[PATCH v2 1/4] kbuild: make sha256sum command available generally

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

We currently use the command only for generation a SHA256 sum of the
barebox proper binary. In preparation for using it in othe Makefiles
as well, move it to a central location and use the occasion to give
it a short comment.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
v1 -> v2:
  - no change
---
 images/Makefile      |  7 -------
 scripts/Makefile.lib | 11 +++++++++++
 2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/images/Makefile b/images/Makefile
index 7a8bb94fe0df..218a24ff1ddd 100644
--- a/images/Makefile
+++ b/images/Makefile
@@ -112,13 +112,6 @@ $(obj)/piggy.o: $(obj)/barebox.z FORCE
 
 $(obj)/sha_sum.o: $(obj)/barebox.sha.bin FORCE
 
-quiet_cmd_sha256bin ?= SHA-BIN $@
-      cmd_sha256bin = printf "$(shell sed 's/ .*$$//;s/../0x&\n/g;s/\n$$//' $(obj)/barebox.sum | \
-			while read -r byte; do printf '\%o' $$byte; done)" > $@
-
-quiet_cmd_sha256sum ?= SHA     $@
-      cmd_sha256sum ?= sha256sum $(obj)/barebox.z > $@
-
 $(obj)/barebox.sha.bin: $(obj)/barebox.sum FORCE
 	$(call if_changed,sha256bin)
 
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 46042dab3c8f..16308497b845 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -272,6 +272,17 @@ cmd_ld = $(LD) $(KBUILD_LDFLAGS) $(EXTRA_LDFLAGS) $(LDFLAGS_$(@F)) \
 quiet_cmd_objcopy = OBJCOPY $@
 cmd_objcopy = $(OBJCOPY) $(OBJCOPYFLAGS) $(OBJCOPYFLAGS_$(@F)) $< $@
 
+# Hashing
+# ---------------------------------------------------------------------------
+# POSIX printf (e.g. dash's) doesn't support \xHH, but octal sequences are fine
+
+quiet_cmd_sha256bin ?= SHA-BIN $@
+      cmd_sha256bin = printf "$(shell sed 's/ .*$$//;s/../0x&\n/g;s/\n$$//' $< | \
+			while read -r byte; do printf '\%o' $$byte; done)" > $@
+
+quiet_cmd_sha256sum ?= SHA     $@
+      cmd_sha256sum ?= sha256sum $< > $@
+
 # Decompressor for barebox proper binary when using PBL
 # ---------------------------------------------------------------------------
 
-- 
2.30.2