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