Minor C cleanup (#27)

* Minor C cleanup

 - some symbols can be made static:
    1. set_gov_state
    2. everything in gamemode_client.h
 - daemonize() can also take a const char*, since the name is only
   passed to printf() or syslog()
 - prevent shadowing of variables
 - use explicit (void) as parameter-list more consistently
 - use some more const.
   Move cast to more appropriate place and document that execv() behaves
   as if args where of type const *char and we trust on that.
 - example: Just use main(void), which is also an acceptable ISO-C decl
 - example: Use stderr for errors

* Fix -Wold-style-declaration issue

daemon/cpugovctl.c

@@ -40,7 +40,7 @@ POSSIBILITY OF SUCH DAMAGE.
 /**
  * Sets all governors to a value
  */
-void set_gov_state(const char *value)
+static void set_gov_state(const char *value)
 {
 	char governors[MAX_GOVERNORS][MAX_GOVERNOR_LENGTH] = { { 0 } };
 	int num = fetch_governors(governors);

daemon/daemonize.c

@@ -39,7 +39,7 @@ POSSIBILITY OF SUCH DAMAGE.
 /**
  * Helper to perform standard UNIX daemonization
  */
-void daemonize(char *name)
+void daemonize(const char *name)
 {
 	/* Initial fork */
 	pid_t pid = fork();

daemon/daemonize.h

@@ -35,4 +35,4 @@ POSSIBILITY OF SUCH DAMAGE.
  * Attempt daemonization of the process.
  * If this fails, the process will exit
  */
-void daemonize(char *name);
+void daemonize(const char *name);

daemon/governors-query.c

@@ -77,7 +77,7 @@ int fetch_governors(char governors[MAX_GOVERNORS][MAX_GOVERNOR_LENGTH])
 		}
 
 		/* Only add this governor if it is unique */
-		for (int i = 0; i < num_governors; i++) {
+		for (int j = 0; j < num_governors; j++) {
 			if (strncmp(fullpath, governors[i], MAX_GOVERNOR_LENGTH) == 0) {
 				continue;
 			}
@@ -95,7 +95,7 @@ int fetch_governors(char governors[MAX_GOVERNORS][MAX_GOVERNOR_LENGTH])
 /**
  * Return the current governor state
  */
-const char *get_gov_state()
+const char *get_gov_state(void)
 {
 	/* Cached primary governor state */
 	static char governor[64] = { 0 };

daemon/governors.c

@@ -46,7 +46,7 @@ static const char *initial = NULL;
 /**
  * Cache the governor state as seen at startup
  */
-void update_initial_gov_state()
+void update_initial_gov_state(void)
 {
 	initial = get_gov_state();
 }
@@ -61,9 +61,9 @@ bool set_governors(const char *value)
 	int ret = 0;
 	int r = -1;
 
-	const char *govern = value ? value : initial;
-	char *exec_args[] = {
-		"/usr/bin/pkexec", LIBEXECDIR "/cpugovctl", "set", (char *)govern, NULL,
+	const char *const govern = value ? value : initial;
+	const char *const exec_args[] = {
+		"/usr/bin/pkexec", LIBEXECDIR "/cpugovctl", "set", govern, NULL,
 	};
 
 	LOG_MSG("Requesting update of governor policy to %s\n", govern);
@@ -73,7 +73,13 @@ bool set_governors(const char *value)
 		return false;
 	} else if (p == 0) {
 		/* Execute the command */
-		if ((r = execv(exec_args[0], exec_args)) != 0) {
+		/* Note about cast:
+		 *   The statement about argv[] and envp[] being constants is
+		 *   included to make explicit to future writers of language
+		 *   bindings that these objects are completely constant.
+		 * http://pubs.opengroup.org/onlinepubs/9699919799/functions/exec.html
+		 */
+		if ((r = execv(exec_args[0], (char *const *)exec_args)) != 0) {
 			LOG_ERROR("Failed to execute cpugovctl helper: %s %s\n", exec_args[1], strerror(errno));
 			exit(EXIT_FAILURE);
 		}
@@ -100,7 +106,7 @@ bool set_governors(const char *value)
 /**
  * Return the cached governor seen at startup
  */
-const char *get_initial_governor()
+const char *get_initial_governor(void)
 {
 	return initial;
 }

daemon/logging.c

@@ -47,7 +47,7 @@ void set_use_syslog(const char *name)
 /**
  *  Simple getter for the syslog var
  */
-bool get_use_syslog()
+bool get_use_syslog(void)
 {
 	return use_syslog;
 }