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Added structs and functions for manual allocation
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elichai committed Jul 4, 2019
1 parent b4b52a9 commit 1c0ae7d
Showing 1 changed file with 86 additions and 1 deletion.
87 changes: 86 additions & 1 deletion src/context.rs
Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
use core::marker::PhantomData;
use {ffi, types::{c_uint, c_void}, Error, Secp256k1, };
use {ffi, types::{c_uint, c_void}, Error, Secp256k1};

#[cfg(feature = "std")]
pub use self::std_only::*;
Expand All @@ -21,6 +21,20 @@ pub trait Signing: Context {}
/// Marker trait for indicating that an instance of `Secp256k1` can be used for verification.
pub trait Verification: Context {}

/// Represents the set of capabilities needed for signing with a user preallocated memory.
pub struct SignOnlyPreallocated<'buf> {
phantom: PhantomData<&'buf ()>,
}

/// Represents the set of capabilities needed for verification with a user preallocated memory.
pub struct VerifyOnlyPreallocated<'buf> {
phantom: PhantomData<&'buf ()>,
}

/// Represents the set of all capabilities with a user preallocated memory.
pub struct AllPreallocated<'buf> {
phantom: PhantomData<&'buf ()>,
}

#[cfg(feature = "std")]
mod std_only {
Expand Down Expand Up @@ -120,3 +134,74 @@ mod std_only {
}

}

impl<'buf> Signing for SignOnlyPreallocated<'buf> {}
impl<'buf> Signing for AllPreallocated<'buf> {}

impl<'buf> Verification for VerifyOnlyPreallocated<'buf> {}
impl<'buf> Verification for AllPreallocated<'buf> {}

unsafe impl<'buf> Context for SignOnlyPreallocated<'buf> {
const FLAGS: c_uint = ffi::SECP256K1_START_SIGN;
const DESCRIPTION: &'static str = "signing only";

fn deallocate(ptr: *mut [u8]) {
let _ = ptr;
}
}

unsafe impl<'buf> Context for VerifyOnlyPreallocated<'buf> {
const FLAGS: c_uint = ffi::SECP256K1_START_VERIFY;
const DESCRIPTION: &'static str = "verification only";

fn deallocate(ptr: *mut [u8]) {
let _ = ptr;
}
}

unsafe impl<'buf> Context for AllPreallocated<'buf> {
const FLAGS: c_uint = SignOnlyPreallocated::FLAGS | VerifyOnlyPreallocated::FLAGS;
const DESCRIPTION: &'static str = "all capabilities";

fn deallocate(ptr: *mut [u8]) {
let _ = ptr;
}
}

impl<'buf, C: Context + 'buf> Secp256k1<C> {
fn preallocated_gen_new(buf: &'buf mut [u8]) -> Result<Secp256k1<C>, Error> {
if buf.len() < Self::preallocate_size() {
return Err(Error::NotEnoughMemory);
}
Ok(Secp256k1 {
ctx: unsafe {
ffi::secp256k1_context_preallocated_create(
buf.as_mut_ptr() as *mut c_void,
AllPreallocated::FLAGS)
},
phantom: PhantomData,
buf: buf as *mut [u8],
})
}
}

impl<'buf> Secp256k1<AllPreallocated<'buf>> {
/// Creates a new Secp256k1 context with all capabilities
pub fn preallocated_new(buf: &'buf mut [u8]) -> Result<Secp256k1<AllPreallocated<'buf>>, Error> {
Secp256k1::preallocated_gen_new(buf)
}
}

impl<'buf> Secp256k1<SignOnlyPreallocated<'buf>> {
/// Creates a new Secp256k1 context that can only be used for signing
pub fn preallocated_new(buf: &'buf mut [u8]) -> Result<Secp256k1<SignOnlyPreallocated<'buf>>, Error> {
Secp256k1::preallocated_gen_new(buf)
}
}

impl<'buf> Secp256k1<VerifyOnlyPreallocated<'buf>> {
/// Creates a new Secp256k1 context that can only be used for verification
pub fn preallocated_new(buf: &'buf mut [u8]) -> Result<Secp256k1<VerifyOnlyPreallocated<'buf>>, Error> {
Secp256k1::preallocated_gen_new(buf)
}
}

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