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/*
* link.c --- create links in a ext2fs directory
*
* Copyright (C) 1993, 1994 Theodore Ts'o.
*
* %Begin-Header%
* This file may be redistributed under the terms of the GNU Library
* General Public License, version 2.
* %End-Header%
*/
#include "config.h"
#include <stdio.h>
#include <string.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include "ext2_fs.h"
#include "ext2fs.h"
struct link_struct {
ext2_filsys fs;
const char *name;
int namelen;
ext2_ino_t inode;
int flags;
int done;
unsigned int blocksize;
errcode_t err;
struct ext2_super_block *sb;
};
static int link_proc(struct ext2_dir_entry *dirent,
int offset,
int blocksize,
char *buf,
void *priv_data)
{
struct link_struct *ls = (struct link_struct *) priv_data;
struct ext2_dir_entry *next;
unsigned int rec_len, min_rec_len, curr_rec_len;
int ret = 0;
int csum_size = 0;
struct ext2_dir_entry_tail *t;
if (ls->done)
return DIRENT_ABORT;
rec_len = EXT2_DIR_REC_LEN(ls->namelen);
ls->err = ext2fs_get_rec_len(ls->fs, dirent, &curr_rec_len);
if (ls->err)
return DIRENT_ABORT;
if (ext2fs_has_feature_metadata_csum(ls->fs->super))
csum_size = sizeof(struct ext2_dir_entry_tail);
/*
* See if the following directory entry (if any) is unused;
* if so, absorb it into this one.
*/
next = (struct ext2_dir_entry *) (buf + offset + curr_rec_len);
if ((offset + (int) curr_rec_len < blocksize - (8 + csum_size)) &&
(next->inode == 0) &&
(offset + (int) curr_rec_len + (int) next->rec_len <= blocksize)) {
curr_rec_len += next->rec_len;
ls->err = ext2fs_set_rec_len(ls->fs, curr_rec_len, dirent);
if (ls->err)
return DIRENT_ABORT;
ret = DIRENT_CHANGED;
}
/*
* Since ext2fs_link blows away htree data, we need to be
* careful -- if metadata_csum is enabled and we're passed in
* a dirent that contains htree data, we need to create the
* fake entry at the end of the block that hides the checksum.
*/
/* De-convert a dx_node block */
if (csum_size &&
curr_rec_len == ls->fs->blocksize &&
!dirent->inode) {
curr_rec_len -= csum_size;
ls->err = ext2fs_set_rec_len(ls->fs, curr_rec_len, dirent);
if (ls->err)
return DIRENT_ABORT;
t = EXT2_DIRENT_TAIL(buf, ls->fs->blocksize);
ext2fs_initialize_dirent_tail(ls->fs, t);
ret = DIRENT_CHANGED;
}
/* De-convert a dx_root block */
if (csum_size &&
curr_rec_len == ls->fs->blocksize - EXT2_DIR_REC_LEN(1) &&
offset == EXT2_DIR_REC_LEN(1) &&
dirent->name[0] == '.' && dirent->name[1] == '.') {
curr_rec_len -= csum_size;
ls->err = ext2fs_set_rec_len(ls->fs, curr_rec_len, dirent);
if (ls->err)
return DIRENT_ABORT;
t = EXT2_DIRENT_TAIL(buf, ls->fs->blocksize);
ext2fs_initialize_dirent_tail(ls->fs, t);
ret = DIRENT_CHANGED;
}
/*
* If the directory entry is used, see if we can split the
* directory entry to make room for the new name. If so,
* truncate it and return.
*/
if (dirent->inode) {
min_rec_len = EXT2_DIR_REC_LEN(ext2fs_dirent_name_len(dirent));
if (curr_rec_len < (min_rec_len + rec_len))
return ret;
rec_len = curr_rec_len - min_rec_len;
ls->err = ext2fs_set_rec_len(ls->fs, min_rec_len, dirent);
if (ls->err)
return DIRENT_ABORT;
next = (struct ext2_dir_entry *) (buf + offset +
dirent->rec_len);
next->inode = 0;
ext2fs_dirent_set_name_len(next, 0);
ext2fs_dirent_set_file_type(next, 0);
ls->err = ext2fs_set_rec_len(ls->fs, rec_len, next);
if (ls->err)
return DIRENT_ABORT;
return DIRENT_CHANGED;
}
/*
* If we get this far, then the directory entry is not used.
* See if we can fit the request entry in. If so, do it.
*/
if (curr_rec_len < rec_len)
return ret;
dirent->inode = ls->inode;
ext2fs_dirent_set_name_len(dirent, ls->namelen);
strncpy(dirent->name, ls->name, ls->namelen);
if (ext2fs_has_feature_filetype(ls->sb))
ext2fs_dirent_set_file_type(dirent, ls->flags & 0x7);
ls->done++;
return DIRENT_ABORT|DIRENT_CHANGED;
}
/*
* Note: the low 3 bits of the flags field are used as the directory
* entry filetype.
*/
#ifdef __TURBOC__
#pragma argsused
#endif
errcode_t ext2fs_link(ext2_filsys fs, ext2_ino_t dir, const char *name,
ext2_ino_t ino, int flags)
{
errcode_t retval;
struct link_struct ls;
struct ext2_inode inode;
EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
if (!(fs->flags & EXT2_FLAG_RW))
return EXT2_ET_RO_FILSYS;
ls.fs = fs;
ls.name = name;
ls.namelen = name ? strlen(name) : 0;
ls.inode = ino;
ls.flags = flags;
ls.done = 0;
ls.sb = fs->super;
ls.blocksize = fs->blocksize;
ls.err = 0;
retval = ext2fs_dir_iterate(fs, dir, DIRENT_FLAG_INCLUDE_EMPTY,
0, link_proc, &ls);
if (retval)
return retval;
if (ls.err)
return ls.err;
if (!ls.done)
return EXT2_ET_DIR_NO_SPACE;
if ((retval = ext2fs_read_inode(fs, dir, &inode)) != 0)
return retval;
/*
* If this function changes to preserve the htree, remove the
* two hunks in link_proc that shove checksum tails into the
* former dx_root/dx_node blocks.
*/
if (inode.i_flags & EXT2_INDEX_FL) {
inode.i_flags &= ~EXT2_INDEX_FL;
if ((retval = ext2fs_write_inode(fs, dir, &inode)) != 0)
return retval;
}
return 0;
}
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