GUID for gdisk: have Guix inject the hash of the inputs into the source tree

.gitignore

@@ -5,6 +5,9 @@
 /build/check_makefile
 /build/check_makefile_targets
 /build/check_makefile_w_arnings
+/build/gpt_disk_guid
+/build/gpt_partition_guid
+/build/input-hash
 /build/iso_files/boot/iso_boot.sys
 /build/iso_files/os.zip
 /build/makefile_built_directories

Makefile

@@ -70,6 +70,8 @@ ${bld}/makefile_w_arnings: | $${@D}
 ${built_files}: | $${@D}
 
 ${bld}/makefile_w_arnings: ${Makefiles}
+	test -e input-hash || printf "\033[1;31mWARNING: input-hash should be created by guix build.\033[m\n"
+
 	@unset MAKEFLAGS MAKELEVEL MAKE_TERMERR MFLAGS; \
 	   make -n --warn-undefined-variables \
 	        OS_FILENAME=${OS_FILENAME} \

Makefile.example-os

@@ -51,6 +51,9 @@ built_files += ${os_filename} \
                ${bld}/os.hex_with_offsets \
                ${bld}/iso_files/os.zip \
                ${bld}/iso_files/boot/iso_boot.sys \
+               ${bld}/input-hash \
+               ${bld}/gpt_disk_guid \
+               ${bld}/gpt_partition_guid \
                ${more_offset_dec} \
                ${more_offset_hex} \
 
@@ -221,12 +224,39 @@ ${bld}/os.zip.adjusted: ${bld}/os.zip ${dep_bytes_zip_start} ${bld}/check_makefi
 
 gdisk_pipe_commands_slowly=while read str; do echo "$$str"; printf "\033[1;33m%s\033[m\n" "$$str" >&2; sleep 0.01; done
 
-commit_hash_as_guid=$$((git log -1 --pretty=format:%H || echo 0000000000000000000000000000000000000000) | sed -e 's/^\(.\{8\}\)\(.\{4\}\)\(.\{4\}\)\(.\{4\}\)\(.\{12\}\).*$$/\1-\2-\3-\4-\5/' | tr '[:lower:]' '[:upper:]')
-git_dirty=test -n "$$(git diff --shortstat)"
-gpt_disk_guid=${commit_hash_as_guid}$$(if $$git_dirty; then printf '0'; else printf '2'; fi)
-gpt_partition_guid=${commit_hash_as_guid}$$(if $$git_dirty; then printf '1'; else printf '3'; fi)
+.PHONY: force-input-hash
+${bld}/input-hash: force-input-hash ${bld}/check_makefile
+# input-hash must be a 33 (or more) character-long hexadecimal hash of the
+# inputs.  It can be used to generate UUIDs for the generated disk image, for
+# example.
+#
+# We use `git log -1 --pretty=format:%H' to obtain the hash of the current
+# commit as a fallback, but we do not have access to that information
+# within a Guix build environment.
+	h=$$(  cat input-hash \
+	|| git log -1 --pretty=format:%H \
+	|| echo 0000000000000000000000000000000000000000 \
+	); \
+	if test "$$h" != "$$(cat $@ || echo '')"; then \
+	  echo "$$h" > "$@"; \
+	fi
+
+# The last digit is 1, to distinguish the disk GUID from the partition GUID
+${bld}/gpt_disk_guid: ${bld}/input-hash ${bld}/check_makefile
+	  cat $< \
+	| sed -e 's/^\(.\{8\}\)\(.\{4\}\)\(.\{4\}\)\(.\{4\}\)\(.\{11\}\).*$$/\1-\2-\3-\4-\51/' \
+	| tr '[:lower:]' '[:upper:]' \
+	> $@
+
+# The last digit is 2, to distinguish the disk GUID from the partition GUID
+${bld}/gpt_partition_guid: ${bld}/input-hash ${bld}/check_makefile
+	  cat $< \
+	| sed -e 's/^\(.\{8\}\)\(.\{4\}\)\(.\{4\}\)\(.\{4\}\)\(.\{11\}\).*$$/\1-\2-\3-\4-\52/' \
+	| tr '[:lower:]' '[:upper:]' \
+	> $@
 
 ${os_filename}: ${bld}/os.32k ${bld}/os.iso ${bld}/os.fat12 ${bld}/os.zip.adjusted \
+                ${bld}/gpt_disk_guid ${bld}/gpt_partition_guid \
                 ${dep_bytes_header_32k_start} \
                 ${dep_bytes_header_32k_size} \
                 ${dep_bytes_fat12_start} \
@@ -266,8 +296,8 @@ ${os_filename}: ${bld}/os.32k ${bld}/os.iso ${bld}/os.fat12 ${bld}/os.zip.adjust
 	 printf "1\nN\n"; \
 	 printf "01\nY\nN\n"; \
 	 printf "x\n"; \
-	 printf "g\n${gpt_disk_guid}\n"; \
-	 printf "c\n${gpt_partition_guid}\n"; \
+	 printf "g\n$$(cat ${bld}/gpt_disk_guid)\n"; \
+	 printf "c\n$$(cat ${bld}/gpt_partition_guid)\n"; \
 	 printf "p\no\nw\nY\n") | ${gdisk_pipe_commands_slowly} | gdisk $@
 # Inject MS-DOS newlines (CR+LF) and comments (":: ") in the GUID field of unused partition table entries,
 # so that the part that is to be skipped by MS-DOS does not form a line longer than the MS-DOS maximum

guix.scm

@@ -25,6 +25,8 @@
              (ice-9 popen)
              (ice-9 rdelim)
              (gnu packages version-control)
+             (gnu packages vim)
+             (gnu packages package-management)
              (gnu packages assembly)
              (gnu packages base)
              (gnu packages mtools)
@@ -75,6 +77,17 @@
       `(#:phases
         (modify-phases %standard-phases
           ;; unpack                ;; this phase is enabled
+          (add-after 'unpack 'compute-input-hash
+            (lambda* (#:key inputs #:allow-other-keys)
+              (invoke "sh" "-c"
+                (string-append
+                 "   guix hash -rx . --format=base32"
+                 " | tr '[:lower:]' '[:upper:]'"
+                 " | head -c 48"
+                 " | base32 -d"
+                 " | xxd -ps"
+                 " | head -c 60"
+                 " > input-hash"))))
           ;; patch-source-shebangs ;; this phase is enabled
           (add-after 'patch-source-shebangs 'make-clean
             (lambda* (#:key inputs #:allow-other-keys)
@@ -99,6 +112,8 @@
         (list "in-guix" ,makefile-commit-timestamp)))
      (native-inputs
       `(("git" ,git)
+        ("xxd" ,xxd)
+        ("guix" ,guix)
         ("nasm" ,nasm)
         ("which" ,which)
         ("mtools" ,mtools)