link.c revision 65f0aab98b20b5994a726ab90d355248bcddfffd 
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	rec_len = EXT2_DIR_REC_LEN(ls->namelen);
45
46	ls->err = ext2fs_get_rec_len(ls->fs, dirent, &curr_rec_len);
47	if (ls->err)
48		return DIRENT_ABORT;
49
50	/*
51	 * See if the following directory entry (if any) is unused;
52	 * if so, absorb it into this one.
53	 */
54	next = (struct ext2_dir_entry *) (buf + offset + curr_rec_len);
55	if ((offset + curr_rec_len < blocksize - 8) &&
56	    (next->inode == 0) &&
57	    (offset + curr_rec_len + next->rec_len <= blocksize)) {
58		curr_rec_len += next->rec_len;
59		ls->err = ext2fs_set_rec_len(ls->fs, curr_rec_len, dirent);
60		if (ls->err)
61			return DIRENT_ABORT;
62		ret = DIRENT_CHANGED;
63	}
64
65	/*
66	 * If the directory entry is used, see if we can split the
67	 * directory entry to make room for the new name.  If so,
68	 * truncate it and return.
69	 */
70	if (dirent->inode) {
71		min_rec_len = EXT2_DIR_REC_LEN(dirent->name_len & 0xFF);
72		if (curr_rec_len < (min_rec_len + rec_len))
73			return ret;
74		rec_len = curr_rec_len - min_rec_len;
75		ls->err = ext2fs_set_rec_len(ls->fs, min_rec_len, dirent);
76		if (ls->err)
77			return DIRENT_ABORT;
78		next = (struct ext2_dir_entry *) (buf + offset +
79						  dirent->rec_len);
80		next->inode = 0;
81		next->name_len = 0;
82		ls->err = ext2fs_set_rec_len(ls->fs, rec_len, next);
83		if (ls->err)
84			return DIRENT_ABORT;
85		return DIRENT_CHANGED;
86	}
87
88	/*
89	 * If we get this far, then the directory entry is not used.
90	 * See if we can fit the request entry in.  If so, do it.
91	 */
92	if (curr_rec_len < rec_len)
93		return ret;
94	dirent->inode = ls->inode;
95	dirent->name_len = ls->namelen;
96	strncpy(dirent->name, ls->name, ls->namelen);
97	if (ls->sb->s_feature_incompat & EXT2_FEATURE_INCOMPAT_FILETYPE)
98		dirent->name_len |= (ls->flags & 0x7) << 8;
99
100	ls->done++;
101	return DIRENT_ABORT|DIRENT_CHANGED;
102}
103
104/*
105 * Note: the low 3 bits of the flags field are used as the directory
106 * entry filetype.
107 */
108#ifdef __TURBOC__
109 #pragma argsused
110#endif
111errcode_t ext2fs_link(ext2_filsys fs, ext2_ino_t dir, const char *name,
112		      ext2_ino_t ino, int flags)
113{
114	errcode_t		retval;
115	struct link_struct	ls;
116	struct ext2_inode	inode;
117
118	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
119
120	if (!(fs->flags & EXT2_FLAG_RW))
121		return EXT2_ET_RO_FILSYS;
122
123	ls.fs = fs;
124	ls.name = name;
125	ls.namelen = name ? strlen(name) : 0;
126	ls.inode = ino;
127	ls.flags = flags;
128	ls.done = 0;
129	ls.sb = fs->super;
130	ls.blocksize = fs->blocksize;
131	ls.err = 0;
132
133	retval = ext2fs_dir_iterate(fs, dir, DIRENT_FLAG_INCLUDE_EMPTY,
134				    0, link_proc, &ls);
135	if (retval)
136		return retval;
137	if (ls.err)
138		return ls.err;
139
140	if (!ls.done)
141		return EXT2_ET_DIR_NO_SPACE;
142
143	if ((retval = ext2fs_read_inode(fs, dir, &inode)) != 0)
144		return retval;
145
146	if (inode.i_flags & EXT2_INDEX_FL) {
147		inode.i_flags &= ~EXT2_INDEX_FL;
148		if ((retval = ext2fs_write_inode(fs, dir, &inode)) != 0)
149			return retval;
150	}
151
152	return 0;
153}
154