bug 1300152 - Add nsIDebug2::rustPanic to allow triggering Rust panic for testing. r=froydnj

For testing purposes it will be useful to be able to trigger crashes in Rust
code. Being able to trigger a panic seems like a good place to start. This
will make it easier to validate improvements in crash reporting.

MozReview-Commit-ID: Bh5rBieLLWW

--HG--
rename : toolkit/crashreporter/test/unit/test_crash_moz_crash.js => toolkit/crashreporter/test/unit/test_crash_rust_panic.js
extra : rebase_source : ba9f626ca2d2852f966e93401b8f8f7543615310
extra : source : 8c9117de1e7f40af42b7cbce25bc3780c032fe45

toolkit/crashreporter/test/unit/test_crash_rust_panic.js

@@ -0,0 +1,11 @@
+function run_test() {
+  // Try crashing with a Rust panic
+  do_crash(function() {
+             Components.classes["@mozilla.org/xpcom/debug;1"].getService(Components.interfaces.nsIDebug2).rustPanic("OH NO");
+           },
+           function(mdump, extra) {
+             //TODO: check some extra things?
+           },
+          // process will exit with a zero exit status
+          true);
+}

toolkit/crashreporter/test/unit/xpcshell.ini

@@ -7,6 +7,9 @@ support-files =
 
 [test_crash_moz_crash.js]
 [test_crash_purevirtual.js]
+[test_crash_rust_panic.js]
+# Fails on Win64, bug 1302078.
+fail-if = os == 'win' && bits == 64
 [test_crash_after_js_oom_reported.js]
 [test_crash_after_js_oom_recovered.js]
 [test_crash_after_js_oom_reported_2.js]

toolkit/library/rust/shared/lib.rs

@@ -10,3 +10,12 @@ extern crate nsstring;
 extern crate rust_url_capi;
 #[cfg(feature = "quantum_render")]
 extern crate webrender_bindings;
+
+use std::ffi::CStr;
+use std::os::raw::c_char;
+
+/// Used to implement `nsIDebug2::RustPanic` for testing purposes.
+#[no_mangle]
+pub extern "C" fn intentional_panic(message: *const c_char) {
+    panic!("{}", unsafe { CStr::from_ptr(message) }.to_string_lossy());
+}

xpcom/base/nsDebugImpl.cpp

@@ -148,6 +148,16 @@ nsDebugImpl::Abort(const char* aFile, int32_t aLine)
   return NS_OK;
 }
 
+// From toolkit/library/rust/lib.rs
+extern "C" void intentional_panic(const char* message);
+
+NS_IMETHODIMP
+nsDebugImpl::RustPanic(const char* aMessage)
+{
+  intentional_panic(aMessage);
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 nsDebugImpl::GetIsDebugBuild(bool* aResult)
 {

xpcom/base/nsIDebug2.idl

@@ -79,4 +79,11 @@ interface nsIDebug2 : nsISupports
      */
     void abort(in string aFile, 
                in long aLine);
+
+    /**
+     * Request the process to trigger a fatal panic!() from Rust code.
+     *
+     * @param aMessage the string to pass to panic!().
+     */
+    void rustPanic(in string aMessage);
 };