// SPDX-License-Identifier: GPL-2.0-only
/*
 * directory.c
 *
 * PURPOSE
 *      Directory related functions
 *
 */

#include "udfdecl.h"
#include "udf_i.h"

#include <linux/fs.h>
#include <linux/string.h>
#include <linux/bio.h>
#include <linux/crc-itu-t.h>
#include <linux/iversion.h>

static int udf_verify_fi(struct udf_fileident_iter *iter)
{
        unsigned int len;

        if (iter->fi.descTag.tagIdent != cpu_to_le16(TAG_IDENT_FID)) {
                udf_err(iter->dir->i_sb,
                        "directory (ino %lu) has entry at pos %llu with incorrect tag %x\n",
                        iter->dir->i_ino, (unsigned long long)iter->pos,
                        le16_to_cpu(iter->fi.descTag.tagIdent));
                return -EFSCORRUPTED;
        }
        len = udf_dir_entry_len(&iter->fi);
        if (le16_to_cpu(iter->fi.lengthOfImpUse) & 3) {
                udf_err(iter->dir->i_sb,
                        "directory (ino %lu) has entry at pos %llu with unaligned length of impUse field\n",
                        iter->dir->i_ino, (unsigned long long)iter->pos);
                return -EFSCORRUPTED;
        }
        /*
         * This is in fact allowed by the spec due to long impUse field but
         * we don't support it. If there is real media with this large impUse
         * field, support can be added.
         */
        if (len > 1 << iter->dir->i_blkbits) {
                udf_err(iter->dir->i_sb,
                        "directory (ino %lu) has too big (%u) entry at pos %llu\n",
                        iter->dir->i_ino, len, (unsigned long long)iter->pos);
                return -EFSCORRUPTED;
        }
        if (iter->pos + len > iter->dir->i_size) {
                udf_err(iter->dir->i_sb,
                        "directory (ino %lu) has entry past directory size at pos %llu\n",
                        iter->dir->i_ino, (unsigned long long)iter->pos);
                return -EFSCORRUPTED;
        }
        if (udf_dir_entry_len(&iter->fi) !=
            sizeof(struct tag) + le16_to_cpu(iter->fi.descTag.descCRCLength)) {
                udf_err(iter->dir->i_sb,
                        "directory (ino %lu) has entry where CRC length (%u) does not match entry length (%u)\n",
                        iter->dir->i_ino,
                        (unsigned)le16_to_cpu(iter->fi.descTag.descCRCLength),
                        (unsigned)(udf_dir_entry_len(&iter->fi) -
                                                        sizeof(struct tag)));
                return -EFSCORRUPTED;
        }
        return 0;
}

static int udf_copy_fi(struct udf_fileident_iter *iter)
{
        struct udf_inode_info *iinfo = UDF_I(iter->dir);
        u32 blksize = 1 << iter->dir->i_blkbits;
        u32 off, len, nameoff;
        int err;

        /* Skip copying when we are at EOF */
        if (iter->pos >= iter->dir->i_size) {
                iter->name = NULL;
                return 0;
        }
        if (iter->dir->i_size < iter->pos + sizeof(struct fileIdentDesc)) {
                udf_err(iter->dir->i_sb,
                        "directory (ino %lu) has entry straddling EOF\n",
                        iter->dir->i_ino);
                return -EFSCORRUPTED;
        }
        if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
                memcpy(&iter->fi, iinfo->i_data + iinfo->i_lenEAttr + iter->pos,
                       sizeof(struct fileIdentDesc));
                err = udf_verify_fi(iter);
                if (err < 0)
                        return err;
                iter->name = iinfo->i_data + iinfo->i_lenEAttr + iter->pos +
                        sizeof(struct fileIdentDesc) +
                        le16_to_cpu(iter->fi.lengthOfImpUse);
                return 0;
        }

        off = iter->pos & (blksize - 1);
        len = min_t(u32, sizeof(struct fileIdentDesc), blksize - off);
        memcpy(&iter->fi, iter->bh[0]->b_data + off, len);
        if (len < sizeof(struct fileIdentDesc))
                memcpy((char *)(&iter->fi) + len, iter->bh[1]->b_data,
                       sizeof(struct fileIdentDesc) - len);
        err = udf_verify_fi(iter);
        if (err < 0)
                return err;

