// SPDX-License-Identifier: GPL-2.0-only
/*
 * dir.c
 *
 * PURPOSE
 *  Directory handling routines for the OSTA-UDF(tm) filesystem.
 *
 * COPYRIGHT
 *  (C) 1998-2004 Ben Fennema
 *
 * HISTORY
 *
 *  10/05/98 dgb  Split directory operations into its own file
 *                Implemented directory reads via do_udf_readdir
 *  10/06/98      Made directory operations work!
 *  11/17/98      Rewrote directory to support ICBTAG_FLAG_AD_LONG
 *  11/25/98 blf  Rewrote directory handling (readdir+lookup) to support reading
 *                across blocks.
 *  12/12/98      Split out the lookup code to namei.c. bulk of directory
 *                code now in directory.c:udf_fileident_read.
 */

#include "udfdecl.h"

#include <linux/string.h>
#include <linux/errno.h>
#include <linux/filelock.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/bio.h>
#include <linux/iversion.h>

#include "udf_i.h"
#include "udf_sb.h"

static int udf_readdir(struct file *file, struct dir_context *ctx)
{
        struct inode *dir = file_inode(file);
        loff_t nf_pos, emit_pos = 0;
        int flen;
        unsigned char *fname = NULL;
        int ret = 0;
        struct super_block *sb = dir->i_sb;
        bool pos_valid = false;
        struct udf_fileident_iter iter;

        if (ctx->pos == 0) {
                if (!dir_emit_dot(file, ctx))
                        return 0;
                ctx->pos = 1;
        }
        nf_pos = (ctx->pos - 1) << 2;
        if (nf_pos >= dir->i_size)
                goto out;

        /*
         * Something changed since last readdir (either lseek was called or dir
         * changed)?  We need to verify the position correctly points at the
         * beginning of some dir entry so that the directory parsing code does
         * not get confused. Since UDF does not have any reliable way of
         * identifying beginning of dir entry (names are under user control),
         * we need to scan the directory from the beginning.
         */
        if (!inode_eq_iversion(dir, *(u64 *)file->private_data)) {
                emit_pos = nf_pos;
                nf_pos = 0;
        } else {
                pos_valid = true;
        }

        fname = kmalloc(UDF_NAME_LEN, GFP_KERNEL);
        if (!fname) {
                ret = -ENOMEM;
                goto out;
        }

        for (ret = udf_fiiter_init(&iter, dir, nf_pos);
             !ret && iter.pos < dir->i_size;
             ret = udf_fiiter_advance(&iter)) {
                struct kernel_lb_addr tloc;
                udf_pblk_t iblock;

                /* Still not at offset where user asked us to read from? */
                if (iter.pos < emit_pos)
                        continue;

                /* Update file position only if we got past the current one */
                pos_valid = true;
                ctx->pos = (iter.pos >> 2) + 1;

                if (iter.fi.fileCharacteristics & FID_FILE_CHAR_DELETED) {
                        if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNDELETE))
                                continue;
                }

                if (iter.fi.fileCharacteristics & FID_FILE_CHAR_HIDDEN) {
                        if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNHIDE))
                                continue;
                }

                if (iter.fi.fileCharacteristics & FID_FILE_CHAR_PARENT) {
                        if (!dir_emit_dotdot(file, ctx))
                                goto out_iter;
                        continue;
                }

                flen = udf_get_filename(sb, iter.name,
                                iter.fi.lengthFileIdent, fname, UDF_NAME_LEN);
                if (flen < 0)
                        continue;

                tloc = lelb_to_cpu(iter.fi.icb.extLocation);
                iblock = udf_get_lb_pblock(sb, &tloc, 0);
                if (!dir_emit(ctx, fname, flen, iblock, DT_UNKNOWN))
                        goto out_iter;
        }

        if (!ret) {
                ctx->pos = (iter.pos >> 2) + 1;
                pos_valid = true;
        }
out_iter:
        udf_fiiter_release(&iter);
out:
        if (pos_valid)
                *(u64 *)file->private_data = inode_query_iversion(dir);
        kfree(fname);

        return ret;
}

static int udf_dir_open(struct inode *inode, struct file *file)
{
        file->private_data = kzalloc(sizeof(u64), GFP_KERNEL);
        if (!file->private_data)
                return -ENOMEM;
        return 0;
}

static int udf_dir_release(struct inode *inode, struct file *file)
{
        kfree(file->private_data);
        return 0;
}

static loff_t udf_dir_llseek(struct file *file, loff_t offset, int whence)
{
        return generic_llseek_cookie(file, offset, whence,
                                     (u64 *)file->private_data);
}

/* readdir and lookup functions */
const struct file_operations udf_dir_operations = {
        .open                   = udf_dir_open,
        .release                = udf_dir_release,
        .llseek                 = udf_dir_llseek,
        .read                   = generic_read_dir,
        .iterate_shared         = udf_readdir,
        .unlocked_ioctl         = udf_ioctl,
        .fsync                  = generic_file_fsync,
        .setlease               = generic_setlease,
};