[ecash-secp256k1] Add ecash-secp256k1-sys

Summary:
Import the `secp256k1-sys` crate from [[ https://github.com/rust-bitcoin/rust-secp256k1 | rust-secp256k1 ]] repository, and apply the following modifications:
- Removed the vendored secp256k1 library imported from bitcoin-core
- Use our secp256k1 library of the monorepo
- Add ABC's `secp256k1_schnorr_sign` and `secp256k1_schnorr_verify`, which are the Schnorr signatures used by ABC. These are distinct from the x-only pubkey BIP340 signatures from BTC, but we keep them to simplify backports, and to (in the future) allow eCash apps to also talk some BTC.
- Port the GitHub CI from the repository to a test.sh. Those depend on https://github.com/rust-bitcoin/rust-bitcoin-maintainer-tools, so the relevant parts have been ported and cleaned up.
- Adapt the Rust workspace structure to our workspace.
- Reformat everything with our formatting rules.

Test Plan: `./modules/ecash-secp256k1/contrib/test.sh`

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D16953

Author: EyeOfPython

Cargo.lock

@@ -18,6 +18,7 @@ members = [
     "chronik/chronik-proto",
     "chronik/chronik-util",
     "modules/ecash-lib-wasm",
+    "modules/ecash-secp256k1/ecash-secp256k1-sys",
 ]
 
 [workspace.package]

Cargo.toml

@@ -552,6 +552,14 @@ builds:
       - - bench-secp256k1
     timeout: 1200
 
+  build-ecash-secp256k1:
+    runOnDiffRegex:
+      - src/secp256k1/
+      - modules/ecash-secp256k1/
+    script: |
+      "${TOPLEVEL}/modules/ecash-secp256k1/contrib/test.sh"
+    timeout: 1200
+
   build-tsan:
     Werror: true
     clang: true

contrib/teamcity/build-configurations.yml

@@ -0,0 +1,105 @@
+#!/usr/bin/env bash
+
+export LC_ALL=C.UTF-8
+
+set -euox pipefail
+
+# Setup
+: "${TOPLEVEL:=$(git rev-parse --show-toplevel)}"
+
+# Use the current `Cargo.lock` file without updating it.
+CARGO="cargo --locked"
+
+# Make all cargo invocations verbose.
+export CARGO_TERM_VERBOSE=true
+
+main() {
+    ecash_secp256k1_sys
+}
+
+ecash_secp256k1_sys() {
+    FEATURES_WITH_STD="lowmemory recovery"
+    FEATURES_WITHOUT_STD="lowmemory recovery alloc"
+
+    # Navigate to ecash-secp256k1-sys
+    pushd "${TOPLEVEL}/modules/ecash-secp256k1/ecash-secp256k1-sys"
+
+    run_tests
+}
+
+run_tests() {
+    # Defaults / sanity checks
+    $CARGO build
+    $CARGO clippy
+    $CARGO test
+
+    # All features disabled
+    $CARGO build --no-default-features
+    $CARGO clippy --no-default-features
+    $CARGO test --no-default-features
+
+    # Test feature combinations
+    loop_features "std" "${FEATURES_WITH_STD}"
+    loop_features "" "${FEATURES_WITHOUT_STD}"
+
+    # Extra tests
+    RUSTFLAGS='--cfg=secp256k1_fuzz' RUSTDOCFLAGS='--cfg=secp256k1_fuzz' $CARGO test --locked
+    RUSTFLAGS='--cfg=secp256k1_fuzz' RUSTDOCFLAGS='--cfg=secp256k1_fuzz' $CARGO test --locked --features="$FEATURES_WITH_STD"
+
+    build_docs
+    build_wasm
+
+    popd
+}
+
+# Build with each feature as well as all combinations of two features.
+#
+# Usage: loop_features "std" "this-feature that-feature other"
+loop_features() {
+    local use="${1:-}"          # Allow empty string.
+    local features="$2"         # But require features.
+
+    # All the provided features including $use
+    $CARGO build --no-default-features --features="$use $features"
+    $CARGO test --no-default-features --features="$use $features"
+    $CARGO clippy --no-default-features --features="$use $features"
+
+    read -r -a array <<< "$features"
+    local len="${#array[@]}"
+
+    if (( len > 1 )); then
+        for ((i = 0 ; i < len ; i++ ));
+        do
+            $CARGO build --no-default-features --features="$use ${array[i]}"
+            $CARGO test --no-default-features --features="$use ${array[i]}"
+            $CARGO clippy --no-default-features --features="$use ${array[i]}"
+
+            if (( i < len - 1 )); then
+               for ((j = i + 1 ; j < len ; j++ ));
+               do
+                   $CARGO build --no-default-features --features="$use ${array[i]} ${array[j]}"
+                   $CARGO test --no-default-features --features="$use ${array[i]} ${array[j]}"
+                   $CARGO clippy --no-default-features --features="$use ${array[i]} ${array[j]}"
+               done
+            fi
+        done
+    fi
+}
+
+# Build the docs with a stable toolchain, in unison with the function
+# above this checks that we feature guarded docs imports correctly.
+build_docs() {
+    RUSTDOCFLAGS="-D warnings" $CARGO doc --all-features
+}
+
+build_wasm() {
+    CFLAGS="-Wno-pointer-sign -Wno-implicit-function-declaration" \
+    RUSTFLAGS="-C strip=debuginfo" \
+    $CARGO build \
+        --profile=release-wasm \
+        --target=wasm32-unknown-unknown
+}
+
+# Main script
+main "$@"
+exit 0