        /* Handle directory entry name */
        nameoff = off + sizeof(struct fileIdentDesc) +
                                le16_to_cpu(iter->fi.lengthOfImpUse);
        if (off + udf_dir_entry_len(&iter->fi) <= blksize) {
                iter->name = iter->bh[0]->b_data + nameoff;
        } else if (nameoff >= blksize) {
                iter->name = iter->bh[1]->b_data + (nameoff - blksize);
        } else {
                iter->name = iter->namebuf;
                len = blksize - nameoff;
                memcpy(iter->name, iter->bh[0]->b_data + nameoff, len);
                memcpy(iter->name + len, iter->bh[1]->b_data,
                       iter->fi.lengthFileIdent - len);
        }
        return 0;
}

/* Readahead 8k once we are at 8k boundary */
static void udf_readahead_dir(struct udf_fileident_iter *iter)
{
        unsigned int ralen = 16 >> (iter->dir->i_blkbits - 9);
        struct buffer_head *tmp, *bha[16];
        int i, num;
        udf_pblk_t blk;

        if (iter->loffset & (ralen - 1))
                return;

        if (iter->loffset + ralen > (iter->elen >> iter->dir->i_blkbits))
                ralen = (iter->elen >> iter->dir->i_blkbits) - iter->loffset;
        num = 0;
        for (i = 0; i < ralen; i++) {
                blk = udf_get_lb_pblock(iter->dir->i_sb, &iter->eloc,
                                        iter->loffset + i);
                tmp = sb_getblk(iter->dir->i_sb, blk);
                if (tmp && !buffer_uptodate(tmp) && !buffer_locked(tmp))
                        bha[num++] = tmp;
                else
                        brelse(tmp);
        }
        if (num) {
                bh_readahead_batch(num, bha, REQ_RAHEAD);
                for (i = 0; i < num; i++)
                        brelse(bha[i]);
        }
}

static struct buffer_head *udf_fiiter_bread_blk(struct udf_fileident_iter *iter)
{
        udf_pblk_t blk;

        udf_readahead_dir(iter);
        blk = udf_get_lb_pblock(iter->dir->i_sb, &iter->eloc, iter->loffset);
        return sb_bread(iter->dir->i_sb, blk);
}

/*
 * Updates loffset to point to next directory block; eloc, elen & epos are
 * updated if we need to traverse to the next extent as well.
 */
static int udf_fiiter_advance_blk(struct udf_fileident_iter *iter)
{
        int8_t etype = -1;
        int err = 0;

        iter->loffset++;
        if (iter->loffset < DIV_ROUND_UP(iter->elen, 1<<iter->dir->i_blkbits))
                return 0;

        iter->loffset = 0;
        err = udf_next_aext(iter->dir, &iter->epos, &iter->eloc,
                            &iter->elen, &etype, 1);
        if (err < 0)
                return err;
        else if (err == 0 || etype != (EXT_RECORDED_ALLOCATED >> 30)) {
                if (iter->pos == iter->dir->i_size) {
                        iter->elen = 0;
                        return 0;
                }
                udf_err(iter->dir->i_sb,
                        "extent after position %llu not allocated in directory (ino %lu)\n",
                        (unsigned long long)iter->pos, iter->dir->i_ino);
                return -EFSCORRUPTED;
        }
        return 0;
}

static int udf_fiiter_load_bhs(struct udf_fileident_iter *iter)
{
        int blksize = 1 << iter->dir->i_blkbits;
        int off = iter->pos & (blksize - 1);
        int err;
        struct fileIdentDesc *fi;

