link.c revision d1154eb460efe588eaed3d439c1caaca149fa362 
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	rec_len = EXT2_DIR_REC_LEN(ls->namelen);
46
47	ls->err = ext2fs_get_rec_len(ls->fs, dirent, &curr_rec_len);
48	if (ls->err)
49		return DIRENT_ABORT;
50
51	/*
52	 * See if the following directory entry (if any) is unused;
53	 * if so, absorb it into this one.
54	 */
55	next = (struct ext2_dir_entry *) (buf + offset + curr_rec_len);
56	if ((offset + (int) curr_rec_len < blocksize - 8) &&
57	    (next->inode == 0) &&
58	    (offset + (int) curr_rec_len + (int) next->rec_len <= blocksize)) {
59		curr_rec_len += next->rec_len;
60		ls->err = ext2fs_set_rec_len(ls->fs, curr_rec_len, dirent);
61		if (ls->err)
62			return DIRENT_ABORT;
63		ret = DIRENT_CHANGED;
64	}
65
66	/*
67	 * If the directory entry is used, see if we can split the
68	 * directory entry to make room for the new name.  If so,
69	 * truncate it and return.
70	 */
71	if (dirent->inode) {
72		min_rec_len = EXT2_DIR_REC_LEN(dirent->name_len & 0xFF);
73		if (curr_rec_len < (min_rec_len + rec_len))
74			return ret;
75		rec_len = curr_rec_len - min_rec_len;
76		ls->err = ext2fs_set_rec_len(ls->fs, min_rec_len, dirent);
77		if (ls->err)
78			return DIRENT_ABORT;
79		next = (struct ext2_dir_entry *) (buf + offset +
80						  dirent->rec_len);
81		next->inode = 0;
82		next->name_len = 0;
83		ls->err = ext2fs_set_rec_len(ls->fs, rec_len, next);
84		if (ls->err)
85			return DIRENT_ABORT;
86		return DIRENT_CHANGED;
87	}
88
89	/*
90	 * If we get this far, then the directory entry is not used.
91	 * See if we can fit the request entry in.  If so, do it.
92	 */
93	if (curr_rec_len < rec_len)
94		return ret;
95	dirent->inode = ls->inode;
96	dirent->name_len = ls->namelen;
97	strncpy(dirent->name, ls->name, ls->namelen);
98	if (ls->sb->s_feature_incompat & EXT2_FEATURE_INCOMPAT_FILETYPE)
99		dirent->name_len |= (ls->flags & 0x7) << 8;
100
101	ls->done++;
102	return DIRENT_ABORT|DIRENT_CHANGED;
103}
104
105/*
106 * Note: the low 3 bits of the flags field are used as the directory
107 * entry filetype.
108 */
109#ifdef __TURBOC__
110 #pragma argsused
111#endif
112errcode_t ext2fs_link(ext2_filsys fs, ext2_ino_t dir, const char *name,
113		      ext2_ino_t ino, int flags)
114{
115	errcode_t		retval;
116	struct link_struct	ls;
117	struct ext2_inode	inode;
118
119	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
120
121	if (!(fs->flags & EXT2_FLAG_RW))
122		return EXT2_ET_RO_FILSYS;
123
124	ls.fs = fs;
125	ls.name = name;
126	ls.namelen = name ? strlen(name) : 0;
127	ls.inode = ino;
128	ls.flags = flags;
129	ls.done = 0;
130	ls.sb = fs->super;
131	ls.blocksize = fs->blocksize;
132	ls.err = 0;
133
134	retval = ext2fs_dir_iterate(fs, dir, DIRENT_FLAG_INCLUDE_EMPTY,
135				    0, link_proc, &ls);
136	if (retval)
137		return retval;
138	if (ls.err)
139		return ls.err;
140
141	if (!ls.done)
142		return EXT2_ET_DIR_NO_SPACE;
143
144	if ((retval = ext2fs_read_inode(fs, dir, &inode)) != 0)
145		return retval;
146
147	if (inode.i_flags & EXT2_INDEX_FL) {
148		inode.i_flags &= ~EXT2_INDEX_FL;
149		if ((retval = ext2fs_write_inode(fs, dir, &inode)) != 0)
150			return retval;
151	}
152
153	return 0;
154}
155