lib/libstand/gzipfs.c

	gzipfs.c revision 199767f8919635c4928607450d9e0abb932109ce
/*
 * Copyright (c) 1998 Michael Smith.
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 THE AUTHOR OR CONTRIBUTORS 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("$FreeBSD$");

#include "stand.h"

#include <sys/stat.h>
#include <string.h>
#include <zlib.h>

#define Z_BUFSIZE 2048  /* XXX larger? */

struct z_file
{
    int         zf_rawfd;
    off_t       zf_dataoffset;
    z_stream        zf_zstream;
    char        zf_buf[Z_BUFSIZE];
    int         zf_endseen;
};

static int  zf_fill(struct z_file *z);
static int  zf_open(const char *path, struct open_file *f);
static int  zf_close(struct open_file *f);
static int  zf_read(struct open_file *f, void *buf, size_t size, size_t *resid);
static off_t    zf_seek(struct open_file *f, off_t offset, int where);
static int  zf_stat(struct open_file *f, struct stat *sb);

struct fs_ops gzipfs_fsops = {
    "zip",
    zf_open,
    zf_close,
    zf_read,
    null_write,
    zf_seek,
    zf_stat,
    null_readdir
};

static int
zf_fill(struct z_file *zf)
{
    int     result;
    int     req;

    req = Z_BUFSIZE - zf->zf_zstream.avail_in;
    result = 0;

    /* If we need more */
    if (req > 0) {
    /* move old data to bottom of buffer */
    if (req < Z_BUFSIZE)
        bcopy(zf->zf_buf + req, zf->zf_buf, Z_BUFSIZE - req);

    /* read to fill buffer and update availibility data */
    result = read(zf->zf_rawfd, zf->zf_buf + zf->zf_zstream.avail_in, req);
    zf->zf_zstream.next_in = zf->zf_buf;
    if (result >= 0)
        zf->zf_zstream.avail_in += result;
    }
    return(result);
}

/*
 * Adapted from get_byte/check_header in libz
 *
 * Returns 0 if the header is OK, nonzero if not.
 */
static int
get_byte(struct z_file *zf, off_t *curoffp)
{
    if ((zf->zf_zstream.avail_in == 0) && (zf_fill(zf) == -1))
    return(-1);
    zf->zf_zstream.avail_in--;
    ++*curoffp;
    return(*(zf->zf_zstream.next_in)++);
}

static int gz_magic[2] = {0x1f, 0x8b}; /* gzip magic header */

/* gzip flag byte */
#define ASCII_FLAG  0x01 /* bit 0 set: file probably ascii text */
#define HEAD_CRC    0x02 /* bit 1 set: header CRC present */
#define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
#define ORIG_NAME   0x08 /* bit 3 set: original file name present */
#define COMMENT     0x10 /* bit 4 set: file comment present */
#define RESERVED    0xE0 /* bits 5..7: reserved */

static int
check_header(struct z_file *zf)
{
    int     method; /* method byte */
    int     flags;  /* flags byte */
    uInt    len;
    int     c;

    zf->zf_dataoffset = 0;
    /* Check the gzip magic header */
    for (len = 0; len < 2; len++) {
    c = get_byte(zf, &zf->zf_dataoffset);
    if (c != gz_magic[len]) {
        return(1);
    }
    }
    method = get_byte(zf, &zf->zf_dataoffset);
    flags = get_byte(zf, &zf->zf_dataoffset);
    if (method != Z_DEFLATED || (flags & RESERVED) != 0) {
    return(1);
    }

    /* Discard time, xflags and OS code: */
    for (len = 0; len < 6; len++) (void)get_byte(zf, &zf->zf_dataoffset);

    if ((flags & EXTRA_FIELD) != 0) { /* skip the extra field */
    len  =  (uInt)get_byte(zf, &zf->zf_dataoffset);
    len += ((uInt)get_byte(zf, &zf->zf_dataoffset))<<8;
    /* len is garbage if EOF but the loop below will quit anyway */
    while (len-- != 0 && get_byte(zf, &zf->zf_dataoffset) != -1) ;
    }
    if ((flags & ORIG_NAME) != 0) { /* skip the original file name */
    while ((c = get_byte(zf, &zf->zf_dataoffset)) != 0 && c != -1) ;
    }
    if ((flags & COMMENT) != 0) {   /* skip the .gz file comment */
    while ((c = get_byte(zf, &zf->zf_dataoffset)) != 0 && c != -1) ;
    }
    if ((flags & HEAD_CRC) != 0) {  /* skip the header crc */
    for (len = 0; len < 2; len++) c = get_byte(zf, &zf->zf_dataoffset);
    }
    /* if there's data left, we're in business */
    return((c == -1) ? 1 : 0);
}

static int
zf_open(const char *fname, struct open_file *f)
{
    char        *zfname;
    int         rawfd;
    struct z_file   *zf;
    char        *cp;
    int         error;
    struct stat     sb;

    /* Have to be in "just read it" mode */
    if (f->f_flags != F_READ)
    return(EPERM);

    /* If the name already ends in .gz or .bz2, ignore it */
    if ((cp = strrchr(fname, '.')) && (!strcmp(cp, ".gz")
        || !strcmp(cp, ".bz2") || !strcmp(cp, ".split")))
    return(ENOENT);

