1 files changed, 373 insertions, 0 deletions
diff --git a/libs/binder/rust/src/error.rs b/libs/binder/rust/src/error.rs
new file mode 100644
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+++ b/libs/binder/rust/src/error.rs
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+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+use crate::binder::AsNative;
+use crate::sys;
+
+use std::error;
+use std::ffi::CStr;
+use std::fmt::{Debug, Display, Formatter, Result as FmtResult};
+use std::result;
+
+pub use sys::binder_status_t as status_t;
+
+/// Low-level status codes from Android `libutils`.
+// All error codes are negative integer values. Derived from the anonymous enum
+// in utils/Errors.h
+pub use sys::android_c_interface_StatusCode as StatusCode;
+
+/// A specialized [`Result`](result::Result) for binder operations.
+pub type Result<T> = result::Result<T, StatusCode>;
+
+/// Convert a low-level status code into an empty result.
+///
+/// An OK status is converted into an `Ok` result, any other status is converted
+/// into an `Err` result holding the status code.
+pub fn status_result(status: status_t) -> Result<()> {
+    match parse_status_code(status) {
+        StatusCode::OK => Ok(()),
+        e => Err(e),
+    }
+}
+
+fn parse_status_code(code: i32) -> StatusCode {
+    match code {
+        e if e == StatusCode::OK as i32 => StatusCode::OK,
+        e if e == StatusCode::NO_MEMORY as i32 => StatusCode::NO_MEMORY,
+        e if e == StatusCode::INVALID_OPERATION as i32 => StatusCode::INVALID_OPERATION,
+        e if e == StatusCode::BAD_VALUE as i32 => StatusCode::BAD_VALUE,
+        e if e == StatusCode::BAD_TYPE as i32 => StatusCode::BAD_TYPE,
+        e if e == StatusCode::NAME_NOT_FOUND as i32 => StatusCode::NAME_NOT_FOUND,
+        e if e == StatusCode::PERMISSION_DENIED as i32 => StatusCode::PERMISSION_DENIED,
+        e if e == StatusCode::NO_INIT as i32 => StatusCode::NO_INIT,
+        e if e == StatusCode::ALREADY_EXISTS as i32 => StatusCode::ALREADY_EXISTS,
+        e if e == StatusCode::DEAD_OBJECT as i32 => StatusCode::DEAD_OBJECT,
+        e if e == StatusCode::FAILED_TRANSACTION as i32 => StatusCode::FAILED_TRANSACTION,
+        e if e == StatusCode::BAD_INDEX as i32 => StatusCode::BAD_INDEX,
+        e if e == StatusCode::NOT_ENOUGH_DATA as i32 => StatusCode::NOT_ENOUGH_DATA,
+        e if e == StatusCode::WOULD_BLOCK as i32 => StatusCode::WOULD_BLOCK,
+        e if e == StatusCode::TIMED_OUT as i32 => StatusCode::TIMED_OUT,
+        e if e == StatusCode::UNKNOWN_TRANSACTION as i32 => StatusCode::UNKNOWN_TRANSACTION,
+        e if e == StatusCode::FDS_NOT_ALLOWED as i32 => StatusCode::FDS_NOT_ALLOWED,
+        e if e == StatusCode::UNEXPECTED_NULL as i32 => StatusCode::UNEXPECTED_NULL,
+        _ => StatusCode::UNKNOWN_ERROR,
+    }
+}
+
+pub use sys::android_c_interface_ExceptionCode as ExceptionCode;
+
+fn parse_exception_code(code: i32) -> ExceptionCode {
+    match code {
+        e if e == ExceptionCode::NONE as i32 => ExceptionCode::NONE,
+        e if e == ExceptionCode::SECURITY as i32 => ExceptionCode::SECURITY,
+        e if e == ExceptionCode::BAD_PARCELABLE as i32 => ExceptionCode::BAD_PARCELABLE,
+        e if e == ExceptionCode::ILLEGAL_ARGUMENT as i32 => ExceptionCode::ILLEGAL_ARGUMENT,
+        e if e == ExceptionCode::NULL_POINTER as i32 => ExceptionCode::NULL_POINTER,
+        e if e == ExceptionCode::ILLEGAL_STATE as i32 => ExceptionCode::ILLEGAL_STATE,
+        e if e == ExceptionCode::NETWORK_MAIN_THREAD as i32 => ExceptionCode::NETWORK_MAIN_THREAD,
+        e if e == ExceptionCode::UNSUPPORTED_OPERATION as i32 => {
+            ExceptionCode::UNSUPPORTED_OPERATION
+        }
+        e if e == ExceptionCode::SERVICE_SPECIFIC as i32 => ExceptionCode::SERVICE_SPECIFIC,
+        _ => ExceptionCode::TRANSACTION_FAILED,
+    }
+}
+
+// Safety: `Status` always contains a owning pointer to a valid `AStatus`. The
+// lifetime of the contained pointer is the same as the `Status` object.
+/// High-level binder status object that encapsulates a standard way to keep
+/// track of and chain binder errors along with service specific errors.
+///
+/// Used in AIDL transactions to represent failed transactions.
