From 1cf08f39294f771ba867bd2f51aaa9bbeb3d00a9 Mon Sep 17 00:00:00 2001
From: Daniel Eischen <deischen@FreeBSD.org>
Date: Wed, 18 Apr 2001 12:40:30 +0000
Subject: [PATCH] Reinstall the alternate signal stack after a fork.

PR:		25110
Tested by:	knu
---
 lib/libc_r/uthread/uthread_fork.c | 12 +++++++++++-
 lib/libkse/thread/thr_fork.c      | 12 +++++++++++-
 lib/libpthread/thread/thr_fork.c  | 12 +++++++++++-
 3 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/lib/libc_r/uthread/uthread_fork.c b/lib/libc_r/uthread/uthread_fork.c
index 4437d886a80..a2aabbe149b 100644
--- a/lib/libc_r/uthread/uthread_fork.c
+++ b/lib/libc_r/uthread/uthread_fork.c
@@ -32,6 +32,7 @@
  * $FreeBSD$
  */
 #include <errno.h>
+#include <signal.h>
 #include <string.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -112,7 +113,16 @@ _fork(void)
 		else if (_pq_init(&_readyq) != 0) {
 			/* Abort this application: */
 			PANIC("Cannot initialize priority ready queue.");
-		} else {
+		} else if ((_thread_sigstack.ss_sp == NULL) &&
+		    ((_thread_sigstack.ss_sp = malloc(SIGSTKSZ)) == NULL))
+			PANIC("Unable to allocate alternate signal stack");
+		else {
+			/* Install the alternate signal stack: */
+			_thread_sigstack.ss_size = SIGSTKSZ;
+			_thread_sigstack.ss_flags = 0;
+			if (__sys_sigaltstack(&_thread_sigstack, NULL) != 0)
+				PANIC("Unable to install alternate signal stack");
+
 			/*
 			 * Enter a loop to remove all threads other than
 			 * the running thread from the thread list:
diff --git a/lib/libkse/thread/thr_fork.c b/lib/libkse/thread/thr_fork.c
index 4437d886a80..a2aabbe149b 100644
--- a/lib/libkse/thread/thr_fork.c
+++ b/lib/libkse/thread/thr_fork.c
@@ -32,6 +32,7 @@
  * $FreeBSD$
  */
 #include <errno.h>
+#include <signal.h>
 #include <string.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -112,7 +113,16 @@ _fork(void)
 		else if (_pq_init(&_readyq) != 0) {
 			/* Abort this application: */
 			PANIC("Cannot initialize priority ready queue.");
-		} else {
+		} else if ((_thread_sigstack.ss_sp == NULL) &&
+		    ((_thread_sigstack.ss_sp = malloc(SIGSTKSZ)) == NULL))
+			PANIC("Unable to allocate alternate signal stack");
+		else {
+			/* Install the alternate signal stack: */
+			_thread_sigstack.ss_size = SIGSTKSZ;
+			_thread_sigstack.ss_flags = 0;
+			if (__sys_sigaltstack(&_thread_sigstack, NULL) != 0)
+				PANIC("Unable to install alternate signal stack");
+
 			/*
 			 * Enter a loop to remove all threads other than
 			 * the running thread from the thread list:
diff --git a/lib/libpthread/thread/thr_fork.c b/lib/libpthread/thread/thr_fork.c
index 4437d886a80..a2aabbe149b 100644
--- a/lib/libpthread/thread/thr_fork.c
+++ b/lib/libpthread/thread/thr_fork.c
@@ -32,6 +32,7 @@
  * $FreeBSD$
  */
 #include <errno.h>
+#include <signal.h>
 #include <string.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -112,7 +113,16 @@ _fork(void)
 		else if (_pq_init(&_readyq) != 0) {
 			/* Abort this application: */
 			PANIC("Cannot initialize priority ready queue.");
-		} else {
+		} else if ((_thread_sigstack.ss_sp == NULL) &&
+		    ((_thread_sigstack.ss_sp = malloc(SIGSTKSZ)) == NULL))
+			PANIC("Unable to allocate alternate signal stack");
+		else {
+			/* Install the alternate signal stack: */
+			_thread_sigstack.ss_size = SIGSTKSZ;
+			_thread_sigstack.ss_flags = 0;
+			if (__sys_sigaltstack(&_thread_sigstack, NULL) != 0)
+				PANIC("Unable to install alternate signal stack");
+
 			/*
 			 * Enter a loop to remove all threads other than
 			 * the running thread from the thread list: