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/mm.h> 28 #include <linux/slab.h> 29 #include <linux/bio.h> 30 #include <linux/iversion.h> 31 32 #include "udf_i.h" 33 #include "udf_sb.h" 34 35 static int udf_readdir(struct file *file, struct dir_context *ctx) 36 { 37 struct inode *dir = file_inode(file); 38 loff_t nf_pos, emit_pos = 0; 39 int flen; 40 unsigned char *fname = NULL; 41 int ret = 0; 42 struct super_block *sb = dir->i_sb; 43 bool pos_valid = false; 44 struct udf_fileident_iter iter; 45 46 if (ctx->pos == 0) { 47 if (!dir_emit_dot(file, ctx)) 48 return 0; 49 ctx->pos = 1; 50 } 51 nf_pos = (ctx->pos - 1) << 2; 52 if (nf_pos >= dir->i_size) 53 goto out; 54 55 /* 56 * Something changed since last readdir (either lseek was called or dir 57 * changed)? We need to verify the position correctly points at the 58 * beginning of some dir entry so that the directory parsing code does 59 * not get confused. Since UDF does not have any reliable way of 60 * identifying beginning of dir entry (names are under user control), 61 * we need to scan the directory from the beginning. 62 */ 63 if (!inode_eq_iversion(dir, file->f_version)) { 64 emit_pos = nf_pos; 65 nf_pos = 0; 66 } else { 67 pos_valid = true; 68 } 69 70 fname = kmalloc(UDF_NAME_LEN, GFP_NOFS); 71 if (!fname) { 72 ret = -ENOMEM; 73 goto out; 74 } 75 76 for (ret = udf_fiiter_init(&iter, dir, nf_pos); 77 !ret && iter.pos < dir->i_size; 78 ret = udf_fiiter_advance(&iter)) { 79 struct kernel_lb_addr tloc; 80 udf_pblk_t iblock; 81 82 /* Still not at offset where user asked us to read from? */ 83 if (iter.pos < emit_pos) 84 continue; 85 86 /* Update file position only if we got past the current one */ 87 pos_valid = true; 88 ctx->pos = (iter.pos >> 2) + 1; 89 90 if (iter.fi.fileCharacteristics & FID_FILE_CHAR_DELETED) { 91 if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNDELETE)) 92 continue; 93 } 94 95 if (iter.fi.fileCharacteristics & FID_FILE_CHAR_HIDDEN) { 96 if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNHIDE)) 97 continue; 98 } 99 100 if (iter.fi.fileCharacteristics & FID_FILE_CHAR_PARENT) { 101 if (!dir_emit_dotdot(file, ctx)) 102 goto out_iter; 103 continue; 104 } 105 106 flen = udf_get_filename(sb, iter.name, 107 iter.fi.lengthFileIdent, fname, UDF_NAME_LEN); 108 if (flen < 0) 109 continue; 110 111 tloc = lelb_to_cpu(iter.fi.icb.extLocation); 112 iblock = udf_get_lb_pblock(sb, &tloc, 0); 113 if (!dir_emit(ctx, fname, flen, iblock, DT_UNKNOWN)) 114 goto out_iter; 115 } 116 117 if (!ret) { 118 ctx->pos = (iter.pos >> 2) + 1; 119 pos_valid = true; 120 } 121 out_iter: 122 udf_fiiter_release(&iter); 123 out: 124 if (pos_valid) 125 file->f_version = inode_query_iversion(dir); 126 kfree(fname); 127 128 return ret; 129 } 130 131 /* readdir and lookup functions */ 132 const struct file_operations udf_dir_operations = { 133 .llseek = generic_file_llseek, 134 .read = generic_read_dir, 135 .iterate_shared = udf_readdir, 136 .unlocked_ioctl = udf_ioctl, 137 .fsync = generic_file_fsync, 138 }; 139