symlink.c revision 62f17f36031102a2a40fac338e063c556f73b94a 
1/*
2 * symlink.c --- make a symlink in the filesystem, based on mkdir.c
3 *
4 * Copyright (c) 2012, Intel Corporation.
5 * All Rights Reserved.
6 *
7 * %Begin-Header%
8 * This file may be redistributed under the terms of the GNU Library
9 * General Public License, version 2.
10 * %End-Header%
11 */
12
13#include "config.h"
14#include <stdio.h>
15#include <string.h>
16#if HAVE_UNISTD_H
17#include <unistd.h>
18#endif
19#include <fcntl.h>
20#include <time.h>
21#if HAVE_SYS_STAT_H
22#include <sys/stat.h>
23#endif
24#if HAVE_SYS_TYPES_H
25#include <sys/types.h>
26#endif
27
28#include "ext2_fs.h"
29#include "ext2fs.h"
30
31errcode_t ext2fs_symlink(ext2_filsys fs, ext2_ino_t parent, ext2_ino_t ino,
32			 const char *name, char *target)
33{
34	ext2_extent_handle_t	handle;
35	errcode_t		retval;
36	struct ext2_inode	inode;
37	ext2_ino_t		scratch_ino;
38	blk64_t			blk;
39	int			fastlink;
40	unsigned int		target_len;
41	char			*block_buf = 0;
42
43	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
44
45	/* The Linux kernel doesn't allow for links longer than a block */
46	target_len = strlen(target);
47	if (target_len > fs->blocksize) {
48		retval = EXT2_ET_INVALID_ARGUMENT;
49		goto cleanup;
50	}
51
52	/*
53	 * Allocate a data block for slow links
54	 */
55	fastlink = (target_len < sizeof(inode.i_block));
56	if (!fastlink) {
57		retval = ext2fs_new_block2(fs, 0, 0, &blk);
58		if (retval)
59			goto cleanup;
60		retval = ext2fs_get_mem(fs->blocksize, &block_buf);
61		if (retval)
62			goto cleanup;
63	}
64
65	/*
66	 * Allocate an inode, if necessary
67	 */
68	if (!ino) {
69		retval = ext2fs_new_inode(fs, parent, LINUX_S_IFLNK | 0755,
70					  0, &ino);
71		if (retval)
72			goto cleanup;
73	}
74
75	/*
76	 * Create the inode structure....
77	 */
78	memset(&inode, 0, sizeof(struct ext2_inode));
79	inode.i_mode = LINUX_S_IFLNK | 0777;
80	inode.i_uid = inode.i_gid = 0;
81	ext2fs_iblk_set(fs, &inode, fastlink ? 0 : 1);
82	inode.i_links_count = 1;
83	inode.i_size = target_len;
84	/* The time fields are set by ext2fs_write_new_inode() */
85
86	if (fastlink) {
87		/* Fast symlinks, target stored in inode */
88		strcpy((char *)&inode.i_block, target);
89	} else {
90		/* Slow symlinks, target stored in the first block */
91		memset(block_buf, 0, fs->blocksize);
92		strcpy(block_buf, target);
93		if (fs->super->s_feature_incompat &
94		    EXT3_FEATURE_INCOMPAT_EXTENTS) {
95			/*
96			 * The extent bmap is setup after the inode and block
97			 * have been written out below.
98			 */
99			inode.i_flags |= EXT4_EXTENTS_FL;
100		}
101	}
102
103	/*
104	 * Write out the inode and inode data block.  The inode generation
105	 * number is assigned by write_new_inode, which means that the
106	 * operations using ino must come after it.
107	 */
108	retval = ext2fs_write_new_inode(fs, ino, &inode);
109	if (retval)
110		goto cleanup;
111
112	if (!fastlink) {
113		retval = ext2fs_bmap2(fs, ino, &inode, NULL, BMAP_SET, 0, NULL,
114				      &blk);
115		if (retval)
116			goto cleanup;
117
118		retval = io_channel_write_blk64(fs->io, blk, 1, block_buf);
119		if (retval)
120			goto cleanup;
121	}
122
123	/*
124	 * Link the symlink into the filesystem hierarchy
125	 */
126	if (name) {
127		retval = ext2fs_lookup(fs, parent, name, strlen(name), 0,
128				       &scratch_ino);
129		if (!retval) {
130			retval = EXT2_ET_FILE_EXISTS;
131			goto cleanup;
132		}
133		if (retval != EXT2_ET_FILE_NOT_FOUND)
134			goto cleanup;
135		retval = ext2fs_link(fs, parent, name, ino, EXT2_FT_SYMLINK);
136		if (retval)
137			goto cleanup;
138	}
139
140	/*
141	 * Update accounting....
142	 */
143	if (!fastlink)
144		ext2fs_block_alloc_stats2(fs, blk, +1);
145	ext2fs_inode_alloc_stats2(fs, ino, +1, 0);
146
147cleanup:
148	if (block_buf)
149		ext2fs_free_mem(&block_buf);
150	return retval;
151}
152