diff options
Diffstat (limited to 'lib/ext2fs/symlink.c')
| -rw-r--r-- | lib/ext2fs/symlink.c | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/lib/ext2fs/symlink.c b/lib/ext2fs/symlink.c new file mode 100644 index 0000000..a66fb7e --- /dev/null +++ b/lib/ext2fs/symlink.c @@ -0,0 +1,212 @@ +/* + * 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); +} |