lib/libstand/cd9660.c

/*  $NetBSD: cd9660.c,v 1.5 1997/06/26 19:11:33 drochner Exp $  */

/*
 * Copyright (C) 1996 Wolfgang Solfrank.
 * Copyright (C) 1996 TooLs GmbH.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *  This product includes software developed by TooLs GmbH.
 * 4. The name of TooLs GmbH may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

/*
 * Stand-alone ISO9660 file reading package.
 *
 * Note: This doesn't support Rock Ridge extensions, extended attributes,
 * blocksizes other than 2048 bytes, multi-extent files, etc.
 */
#include <sys/param.h>
#include <string.h>
#include <sys/dirent.h>
#include <isofs/cd9660/iso.h>
#include <isofs/cd9660/cd9660_rrip.h>

#include "stand.h"

#define SUSP_CONTINUATION   "CE"
#define SUSP_PRESENT        "SP"
#define SUSP_STOP       "ST"
#define SUSP_EXTREF     "ER"
#define RRIP_NAME       "NM"

typedef struct {
    ISO_SUSP_HEADER     h;
    u_char signature    [ISODCL (  5,    6)];
    u_char len_skp      [ISODCL (  7,    7)]; /* 711 */
} ISO_SUSP_PRESENT;

static int  buf_read_file(struct open_file *f, char **buf_p,
            size_t *size_p);
static int  cd9660_open(const char *path, struct open_file *f);
static int  cd9660_close(struct open_file *f);
static int  cd9660_read(struct open_file *f, void *buf, size_t size,
            size_t *resid);
static int  cd9660_write(struct open_file *f, void *buf, size_t size,
            size_t *resid);
static off_t    cd9660_seek(struct open_file *f, off_t offset, int where);
static int  cd9660_stat(struct open_file *f, struct stat *sb);
static int  cd9660_readdir(struct open_file *f, struct dirent *d);
static int  dirmatch(struct open_file *f, const char *path,
            struct iso_directory_record *dp, int use_rrip, int lenskip);
static int  rrip_check(struct open_file *f, struct iso_directory_record *dp,
            int *lenskip);
static char *rrip_lookup_name(struct open_file *f,
            struct iso_directory_record *dp, int lenskip, size_t *len);
static ISO_SUSP_HEADER *susp_lookup_record(struct open_file *f,
            const char *identifier, struct iso_directory_record *dp,
            int lenskip);

struct fs_ops cd9660_fsops = {
    "cd9660",
    cd9660_open,
    cd9660_close,
    cd9660_read,
    cd9660_write,
    cd9660_seek,
    cd9660_stat,
    cd9660_readdir
};

#define F_ISDIR     0x0001      /* Directory */
#define F_ROOTDIR   0x0002      /* Root directory */
#define F_RR        0x0004      /* Rock Ridge on this volume */

struct file {
    int         f_flags;    /* file flags */
    off_t       f_off;      /* Current offset within file */
    daddr_t     f_bno;      /* Starting block number */
    off_t       f_size;     /* Size of file */
    daddr_t     f_buf_blkno;    /* block number of data block */
    char        *f_buf;     /* buffer for data block */
    int     f_susp_skip;    /* len_skip for SUSP records */
};

struct ptable_ent {
    char namlen [ISODCL( 1, 1)];    /* 711 */
    char extlen [ISODCL( 2, 2)];    /* 711 */
    char block  [ISODCL( 3, 6)];    /* 732 */
    char parent [ISODCL( 7, 8)];    /* 722 */
    char name   [1];
};
#define PTFIXSZ     8
#define PTSIZE(pp)  roundup(PTFIXSZ + isonum_711((pp)->namlen), 2)

#define cdb2devb(bno)   ((bno) * ISO_DEFAULT_BLOCK_SIZE / DEV_BSIZE)

static ISO_SUSP_HEADER *
susp_lookup_record(struct open_file *f, const char *identifier,
    struct iso_directory_record *dp, int lenskip)
{
    static char susp_buffer[ISO_DEFAULT_BLOCK_SIZE];
    ISO_SUSP_HEADER *sh;
    ISO_RRIP_CONT *shc;
    char *p, *end;
    int error;
    size_t read;

    p = dp->name + isonum_711(dp->name_len) + lenskip;
    /* Names of even length have a padding byte after the name. */
    if ((isonum_711(dp->name_len) & 1) == 0)
        p++;
    end = (char *)dp + isonum_711(dp->length);
    while (p + 3 < end) {
        sh = (ISO_SUSP_HEADER *)p;
        if (bcmp(sh->type, identifier, 2) == 0)
            return (sh);
        if (bcmp(sh->type, SUSP_STOP, 2) == 0)
            return (NULL);
        if (bcmp(sh->type, SUSP_CONTINUATION, 2) == 0) {
            shc = (ISO_RRIP_CONT *)sh;
            error = f->f_dev->dv_strategy(f->f_devdata, F_READ,
                cdb2devb(isonum_733(shc->location)), 0,
                ISO_DEFAULT_BLOCK_SIZE, susp_buffer, &read);

