Fix Ninja exit code when interrupted.

This fixes ##2681, a regression that was introduced during PR #2540
where Ninja would return a status code of 0 when interrupted.

The problem comes from RealCommandRunner::WaitForCommand() not
updating the result->status field in case of interrupt being
detected in Subprocess::DoWork().

This fixes the issue and adds a regression test for it.

+ Fix the CommandRunner::Result constructor to ensure that
  the `status` field is always initialized, even though it
  should now always be replaced at the end of a command.

Author: digit-google

misc/output_test.py

@@ -7,9 +7,11 @@
 
 import os
 import platform
+import signal
 import subprocess
 import sys
 import tempfile
+import time
 import unittest
 from textwrap import dedent
 import typing as T
@@ -631,5 +633,23 @@ def test_issue_2621(self):
 """,
         )
 
+    def test_issue_2681(self):
+        """Ninja should return a status code of 130 when interrupted."""
+        plan = r"""rule sleep
+  command = sleep 10
+
+build foo: sleep
+"""
+        with BuildDir(plan) as b:
+            for signum in (signal.SIGINT, signal.SIGHUP, signal.SIGTERM):
+                proc = subprocess.Popen([NINJA_PATH, "foo"], cwd=b.path, env=default_env, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+                # Sleep a bit to let Ninja start the build, otherwise the signal could be received
+                # before it, and returncode will be -2.
+                time.sleep(0.2)
+                os.kill(proc.pid, signum)
+                proc.wait()
+                self.assertEqual(proc.returncode, 130, msg=f"For signal {signum}")
+
+
 if __name__ == '__main__':
     unittest.main()

src/build.h

@@ -154,9 +154,8 @@ struct CommandRunner {
 
   /// The result of waiting for a command.
   struct Result {
-    Result() : edge(NULL) {}
-    Edge* edge;
-    ExitStatus status;
+    Edge* edge = nullptr;
+    ExitStatus status = ExitFailure;
     std::string output;
     bool success() const { return status == ExitSuccess; }
   };

src/real_command_runner.cc

@@ -98,8 +98,10 @@ bool RealCommandRunner::WaitForCommand(Result* result) {
   Subprocess* subproc;
   while ((subproc = subprocs_.NextFinished()) == NULL) {
     bool interrupted = subprocs_.DoWork();
-    if (interrupted)
+    if (interrupted) {
+      result->status = ExitInterrupted;
       return false;
+    }
   }
 
   result->status = subproc->Finish();