lynx-dev strange HTTP/HTCheckForInterrupt() bug - another patch

[Klaus Weide]

On Mon, 19 Apr 1999, Leonid Pauzner wrote:
> 18-Apr-99 01:24 Leonid Pauzner wrote:
> > 29-Mar-99 16:50 Bela Lubkin wrote:
> 
> >> But I don't think that's what Leonid was running into.  That's something
> >> else, possibly the need to signal((various signals), quench) *before*
> >> fork().

Try this.  Untested, since I didn't get the abnormal exit frequentely.
Disadvantage: requires sigprocmask(), so far we have always avoided
using anything more than just 'signal()'.  For now needs explicit
-DHAVE_SIGPROCMASK.

   Klaus

--- lynx2-8-2.old/WWW/Library/Implementation/HTTCP.c    Tue Apr 13 04:39:16 1999
+++ lynx2-8-2/WWW/Library/Implementation/HTTCP.c        Mon Apr 19 07:06:17 1999
@@ -686,6 +686,10 @@
 
     lynx_nsl_status = HT_INTERNAL;     /* should be set to something else 
below */
 
+#ifdef DEBUG_HOSTENT_CHILD
+    CTRACE_FLUSH(tfp);
+#endif
+
 #ifdef NSL_FORK
     statuses.h_errno_valid = NO;
        /*
@@ -694,6 +698,10 @@
        */
     {
        int got_rehostent = 0;
+#ifdef HAVE_SIGPROCMASK
+       sigset_t old_sigset;
+       sigset_t new_sigset;
+#endif
        /*
        **      Pipe, child pid, status buffers, start time, select()
        **      control variables.
@@ -722,6 +730,31 @@
 
        pipe(pfd);
 
+#ifdef HAVE_SIGPROCMASK
+       /*
+        *  Attempt to prevent a rare situation where the child
+        *  could execute the Lynx signal handlers because it gets
+        *  killed before it even has a chance to reset its handlers.
+        *  - kw
+        */
+       sigemptyset(&new_sigset);
+       sigaddset(&new_sigset, SIGTERM);
+       sigaddset(&new_sigset, SIGINT);
+#ifndef NOSIGHUP
+       sigaddset(&new_sigset, SIGHUP);
+#endif /* NOSIGHUP */
+#ifdef SIGTSTP
+       sigaddset(&new_sigset, SIGTSTP);
+#endif /* SIGTSTP */
+#ifdef SIGWINCH
+       sigaddset(&new_sigset, SIGWINCH);
+#endif /* SIGWINCH */
+       sigaddset(&new_sigset, SIGBUS);
+       sigaddset(&new_sigset, SIGSEGV);
+       sigaddset(&new_sigset, SIGILL);
+       sigprocmask(SIG_BLOCK, &new_sigset, &old_sigset);
+#endif /* HAVE_SIGPROCMASK */
+
        if ((fpid = fork()) == 0 ) {
            struct hostent  *phost;     /* Pointer to host - See netdb.h */
            /*
@@ -759,6 +792,11 @@
            signal(SIGSEGV, SIG_DFL);
            signal(SIGILL, SIG_DFL);
 
+#ifdef HAVE_SIGPROCMASK
+           /* Restore signal mask to whatever it was before the fork. -kw */
+           sigprocmask(SIG_SETMASK, &old_sigset, NULL);
+#endif /* HAVE_SIGPROCMASK */
+
            /*
            **  Child won't use read side.  -BL
            */
@@ -809,6 +847,14 @@
                _exit(1);
            }
        }
+
+#ifdef HAVE_SIGPROCMASK
+       /*
+       **  (parent) Restore signal mask to whatever it was
+       **  before the fork. - kw
+       */
+       sigprocmask(SIG_SETMASK, &old_sigset, NULL);
+#endif /* HAVE_SIGPROCMASK */
 
        /*
        **      (parent) Wait until lookup finishes, or interrupt,