143 lines
3.6 KiB
C
143 lines
3.6 KiB
C
/*
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* dir.c
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*
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* PURPOSE
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* Directory handling routines for the OSTA-UDF(tm) filesystem.
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*
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* COPYRIGHT
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* This file is distributed under the terms of the GNU General Public
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* License (GPL). Copies of the GPL can be obtained from:
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* ftp://prep.ai.mit.edu/pub/gnu/GPL
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* Each contributing author retains all rights to their own work.
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*
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* (C) 1998-2004 Ben Fennema
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*
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* HISTORY
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*
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* 10/05/98 dgb Split directory operations into its own file
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* Implemented directory reads via do_udf_readdir
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* 10/06/98 Made directory operations work!
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* 11/17/98 Rewrote directory to support ICBTAG_FLAG_AD_LONG
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* 11/25/98 blf Rewrote directory handling (readdir+lookup) to support reading
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* across blocks.
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* 12/12/98 Split out the lookup code to namei.c. bulk of directory
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* code now in directory.c:udf_fileident_read.
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*/
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#include "udfdecl.h"
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#include <linux/string.h>
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#include <linux/errno.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/bio.h>
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#include <linux/iversion.h>
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#include "udf_i.h"
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#include "udf_sb.h"
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static int udf_readdir(struct file *file, struct dir_context *ctx)
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{
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struct inode *dir = file_inode(file);
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loff_t nf_pos, emit_pos = 0;
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int flen;
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unsigned char *fname = NULL;
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int ret = 0;
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struct super_block *sb = dir->i_sb;
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bool pos_valid = false;
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struct udf_fileident_iter iter;
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if (ctx->pos == 0) {
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if (!dir_emit_dot(file, ctx))
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return 0;
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ctx->pos = 1;
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}
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nf_pos = (ctx->pos - 1) << 2;
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if (nf_pos >= dir->i_size)
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goto out;
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/*
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* Something changed since last readdir (either lseek was called or dir
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* changed)? We need to verify the position correctly points at the
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* beginning of some dir entry so that the directory parsing code does
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* not get confused. Since UDF does not have any reliable way of
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* identifying beginning of dir entry (names are under user control),
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* we need to scan the directory from the beginning.
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*/
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if (!inode_eq_iversion(dir, file->f_version)) {
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emit_pos = nf_pos;
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nf_pos = 0;
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} else {
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pos_valid = true;
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}
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fname = kmalloc(UDF_NAME_LEN, GFP_NOFS);
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if (!fname) {
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ret = -ENOMEM;
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goto out;
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}
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for (ret = udf_fiiter_init(&iter, dir, nf_pos);
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!ret && iter.pos < dir->i_size;
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ret = udf_fiiter_advance(&iter)) {
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struct kernel_lb_addr tloc;
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udf_pblk_t iblock;
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/* Still not at offset where user asked us to read from? */
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if (iter.pos < emit_pos)
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continue;
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/* Update file position only if we got past the current one */
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pos_valid = true;
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ctx->pos = (iter.pos >> 2) + 1;
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if (iter.fi.fileCharacteristics & FID_FILE_CHAR_DELETED) {
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if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNDELETE))
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continue;
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}
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if (iter.fi.fileCharacteristics & FID_FILE_CHAR_HIDDEN) {
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if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNHIDE))
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continue;
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}
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if (iter.fi.fileCharacteristics & FID_FILE_CHAR_PARENT) {
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if (!dir_emit_dotdot(file, ctx))
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goto out_iter;
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continue;
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}
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flen = udf_get_filename(sb, iter.name,
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iter.fi.lengthFileIdent, fname, UDF_NAME_LEN);
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if (flen < 0)
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continue;
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tloc = lelb_to_cpu(iter.fi.icb.extLocation);
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iblock = udf_get_lb_pblock(sb, &tloc, 0);
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if (!dir_emit(ctx, fname, flen, iblock, DT_UNKNOWN))
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goto out_iter;
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}
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if (!ret) {
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ctx->pos = (iter.pos >> 2) + 1;
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pos_valid = true;
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}
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out_iter:
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udf_fiiter_release(&iter);
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out:
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if (pos_valid)
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file->f_version = inode_query_iversion(dir);
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kfree(fname);
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return ret;
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}
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/* readdir and lookup functions */
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const struct file_operations udf_dir_operations = {
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.llseek = generic_file_llseek,
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.read = generic_read_dir,
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.iterate_shared = udf_readdir,
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.unlocked_ioctl = udf_ioctl,
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.fsync = generic_file_fsync,
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};
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