Correctly handle relative paths for CPIO_FILE

Author: gsingh93

Makefile

@@ -246,6 +246,10 @@ INITRAMFS_DIR ?= $(ROOTFS_DIR)
 CPIO_FILE ?= $(ROOTFS_PARENT_DIR)/$$(basename $(INITRAMFS_DIR)).cpio.gz
 EXT4_SIZE ?= 1G
 
+# The user might set a relative path for `CPIO_FILE`, so we need to get the
+# absolute path, as we need to reference it after we've changed directories
+CPIO_FILE := $(shell realpath $(CPIO_FILE))
+
 $(ROOTFS_DIR):
 	mkdir -p $(ROOTFS_DIR)
 
@@ -269,14 +273,14 @@ ext4: | $(ROOTFS_DIR)
 
 .PHONY: cpio initramfs
 initramfs cpio: | $(INITRAMFS_DIR)
-	cd $(INITRAMFS_DIR) && find . -print0 \
-		| cpio --null --create --verbose --format=newc \
+	(cd $(INITRAMFS_DIR) && find . -print0 \
+		| cpio --null --create --verbose --format=newc) \
 		| gzip --best > $(CPIO_FILE)
 
 .PHONY: uncpio
 uncpio:
 	mkdir -p $(INITRAMFS_DIR)
-	cd $(INITRAMFS_DIR) && zcat ../$(CPIO_FILE) | cpio --extract --make-directories --format=newc --no-absolute-filenames
+	cd $(INITRAMFS_DIR) && zcat $(CPIO_FILE) | cpio --extract --make-directories --format=newc --no-absolute-filenames
 
 .PHONY: rootfs
 rootfs: ext4 cpio