properly handle errors when getting a CapstoneContext instance from Java

lib/src/capstone/context.rs

@@ -32,10 +32,10 @@ impl CapstoneContext {
     }
 
     /// Clones an Arc out of the handle field of the given object.
-    pub fn get(env: &mut JNIEnv, object: &JObject) -> Arc<CapstoneContext> {
+    pub fn get(env: &mut JNIEnv, object: &JObject) -> JResult<Arc<CapstoneContext>> {
         let guard: MutexGuard<Arc<CapstoneContext>> =
-            unsafe { env.get_rust_field(object, HANDLE_FIELD).unwrap() };
-        guard.clone()
+            unsafe { env.get_rust_field(object, HANDLE_FIELD)? };
+        Ok(guard.clone())
     }
 
     /// Surrenders ownership of the context instance to Java.

lib/src/capstone/mod.rs

@@ -3,6 +3,110 @@
  *
  * Use of this source code is governed by the MIT license found in the LICENSE file.
  */
+use crate::capstone::context::CapstoneContext;
+use crate::capstone::mode::CapstoneMode;
+use crate::capstone::output::CapstoneOutput;
+use capstone::arch::BuildsCapstone;
+use capstone::{arch, Capstone, InsnGroupId, InsnGroupIdInt, InsnId, InsnIdInt, RegId, RegIdInt};
+use jni::objects::{JByteArray, JObject, ReleaseMode};
+use jni::sys::{jint, jlong, jshort};
+use jni::JNIEnv;
+use std::ops::BitAnd;
+
 pub mod context;
 pub mod mode;
 pub mod output;
+
+type Result<T> = std::result::Result<T, Box<dyn std::error::Error>>;
+
+pub fn init<'local>(
+    env: &mut JNIEnv<'local>,
+    this: JObject<'local>,
+    mode: JObject<'local>,
+) -> Result<()> {
+    let mode = CapstoneMode::from(env, &mode);
+
+    let capstone = match mode {
+        Some(CapstoneMode::ARM32) => Capstone::new()
+            .arm()
+            .mode(arch::arm::ArchMode::Arm)
+            .detail(true)
+            .build(),
+        Some(CapstoneMode::ARM64) => Capstone::new()
+            .arm64()
+            .mode(arch::arm64::ArchMode::Arm)
+            .detail(true)
+            .build(),
+        _ => return Err("invalid argument 'mode'".into()),
+    }
+    .map_err(|e| e.to_string())?;
+
+    let instance = CapstoneContext::new(capstone, mode.unwrap());
+
+    CapstoneContext::surrender_instance(instance, env, &this)?;
+    Ok(())
+}
+
+pub fn disassemble<'local>(
+    env: &mut JNIEnv<'local>,
+    this: JObject<'local>,
+    result_object: JObject<'local>,
+    data: JByteArray<'local>,
+    count: jint,
+    address: jlong,
+) -> Result<()> {
+    let code: Vec<u8> = {
+        let result = unsafe { env.get_array_elements(&data, ReleaseMode::NoCopyBack)? };
+        result.iter().map(|b| (*b as u8).bitand(0xff)).collect()
+    };
+
+    let ctx = CapstoneContext::get(env, &this)?;
+    let capstone = ctx.capstone.lock().unwrap();
+
+    let instructions = {
+        if count == 0 {
+            capstone.disasm_all(&code, address as u64)
+        } else {
+            capstone.disasm_count(&code, address as u64, count as usize)
+        }
+        .map_err(|e| e.to_string())?
+    };
+
+    let mut output = CapstoneOutput::new(env, &ctx.mode, &capstone, &result_object);
+    output.copy_instructions(instructions)
+}
+
+pub fn get_insn_name<'local>(
+    env: &mut JNIEnv<'local>,
+    this: JObject<'local>,
+    insn_id: jint,
+) -> Result<Option<String>> {
+    let ctx = CapstoneContext::get(env, &this)?;
+    let capstone = ctx.capstone.lock().unwrap();
+    Ok(capstone.insn_name(InsnId(insn_id as InsnIdInt)))
+}
+
+pub fn get_reg_name<'local>(
+    env: &mut JNIEnv<'local>,
+    this: JObject<'local>,
+    reg_id: jint,
+) -> Result<Option<String>> {
+    let ctx = CapstoneContext::get(env, &this)?;
+    let capstone = ctx.capstone.lock().unwrap();
+    Ok(capstone.reg_name(RegId(reg_id as RegIdInt)))
+}
+
+pub fn get_group_name<'local>(
+    env: &mut JNIEnv<'local>,
+    this: JObject<'local>,
+    group_id: jshort,
+) -> Result<Option<String>> {
+    let ctx = CapstoneContext::get(env, &this)?;
+    let capstone = ctx.capstone.lock().unwrap();
+    Ok(capstone.group_name(InsnGroupId(group_id as InsnGroupIdInt)))
+}
+
+pub fn throw(env: &mut JNIEnv, message: &str) {
+    env.throw_new("org/native4j/capstone/exception/CapstoneException", message)
+        .unwrap();
+}

lib/src/lib.rs

@@ -3,50 +3,25 @@
  *
  * Use of this source code is governed by the MIT license found in the LICENSE file.
  */
-use std::ops::BitAnd;
-
-use ::capstone::arch::BuildsCapstone;
-use ::capstone::{arch, Capstone, InsnGroupId, InsnGroupIdInt, InsnId, InsnIdInt, RegId, RegIdInt};
-use jni::objects::{JByteArray, JObject, ReleaseMode};
+use jni::objects::{JByteArray, JObject};
 use jni::sys::{jint, jlong, jshort, jstring};
 use jni::JNIEnv;
 