            /* Bail if it fails. */
            if (error != 0 || read != ISO_DEFAULT_BLOCK_SIZE)
                return (NULL);
            p = susp_buffer + isonum_733(shc->offset);
            end = p + isonum_733(shc->length);
        } else {
            /* Ignore this record and skip to the next. */
            p += isonum_711(sh->length);

            /* Avoid infinite loops with corrupted file systems */
            if (isonum_711(sh->length) == 0)
                return (NULL);
        }
    }
    return (NULL);
}

static char *
rrip_lookup_name(struct open_file *f, struct iso_directory_record *dp,
    int lenskip, size_t *len)
{
    ISO_RRIP_ALTNAME *p;

    if (len == NULL)
        return (NULL);

    p = (ISO_RRIP_ALTNAME *)susp_lookup_record(f, RRIP_NAME, dp, lenskip);
    if (p == NULL)
        return (NULL);
    switch (*p->flags) {
    case ISO_SUSP_CFLAG_CURRENT:
        *len = 1;
        return (".");
    case ISO_SUSP_CFLAG_PARENT:
        *len = 2;
        return ("..");
    case 0:
        *len = isonum_711(p->h.length) - 5;
        return ((char *)p + 5);
    default:
        /*
         * We don't handle hostnames or continued names as they are
         * too hard, so just bail and use the default name.
         */
        return (NULL);
    }
}

static int
rrip_check(struct open_file *f, struct iso_directory_record *dp, int *lenskip)
{
    ISO_SUSP_PRESENT *sp;
    ISO_RRIP_EXTREF *er;
    char *p;

    /* First, see if we can find a SP field. */
    p = dp->name + isonum_711(dp->name_len);
    if (p > (char *)dp + isonum_711(dp->length))
        return (0);
    sp = (ISO_SUSP_PRESENT *)p;
    if (bcmp(sp->h.type, SUSP_PRESENT, 2) != 0)
        return (0);
    if (isonum_711(sp->h.length) != sizeof(ISO_SUSP_PRESENT))
        return (0);
    if (sp->signature[0] != 0xbe || sp->signature[1] != 0xef)
        return (0);
    *lenskip = isonum_711(sp->len_skp);

    /*
     * Now look for an ER field.  If RRIP is present, then there must
     * be at least one of these.  It would be more pedantic to walk
     * through the list of fields looking for a Rock Ridge ER field.
     */
    er = (ISO_RRIP_EXTREF *)susp_lookup_record(f, SUSP_EXTREF, dp, 0);
    if (er == NULL)
        return (0);
    return (1);
}

static int
dirmatch(struct open_file *f, const char *path, struct iso_directory_record *dp,
    int use_rrip, int lenskip)
{
    size_t len;
    char *cp;
    int i, icase;

    if (use_rrip)
        cp = rrip_lookup_name(f, dp, lenskip, &len);
    else
        cp = NULL;
    if (cp == NULL) {
        len = isonum_711(dp->name_len);
        cp = dp->name;
        icase = 1;
    } else
        icase = 0;
    for (i = len; --i >= 0; path++, cp++) {
        if (!*path || *path == '/')
            break;
        if (*path == *cp)
            continue;
        if (!icase && toupper(*path) == *cp)
            continue;
        return 0;
    }
    if (*path && *path != '/')
        return 0;
    /*
     * Allow stripping of trailing dots and the version number.
     * Note that this will find the first instead of the last version
     * of a file.
     */
    if (i >= 0 && (*cp == ';' || *cp == '.')) {
        /* This is to prevent matching of numeric extensions */
        if (*cp == '.' && cp[1] != ';')
            return 0;
        while (--i >= 0)
            if (*++cp != ';' && (*cp < '0' || *cp > '9'))
                return 0;
    }
    return 1;
}

static int
cd9660_open(const char *path, struct open_file *f)
{
    struct file *fp = NULL;
    void *buf;
    struct iso_primary_descriptor *vd;
    size_t buf_size, read, dsize, off;
    daddr_t bno, boff;
    struct iso_directory_record rec;
    struct iso_directory_record *dp = NULL;
    int rc, first, use_rrip, lenskip;