        /* Is there any further extent we can map from? */
        if (!iter->bh[0] && iter->elen) {
                iter->bh[0] = udf_fiiter_bread_blk(iter);
                if (!iter->bh[0]) {
                        err = -ENOMEM;
                        goto out_brelse;
                }
                if (!buffer_uptodate(iter->bh[0])) {
                        err = -EIO;
                        goto out_brelse;
                }
        }
        /* There's no next block so we are done */
        if (iter->pos >= iter->dir->i_size)
                return 0;
        /* Need to fetch next block as well? */
        if (off + sizeof(struct fileIdentDesc) > blksize)
                goto fetch_next;
        fi = (struct fileIdentDesc *)(iter->bh[0]->b_data + off);
        /* Need to fetch next block to get name? */
        if (off + udf_dir_entry_len(fi) > blksize) {
fetch_next:
                err = udf_fiiter_advance_blk(iter);
                if (err)
                        goto out_brelse;
                iter->bh[1] = udf_fiiter_bread_blk(iter);
                if (!iter->bh[1]) {
                        err = -ENOMEM;
                        goto out_brelse;
                }
                if (!buffer_uptodate(iter->bh[1])) {
                        err = -EIO;
                        goto out_brelse;
                }
        }
        return 0;
out_brelse:
        brelse(iter->bh[0]);
        brelse(iter->bh[1]);
        iter->bh[0] = iter->bh[1] = NULL;
        return err;
}

int udf_fiiter_init(struct udf_fileident_iter *iter, struct inode *dir,
                    loff_t pos)
{
        struct udf_inode_info *iinfo = UDF_I(dir);
        int err = 0;
        int8_t etype;

        iter->dir = dir;
        iter->bh[0] = iter->bh[1] = NULL;
        iter->pos = pos;
        iter->elen = 0;
        iter->epos.bh = NULL;
        iter->name = NULL;
        /*
         * When directory is verified, we don't expect directory iteration to
         * fail and it can be difficult to undo without corrupting filesystem.
         * So just do not allow memory allocation failures here.
         */
        iter->namebuf = kmalloc(UDF_NAME_LEN_CS0, GFP_KERNEL | __GFP_NOFAIL);

        if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
                err = udf_copy_fi(iter);
                goto out;
        }

        err = inode_bmap(dir, iter->pos >> dir->i_blkbits, &iter->epos,
                         &iter->eloc, &iter->elen, &iter->loffset, &etype);
        if (err <= 0 || etype != (EXT_RECORDED_ALLOCATED >> 30)) {
                if (pos == dir->i_size)
                        return 0;
                udf_err(dir->i_sb,
                        "position %llu not allocated in directory (ino %lu)\n",
                        (unsigned long long)pos, dir->i_ino);
                err = -EFSCORRUPTED;
                goto out;
        }
        err = udf_fiiter_load_bhs(iter);
        if (err < 0)
                goto out;
        err = udf_copy_fi(iter);
out:
        if (err < 0)
                udf_fiiter_release(iter);
        return err;
}

int udf_fiiter_advance(struct udf_fileident_iter *iter)
{
        unsigned int oldoff, len;
        int blksize = 1 << iter->dir->i_blkbits;
        int err;

        oldoff = iter->pos & (blksize - 1);
        len = udf_dir_entry_len(&iter->fi);
        iter->pos += len;
        if (UDF_I(iter->dir)->i_alloc_type != ICBTAG_FLAG_AD_IN_ICB) {
                if (oldoff + len >= blksize) {
                        brelse(iter->bh[0]);
                        iter->bh[0] = NULL;
                        /* Next block already loaded? */
                        if (iter->bh[1]) {
                                iter->bh[0] = iter->bh[1];
                                iter->bh[1] = NULL;
                        } else {
                                err = udf_fiiter_advance_blk(iter);
                                if (err < 0)
                                        return err;
                        }
                }
                err = udf_fiiter_load_bhs(iter);
                if (err < 0)
                        return err;
        }
        return udf_copy_fi(iter);
}

