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zlib/examples/gun.c  view on Meta::CPAN

        if (flags & 8)                      /* file name */
            while (NEXT() != 0 && last != -1)
                ;
        if (flags & 16)                     /* comment */
            while (NEXT() != 0 && last != -1)
                ;
        if (flags & 2) {                    /* header crc */
            NEXT();
            NEXT();
        }
        if (last == -1) break;

        /* set up output */
        outd.outfile = outfile;
        outd.check = 1;
        outd.crc = crc32(0L, Z_NULL, 0);
        outd.total = 0;

        /* decompress data to output */
        strm->next_in = next;
        strm->avail_in = have;
        ret = inflateBack(strm, in, indp, out, &outd);
        if (ret != Z_STREAM_END) break;
        next = strm->next_in;
        have = strm->avail_in;
        strm->next_in = Z_NULL;             /* so Z_BUF_ERROR means EOF */

        /* check trailer */
        ret = Z_BUF_ERROR;
        if (NEXT() != (int)(outd.crc & 0xff) ||
            NEXT() != (int)((outd.crc >> 8) & 0xff) ||
            NEXT() != (int)((outd.crc >> 16) & 0xff) ||
            NEXT() != (int)((outd.crc >> 24) & 0xff)) {
            /* crc error */
            if (last != -1) {
                strm->msg = (char *)"incorrect data check";
                ret = Z_DATA_ERROR;
            }
            break;
        }
        if (NEXT() != (int)(outd.total & 0xff) ||
            NEXT() != (int)((outd.total >> 8) & 0xff) ||
            NEXT() != (int)((outd.total >> 16) & 0xff) ||
            NEXT() != (int)((outd.total >> 24) & 0xff)) {
            /* length error */
            if (last != -1) {
                strm->msg = (char *)"incorrect length check";
                ret = Z_DATA_ERROR;
            }
            break;
        }

        /* go back and look for another gzip stream */
    }

    /* clean up and return */
    return ret;
}

/* Copy file attributes, from -> to, as best we can.  This is best effort, so
   no errors are reported.  The mode bits, including suid, sgid, and the sticky
   bit are copied (if allowed), the owner's user id and group id are copied
   (again if allowed), and the access and modify times are copied. */
local void copymeta(char *from, char *to)
{
    struct stat was;
    struct utimbuf when;

    /* get all of from's Unix meta data, return if not a regular file */
    if (stat(from, &was) != 0 || (was.st_mode & S_IFMT) != S_IFREG)
        return;

    /* set to's mode bits, ignore errors */
    (void)chmod(to, was.st_mode & 07777);

    /* copy owner's user and group, ignore errors */
    (void)chown(to, was.st_uid, was.st_gid);

    /* copy access and modify times, ignore errors */
    when.actime = was.st_atime;
    when.modtime = was.st_mtime;
    (void)utime(to, &when);
}

/* Decompress the file inname to the file outnname, of if test is true, just
   decompress without writing and check the gzip trailer for integrity.  If
   inname is NULL or an empty string, read from stdin.  If outname is NULL or
   an empty string, write to stdout.  strm is a pre-initialized inflateBack
   structure.  When appropriate, copy the file attributes from inname to
   outname.

   gunzip() returns 1 if there is an out-of-memory error or an unexpected
   return code from gunpipe().  Otherwise it returns 0.
 */
local int gunzip(z_stream *strm, char *inname, char *outname, int test)
{
    int ret;
    int infile, outfile;

    /* open files */
    if (inname == NULL || *inname == 0) {
        inname = "-";
        infile = 0;     /* stdin */
    }
    else {
        infile = open(inname, O_RDONLY, 0);
        if (infile == -1) {
            fprintf(stderr, "gun cannot open %s\n", inname);
            return 0;
        }
    }
    if (test)
        outfile = -1;
    else if (outname == NULL || *outname == 0) {
        outname = "-";
        outfile = 1;    /* stdout */
    }
    else {
        outfile = open(outname, O_CREAT | O_TRUNC | O_WRONLY, 0666);
        if (outfile == -1) {
            close(infile);
            fprintf(stderr, "gun cannot create %s\n", outname);
            return 0;
        }
    }
    errno = 0;

    /* decompress */
    ret = gunpipe(strm, infile, outfile);
    if (outfile > 2) close(outfile);
    if (infile > 2) close(infile);

    /* interpret result */
    switch (ret) {
    case Z_OK:
    case Z_ERRNO:
        if (infile > 2 && outfile > 2) {