Added signal tracing demo

CMakeLists.txt

@@ -494,6 +494,10 @@ if(CPPTRACE_BUILD_TESTING)
   endif()
 
   if(UNIX)
+    add_executable(signal_demo test/signal_demo.cpp)
+    target_compile_features(signal_demo PRIVATE cxx_std_11)
+    target_link_libraries(signal_demo PRIVATE ${target_name})
+
     add_executable(signal_tracer test/signal_tracer.cpp)
     target_compile_features(signal_tracer PRIVATE cxx_std_11)
     target_link_libraries(signal_tracer PRIVATE ${target_name})

test/signal_demo.cpp

@@ -0,0 +1,81 @@
+#include <cpptrace/cpptrace.hpp>
+
+#include <algorithm>
+#include <cctype>
+#include <iostream>
+#include <string>
+
+#include <sys/wait.h>
+#include <cstring>
+#include <signal.h>
+#include <csignal>
+#include <unistd.h>
+
+void trace() {
+    *(char*)0 = 2;
+}
+
+void bar() {
+    trace();
+}
+
+void foo() {
+    bar();
+}
+
+struct pipe_t {
+    union {
+        struct {
+            int read_end;
+            int write_end;
+        };
+        int data[2];
+    };
+};
+static_assert(sizeof(pipe_t) == 2 * sizeof(int), "Unexpected struct packing");
+
+void handler(int signo, siginfo_t* info, void* context) {
+    const char* message = "SIGSEGV ocurred:\n";
+    write(STDERR_FILENO, message, strlen(message));
+    cpptrace::frame_ptr buffer[100];
+    std::size_t count = cpptrace::safe_generate_raw_trace(buffer, 100);
+    pipe_t input_pipe;
+    pipe(input_pipe.data);
+    const pid_t pid = fork();
+    if(pid == -1) { return; }
+    if(pid == 0) { // child
+        dup2(input_pipe.read_end, STDIN_FILENO);
+        close(input_pipe.read_end);
+        close(input_pipe.write_end);
+        execl(
+            "signal_tracer",
+            "signal_tracer",
+            nullptr
+        );
+        _exit(1);
+    }
+    for(std::size_t i = 0; i < count; i++) {
+        cpptrace::minimal_object_frame frame;
+        cpptrace::get_minimal_object_frame(buffer[i], &frame);
+        write(input_pipe.write_end, &frame, sizeof(frame));
+    }
+    close(input_pipe.read_end);
+    close(input_pipe.write_end);
+    waitpid(pid, nullptr, 0);
+    _exit(1);
+}
+
+int main() {
+    cpptrace::absorb_trace_exceptions(false);
+    cpptrace::register_terminate_handler();
+
+    struct sigaction action = { 0 };
+    action.sa_flags = 0;
+    action.sa_sigaction = &handler;
+    if (sigaction(SIGSEGV, &action, NULL) == -1) {
+        perror("sigaction");
+        exit(EXIT_FAILURE);
+    }
+
+    foo();
+}