fix(ssi, crashtracker): load receiver script manually when not available in PATH [backport 3.12] (#14424)

Backport ef44d8c from #14421 to 3.12.

When ddtrace is injected, `_dd_crashtracker_receiver` command is not
available and we need to manually specify the script path.

Without this change

```
apt update
apt install -y curl php systemctl
DD_INSTALLER=true DD_NO_AGENT_INSTALL=true bash -c "$(curl -L https://s3.amazonaws.com/dd-agent/scripts/install_script_agent7.sh)"

datadog-installer install "oci://docker.io/datadog/apm-library-python-package:latest"
datadog-installer install "oci://docker.io/datadog/apm-inject-package:latest"
datadog-installer apm instrument

bash # a new shell is required to enable the preload

python3 -c 'print("Hello, World!")'
```

Gives us

```
Failed to find _dd_crashtracker_receiver
Failed to start crashtracker: failed to construct crashtracker configuration
Hello, World!
```

## Checklist
- [x] PR author has checked that all the criteria below are met
- The PR description includes an overview of the change
- The PR description articulates the motivation for the change
- The change includes tests OR the PR description describes a testing
strategy
- The PR description notes risks associated with the change, if any
- Newly-added code is easy to change
- The change follows the [library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
- The change includes or references documentation updates if necessary
- Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist
- [x] Reviewer has checked that all the criteria below are met 
- Title is accurate
- All changes are related to the pull request's stated goal
- Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes
- Testing strategy adequately addresses listed risks
- Newly-added code is easy to change
- Release note makes sense to a user of the library
- If necessary, author has acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment
- Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)


[PROF-12387](https://datadoghq.atlassian.net/browse/PROF-12387)

[PROF-12387]:
https://datadoghq.atlassian.net/browse/PROF-12387?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ

Co-authored-by: Taegyun Kim <[email protected]>
Co-authored-by: Brett Langdon <[email protected]>

Author: 3 people

ddtrace/internal/core/crashtracking.py

@@ -1,3 +1,4 @@
+import os
 import platform
 import shutil
 from typing import Dict
@@ -77,6 +78,14 @@ def _get_tags(additional_tags: Optional[Dict[str, str]]) -> Dict[str, str]:
 
 def _get_args(additional_tags: Optional[Dict[str, str]]):
     dd_crashtracker_receiver = shutil.which("_dd_crashtracker_receiver")
+
+    # If not found in PATH, try ddtrace installation directory. This can happen
+    # in an injected environment
+    if dd_crashtracker_receiver is None:
+        script_path = os.path.join(os.path.dirname(__file__), "..", "..", "commands", "_dd_crashtracker_receiver.py")
+        if os.path.exists(script_path):
+            dd_crashtracker_receiver = script_path
+
     if dd_crashtracker_receiver is None:
         print("Failed to find _dd_crashtracker_receiver")
         return (None, None, None)

releasenotes/notes/ssi-crashtracker-receiver-753abd766a86446d.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    ssi, crashtracker: This fix resolves an issue where crashtracker receiver
+    binary was not available in an injected environment.
+

tests/internal/crashtracker/test_crashtracker.py

@@ -90,6 +90,37 @@ def test_crashtracker_started():
         pytest.fail("contents of stdout.log: %s, stderr.log: %s" % (stdout_msg, stderr_msg))
 
 
+@pytest.mark.skipif(not sys.platform.startswith("linux"), reason="Linux only")
+@pytest.mark.subprocess()
+def test_crashtracker_receiver_not_in_path():
+    import os
+    import shutil
+
+    import pytest
+
+    from ddtrace.internal.core import crashtracking
+    from tests.internal.crashtracker.utils import CrashtrackerWrapper
+
+    try:
+        # Remove the receiver from the path. This mimics the case where we don't
+        # have _dd_crashtracker_receiver in the PATH, for example when running
+        # in an injected environment. And we should just load the script
+        # directly.
+        os.environ["PATH"] = ""
+        dd_crashtracker_receiver = shutil.which("_dd_crashtracker_receiver")
+        assert dd_crashtracker_receiver is None
+
+        ct = CrashtrackerWrapper(1234, "started")
+        assert ct.start()
+        assert crashtracking.is_started()  # Confirmation at the module level
+    except Exception:
+        pytest.fail("Exception when starting crashtracker")
+
+    stdout_msg, stderr_msg = ct.logs()
+    if stdout_msg or stderr_msg:
+        pytest.fail("contents of stdout.log: %s, stderr.log: %s" % (stdout_msg, stderr_msg))
+
+
 @pytest.mark.skipif(not sys.platform.startswith("linux"), reason="Linux only")
 @pytest.mark.subprocess()
 def test_crashtracker_simple():