meta: add fx.diagnostics namespace and assembly

the fx.diagnostics namespace includes a process class for starting and managing processes

fx.diagnostics/test/redirect.c

@@ -0,0 +1,44 @@
+#include <fx/diagnostics/process.h>
+
+int main(int argc, const char **argv)
+{
+	if (argc < 3) {
+		return -1;
+	}
+
+	const char *exec = argv[1];
+	const char *msg = argv[2];
+
+	fx_process_start_info info = {
+		.proc_args = NULL,
+		.proc_args_count = 0,
+		.proc_redirect_stdin = true,
+		.proc_file_name = exec,
+	};
+
+	fx_process *process = fx_process_create(&info);
+	if (!process) {
+		fprintf(stderr, "Process creation failed\n");
+		return -1;
+	}
+
+	fx_status status = fx_process_start(process);
+	if (!FX_OK(status)) {
+		fprintf(stderr,
+		        "Process creation failed: %s\n",
+		        fx_status_description(status));
+		return -1;
+	}
+
+#if 1
+	fx_stream *in = fx_process_get_stdin(process);
+	fx_stream_write_cstr(in, "Hello, world!\n", NULL);
+	fx_process_close_stdin(process);
+#endif
+
+	int result;
+	fx_process_wait(process, &result);
+	fx_process_unref(process);
+
+	return 0;
+}