process: terminate the child if the parent dies

It's annoying to have the forked X server linger around when the test
segfaults, so make sure we take it down with us.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Chase Douglas <chase.douglas@canonical.com>

2 files changed, 50 insertions, 0 deletions

diff --git a/src/process.cpp b/src/process.cpp
index ec39c97..1a1739a 100644
--- a/src/process.cpp
+++ b/src/process.cpp
@@ -27,6 +27,7 @@
 
 #include "xorg/gtest/xorg-gtest-process.h"
 
+#include <sys/prctl.h>
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <unistd.h>
@@ -81,6 +82,10 @@ void xorg::testing::Process::Start(const std::string &program, const std::vector
       close(2);
     }
 
+#ifdef __linux
+    prctl(PR_SET_PDEATHSIG, SIGTERM);
+#endif
+
     std::vector<char*> args;
     std::vector<std::string>::const_iterator it;
 
diff --git a/test/process-test.cpp b/test/process-test.cpp
index dc5402c..183b9f8 100644
--- a/test/process-test.cpp
+++ b/test/process-test.cpp
@@ -1,3 +1,5 @@
+#include <errno.h>
+#include <unistd.h>
 #include <sys/types.h>
 #include <sys/wait.h>
 
@@ -63,6 +65,49 @@ TEST(Process, TerminationFailure)
   ASSERT_EQ(p.GetState(), Process::FINISHED_FAILURE);
 }
 
+TEST(Process, ChildTearDown)
+{
+  SCOPED_TRACE("TESTCASE: ensure child process dies when parent does");
+
+  int pipefd[2];
+  ASSERT_NE(pipe(pipefd), -1);
+
+  /* Fork, the child will spawn a Process, write that Process's PID to a
+     pipe and then kill itself. The parent checks that the child was
+     terminated when the parent was killed.
+   */
+  pid_t pid = fork();
+  if (pid == 0) { /* child */
+    close(pipefd[0]);
+
+    Process p;
+    p.Start("sleep", "1000", NULL); /* forks another child */
+    ASSERT_GT(p.Pid(), 0);
+
+    char *buffer;
+    ASSERT_GT(asprintf(&buffer, "%d", p.Pid()), 0);
+    ASSERT_EQ(write(pipefd[1], buffer, strlen(buffer)), (int)strlen(buffer));
+    close(pipefd[1]);
+
+    raise(SIGKILL);
+  } else { /* parent */
+    close(pipefd[1]);
+
+    char buffer[20] = {0};
+    ASSERT_GT(read(pipefd[0], buffer, sizeof(buffer)), 0);
+    close(pipefd[0]);
+
+    pid_t child_pid = atoi(buffer);
+    for (int i = 0; i < 10; i++) {
+      if (kill(child_pid, 0) != -1)
+        usleep(100);
+
+    }
+    ASSERT_EQ(kill(child_pid, 0), -1);
+    ASSERT_EQ(errno, ESRCH);
+  }
+}
+
 
 int main(int argc, char *argv[]) {
   testing::InitGoogleTest(&argc, argv);