// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/fs/isofs/dir.c
 *
 *  (C) 1992, 1993, 1994  Eric Youngdale Modified for ISO 9660 filesystem.
 *
 *  (C) 1991  Linus Torvalds - minix filesystem
 *
 *  Steve Beynon                       : Missing last directory entries fixed
 *  (stephen@askone.demon.co.uk)      : 21st June 1996
 *
 *  isofs directory handling functions
 */
#include <linux/gfp.h>
#include "isofs.h"

int isofs_name_translate(struct iso_directory_record *de, char *new, struct inode *inode)
{
        char * old = de->name;
        int len = de->name_len[0];
        int i;

        for (i = 0; i < len; i++) {
                unsigned char c = old[i];
                if (!c)
                        break;

                if (c >= 'A' && c <= 'Z')
                        c |= 0x20;      /* lower case */

                /* Drop trailing '.;1' (ISO 9660:1988 7.5.1 requires period) */
                if (c == '.' && i == len - 3 && old[i + 1] == ';' && old[i + 2] == '1')
                        break;

                /* Drop trailing ';1' */
                if (c == ';' && i == len - 2 && old[i + 1] == '1')
                        break;

                /* Convert remaining ';' to '.' */
                /* Also '/' to '.' (broken Acorn-generated ISO9660 images) */
                if (c == ';' || c == '/')
                        c = '.';

                new[i] = c;
        }
        return i;
}

/* Acorn extensions written by Matthew Wilcox <willy@infradead.org> 1998 */
int get_acorn_filename(struct iso_directory_record *de,
                            char *retname, struct inode *inode)
{
        int std;
        unsigned char *chr;
        int retnamlen = isofs_name_translate(de, retname, inode);

        if (retnamlen == 0)
                return 0;
        std = sizeof(struct iso_directory_record) + de->name_len[0];
        if (std & 1)
                std++;
        if (de->length[0] - std != 32)
                return retnamlen;
        chr = ((unsigned char *) de) + std;
        if (strncmp(chr, "ARCHIMEDES", 10))
                return retnamlen;
        if ((*retname == '_') && ((chr[19] & 1) == 1))
                *retname = '!';
        if (((de->flags[0] & 2) == 0) && (chr[13] == 0xff)
                && ((chr[12] & 0xf0) == 0xf0)) {
                retname[retnamlen] = ',';
                sprintf(retname+retnamlen+1, "%3.3x",
                        ((chr[12] & 0xf) << 8) | chr[11]);
                retnamlen += 4;
        }
        return retnamlen;
}

/*
 * This should _really_ be cleaned up some day..
 */
static int do_isofs_readdir(struct inode *inode, struct file *file,
                struct dir_context *ctx,
                char *tmpname, struct iso_directory_record *tmpde)
{
        unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
        unsigned char bufbits = ISOFS_BUFFER_BITS(inode);
        unsigned long block, offset, block_saved, offset_saved;
        unsigned long inode_number = 0; /* Quiet GCC */
        struct buffer_head *bh = NULL;
        int len;
        int map;
        int first_de = 1;
        char *p = NULL;         /* Quiet GCC */
        struct iso_directory_record *de;
        struct isofs_sb_info *sbi = ISOFS_SB(inode->i_sb);

        offset = ctx->pos & (bufsize - 1);
        block = ctx->pos >> bufbits;

        while (ctx->pos < inode->i_size) {
                int de_len;

                if (!bh) {
                        bh = isofs_bread(inode, block);
                        if (!bh)
                                return 0;
                }

                de = (struct iso_directory_record *) (bh->b_data + offset);

                de_len = *(unsigned char *)de;

                /*
                 * If the length byte is zero, we should move on to the next
                 * CDROM sector.  If we are at the end of the directory, we
                 * kick out of the while loop.
                 */

                if (de_len == 0) {
                        brelse(bh);
                        bh = NULL;
                        ctx->pos = (ctx->pos + ISOFS_BLOCK_SIZE) & ~(ISOFS_BLOCK_SIZE - 1);
                        block = ctx->pos >> bufbits;
                        offset = 0;
                        continue;
                }

                block_saved = block;
                offset_saved = offset;
                offset += de_len;

