MagiskSU rewrite for unified binary

misc.c

@@ -0,0 +1,54 @@
+/* misc.c - Miscellaneous stuffs for su
+ */
+
+#define _GNU_SOURCE
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <signal.h>
+#include <unistd.h>
+#include <sys/types.h>
+
+#include "magisk.h"
+#include "su.h"
+
+int quit_signals[] = { SIGALRM, SIGABRT, SIGHUP, SIGPIPE, SIGQUIT, SIGTERM, SIGINT, 0 };
+
+void setup_sighandlers(void (*handler)(int)) {
+	struct sigaction act;
+
+	// Install the termination handlers
+	// Note: we're assuming that none of these signal handlers are already trapped.
+	// If they are, we'll need to modify this code to save the previous handler and
+	// call it after we restore stdin to its previous state.
+	memset(&act, 0, sizeof(act));
+	act.sa_handler = handler;
+	for (int i = 0; quit_signals[i]; ++i) {
+		sigaction(quit_signals[i], &act, NULL);
+	}
+}
+
+void set_identity(unsigned uid) {
+	/*
+	 * Set effective uid back to root, otherwise setres[ug]id will fail
+	 * if uid isn't root.
+	 */
+	if (seteuid(0)) {
+		PLOGE("seteuid (root)");
+	}
+	if (setresgid(uid, uid, uid)) {
+		PLOGE("setresgid (%u)", uid);
+	}
+	if (setresuid(uid, uid, uid)) {
+		PLOGE("setresuid (%u)", uid);
+	}
+}
+
+char *get_command(const struct su_request *to) {
+	if (to->command)
+		return to->command;
+	if (to->shell)
+		return to->shell;
+	return DEFAULT_SHELL;
+}
+