* Catch SIGINT to terminate cleanly when the user tries to interrupt

  Nix.  This is to prevent Berkeley DB from becoming wedged.

  Unfortunately it is not possible to throw C++ exceptions from a
  signal handler.  In fact, you can't do much of anything except
  change variables of type `volatile sig_atomic_t'.  So we set an
  interrupt flag in the signal handler and check it at various
  strategic locations in the code (by calling checkInterrupt()).
  Since this is unlikely to cover all cases (e.g., (semi-)infinite
  loops), sometimes SIGTERM may now be required to kill Nix.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/libstore/normalise.cc b/src/libstore/normalise.cc
index 7ef45e292352..51f90207ead3 100644
--- a/src/libstore/normalise.cc
+++ b/src/libstore/normalise.cc
@@ -96,6 +96,7 @@ Path normaliseStoreExpr(const Path & _nePath, PathSet pending)
     for (PathSet::iterator i = ne.derivation.inputs.begin();
          i != ne.derivation.inputs.end(); i++)
     {
+        checkInterrupt();
         Path nfPath = normaliseStoreExpr(*i, pending);
         realiseClosure(nfPath, pending);
         /* !!! nfPath should be a root of the garbage collector while
@@ -193,6 +194,7 @@ Path normaliseStoreExpr(const Path & _nePath, PathSet pending)
         for (Paths::iterator j = refPaths.begin();
 	     j != refPaths.end(); j++)
 	{
+            checkInterrupt();
 	    Path path = *j;
 	    elem.refs.insert(path);
             if (inClosures.find(path) != inClosures.end())
@@ -209,6 +211,7 @@ Path normaliseStoreExpr(const Path & _nePath, PathSet pending)
     PathSet donePaths;
 
     while (!usedPaths.empty()) {
+        checkInterrupt();
 	PathSet::iterator i = usedPaths.begin();
 	Path path = *i;
 	usedPaths.erase(i);
@@ -291,6 +294,7 @@ void ensurePath(const Path & path, PathSet pending)
     for (Paths::iterator i = subPaths.begin(); 
          i != subPaths.end(); i++)
     {
+        checkInterrupt();
         try {
             normaliseStoreExpr(*i, pending);
             if (isValidPath(path)) return;
@@ -337,6 +341,8 @@ static void requisitesWorker(const Path & nePath,
     bool includeExprs, bool includeSuccessors,
     PathSet & paths, PathSet & doneSet)
 {
+    checkInterrupt();
+    
     if (doneSet.find(nePath) != doneSet.end()) return;
     doneSet.insert(nePath);