1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * dir.c 4 * 5 * PURPOSE 6 * Directory handling routines for the OSTA-UDF(tm) filesystem. 7 * 8 * COPYRIGHT 9 * (C) 1998-2004 Ben Fennema 10 * 11 * HISTORY 12 * 13 * 10/05/98 dgb Split directory operations into its own file 14 * Implemented directory reads via do_udf_readdir 15 * 10/06/98 Made directory operations work! 16 * 11/17/98 Rewrote directory to support ICBTAG_FLAG_AD_LONG 17 * 11/25/98 blf Rewrote directory handling (readdir+lookup) to support reading 18 * across blocks. 19 * 12/12/98 Split out the lookup code to namei.c. bulk of directory 20 * code now in directory.c:udf_fileident_read. 21 */ 22 23 #include "udfdecl.h" 24 25 #include <linux/string.h> 26 #include <linux/errno.h> 27 #include <linux/filelock.h> 28 #include <linux/mm.h> 29 #include <linux/slab.h> 30 #include <linux/bio.h> 31 #include <linux/iversion.h> 32 33 #include "udf_i.h" 34 #include "udf_sb.h" 35 36 static int udf_readdir(struct file *file, struct dir_context *ctx) 37 { 38 struct inode *dir = file_inode(file); 39 loff_t nf_pos, emit_pos = 0; 40 int flen; 41 unsigned char *fname = NULL; 42 int ret = 0; 43 struct super_block *sb = dir->i_sb; 44 bool pos_valid = false; 45 struct udf_fileident_iter iter; 46 47 if (ctx->pos == 0) { 48 if (!dir_emit_dot(file, ctx)) 49 return 0; 50 ctx->pos = 1; 51 } 52 nf_pos = (ctx->pos - 1) << 2; 53 if (nf_pos >= dir->i_size) 54 goto out; 55 56 /* 57 * Something changed since last readdir (either lseek was called or dir 58 * changed)? We need to verify the position correctly points at the 59 * beginning of some dir entry so that the directory parsing code does 60 * not get confused. Since UDF does not have any reliable way of 61 * identifying beginning of dir entry (names are under user control), 62 * we need to scan the directory from the beginning. 63 */ 64 if (!inode_eq_iversion(dir, *(u64 *)file->private_data)) { 65 emit_pos = nf_pos; 66 nf_pos = 0; 67 } else { 68 pos_valid = true; 69 } 70 71 fname = kmalloc(UDF_NAME_LEN, GFP_KERNEL); 72 if (!fname) { 73 ret = -ENOMEM; 74 goto out; 75 } 76 77 for (ret = udf_fiiter_init(&iter, dir, nf_pos); 78 !ret && iter.pos < dir->i_size; 79 ret = udf_fiiter_advance(&iter)) { 80 struct kernel_lb_addr tloc; 81 udf_pblk_t iblock; 82 83 /* Still not at offset where user asked us to read from? */ 84 if (iter.pos < emit_pos) 85 continue; 86 87 /* Update file position only if we got past the current one */ 88 pos_valid = true; 89 ctx->pos = (iter.pos >> 2) + 1; 90 91 if (iter.fi.fileCharacteristics & FID_FILE_CHAR_DELETED) { 92 if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNDELETE)) 93 continue; 94 } 95 96 if (iter.fi.fileCharacteristics & FID_FILE_CHAR_HIDDEN) { 97 if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNHIDE)) 98 continue; 99 } 100 101 if (iter.fi.fileCharacteristics & FID_FILE_CHAR_PARENT) { 102 if (!dir_emit_dotdot(file, ctx)) 103 goto out_iter; 104 continue; 105 } 106 107 flen = udf_get_filename(sb, iter.name, 108 iter.fi.lengthFileIdent, fname, UDF_NAME_LEN); 109 if (flen < 0) 110 continue; 111 112 tloc = lelb_to_cpu(iter.fi.icb.extLocation); 113 iblock = udf_get_lb_pblock(sb, &tloc, 0); 114 if (!dir_emit(ctx, fname, flen, iblock, DT_UNKNOWN)) 115 goto out_iter; 116 } 117 118 if (!ret) { 119 ctx->pos = (iter.pos >> 2) + 1; 120 pos_valid = true; 121 } 122 out_iter: 123 udf_fiiter_release(&iter); 124 out: 125 if (pos_valid) 126 *(u64 *)file->private_data = inode_query_iversion(dir); 127 kfree(fname); 128 129 return ret; 130 } 131 132 static int udf_dir_open(struct inode *inode, struct file *file) 133 { 134 file->private_data = kzalloc(sizeof(u64), GFP_KERNEL); 135 if (!file->private_data) 136 return -ENOMEM; 137 return 0; 138 } 139 140 static int udf_dir_release(struct inode *inode, struct file *file) 141 { 142 kfree(file->private_data); 143 return 0; 144 } 145 146 static loff_t udf_dir_llseek(struct file *file, loff_t offset, int whence) 147 { 148 return generic_llseek_cookie(file, offset, whence, 149 (u64 *)file->private_data); 150 } 151 152 /* readdir and lookup functions */ 153 const struct file_operations udf_dir_operations = { 154 .open = udf_dir_open, 155 .release = udf_dir_release, 156 .llseek = udf_dir_llseek, 157 .read = generic_read_dir, 158 .iterate_shared = udf_readdir, 159 .unlocked_ioctl = udf_ioctl, 160 .fsync = generic_file_fsync, 161 .setlease = generic_setlease, 162 }; 163