    /* First find the volume descriptor */
    buf = malloc(buf_size = ISO_DEFAULT_BLOCK_SIZE);
    vd = buf;
    for (bno = 16;; bno++) {
        twiddle(1);
        rc = f->f_dev->dv_strategy(f->f_devdata, F_READ, cdb2devb(bno),
            0, ISO_DEFAULT_BLOCK_SIZE, buf, &read);
        if (rc)
            goto out;
        if (read != ISO_DEFAULT_BLOCK_SIZE) {
            rc = EIO;
            goto out;
        }
        rc = EINVAL;
        if (bcmp(vd->id, ISO_STANDARD_ID, sizeof vd->id) != 0)
            goto out;
        if (isonum_711(vd->type) == ISO_VD_END)
            goto out;
        if (isonum_711(vd->type) == ISO_VD_PRIMARY)
            break;
    }
    if (isonum_723(vd->logical_block_size) != ISO_DEFAULT_BLOCK_SIZE)
        goto out;

    rec = *(struct iso_directory_record *) vd->root_directory_record;
    if (*path == '/') path++; /* eat leading '/' */

    first = 1;
    use_rrip = 0;
    while (*path) {
        bno = isonum_733(rec.extent) + isonum_711(rec.ext_attr_length);
        dsize = isonum_733(rec.size);
        off = 0;
        boff = 0;

        while (off < dsize) {
            if ((off % ISO_DEFAULT_BLOCK_SIZE) == 0) {
                twiddle(1);
                rc = f->f_dev->dv_strategy
                    (f->f_devdata, F_READ,
                     cdb2devb(bno + boff),
                     0, ISO_DEFAULT_BLOCK_SIZE,
                     buf, &read);
                if (rc)
                    goto out;
                if (read != ISO_DEFAULT_BLOCK_SIZE) {
                    rc = EIO;
                    goto out;
                }
                boff++;
                dp = (struct iso_directory_record *) buf;
            }
            if (isonum_711(dp->length) == 0) {
                /* skip to next block, if any */
                off = boff * ISO_DEFAULT_BLOCK_SIZE;
                continue;
            }

            /* See if RRIP is in use. */
            if (first)
                use_rrip = rrip_check(f, dp, &lenskip);

            if (dirmatch(f, path, dp, use_rrip,
                first ? 0 : lenskip)) {
                first = 0;
                break;
            } else
                first = 0;

            dp = (struct iso_directory_record *)
                ((char *) dp + isonum_711(dp->length));
            /* If the new block has zero length, it is padding. */
            if (isonum_711(dp->length) == 0) {
                /* Skip to next block, if any. */
                off = boff * ISO_DEFAULT_BLOCK_SIZE;
                continue;
            }
            off += isonum_711(dp->length);
        }
        if (off >= dsize) {
            rc = ENOENT;
            goto out;
        }

        rec = *dp;
        while (*path && *path != '/') /* look for next component */
            path++;
        if (*path) path++; /* skip '/' */
    }

    /* allocate file system specific data structure */
    fp = malloc(sizeof(struct file));
    bzero(fp, sizeof(struct file));
    f->f_fsdata = (void *)fp;

    if ((isonum_711(rec.flags) & 2) != 0) {
        fp->f_flags = F_ISDIR;
    }
    if (first) {
        fp->f_flags |= F_ROOTDIR;

        /* Check for Rock Ridge since we didn't in the loop above. */
        bno = isonum_733(rec.extent) + isonum_711(rec.ext_attr_length);
        twiddle(1);
        rc = f->f_dev->dv_strategy(f->f_devdata, F_READ, cdb2devb(bno),
            0, ISO_DEFAULT_BLOCK_SIZE, buf, &read);
        if (rc)
            goto out;
        if (read != ISO_DEFAULT_BLOCK_SIZE) {
            rc = EIO;
            goto out;
        }
        dp = (struct iso_directory_record *)buf;
        use_rrip = rrip_check(f, dp, &lenskip);
    }
    if (use_rrip) {
        fp->f_flags |= F_RR;
        fp->f_susp_skip = lenskip;
    }
    fp->f_off = 0;
    fp->f_bno = isonum_733(rec.extent) + isonum_711(rec.ext_attr_length);
    fp->f_size = isonum_733(rec.size);
    free(buf);

    return 0;

out:
    if (fp)
        free(fp);
    free(buf);

    return rc;
}

static int
cd9660_close(struct open_file *f)
{
    struct file *fp = (struct file *)f->f_fsdata;

    f->f_fsdata = NULL;
    free(fp);

    return 0;
}

static int
buf_read_file(struct open_file *f, char **buf_p, size_t *size_p)
{
    struct file *fp = (struct file *)f->f_fsdata;
    daddr_t blkno, blkoff;
    int rc = 0;
    size_t read;

    blkno = fp->f_off / ISO_DEFAULT_BLOCK_SIZE + fp->f_bno;
    blkoff = fp->f_off % ISO_DEFAULT_BLOCK_SIZE;

