Rust: Add a nicer wrapper around the libunit-wasm bindings

This adds a nice wrapper (aka rusty) around the generated libunit-wasm
bindings.

This should provide a more native rust like experience with the
following benefits

  - No casting. So no things like 'as *mut c_void'
  - Native rust strings. So no things like '.as_ptr() as *const c_char'
  - Better ctx initialisation. Filed initialisation is now hidden away
  - Great reduction in the amount of unsafe {} blocks required
  - Generally more compact

There are also some new macros

  - C2S!() converts a CStr to a Str
  - S2C!() converts a formatted Str to a Cstr using format!()
  - uwr_write_str!() a wrapper around luw_mem_writep_data and format!()

This wrapper uses a uwr (Unit Wasm Rust) prefix under a 'rusty'
namespace.

The luw_http_hdr_iter() function proved tricky to wrap and the callback
function still takes C style arguments due to the fact that this
function is called from the libunit-wasm C library.

The provided wrapper simply means we can use this without having to use
an unsafe {} block around it in application code.

Similarly with other functions that technically didn't need to be
wrapped, wrapping them means that the unsafe {} blocks are hidden away.

Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/src/rust/unit-wasm-sys/macros.rs b/src/rust/unit-wasm-sys/macros.rs
index d7fde22..059fef3 100644
--- a/src/rust/unit-wasm-sys/macros.rs
+++ b/src/rust/unit-wasm-sys/macros.rs
@@ -13,3 +13,8 @@ pub const LUW_VERSION_NUMBER: i32 =
     (LUW_VERSION_MAJOR << 24) |
     (LUW_VERSION_MINOR << 16) |
     (LUW_VERSION_PATCH << 8);
+
+pub const LUW_SRB_NONE:      u32 = luw_srb_flags_t_LUW_SRB_NONE;
+pub const LUW_SRB_APPEND:    u32 = luw_srb_flags_t_LUW_SRB_APPEND;
+pub const LUW_SRB_ALLOC:     u32 = luw_srb_flags_t_LUW_SRB_ALLOC;
+pub const LUW_SRB_FULL_SIZE: u32 = luw_srb_flags_t_LUW_SRB_FLAGS_ALL;