return (int)(len - s->stream.avail_out);
}


/* ===========================================================================
      Reads one byte from the compressed file. gzgetc returns this byte
   or -1 in case of end of file or error.
*/
int ZEXPORT gzgetc( gzFile file)
   
{
    unsigned char c;

    return gzread(file, &c, 1) == 1 ? c : -1;
}


/* ===========================================================================
      Reads bytes from the compressed file until len-1 characters are
   read, or a newline character is read and transferred to buf, or an
   end-of-file condition is encountered.  The string is then terminated
   with a null character.
      gzgets returns buf, or Z_NULL in case of error.

      The current implementation is not optimized at all.
*/
char * ZEXPORT gzgets(   gzFile file,
    char *buf,
    int len)
 
{
    char *b = buf;
    if (buf == Z_NULL || len <= 0) return Z_NULL;

    while (--len > 0 && gzread(file, buf, 1) == 1 && *buf++ != '\n') ;
    *buf = '\0';
    return b == buf && len > 0 ? Z_NULL : b;
}


#ifndef NO_DEFLATE
/* ===========================================================================
     Writes the given number of uncompressed bytes into the compressed file.
   gzwrite returns the number of bytes actually written (0 in case of error).
*/
int ZEXPORT gzwrite (  gzFile file,
    const voidp buf,
    unsigned len)
  
{
    gz_stream *s = (gz_stream*)file;

    if (s == NULL || s->mode != 'w') return Z_STREAM_ERROR;

    s->stream.next_in = (Bytef*)buf;
    s->stream.avail_in = len;

    while (s->stream.avail_in != 0) {

        if (s->stream.avail_out == 0) {

            s->stream.next_out = s->outbuf;
            if (fwrite(s->outbuf, 1, Z_BUFSIZE, s->file) != Z_BUFSIZE) {
                s->z_err = Z_ERRNO;
                break;
            }
            s->stream.avail_out = Z_BUFSIZE;
        }
        s->z_err = deflate(&(s->stream), Z_NO_FLUSH);
        if (s->z_err != Z_OK) break;
    }
    s->crc = crc32(s->crc, (const Bytef *)buf, len);

    return (int)(len - s->stream.avail_in);
}

/* ===========================================================================
     Converts, formats, and writes the args to the compressed file under
   control of the format string, as in fprintf. gzprintf returns the number of
   uncompressed bytes actually written (0 in case of error).
*/
#ifdef STDC
#include <stdarg.h>

int ZEXPORTVA gzprintf (gzFile file, const char *format, /* args */ ...)
{
    char buf[Z_PRINTF_BUFSIZE];
    va_list va;
    int len;

    va_start(va, format);
#ifdef HAS_vsnprintf
    (void)vsnprintf(buf, sizeof(buf), format, va);
#else
    (void)vsprintf(buf, format, va);
#endif
    va_end(va);
    len = strlen(buf); /* some *sprintf don't return the nb of bytes written */
    if (len <= 0) return 0;

    return gzwrite(file, buf, (unsigned)len);
}
#else /* not ANSI C */

int ZEXPORTVA gzprintf (file, format, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10,
	               a11, a12, a13, a14, a15, a16, a17, a18, a19, a20)
    gzFile file;
    const char *format;
    int a1, a2, a3, a4, a5, a6, a7, a8, a9, a10,
	a11, a12, a13, a14, a15, a16, a17, a18, a19, a20;
{
    char buf[Z_PRINTF_BUFSIZE];
    int len;

#ifdef HAS_snprintf
    snprintf(buf, sizeof(buf), format, a1, a2, a3, a4, a5, a6, a7, a8,
	     a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
#else
    sprintf(buf, format, a1, a2, a3, a4, a5, a6, a7, a8,
	    a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
#endif
    len = strlen(buf); /* old sprintf doesn't return the nb of bytes written */
    if (len <= 0) return 0;

    return gzwrite(file, buf, len);
}
#endif

/* ===========================================================================
      Writes c, converted to an unsigned char, into the compressed file.
   gzputc returns the value that was written, or -1 in case of error.
*/
int ZEXPORT gzputc(   gzFile file,
    int c)
 
{
    unsigned char cc = (unsigned char) c; /* required for big endian systems */

    return gzwrite(file, &cc, 1) == 1 ? (int)cc : -1;
}


/* ===========================================================================
      Writes the given null-terminated string to the compressed file, excluding
   the terminating null character.
      gzputs returns the number of characters written, or -1 in case of error.
*/
int ZEXPORT gzputs(    gzFile file,
    const char *s)

