fix: Add cache_dir header for external crash reports

External crash reporters only receive the envelope path, so include the cache
directory in envelope headers when cache_keep is enabled. This lets capable
reporters cache related files without changing the one-argument protocol.

Fixes GH-1688
Co-Authored-By: OpenAI Codex <noreply@openai.com>

Author: jpnurmi

src/backends/sentry_backend_crashpad.cpp

@@ -253,6 +253,10 @@ flush_external_crash_report(
         sentry__envelope_add_session(envelope, options->session);
     }
 
+    if (options->cache_keep) {
+        sentry__envelope_set_header(envelope, "cache_dir",
+            sentry_value_new_string(options->run->cache_path->path));
+    }
     sentry__run_write_external(options->run, envelope);
     sentry_envelope_free(envelope);
 }

src/sentry_core.c

@@ -1690,6 +1690,14 @@ sentry__launch_external_crash_reporter(
         sentry_free(envelope_filename);
         return false;
     }
+    if (options->cache_keep) {
+        if (sentry__envelope_materialize(envelope)) {
+            sentry__envelope_set_header(envelope, "cache_dir",
+                sentry_value_new_string(options->run->cache_path->path));
+        } else {
+            SENTRY_WARN("failed to add cache_dir to external crash report");
+        }
+    }
     sentry__transport_send_envelope(disk_transport, envelope);
     sentry__transport_dump_queue(disk_transport, options->run);
     sentry_transport_free(disk_transport);

tests/test_integration_crashpad.py

@@ -768,6 +768,7 @@ def test_crashpad_external_crash_reporter(cmake, httpserver, run_args):
     tmp_path = cmake(
         ["sentry_example", "sentry_crash_reporter"], {"SENTRY_BACKEND": "crashpad"}
     )
+    cache_dir = tmp_path.joinpath(".sentry-native/cache")
 
     env = dict(os.environ, SENTRY_DSN=make_dsn(httpserver))
     httpserver.expect_oneshot_request("/api/123456/envelope/").respond_with_data("OK")
@@ -777,7 +778,7 @@ def test_crashpad_external_crash_reporter(cmake, httpserver, run_args):
         run(
             tmp_path,
             "sentry_example",
-            ["log", "crash-reporter"] + run_args,
+            ["log", "crash-reporter", "cache-keep"] + run_args,
             expect_failure=True,
             env=env,
         )
@@ -791,6 +792,7 @@ def test_crashpad_external_crash_reporter(cmake, httpserver, run_args):
     crash = crash_request.get_data()
 
     envelope = Envelope.deserialize(crash)
+    assert envelope.headers["cache_dir"] == str(cache_dir)
     assert_meta(envelope, integration="crashpad")
     assert_breadcrumb(envelope)
 

tests/test_integration_http.py

@@ -314,6 +314,7 @@ def test_user_report_http(cmake, httpserver):
 )
 def test_external_crash_reporter_http(cmake, httpserver, build_args):
     tmp_path = cmake(["sentry_example", "sentry_crash_reporter"], build_args)
+    cache_dir = tmp_path.joinpath(".sentry-native/cache")
 
     httpserver.expect_oneshot_request(
         "/api/123456/envelope/",
@@ -329,7 +330,7 @@ def test_external_crash_reporter_http(cmake, httpserver, build_args):
         run(
             tmp_path,
             "sentry_example",
-            ["log", "crash-reporter", "crash"],
+            ["log", "crash-reporter", "cache-keep", "crash"],
             expect_failure=True,
             env=env,
         )
@@ -354,6 +355,7 @@ def test_external_crash_reporter_http(cmake, httpserver, build_args):
     crash = crash_request.get_data()
 
     envelope = Envelope.deserialize(crash)
+    assert envelope.headers["cache_dir"] == str(cache_dir)
     assert_meta(envelope, integration=build_args.get("SENTRY_BACKEND", ""))
 
     envelope = Envelope.deserialize(feedback)

tests/test_integration_native.py

@@ -398,6 +398,7 @@ def test_native_external_crash_reporter(cmake, httpserver):
     tmp_path = cmake(
         ["sentry_example", "sentry_crash_reporter"], {"SENTRY_BACKEND": "native"}
     )
+    cache_dir = tmp_path.joinpath(".sentry-native/cache")
 
     env = dict(os.environ, SENTRY_DSN=make_dsn(httpserver))
     httpserver.expect_oneshot_request("/api/123456/envelope/").respond_with_data("OK")
@@ -408,7 +409,7 @@ def test_native_external_crash_reporter(cmake, httpserver):
         run_crash(
             tmp_path,
             "sentry_example",
-            ["log", "crash-reporter", "crash"],
+            ["log", "crash-reporter", "cache-keep", "crash"],
             env=env,
         )
     assert waiting.result
@@ -423,6 +424,7 @@ def test_native_external_crash_reporter(cmake, httpserver):
 
     # Verify it's a minidump crash report and user feedback
     envelope = Envelope.deserialize(crash)
+    assert envelope.headers["cache_dir"] == str(cache_dir)
     assert_meta(envelope)
     assert_breadcrumb(envelope)