* 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/libutil/archive.cc b/src/libutil/archive.cc
index 90a039164b58..2b8fb2f10adb 100644
--- a/src/libutil/archive.cc
+++ b/src/libutil/archive.cc
@@ -83,6 +83,7 @@ static void dumpContents(const Path & path, unsigned int size,
     unsigned int total = 0;
     ssize_t n;
     while ((n = read(fd, buf, sizeof(buf)))) {
+        checkInterrupt();
         if (n == -1) throw SysError("reading file " + path);
         total += n;
         sink(buf, n);
@@ -200,6 +201,8 @@ static void restoreEntry(const Path & path, RestoreSource & source)
     if (s != "(") throw badArchive("expected open tag");
 
     while (1) {
+        checkInterrupt();
+
         s = readString(source);
 
         if (s == ")") {
@@ -224,6 +227,7 @@ static void restoreContents(int fd, const Path & path, RestoreSource & source)
     unsigned char buf[65536];
 
     while (left) {
+        checkInterrupt();
         unsigned int n = sizeof(buf);
         if (n > left) n = left;
         source(buf, n);
@@ -247,6 +251,8 @@ static void restore(const Path & path, RestoreSource & source)
     AutoCloseFD fd;
 
     while (1) {
+        checkInterrupt();
+
         s = readString(source);
 
         if (s == ")") {