{
    return gzwrite(file, (char*)s, (unsigned)strlen(s));
}


/* ===========================================================================
     Flushes all pending output into the compressed file. The parameter
   flush is as in the deflate() function.
*/
local int do_flush (    gzFile file,
    int flush)

{
    uInt len;
    int done = 0;
    gz_stream *s = (gz_stream*)file;

    if (s == NULL || s->mode != 'w') return Z_STREAM_ERROR;

    s->stream.avail_in = 0; /* should be zero already anyway */

    for (;;) {
        len = Z_BUFSIZE - s->stream.avail_out;

        if (len != 0) {
            if ((uInt)fwrite(s->outbuf, 1, len, s->file) != len) {
                s->z_err = Z_ERRNO;
                return Z_ERRNO;
            }
            s->stream.next_out = s->outbuf;
            s->stream.avail_out = Z_BUFSIZE;
        }
        if (done) break;
        s->z_err = deflate(&(s->stream), flush);

	/* Ignore the second of two consecutive flushes: */
	if (len == 0 && s->z_err == Z_BUF_ERROR) s->z_err = Z_OK;

        /* deflate has finished flushing only when it hasn't used up
         * all the available space in the output buffer: 
         */
        done = (s->stream.avail_out != 0 || s->z_err == Z_STREAM_END);
 
        if (s->z_err != Z_OK && s->z_err != Z_STREAM_END) break;
    }
    return  s->z_err == Z_STREAM_END ? Z_OK : s->z_err;
}

int ZEXPORT gzflush (     gzFile file,
     int flush)

{
    gz_stream *s = (gz_stream*)file;
    int err = do_flush (file, flush);

    if (err) return err;
    fflush(s->file);
    return  s->z_err == Z_STREAM_END ? Z_OK : s->z_err;
}
#endif /* NO_DEFLATE */

/* ===========================================================================
      Sets the starting position for the next gzread or gzwrite on the given
   compressed file. The offset represents a number of bytes in the
      gzseek returns the resulting offset location as measured in bytes from
   the beginning of the uncompressed stream, or -1 in case of error.
      SEEK_END is not implemented, returns error.
      In this version of the library, gzseek can be extremely slow.
*/
z_off_t ZEXPORT gzseek ( gzFile file,
    z_off_t offset,
    int whence)
   
{
    gz_stream *s = (gz_stream*)file;

    if (s == NULL || whence == SEEK_END ||
	s->z_err == Z_ERRNO || s->z_err == Z_DATA_ERROR) {
	return -1L;
    }
    
    if (s->mode == 'w') {
#ifdef NO_DEFLATE
	return -1L;
#else
	if (whence == SEEK_SET) {
	    offset -= s->stream.total_in;
	}
	if (offset < 0) return -1L;

	/* At this point, offset is the number of zero bytes to write. */
	if (s->inbuf == Z_NULL) {
	    s->inbuf = (Byte*)ALLOC(Z_BUFSIZE); /* for seeking */
	    zmemzero(s->inbuf, Z_BUFSIZE);
	}
	while (offset > 0)  {
	    uInt size = Z_BUFSIZE;
	    if (offset < Z_BUFSIZE) size = (uInt)offset;

	    size = gzwrite(file, s->inbuf, size);
	    if (size == 0) return -1L;

	    offset -= size;
	}
	return (z_off_t)s->stream.total_in;
#endif
    }
    /* Rest of function is for reading only */

    /* compute absolute position */
    if (whence == SEEK_CUR) {
	offset += s->stream.total_out;
    }
    if (offset < 0) return -1L;

    if (s->transparent) {
	/* map to fseek */
	s->stream.avail_in = 0;
	s->stream.next_in = s->inbuf;
        if (fseek(s->file, offset, SEEK_SET) < 0) return -1L;

	s->stream.total_in = s->stream.total_out = (uLong)offset;
	return offset;
    }

    /* For a negative seek, rewind and use positive seek */
    if ((uLong)offset >= s->stream.total_out) {
	offset -= s->stream.total_out;
    } else if (gzrewind(file) < 0) {
	return -1L;
    }
    /* offset is now the number of bytes to skip. */

    if (offset != 0 && s->outbuf == Z_NULL) {
	s->outbuf = (Byte*)ALLOC(Z_BUFSIZE);
    }
    while (offset > 0)  {
	int size = Z_BUFSIZE;
	if (offset < Z_BUFSIZE) size = (int)offset;

	size = gzread(file, s->outbuf, (uInt)size);
	if (size <= 0) return -1L;
	offset -= size;
    }
    return (z_off_t)s->stream.total_out;
}