                /* Make sure we have a full directory entry */
                if (offset >= bufsize) {
                        int slop = bufsize - offset + de_len;
                        memcpy(tmpde, de, slop);
                        offset &= bufsize - 1;
                        block++;
                        brelse(bh);
                        bh = NULL;
                        if (offset) {
                                bh = isofs_bread(inode, block);
                                if (!bh)
                                        return 0;
                                memcpy((void *) tmpde + slop, bh->b_data, offset);
                        }
                        de = tmpde;
                }
                /* Basic sanity check, whether name doesn't exceed dir entry */
                if (de_len < de->name_len[0] +
                                        sizeof(struct iso_directory_record)) {
                        printk(KERN_NOTICE "iso9660: Corrupted directory entry"
                               " in block %lu of inode %lu\n", block,
                               inode->i_ino);
                        brelse(bh);
                        return -EIO;
                }

                if (first_de) {
                        isofs_normalize_block_and_offset(de,
                                                        &block_saved,
                                                        &offset_saved);
                        inode_number = isofs_get_ino(block_saved,
                                                        offset_saved, bufbits);
                }

                if (de->flags[-sbi->s_high_sierra] & 0x80) {
                        first_de = 0;
                        ctx->pos += de_len;
                        continue;
                }
                first_de = 1;

                /* Handle the case of the '.' directory */
                if (de->name_len[0] == 1 && de->name[0] == 0) {
                        if (!dir_emit_dot(file, ctx))
                                break;
                        ctx->pos += de_len;
                        continue;
                }

                len = 0;

                /* Handle the case of the '..' directory */
                if (de->name_len[0] == 1 && de->name[0] == 1) {
                        if (!dir_emit_dotdot(file, ctx))
                                break;
                        ctx->pos += de_len;
                        continue;
                }

                /* Handle everything else.  Do name translation if there
                   is no Rock Ridge NM field. */

                /*
                 * Do not report hidden files if so instructed, or associated
                 * files unless instructed to do so
                 */
                if ((sbi->s_hide && (de->flags[-sbi->s_high_sierra] & 1)) ||
                    (!sbi->s_showassoc &&
                                (de->flags[-sbi->s_high_sierra] & 4))) {
                        ctx->pos += de_len;
                        continue;
                }

                map = 1;
                if (sbi->s_rock) {
                        len = get_rock_ridge_filename(de, tmpname, inode);
                        if (len != 0) {         /* may be -1 */
                                p = tmpname;
                                map = 0;
                        }
                }
                if (map) {
#ifdef CONFIG_JOLIET
                        if (sbi->s_joliet_level) {
                                len = get_joliet_filename(de, tmpname, inode);
                                p = tmpname;
                        } else
#endif
                        if (sbi->s_mapping == 'a') {
                                len = get_acorn_filename(de, tmpname, inode);
                                p = tmpname;
                        } else
                        if (sbi->s_mapping == 'n') {
                                len = isofs_name_translate(de, tmpname, inode);
                                p = tmpname;
                        } else {
                                p = de->name;
                                len = de->name_len[0];
                        }
                }
                if (len > 0) {
                        if (!dir_emit(ctx, p, len, inode_number, DT_UNKNOWN))
                                break;
                }
                ctx->pos += de_len;
        }
        if (bh)
                brelse(bh);
        return 0;
}

/*
 * Handle allocation of temporary space for name translation and
 * handling split directory entries.. The real work is done by
 * "do_isofs_readdir()".
 */
static int isofs_readdir(struct file *file, struct dir_context *ctx)
{
        int result;
        char *tmpname;
        struct iso_directory_record *tmpde;
        struct inode *inode = file_inode(file);

        tmpname = (char *)__get_free_page(GFP_KERNEL);
        if (tmpname == NULL)
                return -ENOMEM;

        tmpde = (struct iso_directory_record *) (tmpname+1024);

        result = do_isofs_readdir(inode, file, ctx, tmpname, tmpde);

        free_page((unsigned long) tmpname);
        return result;
}

const struct file_operations isofs_dir_operations =
{
        .llseek = generic_file_llseek,
        .read = generic_read_dir,
        .iterate_shared = isofs_readdir,
};

/*
 * directories can handle most operations...
 */
const struct inode_operations isofs_dir_inode_operations =
{
        .lookup = isofs_lookup,
};