Merge pull request #4 from tmandry/type-error

Check attribute types for safety
eiz · Jan 29, 2024 · 589d55a · 589d55a
2 parents 8812e50 + a2ccee3
commit 589d55a
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Showing 3 changed files with 55 additions and 5 deletions.
diff --git a/accessibility-sys/src/error.rs b/accessibility-sys/src/error.rs
@@ -17,3 +17,25 @@ pub const kAXErrorAPIDisabled: i32 = -25211;
 pub const kAXErrorNoValue: i32 = -25212;
 pub const kAXErrorParameterizedAttributeUnsupported: i32 = -25213;
 pub const kAXErrorNotEnoughPrecision: i32 = -25214;
+
+pub fn error_string(error: AXError) -> &'static str {
+    match error {
+        kAXErrorSuccess => "kAXErrorSuccess",
+        kAXErrorFailure => "kAXErrorFailure",
+        kAXErrorIllegalArgument => "kAXErrorIllegalArgument",
+        kAXErrorInvalidUIElement => "kAXErrorInvalidUIElement",
+        kAXErrorInvalidUIElementObserver => "kAXErrorInvalidUIElementObserver",
+        kAXErrorCannotComplete => "kAXErrorCannotComplete",
+        kAXErrorAttributeUnsupported => "kAXErrorAttributeUnsupported",
+        kAXErrorActionUnsupported => "kAXErrorActionUnsupported",
+        kAXErrorNotificationUnsupported => "kAXErrorNotificationUnsupported",
+        kAXErrorNotImplemented => "kAXErrorNotImplemented",
+        kAXErrorNotificationAlreadyRegistered => "kAXErrorNotificationAlreadyRegistered",
+        kAXErrorNotificationNotRegistered => "kAXErrorNotificationNotRegistered",
+        kAXErrorAPIDisabled => "kAXErrorAPIDisabled",
+        kAXErrorNoValue => "kAXErrorNoValue",
+        kAXErrorParameterizedAttributeUnsupported => "kAXErrorParameterizedAttributeUnsupported",
+        kAXErrorNotEnoughPrecision => "kAXErrorNotEnoughPrecision",
+        _ => "unknown error",
+    }
+}
diff --git a/accessibility/src/lib.rs b/accessibility/src/lib.rs
@@ -3,8 +3,13 @@ pub mod attribute;
 pub mod ui_element;
 mod util;
 
-use accessibility_sys::AXError;
-use core_foundation::{array::CFArray, base::TCFType, string::CFString};
+use accessibility_sys::{error_string, AXError};
+use core_foundation::{
+    array::CFArray,
+    base::CFTypeID,
+    base::{CFCopyTypeIDDescription, TCFType},
+    string::CFString,
+};
 use std::{
     cell::{Cell, RefCell},
     thread,
@@ -16,14 +21,28 @@ pub use action::*;
 pub use attribute::*;
 pub use ui_element::*;
 
+#[non_exhaustive]
 #[derive(Debug, TError)]
 pub enum Error {
     #[error("element not found")]
     NotFound,
-    #[error("accessibility error {0:?}")]
+    #[error(
+        "expected attribute type {} but got {}",
+        type_name(*expected),
+        type_name(*received),
+    )]
+    UnexpectedType {
+        expected: CFTypeID,
+        received: CFTypeID,
+    },
+    #[error("accessibility error {}", error_string(*.0))]
     Ax(AXError),
 }
 
+fn type_name(type_id: CFTypeID) -> CFString {
+    unsafe { CFString::wrap_under_create_rule(CFCopyTypeIDDescription(type_id)) }
+}
+
 pub trait TreeVisitor {
     fn enter_element(&self, element: &AXUIElement) -> TreeWalkerFlow;
     fn exit_element(&self, element: &AXUIElement);

diff --git a/accessibility/src/ui_element.rs b/accessibility/src/ui_element.rs
@@ -14,7 +14,7 @@ use cocoa::{
 };
 use core_foundation::{
     array::CFArray,
-    base::{TCFType, TCFTypeRef},
+    base::{CFType, TCFType, TCFTypeRef},
     declare_TCFType, impl_CFTypeDescription, impl_TCFType,
     string::CFString,
 };
@@ -92,7 +92,7 @@ impl AXUIElement {
     }
 
     pub fn attribute<T: TCFType>(&self, attribute: &AXAttribute<T>) -> Result<T, Error> {
-        unsafe {
+        let res = unsafe {
             Ok(T::wrap_under_create_rule(T::Ref::from_void_ptr(
                 ax_call(|x| {
                     AXUIElementCopyAttributeValue(
@@ -103,7 +103,16 @@ impl AXUIElement {
                 })
                 .map_err(Error::Ax)?,
             )))
+        };
+        if let Ok(val) = &res {
+            if T::type_id() != CFType::type_id() && !val.instance_of::<T>() {
+                return Err(Error::UnexpectedType {
+                    expected: T::type_id(),
+                    received: val.type_of(),
+                });
+            }
         }
+        res
     }
 
     pub fn set_attribute<T: TCFType>(