/* ===========================================================================
     Rewinds input file. 
*/
int ZEXPORT gzrewind ( gzFile file)
   
{
    gz_stream *s = (gz_stream*)file;
    
    if (s == NULL || s->mode != 'r') return -1;

    s->z_err = Z_OK;
    s->z_eof = 0;
    s->stream.avail_in = 0;
    s->stream.next_in = s->inbuf;
    s->crc = crc32(0L, Z_NULL, 0);
	
    if (s->startpos == 0) { /* not a compressed file */
	rewind(s->file);
	return 0;
    }

    (void) inflateReset(&s->stream);
    return fseek(s->file, s->startpos, SEEK_SET);
}

/* ===========================================================================
     Returns the starting position for the next gzread or gzwrite on the
   given compressed file. This position represents a number of bytes in the
   uncompressed data stream.
*/
z_off_t ZEXPORT gztell (  gzFile file)
  
{
    return gzseek(file, 0L, SEEK_CUR);
}

/* ===========================================================================
     Returns 1 when EOF has previously been detected reading the given
   input stream, otherwise zero.
*/
int ZEXPORT gzeof (    gzFile file)

{
    gz_stream *s = (gz_stream*)file;
    
    return (s == NULL || s->mode != 'r') ? 0 : s->z_eof;
}

/* ===========================================================================
   Outputs a long in LSB order to the given file
*/
local void putLong (    FILE *file,
    uLong x)

{
    int n;
    for (n = 0; n < 4; n++) {
        fputc((int)(x & 0xff), file);
        x >>= 8;
    }
}

/* ===========================================================================
   Reads a long in LSB order from the given gz_stream. Sets z_err in case
   of error.
*/
local uLong getLong ( gz_stream *s)
 
{
    uLong x = (uLong)get_byte(s);
    int c;

    x += ((uLong)get_byte(s))<<8;
    x += ((uLong)get_byte(s))<<16;
    c = get_byte(s);
    if (c == EOF) s->z_err = Z_DATA_ERROR;
    x += ((uLong)c)<<24;
    return x;
}

/* ===========================================================================
     Flushes all pending output if necessary, closes the compressed file
   and deallocates all the (de)compression state.
*/
int ZEXPORT gzclose (    gzFile file)

{
    int err;
    gz_stream *s = (gz_stream*)file;

    if (s == NULL) return Z_STREAM_ERROR;

    if (s->mode == 'w') {
#ifdef NO_DEFLATE
	return Z_STREAM_ERROR;
#else
        err = do_flush (file, Z_FINISH);
        if (err != Z_OK) return destroy((gz_stream*)file);

        putLong (s->file, s->crc);
        putLong (s->file, s->stream.total_in);
#endif
    }
    return destroy((gz_stream*)file);
}

/* ===========================================================================
     Returns the error message for the last error which occured on the
   given compressed file. errnum is set to zlib error number. If an
   error occured in the file system and not in the compression library,
   errnum is set to Z_ERRNO and the application may consult errno
   to get the exact error code.
*/
const char*  ZEXPORT gzerror (    gzFile file,
    int *errnum)

{
    char *m;
    gz_stream *s = (gz_stream*)file;

    if (s == NULL) {
        *errnum = Z_STREAM_ERROR;
        return (const char*)ERR_MSG(Z_STREAM_ERROR);
    }
    *errnum = s->z_err;
    if (*errnum == Z_OK) return (const char*)"";

    m =  (char*)(*errnum == Z_ERRNO ? zstrerror(errno) : s->stream.msg);

    if (m == NULL || *m == '\0') m = (char*)ERR_MSG(s->z_err);

    TRYFREE(s->msg);
    s->msg = (char*)ALLOC(strlen(s->path) + strlen(m) + 3);
    strcpy(s->msg, s->path);
    strcat(s->msg, ": ");
    strcat(s->msg, m);
    return (const char*)s->msg;
}