namei.c

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/*
 *  linux/fs/isofs/namei.c
 *
 *  (C) 1992  Eric Youngdale Modified for ISO 9660 filesystem.
 *
 *  (C) 1991  Linus Torvalds - minix filesystem
 */

#include <linux/gfp.h>
#include "isofs.h"

/*
 * ok, we cannot use strncmp, as the name is not in our data space.
 * Thus we'll have to use isofs_match. No big problem. Match also makes
 * some sanity tests.
 */
static int
isofs_cmp(struct dentry *dentry, const char *compare, int dlen)
{
    struct qstr qstr;

    if (!compare)
        return 1;

    /* check special "." and ".." files */
    if (dlen == 1) {
        /* "." */
        if (compare[0] == 0) {
            if (!dentry->d_name.len)
                return 0;
            compare = ".";
        } else if (compare[0] == 1) {
            compare = "..";
            dlen = 2;
        }
    }

    qstr.name = compare;
    qstr.len = dlen;
    return dentry->d_op->d_compare(NULL, NULL, NULL, NULL,
            dentry->d_name.len, dentry->d_name.name, &qstr);
}

/*
 *  isofs_find_entry()
 *
 * finds an entry in the specified directory with the wanted name. It
 * returns the inode number of the found entry, or 0 on error.
 */
static unsigned long
isofs_find_entry(struct inode *dir, struct dentry *dentry,
    unsigned long *block_rv, unsigned long *offset_rv,
    char *tmpname, struct iso_directory_record *tmpde)
{
    unsigned long bufsize = ISOFS_BUFFER_SIZE(dir);
    unsigned char bufbits = ISOFS_BUFFER_BITS(dir);
    unsigned long block, f_pos, offset, block_saved, offset_saved;
    struct buffer_head *bh = NULL;
    struct isofs_sb_info *sbi = ISOFS_SB(dir->i_sb);

    if (!ISOFS_I(dir)->i_first_extent)
        return 0;

    f_pos = 0;
    offset = 0;
    block = 0;

    while (f_pos < dir->i_size) {
        struct iso_directory_record *de;
        int de_len, match, i, dlen;
        char *dpnt;

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

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

        de_len = *(unsigned char *) de;
        if (!de_len) {
            brelse(bh);
            bh = NULL;
            f_pos = (f_pos + ISOFS_BLOCK_SIZE) & ~(ISOFS_BLOCK_SIZE - 1);
            block = f_pos >> bufbits;
            offset = 0;
            continue;
        }

        block_saved = bh->b_blocknr;
        offset_saved = offset;
        offset += de_len;
        f_pos += 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(dir, block);
                if (!bh)
                    return 0;
                memcpy((void *) tmpde + slop, bh->b_data, offset);
            }
            de = tmpde;
        }

        dlen = de->name_len[0];
        dpnt = de->name;
        /* Basic sanity check, whether name doesn't exceed dir entry */
        if (de_len < dlen + sizeof(struct iso_directory_record)) {
            printk(KERN_NOTICE "iso9660: Corrupted directory entry"
                   " in block %lu of inode %lu\n", block,
                   dir->i_ino);
            return 0;
        }

        if (sbi->s_rock &&
            ((i = get_rock_ridge_filename(de, tmpname, dir)))) {
            dlen = i;   /* possibly -1 */
            dpnt = tmpname;
#ifdef CONFIG_JOLIET
        } else if (sbi->s_joliet_level) {
            dlen = get_joliet_filename(de, tmpname, dir);
            dpnt = tmpname;
#endif
        } else if (sbi->s_mapping == 'a') {
            dlen = get_acorn_filename(de, tmpname, dir);
            dpnt = tmpname;
        } else if (sbi->s_mapping == 'n') {
            dlen = isofs_name_translate(de, tmpname, dir);
            dpnt = tmpname;
        }

        /*
         * Skip hidden or associated files unless hide or showassoc,
         * respectively, is set
         */
        match = 0;
        if (dlen > 0 &&
            (!sbi->s_hide ||
                (!(de->flags[-sbi->s_high_sierra] & 1))) &&
            (sbi->s_showassoc ||
                (!(de->flags[-sbi->s_high_sierra] & 4)))) {
            match = (isofs_cmp(dentry, dpnt, dlen) == 0);
        }
        if (match) {
            isofs_normalize_block_and_offset(de,
                             &block_saved,
                             &offset_saved);
            *block_rv = block_saved;
            *offset_rv = offset_saved;
            brelse(bh);
            return 1;
        }
    }
    brelse(bh);
    return 0;
}

struct dentry *isofs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
{
    int found;
    unsigned long uninitialized_var(block);
    unsigned long uninitialized_var(offset);
    struct inode *inode;
    struct page *page;

    page = alloc_page(GFP_USER);
    if (!page)
        return ERR_PTR(-ENOMEM);

    found = isofs_find_entry(dir, dentry,
                &block, &offset,
                page_address(page),
                1024 + page_address(page));
    __free_page(page);

    inode = found ? isofs_iget(dir->i_sb, block, offset) : NULL;

    return d_splice_alias(inode, dentry);
}