[147224] trunk/base/src/pextlib1.0/system.c

[raimue at macports.org]

Revision: 147224
          https://trac.macports.org/changeset/147224
Author:   raimue at macports.org
Date:     2016-03-31 08:53:21 -0700 (Thu, 31 Mar 2016)
Log Message:
-----------
pextlib/system: ignore signals SIGINT/SIGQUIT

When a SIGINT/SIGQUIT was generated by the user during execution of a program,
both the program and the waiting parent tclsh process got interrupted by
a signal. However, the handler in the tclsh only generated an unpleasant error
message that a SIGINT/SIGQUIT was received.

With this change, only the child will handle the signal, hopefully ending its
execution. If the program handles SIGINT/SIGQUIT, it might still just terminate
with a normal exit code, so there is no chance for us to determine that it was
killed by a signal.

Modified Paths:
--------------
    trunk/base/src/pextlib1.0/system.c

Modified: trunk/base/src/pextlib1.0/system.c
===================================================================
--- trunk/base/src/pextlib1.0/system.c	2016-03-31 15:33:52 UTC (rev 147223)
+++ trunk/base/src/pextlib1.0/system.c	2016-03-31 15:53:21 UTC (rev 147224)
@@ -56,6 +56,7 @@
 #include <unistd.h>
 #include <limits.h>
 #include <errno.h>
+#include <signal.h>
 
 #include "system.h"
 #include "sip_copy_proc.h"
@@ -187,6 +188,22 @@
         }
     }
 
+    /*
+     * Ignore SIGINT and SIGQUIT, just like system(3)
+     *
+     * system(3) also blocks SIGCHLD during the execution of the program.
+     * However, that would make our wait(2) call more complicated. As we are
+     * not relying on delivery of SIGCHLD anywhere else, we just do not change
+     * the handling here at all.
+     */
+    struct sigaction sa, old_sa_int, old_sa_quit;
+    memset(&sa, 0, sizeof(sa));
+    sa.sa_handler = SIG_IGN;
+    sigemptyset(&sa.sa_mask);
+    sigaction(SIGINT, &sa, &old_sa_int);
+    sigaction(SIGQUIT, &sa, &old_sa_quit);
+
+    /* fork a new process */
     pid = fork();
     switch (pid) {
     case -1: /* error */
@@ -229,6 +246,10 @@
             }
         }
 
+        /* restore original signal handling */
+        sigaction(SIGINT, &old_sa_int, NULL);
+        sigaction(SIGQUIT, &old_sa_quit, NULL);
+
         /* XXX ugly string constants */
         if (sandbox) {
             args[0] = "sandbox-exec";
@@ -342,6 +363,10 @@
         }
     }
 
+    /* restore original signal handling */
+    sigaction(SIGINT, &old_sa_int, NULL);
+    sigaction(SIGQUIT, &old_sa_quit, NULL);
+
     if (odup) {
         /* Cleanup. */
         close(fdset[0]);
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