Function gz_open

zlib/gzio.c:98–208

=========================================================================== Opens a gzip (.gz) file for reading or writing. The mode parameter is as in fopen ("rb" or "wb"). The file is given either by file descriptor or path name (if fd == -1). gz_open returns NULL if the file could not be opened or if there was insufficient memory to allocate the (de)compression state; errno

(path, mode, fd)

   zlib error is Z_MEM_ERROR).
*/
local gzFile gz_open (path, mode, fd)
    const char *path;
    const char *mode;
    int  fd;
{
    int err;
    int level = Z_DEFAULT_COMPRESSION; /* compression level */
    int strategy = Z_DEFAULT_STRATEGY; /* compression strategy */
    char *p = (char*)mode;
    gz_stream *s;
    char fmode[80]; /* copy of mode, without the compression level */
    char *m = fmode;

    if (!path || !mode) return Z_NULL;

    s = (gz_stream *)ALLOC(sizeof(gz_stream));
    if (!s) return Z_NULL;

    s->stream.zalloc = (alloc_func)0;
    s->stream.zfree = (free_func)0;
    s->stream.opaque = (voidpf)0;
    s->stream.next_in = s->inbuf = Z_NULL;
    s->stream.next_out = s->outbuf = Z_NULL;
    s->stream.avail_in = s->stream.avail_out = 0;
    s->file = NULL;
    s->z_err = Z_OK;
    s->z_eof = 0;
    s->in = 0;
    s->out = 0;
    s->back = EOF;
    s->crc = crc32(0L, Z_NULL, 0);
    s->msg = NULL;
    s->transparent = 0;

    s->path = (char*)ALLOC(strlen(path)+1);
    if (s->path == NULL) {
        return destroy(s), (gzFile)Z_NULL;
    }
    strcpy(s->path, path); /* do this early for debugging */

    s->mode = '\0';
    do {
        if (*p == 'r') s->mode = 'r';
        if (*p == 'w' || *p == 'a') s->mode = 'w';
        if (*p >= '0' && *p <= '9') {
            level = *p - '0';
        } else if (*p == 'f') {
          strategy = Z_FILTERED;
        } else if (*p == 'h') {
          strategy = Z_HUFFMAN_ONLY;
        } else if (*p == 'R') {
          strategy = Z_RLE;
        } else {
            *m++ = *p; /* copy the mode */
        }
    } while (*p++ && m != fmode + sizeof(fmode));
    if (s->mode == '\0') return destroy(s), (gzFile)Z_NULL;