modules/ecash-secp256k1/contrib/test.sh

@@ -0,0 +1,38 @@
+[package]
+name = "ecash-secp256k1-sys"
+version = "0.10.0"
+authors = [
+    "Dawid Ciężarkiewicz <[email protected]>",
+    "Andrew Poelstra <[email protected]>",
+    "Steven Roose <[email protected]>",
+    "Tobias Ruck <[email protected]>",
+]
+license = "CC0-1.0"
+homepage = "https://e.cash"
+repository = "https://github.com/Bitcoin-ABC/bitcoin-abc/"
+description = "FFI for the Bitcoin ABC version of Pieter Wuille's `libsecp256k1` library."
+readme = "README.md"
+build = "build.rs"
+edition = "2021"
+rust-version.workspace = true
+
+[package.metadata.docs.rs]
+all-features = true
+rustdoc-args = ["--cfg", "docsrs"]
+
+[build-dependencies]
+cc = "1.0.28"
+
+[dev-dependencies]
+libc = "0.2"
+
+[features]
+default = ["std"]
+recovery = []
+lowmemory = []
+std = ["alloc"]
+alloc = []
+
+[lints.rust.unexpected_cfgs]
+level = "deny"
+check-cfg = ['cfg(bench)', 'cfg(secp256k1_fuzz)']

modules/ecash-secp256k1/ecash-secp256k1-sys/Cargo.toml

@@ -0,0 +1,121 @@
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modules/ecash-secp256k1/ecash-secp256k1-sys/LICENSE

@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: CC0-1.0
+
+//! # Build script
+
+// Coding conventions
+#![deny(non_upper_case_globals)]
+#![deny(non_camel_case_types)]
+#![deny(non_snake_case)]
+#![deny(unused_mut)]
+#![warn(missing_docs)]
+
+use std::env;
+
+// Macro pointing to our secp256k1 library
+macro_rules! secp256k1path {
+    ($path:literal) => {
+        concat!("../../../src/secp256k1", $path)
+    };
+}
+
+fn main() {
+    // Configure building secp256k1
+    let mut base_config = cc::Build::new();
+    base_config
+        .include(secp256k1path!("/"))
+        .include(secp256k1path!("/include"))
+        .include(secp256k1path!("/src"))
+        // some ecmult stuff is defined but not used upstream
+        .flag_if_supported("-Wno-unused-function")
+        // patching out printf causes this warning
+        .flag_if_supported("-Wno-unused-parameter")
+        .define("SECP256K1_API", Some(""))
+        .define("ENABLE_MODULE_ECDH", Some("1"))
+        .define("ENABLE_MODULE_SCHNORRSIG", Some("1"))
+        .define("ENABLE_MODULE_SCHNORR", Some("1"))
+        .define("ENABLE_MODULE_EXTRAKEYS", Some("1"))
+        // upstream sometimes introduces calls to printf, which we cannot
+        // compile with WASM due to its lack of libc. printf is never
+        // necessary and we can just #define it away.
+        .define("printf(...)", Some(""));
+
+    if cfg!(feature = "lowmemory") {
+        // A low-enough value to consume negligible memory
+        base_config.define("ECMULT_WINDOW_SIZE", Some("4"));
+        base_config.define("ECMULT_GEN_PREC_BITS", Some("2"));
+    } else {
+        base_config.define("ECMULT_GEN_PREC_BITS", Some("4"));
+        // This is the default in the configure file (`auto`)
+        base_config.define("ECMULT_WINDOW_SIZE", Some("15"));
+    }
+    base_config.define("USE_EXTERNAL_DEFAULT_CALLBACKS", Some("1"));
+    #[cfg(feature = "recovery")]
+    base_config.define("ENABLE_MODULE_RECOVERY", Some("1"));
+
+    // WASM headers and size/align defines.
+    if env::var("CARGO_CFG_TARGET_ARCH").unwrap() == "wasm32" {
+        base_config.include("wasm/wasm-sysroot").file("wasm/wasm.c");
+    }
+
+    // secp256k1
+    base_config
+        .file(secp256k1path!("/contrib/lax_der_parsing.c"))
+        .file(secp256k1path!("/src/secp256k1.c"));
+
+    if base_config.try_compile("libsecp256k1.a").is_err() {
+        // Some embedded platforms may not have, eg, string.h available, so if
+        // the build fails simply try again with the wasm sysroot (but
+        // without the wasm type sizes) in the hopes that it works.
+        base_config.include("wasm/wasm-sysroot");
+        base_config.compile("libsecp256k1.a");
+    }
+}