1 files changed, 199 insertions, 0 deletions
diff --git a/toolkit/components/bitsdownload/src/bits_interface/dispatch_callback.rs b/toolkit/components/bitsdownload/src/bits_interface/dispatch_callback.rs
new file mode 100644
index 0000000000..b42637a993
--- /dev/null
+++ b/toolkit/components/bitsdownload/src/bits_interface/dispatch_callback.rs
@@ -0,0 +1,199 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+use super::{
+    error::{BitsTaskError, ErrorCode, ErrorType},
+    BitsRequest,
+};
+use log::{error, info, warn};
+use nserror::{nsresult, NS_ERROR_FAILURE, NS_OK};
+use xpcom::{
+    interfaces::{nsIBitsCallback, nsIBitsNewRequestCallback},
+    RefPtr,
+};
+
+#[derive(Debug, PartialEq, Clone, Copy)]
+pub enum IsCallbackExpected {
+    CallbackExpected,
+    CallbackOptional,
+}
+pub use self::IsCallbackExpected::{CallbackExpected, CallbackOptional};
+
+// This is meant to be called at the end of a nsIBits Task. It attempts to
+// return the result via the callback given. If the callback is unavailable, a
+// log message will be printed indicating the results and (possibly) warning
+// than an expected callback was missing.
+pub fn maybe_dispatch_request_via_callback(
+    result: Result<RefPtr<BitsRequest>, BitsTaskError>,
+    maybe_callback: Result<&nsIBitsNewRequestCallback, BitsTaskError>,
+    expected: IsCallbackExpected,
+) -> Result<(), nsresult> {
+    if let Err(error) = maybe_callback.as_ref() {
+        if expected == CallbackExpected || error.error_type == ErrorType::CallbackOnWrongThread {
+            error!(
+                "Unexpected error when {} - No callback: {:?}",
+                error.error_action.description(),
+                error,
+            );
+        }
+    }
+    match result {
+        Ok(request) => match (maybe_callback, expected) {
+            (Ok(callback), _) => unsafe { callback.Success(request.coerce()) },
+            (Err(error), CallbackExpected) => {
+                error!(
+                    "Success {} but there is no callback to return the result with",
+                    error.error_action.description(),
+                );
+                NS_ERROR_FAILURE
+            }
+            (Err(error), CallbackOptional) => {
+                info!("Success {}", error.error_action.description());
+                NS_OK
+            }
+        },
+        Err(error) => match (maybe_callback, expected) {
+            (Ok(callback), _) => match error.error_code {
+                ErrorCode::None => unsafe {
+                    callback.Failure(
+                        error.error_type.bits_code(),
+                        error.error_action.as_error_code(),
+                        error.error_stage.bits_code(),
+                    )
+                },
+                ErrorCode::Hresult(error_code) => unsafe {
+                    callback.FailureHresult(
+                        error.error_type.bits_code(),
+                        error.error_action.as_error_code(),
+                        error.error_stage.bits_code(),
+                        error_code,
+                    )
+                },
+                ErrorCode::Nsresult(error_code) => unsafe {
+                    callback.FailureNsresult(
+                        error.error_type.bits_code(),
+                        error.error_action.as_error_code(),
+                        error.error_stage.bits_code(),
+                        error_code,
+                    )
+                },
+                ErrorCode::Message(message) => unsafe {
+                    callback.FailureString(
+                        error.error_type.bits_code(),
+                        error.error_action.as_error_code(),
+                        error.error_stage.bits_code(),
+                        &*message,
+                    )
+                },
+            },
+            (Err(_), CallbackExpected) => {
+                error!("Error {}: {:?}", error.error_action.description(), error);
+                NS_ERROR_FAILURE
+            }
+            (Err(_), CallbackOptional) => {
+                warn!("Error {}: {:?}", error.error_action.description(), error);
+                NS_ERROR_FAILURE
+            }
+        },
+    }
+    .to_result()
+}
+
+// Intended to be used by an nsIBits XPCOM wrapper to return errors that occur
+// before dispatching a task off-thread. No return value is returned because it
+// will represent the return value of the callback function, which should not be
+// propagated.
+pub fn dispatch_pretask_interface_error(
+    error: BitsTaskError,
+    callback: &nsIBitsNewRequestCallback,
+) {
+    let _ = maybe_dispatch_request_via_callback(Err(error), Ok(callback), CallbackExpected);
+}
+
+// This is meant to be called at the end of a nsIBitsRequest Task. It attempts
+// to return the result via the callback given. If the callback is unavailable,
+// a log message will be printed indicating the results and (possibly) warning
+// than an expected callback was missing.
+pub fn maybe_dispatch_via_callback(
+    result: Result<(), BitsTaskError>,
+    maybe_callback: Result<&nsIBitsCallback, BitsTaskError>,
+    expected: IsCallbackExpected,
+) -> Result<(), nsresult> {
+    if let Err(error) = maybe_callback.as_ref() {
+        if expected == CallbackExpected || error.error_type == ErrorType::CallbackOnWrongThread {
+            error!(
+                "Unexpected error when {} - No callback: {:?}",
+                error.error_action.description(),
+                error,
+            );
+        }
+    }
+    match result {
+        Ok(()) => match (maybe_callback, expected) {
+            (Ok(callback), _) => unsafe { callback.Success() },
+            (Err(error), CallbackExpected) => {
+                error!(
+                    "Success {} but there is no callback to return the result with",
+                    error.error_action.description(),
+                );
+                NS_ERROR_FAILURE
+            }
+            (Err(error), CallbackOptional) => {
+                info!("Success {}", error.error_action.description());
+                NS_OK
+            }
+        },
+        Err(error) => match (maybe_callback, expected) {
+            (Ok(callback), _) => match error.error_code {
+                ErrorCode::None => unsafe {
+                    callback.Failure(
+                        error.error_type.bits_code(),
+                        error.error_action.as_error_code(),
+                        error.error_stage.bits_code(),
+                    )
+                },
+                ErrorCode::Hresult(error_code) => unsafe {
+                    callback.FailureHresult(
+                        error.error_type.bits_code(),
+                        error.error_action.as_error_code(),
+                        error.error_stage.bits_code(),
+                        error_code,
+                    )
+                },
+                ErrorCode::Nsresult(error_code) => unsafe {
+                    callback.FailureNsresult(
+                        error.error_type.bits_code(),
+                        error.error_action.as_error_code(),
+                        error.error_stage.bits_code(),
+                        error_code,
+                    )
+                },
+                ErrorCode::Message(message) => unsafe {
+                    callback.FailureString(
+                        error.error_type.bits_code(),
+                        error.error_action.as_error_code(),
+                        error.error_stage.bits_code(),
+                        &*message,
+                    )
+                },
+            },
+            (Err(_), CallbackExpected) => {
+                error!("Error {}: {:?}", error.error_action.description(), error);
+                NS_ERROR_FAILURE
+            }
+            (Err(_), CallbackOptional) => {
+                warn!("Error {}: {:?}", error.error_action.description(), error);
+                NS_ERROR_FAILURE
+            }
+        },
+    }
+    .to_result()
+}
+
+// Intended to be used by an nsIBitsRequest XPCOM wrapper to return errors that
+// occur before dispatching a task off-thread. No return value is returned
+// because it will represent the return value of the callback function, which
+// should not be propagated.
+pub fn dispatch_pretask_request_error(error: BitsTaskError, callback: &nsIBitsCallback) {
+    let _ = maybe_dispatch_via_callback(Err(error), Ok(callback), CallbackExpected);
+}