Add simplified mmap() and munmap() syscalls.

Userland/.gitignore

@@ -1,4 +1,5 @@
 id
 sh
 ps
+ls
 *.o

Userland/Makefile

@@ -1,12 +1,14 @@
 OBJS = \
        id.o \
        sh.o \
-       ps.o
+       ps.o \
+       ls.o
 
 APPS = \
        id \
        sh \
-       ps
+       ps \
+       ls
 
 ARCH_FLAGS =
 STANDARD_FLAGS = -std=c++17 -nostdinc++ -nostdlib
@@ -35,6 +37,9 @@ sh: sh.o
 ps: ps.o
 	$(LD) -o $@ $(LDFLAGS) $< ../LibC/LibC.a
 
+ls: ls.o
+	$(LD) -o $@ $(LDFLAGS) $< ../LibC/LibC.a
+
 .cpp.o:
 	@echo "CXX $<"; $(CXX) $(CXXFLAGS) -o $@ -c $<
 

Userland/ls.cpp

@@ -0,0 +1,21 @@
+#include <LibC/stdio.h>
+#include <LibC/unistd.h>
+#include <LibC/mman.h>
+
+int main(int c, char** v)
+{
+    int fd = open("/");
+    if (fd == -1) {
+        printf("failed to open / :(\n");
+        return 1;
+    }
+
+    byte* memory = (byte*)mmap(nullptr, 16384);
+    printf("%p\n", memory);
+    memory[0] = 'H';
+    memory[1] = 'i';
+    memory[2] = '!';
+    memory[3] = '\0';
+    printf("%p : %s\n", memory, memory);
+    return 0;
+}