|
||||
ext2_off64_t offset)
|
||||
{
|
||||
ext2_filsys fs = file->fs;
|
||||
char *b = NULL;
|
||||
ext2_off64_t off = offset % fs->blocksize;
|
||||
blk64_t blk;
|
||||
int ret_flags;
|
||||
errcode_t retval;
|
||||
|
||||
if (off == 0)
|
||||
return 0;
|
||||
|
||||
retval = sync_buffer_position(file);
|
||||
if (retval)
|
||||
return retval;
|
||||
|
||||
/* Is there an initialized block at the end? */
|
||||
retval = ext2fs_bmap2(fs, file->ino, NULL, NULL, 0,
|
||||
offset / fs->blocksize, &ret_flags, &blk);
|
||||
if (retval)
|
||||
return retval;
|
||||
if ((blk == 0) || (ret_flags & BMAP_RET_UNINIT))
|
||||
return 0;
|
||||
|
||||
/* Zero to the end of the block */
|
||||
retval = ext2fs_get_mem(fs->blocksize, &b);
|
||||
if (retval)
|
||||
return retval;
|
||||
|
||||
/* Read/zero/write block */
|
||||
retval = io_channel_read_blk64(fs->io, blk, 1, b);
|
||||
if (retval)
|
||||
goto out;
|
||||
|
||||
memset(b + off, 0, fs->blocksize - off);
|
||||
|
||||
retval = io_channel_write_blk64(fs->io, blk, 1, b);
|
||||
if (retval)
|
||||
goto out;
|
||||
|
||||
out:
|
||||
ext2fs_free_mem(&b);
|
||||
return retval;
|
||||
}
|
||||
|
||||
/*
|
||||
* This function sets the size of the file, truncating it if necessary
|
||||
*
|
||||
*/
|
||||
errcode_t ext2fs_file_set_size2(ext2_file_t file, ext2_off64_t size)
|
||||
{
|
||||
ext2_off64_t old_size;
|
||||
errcode_t retval;
|
||||
blk64_t old_truncate, truncate_block;
|
||||
|
||||
EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
|
||||
|
||||
if (size && ext2fs_file_block_offset_too_big(file->fs, &file->inode,
|
||||
(size - 1) / file->fs->blocksize))
|
||||
return EXT2_ET_FILE_TOO_BIG;
|
||||
truncate_block = ((size + file->fs->blocksize - 1) >>
|
||||
EXT2_BLOCK_SIZE_BITS(file->fs->super));
|
||||
old_size = EXT2_I_SIZE(&file->inode);
|
||||
old_truncate = ((old_size + file->fs->blocksize - 1) >>
|
||||
EXT2_BLOCK_SIZE_BITS(file->fs->super));
|
||||
|
||||
retval = ext2fs_inode_size_set(file->fs, &file->inode, size);
|
||||
if (retval)
|
||||
return retval;
|
||||
|
||||
if (file->ino) {
|
||||
retval = ext2fs_write_inode(file->fs, file->ino, &file->inode);
|
||||
if (retval)
|
||||
return retval;
|
||||
}
|
||||
|
||||
retval = ext2fs_file_zero_past_offset(file, size);
|
||||
if (retval)
|
||||
return retval;
|
||||
|
||||
if (truncate_block >= old_truncate)
|
||||
return 0;
|
||||
|
||||
return ext2fs_punch(file->fs, file->ino, &file->inode, 0,
|
||||
truncate_block, ~0ULL);
|
||||
}
|
||||
|
||||
errcode_t ext2fs_file_set_size(ext2_file_t file, ext2_off_t size)
|
||||
{
|
||||
return ext2fs_file_set_size2(file, size);
|
||||
}
|
||||
Loading…
Add table
Add a link
Reference in a new issue