void udf_fiiter_release(struct udf_fileident_iter *iter)
{
        iter->dir = NULL;
        brelse(iter->bh[0]);
        brelse(iter->bh[1]);
        iter->bh[0] = iter->bh[1] = NULL;
        kfree(iter->namebuf);
        iter->namebuf = NULL;
}

static void udf_copy_to_bufs(void *buf1, int len1, void *buf2, int len2,
                             int off, void *src, int len)
{
        int copy;

        if (off >= len1) {
                off -= len1;
        } else {
                copy = min(off + len, len1) - off;
                memcpy(buf1 + off, src, copy);
                src += copy;
                len -= copy;
                off = 0;
        }
        if (len > 0) {
                if (WARN_ON_ONCE(off + len > len2 || !buf2))
                        return;
                memcpy(buf2 + off, src, len);
        }
}

static uint16_t udf_crc_fi_bufs(void *buf1, int len1, void *buf2, int len2,
                                int off, int len)
{
        int copy;
        uint16_t crc = 0;

        if (off >= len1) {
                off -= len1;
        } else {
                copy = min(off + len, len1) - off;
                crc = crc_itu_t(crc, buf1 + off, copy);
                len -= copy;
                off = 0;
        }
        if (len > 0) {
                if (WARN_ON_ONCE(off + len > len2 || !buf2))
                        return 0;
                crc = crc_itu_t(crc, buf2 + off, len);
        }
        return crc;
}

static void udf_copy_fi_to_bufs(char *buf1, int len1, char *buf2, int len2,
                                int off, struct fileIdentDesc *fi,
                                uint8_t *impuse, uint8_t *name)
{
        uint16_t crc;
        int fioff = off;
        int crcoff = off + sizeof(struct tag);
        unsigned int crclen = udf_dir_entry_len(fi) - sizeof(struct tag);
        char zeros[UDF_NAME_PAD] = {};
        int endoff = off + udf_dir_entry_len(fi);

        udf_copy_to_bufs(buf1, len1, buf2, len2, off, fi,
                         sizeof(struct fileIdentDesc));
        off += sizeof(struct fileIdentDesc);
        if (impuse)
                udf_copy_to_bufs(buf1, len1, buf2, len2, off, impuse,
                                 le16_to_cpu(fi->lengthOfImpUse));
        off += le16_to_cpu(fi->lengthOfImpUse);
        if (name) {
                udf_copy_to_bufs(buf1, len1, buf2, len2, off, name,
                                 fi->lengthFileIdent);
                off += fi->lengthFileIdent;
                udf_copy_to_bufs(buf1, len1, buf2, len2, off, zeros,
                                 endoff - off);
        }

        crc = udf_crc_fi_bufs(buf1, len1, buf2, len2, crcoff, crclen);
        fi->descTag.descCRC = cpu_to_le16(crc);
        fi->descTag.descCRCLength = cpu_to_le16(crclen);
        fi->descTag.tagChecksum = udf_tag_checksum(&fi->descTag);

        udf_copy_to_bufs(buf1, len1, buf2, len2, fioff, fi, sizeof(struct tag));
}

void udf_fiiter_write_fi(struct udf_fileident_iter *iter, uint8_t *impuse)
{
        struct udf_inode_info *iinfo = UDF_I(iter->dir);
        void *buf1, *buf2 = NULL;
        int len1, len2 = 0, off;
        int blksize = 1 << iter->dir->i_blkbits;

        off = iter->pos & (blksize - 1);
        if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
                buf1 = iinfo->i_data + iinfo->i_lenEAttr;
                len1 = iter->dir->i_size;
        } else {
                buf1 = iter->bh[0]->b_data;
                len1 = blksize;
                if (iter->bh[1]) {
                        buf2 = iter->bh[1]->b_data;
                        len2 = blksize;
                }
        }

