Move gdbsupport to the top level

[deliverable/binutils-gdb.git] / gdbsupport / alt-stack.h

diff --git a/gdbsupport/alt-stack.h b/gdbsupport/alt-stack.h
new file mode 100644 (file)
index 0000000..e7c6b2f
--- /dev/null
+++ b/gdbsupport/alt-stack.h
@@ -0,0 +1,70 @@
+/* Temporarily install an alternate signal stack
+
+   Copyright (C) 2019-2020 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef GDBSUPPORT_ALT_STACK_H
+#define GDBSUPPORT_ALT_STACK_H
+
+#include <signal.h>
+
+namespace gdb
+{
+
+/* Try to set up an alternate signal stack for SIGSEGV handlers.
+   This allows us to handle SIGSEGV signals generated when the
+   normal process stack is exhausted.  If this stack is not set
+   up (sigaltstack is unavailable or fails) and a SIGSEGV is
+   generated when the normal stack is exhausted then the program
+   will behave as though no SIGSEGV handler was installed.  */
+class alternate_signal_stack
+{
+public:
+  alternate_signal_stack ()
+  {
+#ifdef HAVE_SIGALTSTACK
+    m_stack.reset ((char *) xmalloc (SIGSTKSZ));
+
+    stack_t stack;
+    stack.ss_sp = m_stack.get ();
+    stack.ss_size = SIGSTKSZ;
+    stack.ss_flags = 0;
+
+    sigaltstack (&stack, &m_old_stack);
+#endif
+  }
+
+  ~alternate_signal_stack ()
+  {
+#ifdef HAVE_SIGALTSTACK
+    sigaltstack (&m_old_stack, nullptr);
+#endif
+  }
+
+  DISABLE_COPY_AND_ASSIGN (alternate_signal_stack);
+
+private:
+
+#ifdef HAVE_SIGALTSTACK
+  gdb::unique_xmalloc_ptr<char> m_stack;
+  stack_t m_old_stack;
+#endif
+};
+
+}
+
+#endif /* GDBSUPPORT_ALT_STACK_H */