    if (blkno != fp->f_buf_blkno) {
        if (fp->f_buf == (char *)0)
            fp->f_buf = malloc(ISO_DEFAULT_BLOCK_SIZE);

        twiddle(16);
        rc = f->f_dev->dv_strategy(f->f_devdata, F_READ,
            cdb2devb(blkno), 0, ISO_DEFAULT_BLOCK_SIZE,
            fp->f_buf, &read);
        if (rc)
            return (rc);
        if (read != ISO_DEFAULT_BLOCK_SIZE)
            return (EIO);

        fp->f_buf_blkno = blkno;
    }

    *buf_p = fp->f_buf + blkoff;
    *size_p = ISO_DEFAULT_BLOCK_SIZE - blkoff;

    if (*size_p > fp->f_size - fp->f_off)
        *size_p = fp->f_size - fp->f_off;
    return (rc);
}

static int
cd9660_read(struct open_file *f, void *start, size_t size, size_t *resid)
{
    struct file *fp = (struct file *)f->f_fsdata;
    char *buf, *addr;
    size_t buf_size, csize;
    int rc = 0;

    addr = start;
    while (size) {
        if (fp->f_off < 0 || fp->f_off >= fp->f_size)
            break;

        rc = buf_read_file(f, &buf, &buf_size);
        if (rc)
            break;

        csize = size > buf_size ? buf_size : size;
        bcopy(buf, addr, csize);

        fp->f_off += csize;
        addr += csize;
        size -= csize;
    }
    if (resid)
        *resid = size;
    return (rc);
}

static int
cd9660_readdir(struct open_file *f, struct dirent *d)
{
    struct file *fp = (struct file *)f->f_fsdata;
    struct iso_directory_record *ep;
    size_t buf_size, reclen, namelen;
    int error = 0;
    int lenskip;
    char *buf, *name;

again:
    if (fp->f_off >= fp->f_size)
        return (ENOENT);
    error = buf_read_file(f, &buf, &buf_size);
    if (error)
        return (error);
    ep = (struct iso_directory_record *)buf;

    if (isonum_711(ep->length) == 0) {
        daddr_t blkno;

        /* skip to next block, if any */
        blkno = fp->f_off / ISO_DEFAULT_BLOCK_SIZE;
        fp->f_off = (blkno + 1) * ISO_DEFAULT_BLOCK_SIZE;
        goto again;
    }

    if (fp->f_flags & F_RR) {
        if (fp->f_flags & F_ROOTDIR && fp->f_off == 0)
            lenskip = 0;
        else
            lenskip = fp->f_susp_skip;
        name = rrip_lookup_name(f, ep, lenskip, &namelen);
    } else
        name = NULL;
    if (name == NULL) {
        namelen = isonum_711(ep->name_len);
        name = ep->name;
        if (namelen == 1) {
            if (ep->name[0] == 0)
                name = ".";
            else if (ep->name[0] == 1) {
                namelen = 2;
                name = "..";
            }
        }
    }
    reclen = sizeof(struct dirent) - (MAXNAMLEN+1) + namelen + 1;
    reclen = (reclen + 3) & ~3;

    d->d_fileno = isonum_733(ep->extent);
    d->d_reclen = reclen;
    if (isonum_711(ep->flags) & 2)
        d->d_type = DT_DIR;
    else
        d->d_type = DT_REG;
    d->d_namlen = namelen;

    bcopy(name, d->d_name, d->d_namlen);
    d->d_name[d->d_namlen] = 0;

    fp->f_off += isonum_711(ep->length);
    return (0);
}

static int
cd9660_write(struct open_file *f __unused, void *start __unused, size_t size __unused, size_t *resid __unused)
{
    return EROFS;
}

static off_t
cd9660_seek(struct open_file *f, off_t offset, int where)
{
    struct file *fp = (struct file *)f->f_fsdata;

    switch (where) {
    case SEEK_SET:
        fp->f_off = offset;
        break;
    case SEEK_CUR:
        fp->f_off += offset;
        break;
    case SEEK_END:
        fp->f_off = fp->f_size - offset;
        break;
    default:
        return -1;
    }
    return fp->f_off;
}

static int
cd9660_stat(struct open_file *f, struct stat *sb)
{
    struct file *fp = (struct file *)f->f_fsdata;

    /* only important stuff */
    sb->st_mode = S_IRUSR | S_IRGRP | S_IROTH;
    if (fp->f_flags & F_ISDIR)
        sb->st_mode |= S_IFDIR;
    else
        sb->st_mode |= S_IFREG;
    sb->st_uid = sb->st_gid = 0;
    sb->st_size = fp->f_size;
    return 0;
}