c_no_std binding to show use in C freestanding environments. (#238)

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

bindings/ffi/Cargo.toml

@@ -5,13 +5,18 @@ edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 [lib]
-crate-type = ["cdylib"]
+crate-type = ["cdylib", "staticlib"]
 
 [dependencies]
 anyhow = "1.0"
-regorus = { path  = "../.." }
+regorus = { path  = "../..", default-features = false }
 serde_json = "1.0.113"
 
+[features]
+default = ["std"]
+std = ["regorus/std"]
+custom_allocator = []
+
 [build-dependencies]
 cbindgen = "0.26.0"
 csbindgen = "1.9.0"

bindings/ffi/RegorusFFI.g.cs

@@ -85,4 +85,3 @@ namespace RegorusFFI
 
 
 }
-    

bindings/ffi/cbindgen.toml

@@ -137,9 +137,6 @@ bitflags = false
 
 
 
-
-
-
 ############## Options for How Your Rust library Should Be Parsed ##############
 
 [parse]
@@ -154,5 +151,5 @@ extra_bindings = []
 [parse.expand]
 crates = []
 all_features = false
-default_features = true
+default_features = false
 features = []

bindings/ffi/regorus.ffi.hpp

@@ -90,6 +90,10 @@ RegorusResult regorus_engine_set_input_from_json_file(RegorusEngine *engine, con
 /// * `query`: Rego expression to be evaluate.
 RegorusResult regorus_engine_eval_query(RegorusEngine *engine, const char *query);
 
+extern uint8_t *regorus_aligned_alloc(uintptr_t alignment, uintptr_t size);
+
+extern void regorus_free(uint8_t *ptr);
+
 } // extern "C"
 
 #endif // REGORUS_FFI_HPP

bindings/ffi/regorus.h

@@ -124,4 +124,8 @@ struct RegorusResult regorus_engine_set_input_from_json_file(struct RegorusEngin
  */
 struct RegorusResult regorus_engine_eval_query(struct RegorusEngine *engine, const char *query);
 
+extern uint8_t *regorus_aligned_alloc(uintptr_t alignment, uintptr_t size);
+
+extern void regorus_free(uint8_t *ptr);
+
 #endif /* REGORUS_H */

bindings/ffi/src/lib.rs

@@ -127,7 +127,6 @@ pub extern "C" fn regorus_engine_drop(engine: *mut RegorusEngine) {
 ///
 /// * `path`: A filename to be associated with the policy.
 /// * `rego`: Rego policy.
-
 #[no_mangle]
 pub extern "C" fn regorus_engine_add_policy(
     engine: *mut RegorusEngine,
@@ -141,6 +140,7 @@ pub extern "C" fn regorus_engine_add_policy(
     }())
 }
 
+#[cfg(feature = "std")]
 #[no_mangle]
 pub extern "C" fn regorus_engine_add_policy_from_file(
     engine: *mut RegorusEngine,
@@ -169,6 +169,7 @@ pub extern "C" fn regorus_engine_add_data_json(
     }())
 }
 
+#[cfg(feature = "std")]
 #[no_mangle]
 pub extern "C" fn regorus_engine_add_data_from_json_file(
     engine: *mut RegorusEngine,
@@ -209,6 +210,7 @@ pub extern "C" fn regorus_engine_set_input_json(
     }())
 }
 
+#[cfg(feature = "std")]
 #[no_mangle]
 pub extern "C" fn regorus_engine_set_input_from_json_file(
     engine: *mut RegorusEngine,
@@ -246,3 +248,32 @@ pub extern "C" fn regorus_engine_eval_query(
         Err(e) => to_regorus_result(Err(e)),
     }
 }
+
+#[cfg(feature = "custom_allocator")]
+extern "C" {
+    fn regorus_aligned_alloc(alignment: usize, size: usize) -> *mut u8;
+    fn regorus_free(ptr: *mut u8);
+}
+
+#[cfg(feature = "custom_allocator")]
+mod allocator {
+    use std::alloc::{GlobalAlloc, Layout};
+
+    struct RegorusAllocator {}
+
+    unsafe impl GlobalAlloc for RegorusAllocator {
+        unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+            let size = layout.size();
+            let align = layout.align();
+
+            crate::regorus_aligned_alloc(align, size)
+        }
+
+        unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
+            crate::regorus_free(ptr)
+        }
+    }
+
+    #[global_allocator]
+    static ALLOCATOR: RegorusAllocator = RegorusAllocator {};
+}