Use mktemp when generating the archive

Instead of manually making a temporary directory, do it through
'mktemp', which feels cleaner.

Moreover, the base directory will now by named 'fbos' instead of the
cryptic 'tmp' one. This is quite relevant when you uncompress the
archive into another machine.

Signed-off-by: Miquel Sabaté Solà <[email protected]>

Makefile

@@ -63,7 +63,6 @@ KRNL    = fbos
 USR     = usr/bin/init usr/bin/fizz usr/bin/buzz usr/bin/fizzbuzz
 INIT    = usr/initramfs.cpio
 TESTS   = test/test_dt test/test_initrd
-TMP     = tmp/
 ARCHIVE = fbos.tar.gz
 
 LDFLAGS += -T $(LINKER)
@@ -134,11 +133,10 @@ test/%: test/%.o
 
 .PHONY: archive
 archive: all
-	$(Q) rm -rf $(TMP) && mkdir -p $(TMP)
-	$(Q) cp -r usr/ $(TMP) && rm -r $(TMP)/usr/src
-	$(Q) cp $(KRNL) $(TMP)
-	$(Q) tar czf $(ARCHIVE) $(TMP)
-	$(Q) rm -rf $(TMP)
+	$(Q) $(eval DIR := $(shell mktemp -d))
+	$(Q) mkdir -p $(DIR)/fbos && cp $(KRNL) $(INIT) $(DIR)/fbos/
+	$(Q) cd $(DIR) && tar czf $(ARCHIVE) fbos/
+	$(Q) cp $(DIR)/$(ARCHIVE) .
 	$(E) "	TAR	 $(ARCHIVE)"
 
 ##
@@ -158,7 +156,7 @@ gdb:
 
 .PHONY: clean
 clean:
-	$(Q) rm -rf $(OBJ) $(KRNL) $(LINKER) $(USR) usr/src/*.o $(INIT) test/*.o test/lib/*.o $(TESTS) $(TMP) $(ARCHIVE)
+	$(Q) rm -rf $(OBJ) $(KRNL) $(LINKER) $(USR) usr/src/*.o $(INIT) test/*.o test/lib/*.o $(TESTS) $(ARCHIVE)
 
 .PHONY: lint
 lint: