1 files changed, 71 insertions, 0 deletions
diff --git a/libsbutil/sb_gdb.c b/libsbutil/sb_gdb.c
new file mode 100644
index 0000000..6112379
--- /dev/null
+++ b/libsbutil/sb_gdb.c
@@ -0,0 +1,71 @@
+/*
+ * sb_gdb.c
+ *
+ * Helpers for autolaunching gdb.
+ *
+ * Copyright 1999-2012 Gentoo Foundation
+ * Licensed under the GPL-2
+ */
+
+#include "headers.h"
+#include "sbutil.h"
+
+static int __sb_connect_gdb(void *vpid)
+{
+	char pid[10];
+	snprintf(pid, sizeof(pid), "%i", (pid_t)(uintptr_t)vpid);
+	unsetenv(ENV_LD_PRELOAD);
+	return /*sb_unwrapped_*/execlp("gdb", "gdb",
+		"--quiet",
+		"--pid", pid,
+		"-ex", "set _gdb_poller = 0",
+		"-ex", "fin",
+		"-ex", "bt full",
+		"-ex", "echo \\n",
+		"-ex", "f",
+		NULL);
+}
+
+#define STACK_SIZE 4096
+
+#ifndef HAVE_CLONE
+# ifdef HAVE___CLONE2
+/* Hrm, maybe they have clone2 */
+#  define clone(fn, stack, flags, arg) \
+	__clone2(fn, stack, STACK_SIZE, flags, arg, NULL, NULL, NULL)
+# else
+/* Fake it with fork() ... not as safe, but not much else we can do */
+static int fake_clone(int (*fn)(void *), void *child_stack, int flags, void *arg)
+{
+	pid_t pid = fork();
+	switch (pid) {
+	case 0:
+		_exit(fn(arg));
+	default:
+		return pid;
+	}
+}
+#  define clone(...) fake_clone(__VA_ARGS__)
+# endif
+#endif
+
+void sb_gdb(void)
+{
+	char stack[STACK_SIZE * 2];
+	pid_t pid = getpid();
+	/* Put the child stack in the middle so we don't have to worry about
+	 * the direction of growth.  Most grown down, but some grow up!@
+	 */
+	if (clone(__sb_connect_gdb, stack + STACK_SIZE, 0, (void *)(uintptr_t)pid) != -1) {
+		volatile int _gdb_poller = 1;
+		while (_gdb_poller);
+	}
+}
+
+void sb_maybe_gdb(void)
+{
+	if (is_env_on("SANDBOX_GDB")) {
+		sb_einfo("attempting to autolaunch gdb; please wait ...\n\n");
+		sb_gdb();
+	}
+}