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 
21 struct 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 
link_proc(struct ext2_dir_entry * dirent,int offset,int blocksize,char * buf,void * priv_data)33 static 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
ext2fs_link(ext2_filsys fs,ext2_ino_t dir,const char * name,ext2_ino_t ino,int flags)114 errcode_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