        udf_copy_fi_to_bufs(buf1, len1, buf2, len2, off, &iter->fi, impuse,
                            iter->name == iter->namebuf ? iter->name : NULL);

        if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
                mark_inode_dirty(iter->dir);
        } else {
                mark_buffer_dirty_inode(iter->bh[0], iter->dir);
                if (iter->bh[1])
                        mark_buffer_dirty_inode(iter->bh[1], iter->dir);
        }
        inode_inc_iversion(iter->dir);
}

void udf_fiiter_update_elen(struct udf_fileident_iter *iter, uint32_t new_elen)
{
        struct udf_inode_info *iinfo = UDF_I(iter->dir);
        int diff = new_elen - iter->elen;

        /* Skip update when we already went past the last extent */
        if (!iter->elen)
                return;
        iter->elen = new_elen;
        if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)
                iter->epos.offset -= sizeof(struct short_ad);
        else if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_LONG)
                iter->epos.offset -= sizeof(struct long_ad);
        udf_write_aext(iter->dir, &iter->epos, &iter->eloc, iter->elen, 1);
        iinfo->i_lenExtents += diff;
        mark_inode_dirty(iter->dir);
}

/* Append new block to directory. @iter is expected to point at EOF */
int udf_fiiter_append_blk(struct udf_fileident_iter *iter)
{
        struct udf_inode_info *iinfo = UDF_I(iter->dir);
        int blksize = 1 << iter->dir->i_blkbits;
        struct buffer_head *bh;
        sector_t block;
        uint32_t old_elen = iter->elen;
        int err;
        int8_t etype;

        if (WARN_ON_ONCE(iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB))
                return -EINVAL;

        /* Round up last extent in the file */
        udf_fiiter_update_elen(iter, ALIGN(iter->elen, blksize));

        /* Allocate new block and refresh mapping information */
        block = iinfo->i_lenExtents >> iter->dir->i_blkbits;
        bh = udf_bread(iter->dir, block, 1, &err);
        if (!bh) {
                udf_fiiter_update_elen(iter, old_elen);
                return err;
        }
        err = inode_bmap(iter->dir, block, &iter->epos, &iter->eloc, &iter->elen,
                   &iter->loffset, &etype);
        if (err <= 0 || etype != (EXT_RECORDED_ALLOCATED >> 30)) {
                udf_err(iter->dir->i_sb,
                        "block %llu not allocated in directory (ino %lu)\n",
                        (unsigned long long)block, iter->dir->i_ino);
                return -EFSCORRUPTED;
        }
        if (!(iter->pos & (blksize - 1))) {
                brelse(iter->bh[0]);
                iter->bh[0] = bh;
        } else {
                iter->bh[1] = bh;
        }
        return 0;
}

struct short_ad *udf_get_fileshortad(uint8_t *ptr, int maxoffset, uint32_t *offset,
                              int inc)
{
        struct short_ad *sa;

        if ((!ptr) || (!offset)) {
                pr_err("%s: invalidparms\n", __func__);
                return NULL;
        }

        if ((*offset + sizeof(struct short_ad)) > maxoffset)
                return NULL;
        else {
                sa = (struct short_ad *)ptr;
                if (sa->extLength == 0)
                        return NULL;
        }

        if (inc)
                *offset += sizeof(struct short_ad);
        return sa;
}

struct long_ad *udf_get_filelongad(uint8_t *ptr, int maxoffset, uint32_t *offset, int inc)
{
        struct long_ad *la;

        if ((!ptr) || (!offset)) {
                pr_err("%s: invalidparms\n", __func__);
                return NULL;
        }

        if ((*offset + sizeof(struct long_ad)) > maxoffset)
                return NULL;
        else {
                la = (struct long_ad *)ptr;
                if (la->extLength == 0)
                        return NULL;
        }

        if (inc)
                *offset += sizeof(struct long_ad);
        return la;
}