link.c revision 18a1444b4f1e6a0948fd38fa0de382d86cfe04de 
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 <stdio.h>
13#include <string.h>
14#if HAVE_UNISTD_H
15#include <unistd.h>
16#endif
17
18#include "ext2_fs.h"
19#include "ext2fs.h"
20
21struct link_struct  {
22	ext2_filsys	fs;
23	const char	*name;
24	int		namelen;
25	ext2_ino_t	inode;
26	int		flags;
27	int		done;
28	unsigned int	blocksize;
29	errcode_t	err;
30	struct ext2_super_block *sb;
31};
32
33static int link_proc(struct ext2_dir_entry *dirent,
34		     int	offset,
35		     int	blocksize,
36		     char	*buf,
37		     void	*priv_data)
38{
39	struct link_struct *ls = (struct link_struct *) priv_data;
40	struct ext2_dir_entry *next;
41	unsigned int rec_len, min_rec_len, curr_rec_len;
42	int ret = 0;
43
44	if (ls->done)
45		return DIRENT_ABORT;
46
47	rec_len = EXT2_DIR_REC_LEN(ls->namelen);
48
49	ls->err = ext2fs_get_rec_len(ls->fs, dirent, &curr_rec_len);
50	if (ls->err)
51		return DIRENT_ABORT;
52
53	/*
54	 * See if the following directory entry (if any) is unused;
55	 * if so, absorb it into this one.
56	 */
57	next = (struct ext2_dir_entry *) (buf + offset + curr_rec_len);
58	if ((offset + (int) curr_rec_len < blocksize - 8) &&
59	    (next->inode == 0) &&
60	    (offset + (int) curr_rec_len + (int) next->rec_len <= blocksize)) {
61		curr_rec_len += next->rec_len;
62		ls->err = ext2fs_set_rec_len(ls->fs, curr_rec_len, dirent);
63		if (ls->err)
64			return DIRENT_ABORT;
65		ret = DIRENT_CHANGED;
66	}
67
68	/*
69	 * If the directory entry is used, see if we can split the
70	 * directory entry to make room for the new name.  If so,
71	 * truncate it and return.
72	 */
73	if (dirent->inode) {
74		min_rec_len = EXT2_DIR_REC_LEN(dirent->name_len & 0xFF);
75		if (curr_rec_len < (min_rec_len + rec_len))
76			return ret;
77		rec_len = curr_rec_len - min_rec_len;
78		ls->err = ext2fs_set_rec_len(ls->fs, min_rec_len, dirent);
79		if (ls->err)
80			return DIRENT_ABORT;
81		next = (struct ext2_dir_entry *) (buf + offset +
82						  dirent->rec_len);
83		next->inode = 0;
84		next->name_len = 0;
85		ls->err = ext2fs_set_rec_len(ls->fs, rec_len, next);
86		if (ls->err)
87			return DIRENT_ABORT;
88		return DIRENT_CHANGED;
89	}
90
91	/*
92	 * If we get this far, then the directory entry is not used.
93	 * See if we can fit the request entry in.  If so, do it.
94	 */
95	if (curr_rec_len < rec_len)
96		return ret;
97	dirent->inode = ls->inode;
98	dirent->name_len = ls->namelen;
99	strncpy(dirent->name, ls->name, ls->namelen);
100	if (ls->sb->s_feature_incompat & EXT2_FEATURE_INCOMPAT_FILETYPE)
101		dirent->name_len |= (ls->flags & 0x7) << 8;
102
103	ls->done++;
104	return DIRENT_ABORT|DIRENT_CHANGED;
105}
106
107/*
108 * Note: the low 3 bits of the flags field are used as the directory
109 * entry filetype.
110 */
111#ifdef __TURBOC__
112 #pragma argsused
113#endif
114errcode_t ext2fs_link(ext2_filsys fs, ext2_ino_t dir, const char *name,
115		      ext2_ino_t ino, int flags)
116{
117	errcode_t		retval;
118	struct link_struct	ls;
119	struct ext2_inode	inode;
120
121	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
122
123	if (!(fs->flags & EXT2_FLAG_RW))
124		return EXT2_ET_RO_FILSYS;
125
126	ls.fs = fs;
127	ls.name = name;
128	ls.namelen = name ? strlen(name) : 0;
129	ls.inode = ino;
130	ls.flags = flags;
131	ls.done = 0;
132	ls.sb = fs->super;
133	ls.blocksize = fs->blocksize;
134	ls.err = 0;
135
136	retval = ext2fs_dir_iterate(fs, dir, DIRENT_FLAG_INCLUDE_EMPTY,
137				    0, link_proc, &ls);
138	if (retval)
139		return retval;
140	if (ls.err)
141		return ls.err;
142
143	if (!ls.done)
144		return EXT2_ET_DIR_NO_SPACE;
145
146	if ((retval = ext2fs_read_inode(fs, dir, &inode)) != 0)
147		return retval;
148
149	if (inode.i_flags & EXT2_INDEX_FL) {
150		inode.i_flags &= ~EXT2_INDEX_FL;
151		if ((retval = ext2fs_write_inode(fs, dir, &inode)) != 0)
152			return retval;
153	}
154
155	return 0;
156}
157