Alternative syscall implementations (#136)

* Add a way to stub syscalls with a trait impl
* Add SyscallExecutor trait that implements SyscallImpls via a single syscall func
* Add syscall_to_impls utility function

Author: xxuejie

Cargo.toml

@@ -27,6 +27,8 @@ default = ["allocator", "calc-hash", "ckb-types", "dummy-atomic", "libc"]
 calc-hash = ["ckb-types/calc-hash"]
 allocator = ["buddy-alloc"]
 native-simulator = ["ckb-x64-simulator"]
+stub-syscalls = []
+stub-c-syscalls = ["stub-syscalls"]
 dlopen-c = ["libc"]
 build-with-clang = []
 libc = []
@@ -50,6 +52,7 @@ buddy-alloc = { version = "0.6", optional = true }
 ckb-x64-simulator = { version = "0.11.1", optional = true }
 gcd = "2.3"
 log = { version = "0.4", optional = true, default-features = false }
+int-enum = "1.2.0"
 
 [workspace]
 exclude = ["test"]

src/ckb_constants.rs

@@ -1,3 +1,5 @@
+use int_enum::IntEnum;
+
 pub const SYS_EXIT: u64 = 93;
 pub const SYS_VM_VERSION: u64 = 2041;
 pub const SYS_CURRENT_CYCLES: u64 = 2042;
@@ -27,7 +29,7 @@ pub const SYS_CLOSE: u64 = 2608;
 pub const SYS_LOAD_BLOCK_EXTENSION: u64 = 2104;
 
 pub const CKB_SUCCESS: u64 = 0;
-#[derive(Eq, PartialEq, Debug, Clone, Copy)]
+#[derive(Eq, PartialEq, Debug, Clone, Copy, IntEnum)]
 #[repr(u64)]
 pub enum Source {
     Input = 1,
@@ -38,7 +40,7 @@ pub enum Source {
     GroupOutput = 0x0100000000000002,
 }
 
-#[derive(Eq, PartialEq, Debug, Clone, Copy)]
+#[derive(Eq, PartialEq, Debug, Clone, Copy, IntEnum)]
 #[repr(u64)]
 pub enum CellField {
     Capacity = 0,
@@ -50,15 +52,15 @@ pub enum CellField {
     OccupiedCapacity = 6,
 }
 
-#[derive(Eq, PartialEq, Debug, Clone, Copy)]
+#[derive(Eq, PartialEq, Debug, Clone, Copy, IntEnum)]
 #[repr(u64)]
 pub enum HeaderField {
     EpochNumber = 0,
     EpochStartBlockNumber = 1,
     EpochLength = 2,
 }
 
-#[derive(Eq, PartialEq, Debug, Clone, Copy)]
+#[derive(Eq, PartialEq, Debug, Clone, Copy, IntEnum)]
 #[repr(u64)]
 pub enum InputField {
     OutPoint = 0,

src/error.rs

@@ -28,6 +28,7 @@ pub enum SysError {
 }
 
 impl SysError {
+    #[allow(dead_code)]
     pub(crate) fn build_syscall_result(
         errno: u64,
         load_len: usize,

src/syscalls/internal.rs

@@ -0,0 +1,11 @@
+#[repr(C)]
+pub struct SpawnArgs {
+    /// argc contains the number of arguments passed to the program.
+    pub argc: u64,
+    /// argv is a one-dimensional array of strings.
+    pub argv: *const *const i8,
+    /// a pointer used to save the process_id of the child process.
+    pub process_id: *mut u64,
+    /// an array representing the file descriptors passed to the child process. It must end with zero.
+    pub inherited_fds: *const u64,
+}

src/syscalls/mod.rs

@@ -1,12 +1,20 @@
 // re-export to maintain compatible with old versions
 pub use crate::error::SysError;
 
-#[cfg(not(feature = "native-simulator"))]
+mod internal;
+pub mod traits;
+
+#[cfg(not(any(feature = "native-simulator", feature = "stub-syscalls")))]
 mod native;
-#[cfg(not(feature = "native-simulator"))]
+#[cfg(not(any(feature = "native-simulator", feature = "stub-syscalls")))]
 pub use native::*;
 
 #[cfg(feature = "native-simulator")]
 mod simulator;
 #[cfg(feature = "native-simulator")]
 pub use simulator::*;
+
+#[cfg(feature = "stub-syscalls")]
+mod stub;
+#[cfg(feature = "stub-syscalls")]
+pub use stub::*;