Improvements to libtest

Signed-off-by: Mattias Andrée <m@maandree.se>

1 files changed, 102 insertions, 0 deletions

diff --git a/libtest/libtest_stack_on_signal.c b/libtest/libtest_stack_on_signal.c
new file mode 100644
index 0000000..0f92972
--- /dev/null
+++ b/libtest/libtest_stack_on_signal.c
@@ -0,0 +1,102 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+#ifndef TEST
+
+# ifdef WITH_BACKTRACE
+
+
+static void
+stack_dumper(int sig, siginfo_t *info, void *ucontext)
+{
+	(void) sig;
+	(void) info;
+	libtest_print_backtrace(stderr, "crashed at ", "        by ", 0u, NULL, ucontext);
+}
+
+
+static stack_t ss;
+static size_t have_ss = 0u;
+
+
+static void
+create_altstack(void)
+{
+	if (have_ss++)
+		return;
+	ss.ss_sp = libtest_real_mmap(NULL, (size_t)SIGSTKSZ, PROT_READ | PROT_WRITE,
+	                             MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	assert(ss.ss_sp != MAP_FAILED);
+	ss.ss_size = (size_t)SIGSTKSZ;
+	ss.ss_flags = 0;
+	assert(!sigaltstack(&ss, NULL));
+}
+
+
+static void
+destroy_altstack(void)
+{
+	if (--have_ss)
+		return;
+	assert(!libtest_real_munmap(ss.ss_sp, ss.ss_size));
+}
+
+
+void
+libtest_stack_on_signal(int signo, struct sigaction *old_out)
+{
+	struct sigaction sa;
+
+	create_altstack();
+
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_sigaction = &stack_dumper;
+	sa.sa_flags = (int)(SA_RESETHAND | SA_SIGINFO);
+	if (have_ss)
+		sa.sa_flags |= SA_ONSTACK;
+	sigfillset(&sa.sa_mask);
+
+	assert(!sigaction(signo, &sa, old_out));
+}
+
+
+void
+libtest_stop_stack_on_signal(int signo, const struct sigaction *old)
+{
+	assert(!sigaction(signo, old, NULL));
+	destroy_altstack();
+}
+
+
+#else
+
+
+void
+libtest_stack_on_signal(int signo, struct sigaction *old_out)
+{
+	(void) signo;
+	(void) old_out;
+}
+
+void
+libtest_stop_stack_on_signal(int signo, const struct sigaction *old)
+{
+	(void) signo;
+	(void) old;
+}
+
+
+# endif
+
+
+#else
+
+
+CONST int
+main(void)
+{
+	/* How would one even test this, and what would be the point? */
+	return 0;
+}
+
+
+#endif