Add is_writable() function to check whether a path is writable or not

src/includes/rc-misc.h

@@ -36,6 +36,7 @@
 #include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
 
 #define RC_LEVEL_BOOT           "boot"
 #define RC_LEVEL_DEFAULT        "default"
@@ -166,6 +167,12 @@ int svc_lock(const char *);
 int svc_unlock(const char *, int);
 pid_t exec_service(const char *, const char *);
 
+/*
+ * Check whether path is writable or not,
+ * this also works properly with read-only filesystems
+ */
+int is_writable(const char *);
+
 #define service_start(service) exec_service(service, "start");
 #define service_stop(service)  exec_service(service, "stop");
 

src/rc/rc-misc.c

@@ -331,3 +331,12 @@ parse_mode(mode_t *mode, char *text)
 	errno = EINVAL;
 	return -1;
 }
+
+int
+is_writable(const char *path)
+{
+	if (access(path, W_OK) == 0)
+		return 1;
+
+	return 0;
+}