+pub struct Status(*mut sys::AStatus);
+
+// Safety: The `AStatus` that the `Status` points to must have an entirely thread-safe API for the
+// duration of the `Status` object's lifetime. We ensure this by not allowing mutation of a `Status`
+// in Rust, and the NDK API says we're the owner of our `AStatus` objects so outside code should not
+// be mutating them underneath us.
+unsafe impl Sync for Status {}
+
+// Safety: `Status` always contains an owning pointer to a global, immutable, interned `AStatus`.
+// A thread-local `AStatus` would not be valid.
+unsafe impl Send for Status {}
+
+impl Status {
+    /// Create a status object representing a successful transaction.
+    pub fn ok() -> Self {
+        let ptr = unsafe {
+            // Safety: `AStatus_newOk` always returns a new, heap allocated
+            // pointer to an `ASTatus` object, so we know this pointer will be
+            // valid.
+            //
+            // Rust takes ownership of the returned pointer.
+            sys::AStatus_newOk()
+        };
+        Self(ptr)
+    }
+
+    /// Create a status object from a service specific error
+    pub fn new_service_specific_error(err: i32, message: Option<&CStr>) -> Status {
+        let ptr = if let Some(message) = message {
+            unsafe {
+                // Safety: Any i32 is a valid service specific error for the
+                // error code parameter. We construct a valid, null-terminated
+                // `CString` from the message, which must be a valid C-style
+                // string to pass as the message. This function always returns a
+                // new, heap allocated pointer to an `AStatus` object, so we
+                // know the returned pointer will be valid.
+                //
+                // Rust takes ownership of the returned pointer.
+                sys::AStatus_fromServiceSpecificErrorWithMessage(err, message.as_ptr())
+            }
+        } else {
+            unsafe {
+                // Safety: Any i32 is a valid service specific error for the
+                // error code parameter. This function always returns a new,
+                // heap allocated pointer to an `AStatus` object, so we know the
+                // returned pointer will be valid.
+                //
+                // Rust takes ownership of the returned pointer.
+                sys::AStatus_fromServiceSpecificError(err)
+            }
+        };
+        Self(ptr)
+    }
+
+    /// Create a status object from an exception code
+    pub fn new_exception(exception: ExceptionCode, message: Option<&CStr>) -> Status {
+        if let Some(message) = message {
+            let ptr = unsafe {
+                sys::AStatus_fromExceptionCodeWithMessage(exception as i32, message.as_ptr())
+            };
+            Self(ptr)
+        } else {
+            exception.into()
+        }
+    }
+
+    /// Create a status object from a raw `AStatus` pointer.
+    ///
+    /// # Safety
+    ///
+    /// This constructor is safe iff `ptr` is a valid pointer to an `AStatus`.
+    pub(crate) unsafe fn from_ptr(ptr: *mut sys::AStatus) -> Self {
+        Self(ptr)
+    }
+
+    /// Returns `true` if this status represents a successful transaction.
+    pub fn is_ok(&self) -> bool {
+        unsafe {
+            // Safety: `Status` always contains a valid `AStatus` pointer, so we
+            // are always passing a valid pointer to `AStatus_isOk` here.
+            sys::AStatus_isOk(self.as_native())
+        }
+    }
+
+    /// Returns a description of the status.
+    pub fn get_description(&self) -> String {
+        let description_ptr = unsafe {
+            // Safety: `Status` always contains a valid `AStatus` pointer, so we
+            // are always passing a valid pointer to `AStatus_getDescription`
+            // here.
+            //
+            // `AStatus_getDescription` always returns a valid pointer to a null
+            // terminated C string. Rust is responsible for freeing this pointer
+            // via `AStatus_deleteDescription`.
+            sys::AStatus_getDescription(self.as_native())
+        };
+        let description = unsafe {
+            // Safety: `AStatus_getDescription` always returns a valid C string,
+            // which can be safely converted to a `CStr`.
+            CStr::from_ptr(description_ptr)
+        };
+        let description = description.to_string_lossy().to_string();
+        unsafe {
+            // Safety: `description_ptr` was returned from
+            // `AStatus_getDescription` above, and must be freed via
+            // `AStatus_deleteDescription`. We must not access the pointer after
+            // this call, so we copy it into an owned string above and return
+            // that string.
+            sys::AStatus_deleteDescription(description_ptr);
+        }
+        description
+    }
+
+    /// Returns the exception code of the status.
+    pub fn exception_code(&self) -> ExceptionCode {
+        let code = unsafe {
+            // Safety: `Status` always contains a valid `AStatus` pointer, so we
+            // are always passing a valid pointer to `AStatus_getExceptionCode`
+            // here.
+            sys::AStatus_getExceptionCode(self.as_native())
+        };
+        parse_exception_code(code)
+    }
+
+    /// Return a status code representing a transaction failure, or
+    /// `StatusCode::OK` if there was no transaction failure.
+    ///
+    /// If this method returns `OK`, the status may still represent a different
+    /// exception or a service specific error. To find out if this transaction
+    /// as a whole is okay, use [`is_ok`](Self::is_ok) instead.
