Add memory syscall helpers (#20)

sdk/pinocchio/src/lib.rs

@@ -1,4 +1,4 @@
-//! A library to build a Solana Program in Rust.
+//! A library to build a Solana program in Rust.
 //!
 //! This library is intended to be used by on-chain programs only. It provides
 //! a zero-dependency library to minimise dependencies conflits. For off-chain
@@ -14,6 +14,7 @@ pub mod account_info;
 pub mod entrypoint;
 pub mod instruction;
 pub mod log;
+pub mod memory;
 pub mod program;
 pub mod program_error;
 pub mod pubkey;

sdk/pinocchio/src/memory.rs

@@ -0,0 +1,137 @@
+//! Basic low-level memory operations.
+//!
+//! Within the SBF environment, these are implemented as syscalls and executed by
+//! the runtime in native code.
+
+#[cfg(target_os = "solana")]
+use crate::syscalls;
+
+/// Like C `memcpy`.
+///
+/// # Arguments
+///
+/// - `dst` - Destination
+/// - `src` - Source
+/// - `n` - Number of bytes to copy
+///
+/// # Errors
+///
+/// When executed within a SBF program, the memory regions spanning `n` bytes
+/// from from the start of `dst` and `src` must be mapped program memory. If not,
+/// the program will abort.
+///
+/// The memory regions spanning `n` bytes from `dst` and `src` from the start
+/// of `dst` and `src` must not overlap. If they do, then the program will abort
+/// or, if run outside of the SBF VM, will panic.
+///
+/// # Safety
+///
+/// This function does not verify that `n` is less than or equal to the
+/// lengths of the `dst` and `src` slices passed to it — it will copy
+/// bytes to and from beyond the slices.
+///
+/// Specifying an `n` greater than either the length of `dst` or `src` will
+/// likely introduce undefined behavior.
+#[inline]
+pub unsafe fn sol_memcpy(dst: &mut [u8], src: &[u8], n: usize) {
+    #[cfg(target_os = "solana")]
+    syscalls::sol_memcpy_(dst.as_mut_ptr(), src.as_ptr(), n as u64);
+
+    #[cfg(not(target_os = "solana"))]
+    core::hint::black_box((dst, src, n));
+}
+
+/// Like C `memmove`.
+///
+/// # Arguments
+///
+/// - `dst` - Destination
+/// - `src` - Source
+/// - `n` - Number of bytes to copy
+///
+/// # Errors
+///
+/// When executed within a SBF program, the memory regions spanning `n` bytes
+/// from from `dst` and `src` must be mapped program memory. If not, the program
+/// will abort.
+///
+/// # Safety
+///
+/// The same safety rules apply as in [`ptr::copy`].
+///
+/// [`ptr::copy`]: https://doc.rust-lang.org/std/ptr/fn.copy.html
+#[inline]
+pub unsafe fn sol_memmove(dst: *mut u8, src: *mut u8, n: usize) {
+    #[cfg(target_os = "solana")]
+    syscalls::sol_memmove_(dst, src, n as u64);
+
+    #[cfg(not(target_os = "solana"))]
+    core::hint::black_box((dst, src, n));
+}
+
+/// Like C `memcmp`.
+///
+/// # Arguments
+///
+/// - `s1` - Slice to be compared
+/// - `s2` - Slice to be compared
+/// - `n` - Number of bytes to compare
+///
+/// # Errors
+///
+/// When executed within a SBF program, the memory regions spanning `n` bytes
+/// from from the start of `dst` and `src` must be mapped program memory. If not,
+/// the program will abort.
+///
+/// # Safety
+///
+/// It does not verify that `n` is less than or equal to the lengths of the
+/// `dst` and `src` slices passed to it — it will read bytes beyond the
+/// slices.
+///
+/// Specifying an `n` greater than either the length of `dst` or `src` will
+/// likely introduce undefined behavior.
+#[inline]
+pub unsafe fn sol_memcmp(s1: &[u8], s2: &[u8], n: usize) -> i32 {
+    #[allow(unused_mut)]
+    let mut result = 0;
+
+    #[cfg(target_os = "solana")]
+    syscalls::sol_memcmp_(s1.as_ptr(), s2.as_ptr(), n as u64, &mut result as *mut i32);
+
+    #[cfg(not(target_os = "solana"))]
+    core::hint::black_box((s1, s2, n, result));
+
+    result
+}
+
+/// Like C `memset`.
+///
+/// # Arguments
+///
+/// - `s` - Slice to be set
+/// - `c` - Repeated byte to set
+/// - `n` - Number of bytes to set
+///
+/// # Errors
+///
+/// When executed within a SBF program, the memory region spanning `n` bytes
+/// from from the start of `s` must be mapped program memory. If not, the program
+/// will abort.
+///
+/// # Safety
+///
+/// This function does not verify that `n` is less than or equal to the length
+/// of the `s` slice passed to it — it will write bytes beyond the
+/// slice.
+///
+/// Specifying an `n` greater than the length of `s` will likely introduce
+/// undefined behavior.
+#[inline]
+pub unsafe fn sol_memset(s: &mut [u8], c: u8, n: usize) {
+    #[cfg(target_os = "solana")]
+    syscalls::sol_memset_(s.as_mut_ptr(), c, n as u64);
+
+    #[cfg(not(target_os = "solana"))]
+    core::hint::black_box((s, c, n));
+}