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