[openwrt/openwrt] rules: add AUTORELEASE and COMMITCOUNT variables

[LEDE Commits]

aparcar pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/9ae3c6f94c616cfbf854d3ec749c7fafc9893942

commit 9ae3c6f94c616cfbf854d3ec749c7fafc9893942
Author: Paul Spooren <mail at aparcar.org>
AuthorDate: Fri Jan 1 14:02:12 2021 -1000

    rules: add AUTORELEASE and COMMITCOUNT variables
    
    The lack of bumped PKG_RELEASE variables is a recurring theme on the
    mailing list and in GitHub comments. This costs precious review time,
    a rare good within the OpenWrt project.
    
    Instead of relying on a manually set PKG_RELEASE this commit adds a
    `commitcount` function that uses the number of Git commits to determine
    the release. The function is called via the variables `$(AUTORELEASE)`
    or `$(COMMITCOUNT)`. The `PKG_RELEASE` variable can be set to either of
    the two.
    
    - $(AUTORELEASE):
    
    Release is automagically set to the number of commits since the last
    commit containing either ": update to " or ": bump to ".
    
    Example below:
    
        $ git log packages/foobar/
        foobar: fixup file location
        foobar: disable docs
        foobar: bump to 5.3.2
        foobar: fixup copyright
    
    Resulting package name: foobar_5.3.2-3_all.ipk, two package changes
    since the last upstream version change, using a 1 based counter.
    
    - $(COMMITCOUNT):
    
    For non-traditional versioning (x.y.z), most prominent `base-files`,
    this variable contains the total number of package commits.
    
    The new functionality can also be used by other feeds like packages.git.
    
    In case no build information is available, e.g. when using release
    tarballs, the SOURCE_DATE_EPOCH is used to have a reproducible release
    identifier.
    
    Suggested-by: Daniel Golle <daniel at makrotopia.org>
    Signed-off-by: Paul Spooren <mail at aparcar.org>
---
 rules.mk | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/rules.mk b/rules.mk
index f79340b124..cf4aa30d21 100644
--- a/rules.mk
+++ b/rules.mk
@@ -408,6 +408,32 @@ endef
 # file extension
 ext=$(word $(words $(subst ., ,$(1))),$(subst ., ,$(1)))
 
+# Count Git commits of a package
+# $(1) => if non-empty: count commits since last ": [uU]pdate to " or ": [bB]ump to " in commit message
+define commitcount
+$(shell \
+  if git log -1 >/dev/null 2>/dev/null; then \
+    if [ -n "$(1)" ]; then \
+      last_bump="$$(git log --pretty=format:'%h %s' . | \
+        grep --max-count=1 -e ': [uU]pdate to ' -e ': [bB]ump to ' | \
+        cut -f 1 -d ' ')"; \
+    fi; \
+    if [ -n "$$last_bump" ]; then \
+      echo -n $$(($$(git rev-list --count "$$last_bump..HEAD" .) + 1)); \
+    else \
+      echo -n $$(($$(git rev-list --count HEAD .) + 1)); \
+    fi; \
+  else \
+    secs="$$(($(SOURCE_DATE_EPOCH) % 86400))"; \
+    date="$$(date --utc --date="@$(SOURCE_DATE_EPOCH)" "+%y%m%d")"; \
+    printf '%s.%05d' "$$date" "$$secs"; \
+  fi; \
+)
+endef
+
+COMMITCOUNT = $(if $(DUMP),,$(call commitcount))
+AUTORELEASE = $(if $(DUMP),,$(call commitcount,1))
+
 all:
 FORCE: ;
 .PHONY: FORCE