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 31 errcode_t ext2fs_symlink(ext2_filsys fs, ext2_ino_t parent, ext2_ino_t ino, 32 const char *name, const char *target) 33 { 34 errcode_t retval; 35 struct ext2_inode inode; 36 ext2_ino_t scratch_ino; 37 blk64_t blk; 38 int fastlink, inlinelink; 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 = strnlen(target, fs->blocksize + 1); 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 retval = ext2fs_get_mem(fs->blocksize+1, &block_buf); 55 if (retval) 56 goto cleanup; 57 memset(block_buf, 0, fs->blocksize+1); 58 strncpy(block_buf, target, fs->blocksize); 59 60 memset(&inode, 0, sizeof(struct ext2_inode)); 61 fastlink = (target_len < sizeof(inode.i_block)); 62 if (!fastlink) { 63 retval = ext2fs_new_block2(fs, ext2fs_find_inode_goal(fs, ino, 64 &inode, 65 0), 66 NULL, &blk); 67 if (retval) 68 goto cleanup; 69 } 70 71 /* 72 * Allocate an inode, if necessary 73 */ 74 if (!ino) { 75 retval = ext2fs_new_inode(fs, parent, LINUX_S_IFLNK | 0755, 76 0, &ino); 77 if (retval) 78 goto cleanup; 79 } 80 81 /* 82 * Create the inode structure.... 83 */ 84 inode.i_mode = LINUX_S_IFLNK | 0777; 85 inode.i_uid = inode.i_gid = 0; 86 inode.i_links_count = 1; 87 ext2fs_inode_size_set(fs, &inode, target_len); 88 /* The time fields are set by ext2fs_write_new_inode() */ 89 90 inlinelink = !fastlink && 91 ext2fs_has_feature_inline_data(fs->super) && 92 (target_len < fs->blocksize); 93 if (fastlink) { 94 /* Fast symlinks, target stored in inode */ 95 strcpy((char *)&inode.i_block, target); 96 } else if (inlinelink) { 97 /* Try inserting an inline data symlink */ 98 inode.i_flags |= EXT4_INLINE_DATA_FL; 99 retval = ext2fs_write_new_inode(fs, ino, &inode); 100 if (retval) 101 goto cleanup; 102 retval = ext2fs_inline_data_set(fs, ino, &inode, block_buf, 103 target_len); 104 if (retval) { 105 inode.i_flags &= ~EXT4_INLINE_DATA_FL; 106 inlinelink = 0; 107 goto need_block; 108 } 109 retval = ext2fs_read_inode(fs, ino, &inode); 110 if (retval) 111 goto cleanup; 112 } else { 113 need_block: 114 /* Slow symlinks, target stored in the first block */ 115 ext2fs_iblk_set(fs, &inode, 1); 116 if (ext2fs_has_feature_extents(fs->super)) { 117 /* 118 * The extent bmap is setup after the inode and block 119 * have been written out below. 120 */ 121 inode.i_flags |= EXT4_EXTENTS_FL; 122 } 123 } 124 125 /* 126 * Write out the inode and inode data block. The inode generation 127 * number is assigned by write_new_inode, which means that the 128 * operations using ino must come after it. 129 */ 130 if (inlinelink) 131 retval = ext2fs_write_inode(fs, ino, &inode); 132 else 133 retval = ext2fs_write_new_inode(fs, ino, &inode); 134 if (retval) 135 goto cleanup; 136 137 if (!fastlink && !inlinelink) { 138 retval = ext2fs_bmap2(fs, ino, &inode, NULL, BMAP_SET, 0, NULL, 139 &blk); 140 if (retval) 141 goto cleanup; 142 143 retval = io_channel_write_blk64(fs->io, blk, 1, block_buf); 144 if (retval) 145 goto cleanup; 146 } 147 148 /* 149 * Link the symlink into the filesystem hierarchy 150 */ 151 if (name) { 152 retval = ext2fs_lookup(fs, parent, name, strlen(name), 0, 153 &scratch_ino); 154 if (!retval) { 155 retval = EXT2_ET_FILE_EXISTS; 156 goto cleanup; 157 } 158 if (retval != EXT2_ET_FILE_NOT_FOUND) 159 goto cleanup; 160 retval = ext2fs_link(fs, parent, name, ino, EXT2_FT_SYMLINK); 161 if (retval) 162 goto cleanup; 163 } 164 165 /* 166 * Update accounting.... 167 */ 168 if (!fastlink && !inlinelink) 169 ext2fs_block_alloc_stats2(fs, blk, +1); 170 ext2fs_inode_alloc_stats2(fs, ino, +1, 0); 171 172 cleanup: 173 if (block_buf) 174 ext2fs_free_mem(&block_buf); 175 return retval; 176 } 177
