Add support for removing directories.

It's really only supported in Ext2FS since SynthFS doesn't really want you
mucking around with its files. This is pretty neat though :^)

I ran into some trouble with HashMap while working on this but opted to work
around it and leave that for a separate investigation.

Userland/.gitignore

@@ -26,3 +26,4 @@ guitest2
 sysctl
 rm
 cp
+rmdir

Userland/Makefile

@@ -23,6 +23,7 @@ OBJS = \
        guitest2.o \
        sysctl.o \
        cp.o \
+       rmdir.o \
        rm.o
 
 APPS = \
@@ -51,6 +52,7 @@ APPS = \
        guitest2 \
        sysctl \
        cp \
+       rmdir \
        rm
 
 ARCH_FLAGS =
@@ -149,6 +151,9 @@ cp: cp.o
 rm: rm.o
 	$(LD) -o $@ $(LDFLAGS) $< ../LibC/LibC.a
 
+rmdir: rmdir.o
+	$(LD) -o $@ $(LDFLAGS) $< ../LibC/LibC.a
+
 .cpp.o:
 	@echo "CXX $<"; $(CXX) $(CXXFLAGS) -o $@ -c $<
 

Userland/rmdir.cpp

@@ -0,0 +1,18 @@
+#include <stdio.h>
+#include <errno.h>
+#include <unistd.h>
+
+int main(int argc, char** argv)
+{
+    if (argc != 2) {
+        fprintf(stderr, "usage: rmdir <path>\n");
+        return 1;
+    }
+    int rc = rmdir(argv[1]);
+    if (rc < 0) {
+        perror("rmdir");
+        return 1;
+    }
+    return 0;
+}
+