libutil: make RunningProgram::wait more resilient

this will usually be used either directly (which is always fine) or in
Finally blocks (where it must never throw execptions). make sure that,
exceptions being handled or not, the calling wait() in Finally doesn't
cause crashes due to the Finally no-nested-exceptions-thrown assertion

Change-Id: Ib83a5d9483b1fe83b9a957dcefeefce5d088f06d

1 files changed, 8 insertions, 3 deletions

diff --git a/src/libutil/processes.cc b/src/libutil/processes.cc
index 05b1321e9..866ba9647 100644
--- a/src/libutil/processes.cc
+++ b/src/libutil/processes.cc
@@ -280,9 +280,14 @@ RunningProgram::~RunningProgram()
 
 void RunningProgram::wait()
 {
-    int status = pid.wait();
-    if (status)
-        throw ExecError(status, "program '%1%' %2%", program, statusToString(status));
+    if (std::uncaught_exceptions() == 0) {
+        int status = pid.wait();
+        if (status)
+            throw ExecError(status, "program '%1%' %2%", program, statusToString(status));
+    } else {
+        pid.kill();
+        debug("killed subprocess %1% during exception handling", program);
+    }
 }
 
 RunningProgram runProgram2(const RunOptions & options)