+    pub fn transaction_error(&self) -> StatusCode {
+        let code = unsafe {
+            // Safety: `Status` always contains a valid `AStatus` pointer, so we
+            // are always passing a valid pointer to `AStatus_getStatus` here.
+            sys::AStatus_getStatus(self.as_native())
+        };
+        parse_status_code(code)
+    }
+
+    /// Return a service specific error if this status represents one.
+    ///
+    /// This function will only ever return a non-zero result if
+    /// [`exception_code`](Self::exception_code) returns
+    /// `ExceptionCode::SERVICE_SPECIFIC`. If this function returns 0, the
+    /// status object may still represent a different exception or status. To
+    /// find out if this transaction as a whole is okay, use
+    /// [`is_ok`](Self::is_ok) instead.
+    pub fn service_specific_error(&self) -> i32 {
+        unsafe {
+            // Safety: `Status` always contains a valid `AStatus` pointer, so we
+            // are always passing a valid pointer to
+            // `AStatus_getServiceSpecificError` here.
+            sys::AStatus_getServiceSpecificError(self.as_native())
+        }
+    }
+
+    /// Calls `op` if the status was ok, otherwise returns an `Err` value of
+    /// `self`.
+    pub fn and_then<T, F>(self, op: F) -> result::Result<T, Status>
+    where
+        F: FnOnce() -> result::Result<T, Status>,
+    {
+        <result::Result<(), Status>>::from(self)?;
+        op()
+    }
+}
+
+impl error::Error for Status {}
+
+impl Display for Status {
+    fn fmt(&self, f: &mut Formatter) -> FmtResult {
+        f.write_str(&self.get_description())
+    }
+}
+
+impl Debug for Status {
+    fn fmt(&self, f: &mut Formatter) -> FmtResult {
+        f.write_str(&self.get_description())
+    }
+}
+
+impl PartialEq for Status {
+    fn eq(&self, other: &Status) -> bool {
+        let self_code = self.exception_code();
+        let other_code = other.exception_code();
+
+        match (self_code, other_code) {
+            (ExceptionCode::NONE, ExceptionCode::NONE) => true,
+            (ExceptionCode::TRANSACTION_FAILED, ExceptionCode::TRANSACTION_FAILED) => {
+                self.transaction_error() == other.transaction_error()
+                    && self.get_description() == other.get_description()
+            }
+            (ExceptionCode::SERVICE_SPECIFIC, ExceptionCode::SERVICE_SPECIFIC) => {
+                self.service_specific_error() == other.service_specific_error()
+                    && self.get_description() == other.get_description()
+            }
+            (e1, e2) => e1 == e2 && self.get_description() == other.get_description(),
+        }
+    }
+}
+
+impl Eq for Status {}
+
+impl From<StatusCode> for Status {
+    fn from(status: StatusCode) -> Status {
+        (status as status_t).into()
+    }
+}
+
+impl From<status_t> for Status {
+    fn from(status: status_t) -> Status {
+        let ptr = unsafe {
+            // Safety: `AStatus_fromStatus` expects any `status_t` integer, so
+            // this is a safe FFI call. Unknown values will be coerced into
+            // UNKNOWN_ERROR.
+            sys::AStatus_fromStatus(status)
+        };
+        Self(ptr)
+    }
+}
+
+impl From<ExceptionCode> for Status {
+    fn from(code: ExceptionCode) -> Status {
+        let ptr = unsafe {
+            // Safety: `AStatus_fromExceptionCode` expects any
+            // `binder_exception_t` (i32) integer, so this is a safe FFI call.
+            // Unknown values will be coerced into EX_TRANSACTION_FAILED.
+            sys::AStatus_fromExceptionCode(code as i32)
+        };
+        Self(ptr)
+    }
+}
+
+// TODO: impl Try for Status when try_trait is stabilized
+// https://github.com/rust-lang/rust/issues/42327
+impl From<Status> for result::Result<(), Status> {
+    fn from(status: Status) -> result::Result<(), Status> {
+        if status.is_ok() {
+            Ok(())
+        } else {
+            Err(status)
+        }
+    }
+}
+
+impl From<Status> for status_t {
+    fn from(status: Status) -> status_t {
+        status.transaction_error() as status_t
+    }
+}
+
+impl Drop for Status {
+    fn drop(&mut self) {
+        unsafe {
+            // Safety: `Status` manages the lifetime of its inner `AStatus`
+            // pointee, so we need to delete it here. We know that the pointer
+            // will be valid here since `Status` always contains a valid pointer
+            // while it is alive.
+            sys::AStatus_delete(self.0);
+        }
+    }
+}
+
+/// # Safety
+///
+/// `Status` always contains a valid pointer to an `AStatus` object, so we can
+/// trivially convert it to a correctly-typed raw pointer.
+///
+/// Care must be taken that the returned pointer is only dereferenced while the
+/// `Status` object is still alive.
+unsafe impl AsNative<sys::AStatus> for Status {
+    fn as_native(&self) -> *const sys::AStatus {
+        self.0
+    }
+
+    fn as_native_mut(&mut self) -> *mut sys::AStatus {
+        self.0
+    }
+}