feat: Allow disabling of the crash-handler backend at runtime. (#717)

Co-authored-by: Mischan Toosarani-Hausberger <[email protected]>

CONTRIBUTING.md

@@ -139,3 +139,4 @@ The example currently supports the following commends:
 - `capture-multiple`: Captures a number of events.
 - `sleep`: Introduces a 10 second sleep.
 - `add-stacktrace`: Adds the current thread stacktrace to the captured event.
+- `disable-backend`: Disables the build-configured crash-handler backend.

examples/example.c

@@ -65,6 +65,10 @@ main(int argc, char **argv)
 {
     sentry_options_t *options = sentry_options_new();
 
+    if (has_arg(argc, argv, "disable-backend")) {
+        sentry_options_set_backend(options, NULL);
+    }
+
     // this is an example. for real usage, make sure to set this explicitly to
     // an app specific cache location.
     sentry_options_set_database_path(options, ".sentry-native");

include/sentry.h

@@ -709,6 +709,20 @@ SENTRY_API void sentry_transport_free(sentry_transport_t *transport);
 SENTRY_API sentry_transport_t *sentry_new_function_transport(
     void (*func)(const sentry_envelope_t *envelope, void *data), void *data);
 
+/**
+ * This represents an interface for user-defined backends.
+ *
+ * Backends are responsible to handle crashes. They are maintained at runtime
+ * via various life-cycle hooks from the sentry-core.
+ *
+ * At this point none of those interfaces are exposed in the API including
+ * creation and destruction. The main use-case of the backend in the API at this
+ * point is to disable it via `sentry_options_set_backend` at runtime before it
+ * is initialized.
+ */
+struct sentry_backend_s;
+typedef struct sentry_backend_s sentry_backend_t;
+
 /* -- Options APIs -- */
 
 /**
@@ -1050,6 +1064,16 @@ SENTRY_API void sentry_options_set_shutdown_timeout(
  */
 SENTRY_API uint64_t sentry_options_get_shutdown_timeout(sentry_options_t *opts);
 
+/**
+ * Sets a user-defined backend.
+ *
+ * Since creation and destruction of backends is not exposed in the API, this
+ * can only be used to set the backend to `NULL`, which disables the backend in
+ * the initialization.
+ */
+SENTRY_API void sentry_options_set_backend(
+    sentry_options_t *opts, sentry_backend_t *backend);
+
 /* -- Global APIs -- */
 
 /**

src/sentry_options.c

@@ -425,3 +425,10 @@ sentry_options_get_traces_sample_rate(sentry_options_t *opts)
 {
     return opts->traces_sample_rate;
 }
+
+void
+sentry_options_set_backend(sentry_options_t *opts, sentry_backend_t *backend)
+{
+    sentry__backend_free(opts->backend);
+    opts->backend = backend;
+}

tests/test_integration_crashpad.py

@@ -135,3 +135,24 @@ def test_crashpad_dump_inflight(cmake, httpserver):
 
     # we trigger 10 normal events, and 1 crash
     assert len(httpserver.log) >= 11
+
+
+def test_disable_backend(cmake, httpserver):
+    tmp_path = cmake(["sentry_example"], {"SENTRY_BACKEND": "crashpad"})
+
+    env = dict(os.environ, SENTRY_DSN=make_dsn(httpserver))
+
+    with httpserver.wait(timeout=5, raise_assertions=False) as waiting:
+        child = run(
+            tmp_path, "sentry_example", ["disable-backend", "log", "crash"], env=env
+        )
+        # we crash so process should return non-zero
+        assert child.returncode
+
+    # crashpad is disabled, and we are only crashing, so we expect the wait to timeout
+    assert waiting.result is False
+
+    run(tmp_path, "sentry_example", ["log", "no-setup"], check=True, env=env)
+
+    # crashpad is disabled, and we are only crashing, so we expect no requests
+    assert len(httpserver.log) == 0