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/*
* symlink.c --- make a symlink in the filesystem, based on mkdir.c
*
* Copyright (c) 2012, Intel Corporation.
* All Rights Reserved.
*
* %Begin-Header%
* This file may be redistributed under the terms of the GNU Library
* General Public License, version 2.
* %End-Header%
*/
#include "config.h"
#include <stdio.h>
#include <string.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <fcntl.h>
#include <time.h>
#if HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#if HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#include "ext2_fs.h"
#include "ext2fs.h"
#ifndef HAVE_STRNLEN
/*
* Incredibly, libc5 doesn't appear to have strnlen. So we have to
* provide our own.
*/
static int my_strnlen(const char * s, int count)
{
const char *cp = s;
while (count-- && *cp)
cp++;
return cp - s;
}
#define strnlen(str, x) my_strnlen((str),(x))
#endif
errcode_t ext2fs_symlink(ext2_filsys fs, ext2_ino_t parent, ext2_ino_t ino,
const char *name, const char *target)
{
errcode_t retval;
struct ext2_inode inode;
ext2_ino_t scratch_ino;
blk64_t blk;
int fastlink, inlinelink;
unsigned int target_len;
char *block_buf = 0;
int drop_refcount = 0;
EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
/*
* The Linux kernel doesn't allow for links longer than a block
* (counting the NUL terminator)
*/
target_len = strnlen(target, fs->blocksize + 1);
if (target_len >= fs->blocksize) {
retval = EXT2_ET_INVALID_ARGUMENT;
goto cleanup;
}
/*
* Allocate a data block for slow links
*/
retval = ext2fs_get_mem(fs->blocksize, &block_buf);
if (retval)
goto cleanup;
memset(block_buf, 0, fs->blocksize);
strncpy(block_buf, target, fs->blocksize);
memset(&inode, 0, sizeof(struct ext2_inode));
fastlink = (target_len < sizeof(inode.i_block));
if (!fastlink) {
retval = ext2fs_new_block2(fs, ext2fs_find_inode_goal(fs, ino,
&inode,
0),
NULL, &blk);
if (retval)
goto cleanup;
}
/*
* Allocate an inode, if necessary
*/
if (!ino) {
retval = ext2fs_new_inode(fs, parent, LINUX_S_IFLNK | 0755,
0, &ino);
if (retval)
goto cleanup;
}
/*
* Create the inode structure....
*/
inode.i_mode = LINUX_S_IFLNK | 0777;
inode.i_uid = inode.i_gid = 0;
inode.i_links_count = 1;
ext2fs_inode_size_set(fs, &inode, target_len);
/* The time fields are set by ext2fs_write_new_inode() */
inlinelink = !fastlink && ext2fs_has_feature_inline_data(fs->super);
if (fastlink) {
/* Fast symlinks, target stored in inode */
strcpy((char *)&inode.i_block, target);
} else if (inlinelink) {
/* Try inserting an inline data symlink */
inode.i_flags |= EXT4_INLINE_DATA_FL;
retval = ext2fs_write_new_inode(fs, ino, &inode);
if (retval)
goto cleanup;
retval = ext2fs_inline_data_set(fs, ino, &inode, block_buf,
target_len);
if (retval) {
inode.i_flags &= ~EXT4_INLINE_DATA_FL;
inlinelink = 0;
goto need_block;
}
retval = ext2fs_read_inode(fs, ino, &inode);
if (retval)
goto cleanup;
} else {
need_block:
/* Slow symlinks, target stored in the first block */
ext2fs_iblk_set(fs, &inode, 1);
if (ext2fs_has_feature_extents(fs->super)) {
/*
* The extent bmap is setup after the inode and block
* have been written out below.
*/
inode.i_flags |= EXT4_EXTENTS_FL;
}
}
/*
* Write out the inode and inode data block. The inode generation
* number is assigned by write_new_inode, which means that the
* operations using ino must come after it.
*/
if (inlinelink)
retval = ext2fs_write_inode(fs, ino, &inode);
else
retval = ext2fs_write_new_inode(fs, ino, &inode);
if (retval)
goto cleanup;
if (!fastlink && !inlinelink) {
retval = ext2fs_bmap2(fs, ino, &inode, NULL, BMAP_SET, 0, NULL,
&blk);
if (retval)
goto cleanup;
retval = io_channel_write_blk64(fs->io, blk, 1, block_buf);
if (retval)
goto cleanup;
}
/*
* Update accounting....
*/
if (!fastlink && !inlinelink)
ext2fs_block_alloc_stats2(fs, blk, +1);
ext2fs_inode_alloc_stats2(fs, ino, +1, 0);
drop_refcount = 1;
/*
* Link the symlink into the filesystem hierarchy
*/
if (name) {
retval = ext2fs_lookup(fs, parent, name, strlen(name), 0,
&scratch_ino);
if (!retval) {
retval = EXT2_ET_FILE_EXISTS;
goto cleanup;
}
if (retval != EXT2_ET_FILE_NOT_FOUND)
goto cleanup;
retval = ext2fs_link(fs, parent, name, ino, EXT2_FT_SYMLINK);
if (retval)
goto cleanup;
}
drop_refcount = 0;
cleanup:
if (block_buf)
ext2fs_free_mem(&block_buf);
if (drop_refcount) {
if (!fastlink && !inlinelink)
ext2fs_block_alloc_stats2(fs, blk, -1);
ext2fs_inode_alloc_stats2(fs, ino, -1, 0);
}
return retval;
}
/*
* Test whether an inode is a fast symlink.
*
* A fast symlink has its symlink data stored in inode->i_block.
*/
int ext2fs_is_fast_symlink(struct ext2_inode *inode)
{
return LINUX_S_ISLNK(inode->i_mode) && EXT2_I_SIZE(inode) &&
EXT2_I_SIZE(inode) < sizeof(inode->i_block);
}
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