libc: Implement getuid, geteuid, getgid, getegid

libs/libc/include/unistd.h

@@ -38,6 +38,18 @@ extern "C"
     /* Returns the current process' parent's process ID. */
     pid_t getppid(void);
 
+    /* Returns the current process' real user ID. */
+    uid_t getuid(void);
+
+    /* Returns the current process' effective user ID. */
+    uid_t geteuid(void);
+
+    /* Returns the current process' real group ID. */
+    gid_t getgid(void);
+
+    /* Returns the current process' effective group ID. */
+    gid_t getegid(void);
+
     /* Terminates the program with the status code status. */
     __lc_noreturn void _exit(int status);
 

libs/libc/src/unistd.cpp

@@ -38,6 +38,26 @@ extern "C"
         return getprocid(ID_PPID);
     }
 
+    uid_t getuid(void)
+    {
+        return (uid_t)getprocid(ID_UID);
+    }
+
+    uid_t geteuid(void)
+    {
+        return (uid_t)getprocid(ID_EUID);
+    }
+
+    gid_t getgid(void)
+    {
+        return (gid_t)getprocid(ID_GID);
+    }
+
+    gid_t getegid(void)
+    {
+        return (gid_t)getprocid(ID_EGID);
+    }
+
     unsigned int sleep(unsigned int seconds)
     {
         return msleep(seconds * 1000);