mirror of
https://github.com/saymrwulf/curve25519-dalek-source.git
synced 2026-09-04 20:24:10 +00:00
81 lines
3.2 KiB
Rust
81 lines
3.2 KiB
Rust
//! This selects the curve25519_dalek_bits either by default from target_pointer_width or explicitly set
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#![deny(clippy::unwrap_used, dead_code)]
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#[allow(non_camel_case_types)]
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enum DalekBits {
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#[cfg_attr(curve25519_dalek_bits = "64", allow(dead_code))]
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Dalek32,
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#[cfg_attr(curve25519_dalek_bits = "32", allow(dead_code))]
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Dalek64,
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}
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fn main() {
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#[cfg(curve25519_dalek_bits = "32")]
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let curve25519_dalek_bits = DalekBits::Dalek32;
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#[cfg(curve25519_dalek_bits = "64")]
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let curve25519_dalek_bits = DalekBits::Dalek64;
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#[cfg(all(not(curve25519_dalek_bits = "64"), not(curve25519_dalek_bits = "32")))]
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let curve25519_dalek_bits = deterministic::determine_curve25519_dalek_bits();
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match curve25519_dalek_bits {
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DalekBits::Dalek64 => println!("cargo:rustc-cfg=curve25519_dalek_bits=\"64\""),
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DalekBits::Dalek32 => println!("cargo:rustc-cfg=curve25519_dalek_bits=\"32\""),
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}
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}
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// Deterministic cfg(curve25519_dalek_bits) when this is not explicitly set.
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#[cfg(all(not(curve25519_dalek_bits = "64"), not(curve25519_dalek_bits = "32")))]
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mod deterministic {
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use super::*;
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// Standard Cargo TARGET environment variable of triplet is required
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static ERR_MSG_NO_TARGET: &str = "Standard Cargo TARGET environment variable is not set.";
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// Custom Non-Rust standard target platforms require explicit settings.
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static ERR_MSG_NO_PLATFORM: &str = "Unknown Rust target platform.";
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// Error handling when the bits setting cannot be determined
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fn determine_curve25519_dalek_bits_error(cause: &str) -> ! {
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eprintln!("Error: {cause}");
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eprintln!("Please set cfg(curve25519_dalek_bits) explicitly either as 32 or 64.");
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std::process::exit(1)
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}
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// Determine the curve25519_dalek_bits based on Rust standard TARGET triplet
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pub(super) fn determine_curve25519_dalek_bits() -> DalekBits {
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use platforms::target::PointerWidth;
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// TARGET environment is supplied by Cargo
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// https://doc.rust-lang.org/cargo/reference/environment-variables.html
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let target_triplet = match std::env::var("TARGET") {
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Ok(t) => t,
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Err(_) => determine_curve25519_dalek_bits_error(ERR_MSG_NO_TARGET),
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};
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// platforms crate is the source of truth used to determine the platform
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let platform = match platforms::Platform::find(&target_triplet) {
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Some(p) => p,
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None => determine_curve25519_dalek_bits_error(ERR_MSG_NO_PLATFORM),
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};
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#[allow(clippy::match_single_binding)]
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match platform.target_arch {
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//Issues: 449 and 456
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//TODO(Arm): Needs tests + benchmarks to back this up
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//platforms::target::Arch::Arm => DalekBits::Dalek64,
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//TODO(Wasm32): Needs tests + benchmarks to back this up
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//platforms::target::Arch::Wasm32 => DalekBits::Dalek64,
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_ => match platform.target_pointer_width {
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PointerWidth::U64 => DalekBits::Dalek64,
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PointerWidth::U32 => DalekBits::Dalek32,
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// Intended default solely for non-32/64 target pointer widths
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// Otherwise known target platforms only.
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_ => DalekBits::Dalek32,
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},
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}
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}
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}
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