    /* Try to open the compressed datafile */
    rawfd = open(fname, O_RDONLY | F_GZIP);
    if (rawfd == -1) {
    /* add .gz sufix and try again */
    zfname = malloc(strlen(fname) + 4);
    if (zfname == NULL)
        return(ENOMEM);
    sprintf(zfname, "%s.gz", fname);
    rawfd = open(zfname, O_RDONLY);
    free(zfname);
    if (rawfd == -1)
        return(ENOENT);
    }

    if (fstat(rawfd, &sb) < 0) {
    printf("zf_open: stat failed\n");
    close(rawfd);
    return(ENOENT);
    }
    if (!S_ISREG(sb.st_mode)) {
    close(rawfd);
    return(EISDIR);         /* best guess */
    }

    /* Allocate a z_file structure, populate it */
    zf = malloc(sizeof(struct z_file));
    if (zf == NULL)
        return(ENOMEM);
    bzero(zf, sizeof(struct z_file));
    zf->zf_rawfd = rawfd;

    /* Verify that the file is gzipped */
    if (check_header(zf)) {
    close(zf->zf_rawfd);
    free(zf);
    return(EFTYPE);
    }

    /* Initialise the inflation engine */
    if ((error = inflateInit2(&(zf->zf_zstream), -15)) != Z_OK) {
    printf("zf_open: inflateInit returned %d : %s\n", error, zf->zf_zstream.msg);
    close(zf->zf_rawfd);
    free(zf);
    return(EIO);
    }

    /* Looks OK, we'll take it */
    f->f_fsdata = zf;
    return(0);
}

static int
zf_close(struct open_file *f)
{
    struct z_file   *zf = (struct z_file *)f->f_fsdata;

    inflateEnd(&(zf->zf_zstream));
    close(zf->zf_rawfd);
    free(zf);
    return(0);
}

static int
zf_read(struct open_file *f, void *buf, size_t size, size_t *resid)
{
    struct z_file   *zf = (struct z_file *)f->f_fsdata;
    int         error;

    zf->zf_zstream.next_out = buf;          /* where and how much */
    zf->zf_zstream.avail_out = size;

    while (zf->zf_zstream.avail_out && zf->zf_endseen == 0) {
    if ((zf->zf_zstream.avail_in == 0) && (zf_fill(zf) == -1)) {
        printf("zf_read: fill error\n");
        return(EIO);
    }
    if (zf->zf_zstream.avail_in == 0) {     /* oops, unexpected EOF */
        printf("zf_read: unexpected EOF\n");
        if (zf->zf_zstream.avail_out == size)
        return(EIO);
        break;
    }

    error = inflate(&zf->zf_zstream, Z_SYNC_FLUSH); /* decompression pass */
    if (error == Z_STREAM_END) {            /* EOF, all done */
        zf->zf_endseen = 1;
        break;
    }
    if (error != Z_OK) {                /* argh, decompression error */
        printf("inflate: %s\n", zf->zf_zstream.msg);
        return(EIO);
    }
    }
    if (resid != NULL)
    *resid = zf->zf_zstream.avail_out;
    return(0);
}

static int
zf_rewind(struct open_file *f)
{
    struct z_file   *zf = (struct z_file *)f->f_fsdata;

    if (lseek(zf->zf_rawfd, zf->zf_dataoffset, SEEK_SET) == -1)
    return(-1);
    zf->zf_zstream.avail_in = 0;
    zf->zf_zstream.next_in = NULL;
    zf->zf_endseen = 0;
    (void)inflateReset(&zf->zf_zstream);

    return(0);
}

static off_t
zf_seek(struct open_file *f, off_t offset, int where)
{
    struct z_file   *zf = (struct z_file *)f->f_fsdata;
    off_t       target;
    char        discard[16];

    switch (where) {
    case SEEK_SET:
    target = offset;
    break;
    case SEEK_CUR:
    target = offset + zf->zf_zstream.total_out;
    break;
    case SEEK_END:
    target = -1;
    default:
    errno = EINVAL;
    return(-1);
    }

    /* rewind if required */
    if (target < zf->zf_zstream.total_out && zf_rewind(f) != 0)
    return(-1);

    /* skip forwards if required */
    while (target > zf->zf_zstream.total_out) {
    errno = zf_read(f, discard, min(sizeof(discard),
        target - zf->zf_zstream.total_out), NULL);
    if (errno)
        return(-1);
    }
    /* This is where we are (be honest if we overshot) */
    return(zf->zf_zstream.total_out);
}


static int
zf_stat(struct open_file *f, struct stat *sb)
{
    struct z_file   *zf = (struct z_file *)f->f_fsdata;
    int         result, res;
    off_t       pos1, pos2;
    uint32_t        size;

    /* stat as normal, but indicate that size is unknown */
    if ((result = fstat(zf->zf_rawfd, sb)) == 0) {
    if (sb->st_size == -1)
        return (result);
    pos1 = lseek(zf->zf_rawfd, 0, SEEK_CUR);
    pos2 = lseek(zf->zf_rawfd, sb->st_size - 4, SEEK_SET);
    if (pos2 != -1) {
        if (read(zf->zf_rawfd, &size, 4) == 4)
        sb->st_size = (off_t) size;
        else
        sb->st_size = -1;
    } else
        sb->st_size = -1;

    pos1 = lseek(zf->zf_rawfd, pos1, SEEK_SET);
    }
    return(result);
}