Switch to static linking of secp256k1

Pieter moved some stuff I need into the contrib/ directory which does
not expose anything through the shared lib, so I need to statically
link.

I might also use this to do evil things to expose the SHA256 code
in libsecp, but not for now ;).

.travis.yml

@@ -7,11 +7,6 @@ matrix:
     - rust: nightly
 
 install:
-  - git clone https://github.com/bitcoin/secp256k1.git
-  - cd secp256k1
-  - ./autogen.sh && ./configure --enable-module-ecdh --enable-module-recovery && make && sudo make install
-  - sudo ldconfig /usr/local/lib
-  - cd ..
   - |
       pip install 'travis-cargo<0.2' --user &&
       export PATH=$HOME/.local/bin:$PATH

Cargo.toml

@@ -12,6 +12,10 @@ description = "Rust bindings for Pieter Wuille's `libsecp256k1` library. Impleme
 keywords = [ "crypto", "ECDSA", "secp256k1", "libsecp256k1", "bitcoin" ]
 readme = "README.md"
 
+build = "build.rs"
+[build-dependencies]
+gcc = "0.3"
+
 [lib]
 name = "secp256k1"
 path = "src/lib.rs"

build.rs

@@ -0,0 +1,44 @@
+// Bitcoin secp256k1 bindings
+// Written in 2015 by
+//   Andrew Poelstra
+//
+// To the extent possible under law, the author(s) have dedicated all
+// copyright and related and neighboring rights to this software to
+// the public domain worldwide. This software is distributed without
+// any warranty.
+//
+// You should have received a copy of the CC0 Public Domain Dedication
+// along with this software.
+// If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
+//
+
+//! # Build script
+
+// Coding conventions
+#![deny(non_upper_case_globals)]
+#![deny(non_camel_case_types)]
+#![deny(non_snake_case)]
+#![deny(unused_mut)]
+#![warn(missing_docs)]
+
+extern crate gcc;
+
+fn main() {
+    gcc::Config::new()
+                .file("depend/secp256k1/src/secp256k1.c")
+                .include("depend/secp256k1/")
+                .include("depend/secp256k1/src")
+                // TODO these three should be changed to use libgmp, at least until secp PR 290 is merged
+                .define("USE_NUM_NONE", Some("1"))
+                .define("USE_FIELD_INV_BUILTIN", Some("1"))
+                .define("USE_SCALAR_INV_BUILTIN", Some("1"))
+                // TODO these should use 64-bit variants on 64-bit systems
+                .define("USE_FIELD_10X26", Some("1"))
+                .define("USE_SCALAR_8X32", Some("1"))
+                .define("USE_ENDOMORPHISM", Some("1"))
+                // These all are OK.
+                .define("ENABLE_MODULE_ECDH", Some("1"))
+                .define("ENABLE_MODULE_RECOVERY", Some("1"))
+                .compile("libsecp256k1.a");
+}
+

src/ffi.rs

@@ -116,7 +116,6 @@ impl SharedSecret {
 unsafe impl Send for Context {}
 unsafe impl Sync for Context {}
 
-#[link(name = "secp256k1")]
 extern "C" {
     pub static secp256k1_nonce_function_rfc6979: NonceFn;