Function deflateSetHeader 

#[unsafe(export_name = "deflateSetHeader")]
pub unsafe extern "C-unwind" fn deflateSetHeader(
    strm: *mut z_stream,
    head: *mut gz_header,
) -> i32

Provides gzip header information for when a gzip stream is requested by deflateInit2_.

deflateSetHeader may be called after deflateInit2_ or deflateReset) and before the first call of deflate. The header’s text, time, os, extra, name, and comment fields in the provided gz_header structure are written to the gzip header (xflag is ignored — the extra flags are set according to the compression level).

The caller must assure that, if not NULL, name and comment are terminated with a zero byte, and that if extra is not NULL, that extra_len bytes are available there. If hcrc is true, a gzip header crc is included.

If deflateSetHeader is not used, the default gzip header has text false, the time set to zero, and os set to the current operating system, with no extra, name, or comment fields. The gzip header is returned to the default state by deflateReset.

Returns

• Z_OK if success
• Z_STREAM_ERROR if the stream state was inconsistent

Safety

• Either
  • strm is NULL
  • strm satisfies the requirements of &mut *strm and was initialized with deflateInit_ or similar
• Either
  • head is NULL
  • head satisfies the requirements of &mut *head and satisfies the following:
    • head.extra is NULL or is readable for at least head.extra_len bytes
    • head.name is NULL or satisfies the requirements of core::ffi::CStr::from_ptr
    • head.comment is NULL or satisfies the requirements of core::ffi::CStr::from_ptr