libc: Add getrusage()

libc/CMakeLists.txt

@@ -26,6 +26,7 @@ set(SOURCES
     src/sys/utsname.cpp
     src/sys/mount.cpp
     src/sys/pstat.cpp
+    src/sys/resource.cpp
 )
 
 if(${LUNA_ARCH} STREQUAL "x86_64")

libc/include/sys/resource.h

@@ -0,0 +1,20 @@
+/* sys/resource.h: System resource management. */
+
+#ifndef _SYS_RESOURCE_H
+#define _SYS_RESOURCE_H
+
+#include <bits/rusage.h>
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+    /* Get this process or its children's resource usage. */
+    int getrusage(int who, struct rusage* ru);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

libc/src/sys/resource.cpp

@@ -0,0 +1,13 @@
+#include <bits/errno-return.h>
+#include <sys/resource.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+extern "C"
+{
+    int getrusage(int who, struct rusage* ru)
+    {
+        long rc = syscall(SYS_getrusage, who, ru);
+        __errno_return(rc, int);
+    }
+}