link.c revision d36e027f9ce175f2437dcf681479935e185755a0 
1/*
2 * link.c --- create links in a ext2fs directory
3 *
4 * Copyright (C) 1993, 1994 Theodore Ts'o.
5 *
6 * %Begin-Header%
7 * This file may be redistributed under the terms of the GNU Library
8 * General Public License, version 2.
9 * %End-Header%
10 */
11
12#include "config.h"
13#include <stdio.h>
14#include <string.h>
15#if HAVE_UNISTD_H
16#include <unistd.h>
17#endif
18
19#include "ext2_fs.h"
20#include "ext2fs.h"
21
22struct link_struct  {
23	ext2_filsys	fs;
24	const char	*name;
25	int		namelen;
26	ext2_ino_t	inode;
27	int		flags;
28	int		done;
29	unsigned int	blocksize;
30	errcode_t	err;
31	struct ext2_super_block *sb;
32};
33
34static int link_proc(struct ext2_dir_entry *dirent,
35		     int	offset,
36		     int	blocksize,
37		     char	*buf,
38		     void	*priv_data)
39{
40	struct link_struct *ls = (struct link_struct *) priv_data;
41	struct ext2_dir_entry *next;
42	unsigned int rec_len, min_rec_len, curr_rec_len;
43	int ret = 0;
44
45	if (ls->done)
46		return DIRENT_ABORT;
47
48	rec_len = EXT2_DIR_REC_LEN(ls->namelen);
49
50	ls->err = ext2fs_get_rec_len(ls->fs, dirent, &curr_rec_len);
51	if (ls->err)
52		return DIRENT_ABORT;
53
54	/*
55	 * See if the following directory entry (if any) is unused;
56	 * if so, absorb it into this one.
57	 */
58	next = (struct ext2_dir_entry *) (buf + offset + curr_rec_len);
59	if ((offset + (int) curr_rec_len < blocksize - 8) &&
60	    (next->inode == 0) &&
61	    (offset + (int) curr_rec_len + (int) next->rec_len <= blocksize)) {
62		curr_rec_len += next->rec_len;
63		ls->err = ext2fs_set_rec_len(ls->fs, curr_rec_len, dirent);
64		if (ls->err)
65			return DIRENT_ABORT;
66		ret = DIRENT_CHANGED;
67	}
68
69	/*
70	 * If the directory entry is used, see if we can split the
71	 * directory entry to make room for the new name.  If so,
72	 * truncate it and return.
73	 */
74	if (dirent->inode) {
75		min_rec_len = EXT2_DIR_REC_LEN(dirent->name_len & 0xFF);
76		if (curr_rec_len < (min_rec_len + rec_len))
77			return ret;
78		rec_len = curr_rec_len - min_rec_len;
79		ls->err = ext2fs_set_rec_len(ls->fs, min_rec_len, dirent);
80		if (ls->err)
81			return DIRENT_ABORT;
82		next = (struct ext2_dir_entry *) (buf + offset +
83						  dirent->rec_len);
84		next->inode = 0;
85		next->name_len = 0;
86		ls->err = ext2fs_set_rec_len(ls->fs, rec_len, next);
87		if (ls->err)
88			return DIRENT_ABORT;
89		return DIRENT_CHANGED;
90	}
91
92	/*
93	 * If we get this far, then the directory entry is not used.
94	 * See if we can fit the request entry in.  If so, do it.
95	 */
96	if (curr_rec_len < rec_len)
97		return ret;
98	dirent->inode = ls->inode;
99	dirent->name_len = ls->namelen;
100	strncpy(dirent->name, ls->name, ls->namelen);
101	if (ls->sb->s_feature_incompat & EXT2_FEATURE_INCOMPAT_FILETYPE)
102		dirent->name_len |= (ls->flags & 0x7) << 8;
103
104	ls->done++;
105	return DIRENT_ABORT|DIRENT_CHANGED;
106}
107
108/*
109 * Note: the low 3 bits of the flags field are used as the directory
110 * entry filetype.
111 */
112#ifdef __TURBOC__
113 #pragma argsused
114#endif
115errcode_t ext2fs_link(ext2_filsys fs, ext2_ino_t dir, const char *name,
116		      ext2_ino_t ino, int flags)
117{
118	errcode_t		retval;
119	struct link_struct	ls;
120	struct ext2_inode	inode;
121
122	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
123
124	if (!(fs->flags & EXT2_FLAG_RW))
125		return EXT2_ET_RO_FILSYS;
126
127	ls.fs = fs;
128	ls.name = name;
129	ls.namelen = name ? strlen(name) : 0;
130	ls.inode = ino;
131	ls.flags = flags;
132	ls.done = 0;
133	ls.sb = fs->super;
134	ls.blocksize = fs->blocksize;
135	ls.err = 0;
136
137	retval = ext2fs_dir_iterate(fs, dir, DIRENT_FLAG_INCLUDE_EMPTY,
138				    0, link_proc, &ls);
139	if (retval)
140		return retval;
141	if (ls.err)
142		return ls.err;
143
144	if (!ls.done)
145		return EXT2_ET_DIR_NO_SPACE;
146
147	if ((retval = ext2fs_read_inode(fs, dir, &inode)) != 0)
148		return retval;
149
150	if (inode.i_flags & EXT2_INDEX_FL) {
151		inode.i_flags &= ~EXT2_INDEX_FL;
152		if ((retval = ext2fs_write_inode(fs, dir, &inode)) != 0)
153			return retval;
154	}
155
156	return 0;
157}
158