link.c revision fe4dd429dc878d877abe08c2c41eed48df4e4651 
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 Public
8 * License.
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	const char	*name;
23	int		namelen;
24	ext2_ino_t	inode;
25	int		flags;
26	int		done;
27	struct ext2_super_block *sb;
28};
29
30static int link_proc(struct ext2_dir_entry *dirent,
31		     int	offset,
32		     int	blocksize,
33		     char	*buf,
34		     void	*priv_data)
35{
36	struct link_struct *ls = (struct link_struct *) priv_data;
37	struct ext2_dir_entry *next;
38	int rec_len, min_rec_len;
39	int ret = 0;
40
41	rec_len = EXT2_DIR_REC_LEN(ls->namelen);
42
43	/*
44	 * See if the following directory entry (if any) is unused;
45	 * if so, absorb it into this one.
46	 */
47	next = (struct ext2_dir_entry *) (buf + offset + dirent->rec_len);
48	if ((offset + dirent->rec_len < blocksize - 8) &&
49	    (next->inode == 0) &&
50	    (offset + dirent->rec_len + next->rec_len <= blocksize)) {
51		dirent->rec_len += next->rec_len;
52		ret = DIRENT_CHANGED;
53	}
54
55	/*
56	 * If the directory entry is used, see if we can split the
57	 * directory entry to make room for the new name.  If so,
58	 * truncate it and return.
59	 */
60	if (dirent->inode) {
61		min_rec_len = EXT2_DIR_REC_LEN(dirent->name_len & 0xFF);
62		if (dirent->rec_len < (min_rec_len + rec_len))
63			return ret;
64		rec_len = dirent->rec_len - min_rec_len;
65		dirent->rec_len = min_rec_len;
66		next = (struct ext2_dir_entry *) (buf + offset +
67						  dirent->rec_len);
68		next->inode = 0;
69		next->name_len = 0;
70		next->rec_len = rec_len;
71		return DIRENT_CHANGED;
72	}
73
74	/*
75	 * If we get this far, then the directory entry is not used.
76	 * See if we can fit the request entry in.  If so, do it.
77	 */
78	if (dirent->rec_len < rec_len)
79		return ret;
80	dirent->inode = ls->inode;
81	dirent->name_len = ls->namelen;
82	strncpy(dirent->name, ls->name, ls->namelen);
83	if (ls->sb->s_feature_incompat & EXT2_FEATURE_INCOMPAT_FILETYPE)
84		dirent->name_len |= (ls->flags & 0x7) << 8;
85
86	ls->done++;
87	return DIRENT_ABORT|DIRENT_CHANGED;
88}
89
90/*
91 * Note: the low 3 bits of the flags field are used as the directory
92 * entry filetype.
93 */
94#ifdef __TURBOC__
95 #pragma argsused
96#endif
97errcode_t ext2fs_link(ext2_filsys fs, ext2_ino_t dir, const char *name,
98		      ext2_ino_t ino, int flags)
99{
100	errcode_t		retval;
101	struct link_struct	ls;
102	struct ext2_inode	inode;
103
104	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
105
106	if (!(fs->flags & EXT2_FLAG_RW))
107		return EXT2_ET_RO_FILSYS;
108
109	ls.name = name;
110	ls.namelen = name ? strlen(name) : 0;
111	ls.inode = ino;
112	ls.flags = flags;
113	ls.done = 0;
114	ls.sb = fs->super;
115
116	retval = ext2fs_dir_iterate(fs, dir, DIRENT_FLAG_INCLUDE_EMPTY,
117				    0, link_proc, &ls);
118	if (retval)
119		return retval;
120
121	if (!ls.done)
122		return EXT2_ET_DIR_NO_SPACE;
123
124	if ((retval = ext2fs_read_inode(fs, dir, &inode)) != 0)
125		return retval;
126
127	if (inode.i_flags & EXT2_INDEX_FL) {
128		inode.i_flags &= ~EXT2_INDEX_FL;
129		if ((retval = ext2fs_write_inode(fs, dir, &inode)) != 0)
130			return retval;
131	}
132
133	return 0;
134}
135