 use crate::capstone::context::CapstoneContext;
-use crate::capstone::mode::CapstoneMode;
-use crate::capstone::output::CapstoneOutput;
 
 mod capstone;
 mod obj;
 mod util;
 mod writer;
+
 #[no_mangle]
 pub extern "system" fn Java_org_native4j_capstone_Capstone_init<'local>(
     mut env: JNIEnv<'local>,
     this: JObject<'local>,
     mode: JObject<'local>,
 ) -> jstring {
-    let mode = CapstoneMode::from(&mut env, &mode);
-
-    let capstone = match mode {
-        Some(CapstoneMode::ARM32) => Capstone::new()
-            .arm()
-            .mode(arch::arm::ArchMode::Arm)
-            .detail(true)
-            .build(),
-        Some(CapstoneMode::ARM64) => Capstone::new()
-            .arm64()
-            .mode(arch::arm64::ArchMode::Arm)
-            .detail(true)
-            .build(),
-        _ => return make_error!(env, "invalid argument 'mode'"),
-    };
-    check_result!(env, capstone);
-
-    let instance = CapstoneContext::new(capstone.unwrap(), mode.unwrap());
-
-    let result = CapstoneContext::surrender_instance(instance, &mut env, &this);
+    let result = capstone::init(&mut env, this, mode);
     check_result!(env, result);
-
     0 as jstring /* null */
 }
 
@@ -57,7 +32,6 @@ pub extern "system" fn Java_org_native4j_capstone_Capstone_shutdown<'local>(
 ) -> jstring {
     let result = CapstoneContext::drop_instance(&mut env, &this);
     check_result!(env, result);
-
     0 as jstring /* null */
 }
 
@@ -70,36 +44,8 @@ pub extern "system" fn Java_org_native4j_capstone_Capstone_disassemble<'local>(
     count: jint,
     address: jlong,
 ) -> jstring {
-    let code: Vec<u8> = {
-        let result = unsafe { env.get_array_elements(&data, ReleaseMode::NoCopyBack) };
-        check_result!(env, result);
-        result
-            .unwrap()
-            .iter()
-            .map(|b| (*b as u8).bitand(0xff))
-            .collect()
-    };
-
-    let ctx = CapstoneContext::get(&mut env, &this);
-    let capstone = ctx.capstone.lock().unwrap();
-
-    let instructions = {
-        let result = if count == 0 {
-            capstone.disasm_all(&code, address as u64)
-        } else {
-            capstone.disasm_count(&code, address as u64, count as usize)
-        };
-        if let Err(e) = result {
-            return make_error!(env, e.to_string());
-        }
-        result.unwrap()
-    };
-
-    let mut output = CapstoneOutput::new(&mut env, &ctx.mode, &capstone, &result_object);
-
-    let result = output.copy_instructions(instructions);
+    let result = capstone::disassemble(&mut env, this, result_object, data, count, address);
     check_result!(env, result);
-
     0 as jstring /* null */
 }
 
@@ -109,12 +55,15 @@ pub extern "system" fn Java_org_native4j_capstone_Capstone_getInsnName<'local>(
     this: JObject<'local>,
     insn_id: jint,
 ) -> jstring {
-    let ctx = CapstoneContext::get(&mut env, &this);
-    let capstone = ctx.capstone.lock().unwrap();
-    match capstone.insn_name(InsnId(insn_id as InsnIdInt)) {
-        Some(str) => make_jstring!(env, str),
-        None => 0 as jstring, /* null */
+    let result = capstone::get_insn_name(&mut env, this, insn_id);
+    if let Err(e) = result {
+        capstone::throw(&mut env, &e.to_string());
+        return 0 as jstring /* null */;
     }
+    result
+        .unwrap()
+        .map(|str| make_jstring!(env, str))
+        .unwrap_or(0 as jstring /* null */)
 }
 
 #[no_mangle]
@@ -123,12 +72,15 @@ pub extern "system" fn Java_org_native4j_capstone_Capstone_getRegName<'local>(
     this: JObject<'local>,
     reg_id: jint,
 ) -> jstring {
-    let ctx = CapstoneContext::get(&mut env, &this);
-    let capstone = ctx.capstone.lock().unwrap();
-    match capstone.reg_name(RegId(reg_id as RegIdInt)) {
-        Some(str) => make_jstring!(env, str),
-        None => 0 as jstring, /* null */
+    let result = capstone::get_reg_name(&mut env, this, reg_id);
+    if let Err(e) = result {
+        capstone::throw(&mut env, &e.to_string());
+        return 0 as jstring /* null */;
     }
+    result
+        .unwrap()
+        .map(|str| make_jstring!(env, str))
+        .unwrap_or(0 as jstring /* null */)
 }
 
 #[no_mangle]
@@ -137,10 +89,13 @@ pub extern "system" fn Java_org_native4j_capstone_Capstone_getGroupName<'local>(
     this: JObject<'local>,
     group_id: jshort,
 ) -> jstring {
-    let ctx = CapstoneContext::get(&mut env, &this);
-    let capstone = ctx.capstone.lock().unwrap();
-    match capstone.group_name(InsnGroupId(group_id as InsnGroupIdInt)) {
-        Some(str) => make_jstring!(env, str),
-        None => 0 as jstring, /* null */
+    let result = capstone::get_group_name(&mut env, this, group_id);
+    if let Err(e) = result {
+        capstone::throw(&mut env, &e.to_string());
+        return 0 as jstring /* null */;
     }
+    result
+        .unwrap()
+        .map(|str| make_jstring!(env, str))
+        .unwrap_or(0 as jstring /* null */)
 }