From a69b4b55ca447dccbf8593bbdc7b6056b9a39828 Mon Sep 17 00:00:00 2001
From: Josh Stone <jistone@redhat.com>
Date: Tue, 10 May 2011 17:25:47 -0700
Subject: [PATCH] Consolidate signal-masking into a utility class

* util.h (stap_sigmasker): New, masks our usual signals for the life of
  the stap_sigmasker object.
* remote.cxx (direct_stapsh::direct_stapsh): Use stap_sigmasker while
  spawning the stapsh child process.
  (ssh_remote::connect): Ditto for the ssh process.
  (remote::run): Use stap_sigmasker around the polling loop.
---
 remote.cxx | 75 ++++++++++++++++++++----------------------------------
 util.h     | 23 ++++++++++++++++-
 2 files changed, 49 insertions(+), 49 deletions(-)

diff --git a/remote.cxx b/remote.cxx
index 37b690f68..9c025f717 100644
--- a/remote.cxx
+++ b/remote.cxx
@@ -406,18 +406,10 @@ class direct_stapsh : public stapsh {
 
         // mask signals while we spawn, so we can simulate manual signals to
         // the "remote" target, as we must for the real ssh_remote case.
-        sigset_t mask, oldmask;
-        sigemptyset (&mask);
-        sigaddset (&mask, SIGHUP);
-        sigaddset (&mask, SIGPIPE);
-        sigaddset (&mask, SIGINT);
-        sigaddset (&mask, SIGTERM);
-        sigprocmask (SIG_BLOCK, &mask, &oldmask);
-
-        child = stap_spawn_piped(s.verbose, cmd, &in, &out);
-
-        // back to normal signals
-        sigprocmask (SIG_SETMASK, &oldmask, NULL);
+        {
+          stap_sigmasker masked;
+          child = stap_spawn_piped(s.verbose, cmd, &in, &out);
+        }
 
         if (child <= 0)
           throw runtime_error(_("error launching stapsh"));
@@ -485,18 +477,10 @@ class ssh_remote : public stapsh {
 
         // mask signals while we spawn, so we can manually send even tty
         // signals *through* ssh rather than to ssh itself
-        sigset_t mask, oldmask;
-        sigemptyset (&mask);
-        sigaddset (&mask, SIGHUP);
-        sigaddset (&mask, SIGPIPE);
-        sigaddset (&mask, SIGINT);
-        sigaddset (&mask, SIGTERM);
-        sigprocmask (SIG_BLOCK, &mask, &oldmask);
-
-        child = stap_spawn_piped(s->verbose, cmd, &in, &out);
-
-        // back to normal signals
-        sigprocmask (SIG_SETMASK, &oldmask, NULL);
+        {
+          stap_sigmasker masked;
+          child = stap_spawn_piped(s->verbose, cmd, &in, &out);
+        }
 
         if (child <= 0)
           throw runtime_error(_("error launching stapsh"));
@@ -874,31 +858,26 @@ remote::run(const vector<remote*>& remotes)
     }
 
   // mask signals while we're preparing to poll
-  sigset_t mask, oldmask;
-  sigemptyset (&mask);
-  sigaddset (&mask, SIGHUP);
-  sigaddset (&mask, SIGPIPE);
-  sigaddset (&mask, SIGINT);
-  sigaddset (&mask, SIGTERM);
-  sigprocmask (SIG_BLOCK, &mask, &oldmask);
-
-  for (;;) // polling loop for remotes that have fds to watch
-    {
-      vector<pollfd> fds;
-      for (unsigned i = 0; i < remotes.size(); ++i)
-	remotes[i]->prepare_poll (fds);
-      if (fds.empty())
-	break;
-
-      rc = ppoll (&fds[0], fds.size(), NULL, &oldmask);
-      if (rc < 0 && errno != EINTR)
-	break;
-
-      for (unsigned i = 0; i < remotes.size(); ++i)
-	remotes[i]->handle_poll (fds);
-    }
+  {
+    stap_sigmasker masked;
 
-  sigprocmask (SIG_SETMASK, &oldmask, NULL);
+    // polling loop for remotes that have fds to watch
+    for (;;)
+      {
+        vector<pollfd> fds;
+        for (unsigned i = 0; i < remotes.size(); ++i)
+          remotes[i]->prepare_poll (fds);
+        if (fds.empty())
+          break;
+
+        rc = ppoll (&fds[0], fds.size(), NULL, &masked.old);
+        if (rc < 0 && errno != EINTR)
+          break;
+
+        for (unsigned i = 0; i < remotes.size(); ++i)
+          remotes[i]->handle_poll (fds);
+      }
+  }
 
   for (unsigned i = 0; i < remotes.size(); ++i)
     {
diff --git a/util.h b/util.h
index 9ee331bf5..055758526 100644
--- a/util.h
+++ b/util.h
@@ -7,9 +7,10 @@
 #include <sstream>
 #include <stdexcept>
 #include <cctype>
+extern "C" {
 #include <libintl.h>
 #include <locale.h>
-extern "C" {
+#include <signal.h>
 #include <stdint.h>
 }
 
@@ -184,4 +185,24 @@ endswith(const std::string & s, const char * suffix)
 }
 
 
+// Mask our usual signals for the life of this object.
+struct stap_sigmasker {
+    sigset_t old;
+    stap_sigmasker()
+      {
+        sigset_t mask;
+        sigemptyset (&mask);
+        sigaddset (&mask, SIGHUP);
+        sigaddset (&mask, SIGPIPE);
+        sigaddset (&mask, SIGINT);
+        sigaddset (&mask, SIGTERM);
+        sigprocmask (SIG_BLOCK, &mask, &old);
+      }
+    ~stap_sigmasker()
+      {
+        sigprocmask (SIG_SETMASK, &old, NULL);
+      }
+};
+
+
 /* vim: set sw=2 ts=8 cino=>4,n-2,{2,^-2,t0,(0,u0,w1,M1 : */
-- 
2.43.5