[openwrt/openwrt] build: make find_md5 reproducible with AUTOREMOVE

[LEDE Commits]

ansuel pushed a commit to openwrt/openwrt.git, branch openwrt-21.02:
https://git.openwrt.org/360d756fbf01e0a051ff47223523deffae647afa

commit 360d756fbf01e0a051ff47223523deffae647afa
Author: Christian Marangi <ansuelsmth at gmail.com>
AuthorDate: Tue Sep 6 16:48:37 2022 +0200

    build: make find_md5 reproducible with AUTOREMOVE
    
    While experimenting with the AUTOREMOVE option in search of a way to use
    prebuilt host tools in different buildroot, it was discovered that the
    md5 generated by find_md5 in depends.mk is not reproducible.
    
    Currently the hash is generated by the path of the file in addition to
    the file mod time. Out of confusion, probably, there was an idea that
    such command was used on the package build_dir. Reality is that this
    command is run on the package files. (Makefile, patches, src)
    
    This is problematic because the package Makefile (for example) change at
    each git clone and base the hash on the Makefile mtime doesn't really
    reflect if the Makefile actually changes across a buildroot or not.
    
    A better approach is to generate an hash of each file and then generate
    an hash on the sort hash list. This way we remove the problem of git
    clone setting a wrong mtime while keeping the integrity of checking if a
    file changed for the package as any change will result in a different
    hash.
    
    Introduce a new kind of find_md5 function, find_md5_reproducible that
    apply this new logic and limit it only with AUTOREMOVE option set to
    prevent any kind of slowdown due to additional hash generation.
    
    (cherry picked from commit 53a08e37437972ba0a8fbf953a93a70a6b784ef4)
    [ reworked mkhash to old implementation ]
    Signed-off-by: Christian Marangi <ansuelsmth at gmail.com>
---
 include/depends.mk      | 1 +
 include/host-build.mk   | 2 +-
 include/kernel-build.mk | 2 +-
 include/package.mk      | 2 +-
 4 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/include/depends.mk b/include/depends.mk
index 0080b97876..7b87f2643f 100644
--- a/include/depends.mk
+++ b/include/depends.mk
@@ -12,6 +12,7 @@
 DEP_FINDPARAMS := -x "*/.svn*" -x ".*" -x "*:*" -x "*\!*" -x "* *" -x "*\\\#*" -x "*/.*_check" -x "*/.*.swp" -x "*/.pkgdir*"
 
 find_md5=find $(wildcard $(1)) -type f $(patsubst -x,-and -not -path,$(DEP_FINDPARAMS) $(2)) -printf "%p%T@\n" | sort | mkhash md5
+find_md5_reproducible=find $(wildcard $(1)) -type f $(patsubst -x,-and -not -path,$(DEP_FINDPARAMS) $(2)) -print0 | xargs -0 mkhash md5 | sort | mkhash md5
 
 define rdep
   .PRECIOUS: $(2)
diff --git a/include/host-build.mk b/include/host-build.mk
index e4a5c48e72..36b3fed1f3 100644
--- a/include/host-build.mk
+++ b/include/host-build.mk
@@ -21,7 +21,7 @@ include $(INCLUDE_DIR)/depends.mk
 include $(INCLUDE_DIR)/quilt.mk
 
 BUILD_TYPES += host
-HOST_STAMP_PREPARED=$(HOST_BUILD_DIR)/.prepared$(if $(HOST_QUILT)$(DUMP),,$(shell $(call find_md5,${CURDIR} $(PKG_FILE_DEPENDS),))_$(call confvar,CONFIG_AUTOREMOVE $(HOST_PREPARED_DEPENDS)))
+HOST_STAMP_PREPARED=$(HOST_BUILD_DIR)/.prepared$(if $(HOST_QUILT)$(DUMP),,$(shell $(call $(if $(CONFIG_AUTOREMOVE),find_md5_reproducible,find_md5),${CURDIR} $(PKG_FILE_DEPENDS),))_$(call confvar,CONFIG_AUTOREMOVE $(HOST_PREPARED_DEPENDS)))
 HOST_STAMP_CONFIGURED:=$(HOST_BUILD_DIR)/.configured
 HOST_STAMP_BUILT:=$(HOST_BUILD_DIR)/.built
 HOST_BUILD_PREFIX?=$(if $(IS_PACKAGE_BUILD),$(STAGING_DIR_HOSTPKG),$(STAGING_DIR_HOST))
diff --git a/include/kernel-build.mk b/include/kernel-build.mk
index 66a9f64c80..1f440f9ee0 100644
--- a/include/kernel-build.mk
+++ b/include/kernel-build.mk
@@ -10,7 +10,7 @@ ifneq ($(DUMP),1)
 endif
 
 KERNEL_FILE_DEPENDS=$(GENERIC_BACKPORT_DIR) $(GENERIC_PATCH_DIR) $(GENERIC_HACK_DIR) $(PATCH_DIR) $(GENERIC_FILES_DIR) $(FILES_DIR)
-STAMP_PREPARED=$(LINUX_DIR)/.prepared$(if $(QUILT)$(DUMP),,_$(shell $(call find_md5,$(KERNEL_FILE_DEPENDS),)))
+STAMP_PREPARED=$(LINUX_DIR)/.prepared$(if $(QUILT)$(DUMP),,_$(shell $(call $(if $(CONFIG_AUTOREMOVE),find_md5_reproducible,find_md5),$(KERNEL_FILE_DEPENDS),)))
 STAMP_CONFIGURED:=$(LINUX_DIR)/.configured
 include $(INCLUDE_DIR)/download.mk
 include $(INCLUDE_DIR)/quilt.mk
diff --git a/include/package.mk b/include/package.mk
index db0a869dab..389ba4243b 100644
--- a/include/package.mk
+++ b/include/package.mk
@@ -84,7 +84,7 @@ ifneq ($(PREV_STAMP_PREPARED),)
   STAMP_PREPARED:=$(PREV_STAMP_PREPARED)
   CONFIG_AUTOREBUILD:=
 else
-  STAMP_PREPARED=$(PKG_BUILD_DIR)/.prepared$(if $(QUILT)$(DUMP),,_$(shell $(call find_md5,${CURDIR} $(PKG_FILE_DEPENDS),))_$(call confvar,CONFIG_AUTOREMOVE $(PKG_PREPARED_DEPENDS)))
+  STAMP_PREPARED=$(PKG_BUILD_DIR)/.prepared$(if $(QUILT)$(DUMP),,_$(shell $(call $(if $(CONFIG_AUTOREMOVE),find_md5_reproducible,find_md5),${CURDIR} $(PKG_FILE_DEPENDS),))_$(call confvar,CONFIG_AUTOREMOVE $(PKG_PREPARED_DEPENDS)))
 endif
 STAMP_CONFIGURED=$(PKG_BUILD_DIR)/.configured$(if $(DUMP),,_$(call confvar,$(PKG_CONFIG_DEPENDS)))
 STAMP_CONFIGURED_WILDCARD=$(PKG_BUILD_DIR)/.configured_*