stable-steal-commits

#!/bin/bash
#
# Try to grab commits from one stable tree into another, stopping to fix
# backports if required.
#

function pick_one {

	# Let's try cherry-picking the given commit first.
	git cherry-pick --strategy=recursive -Xpatience -x $1 &> /dev/null
	if [ $? -gt "0" ]; then
		git reset --hard
		# That didn't work? Let's try that with every variation of the commit
		# in other stable trees.
		for i in $(stable-find-alts $1); do
			git cherry-pick --strategy=recursive -Xpatience -x $i &> /dev/null
			if [ $? = "0" ]; then
				return 0
			fi
			git reset --hard
		done

		# Still no? Let's go back to the original commit and hand it off to
		# the user.
		git cherry-pick --strategy=recursive -Xpatience -x $1 &> /dev/null
	fi

	return $?
}

function check_relevant {
	cmt=$1
	maj=0
	min=0

	# Let's grab the commit that this commit fixes (if exists (based on the "Fixes:" tag)).
	fixescmt=`git show $cmt | grep -i "fixes:" | head -n 1 | sed -e 's/^[ \t]*//' | cut -f 2 -d ':' | sed -e 's/^[ \t]*//' | cut -f 1 -d ' '`

	# If this commit fixes anything, but the broken commit isn't in our branch we don't
	# need this commit either.
	if [ "$fixescmt" != "" ] && [ "$(stable-commit-in-tree $fixescmt)" = "1" ]; then
		return 0
	fi

	# Let's see if there's a version tag in this commit
	full=$(git show $cmt | grep -i 'stable@vger')
	full=$(echo ${full##* } | tr -cd '[[:digit:]]._-' | sed 's/]//g' | sed 's/\[//g' | sed 's/\./ /g')

	maj=$(echo $full | awk {"print \$1"})
	min=$(echo $full | awk {"print \$2"})  

	# Sanity check our extraction
	if [ "$(echo ${full##* } | grep 'stable' | wc -l)" -gt "0" ]; then
		return 1
	fi

	# Sanity check major version
	if [ "$maj" != "2" ] && [ "$maj" != "3" ] && [ "$maj" != "4" ]; then
		return 1
	fi

	# If the version tag is for a major version newer than ours
	if [ "STABLE_MAJ_VER" -gt "$maj" ]; then
		return 1
	fi

	# Or if the overall version is newer than ours
	if [ "STABLE_MAJ_VER" -eq "$maj" ] && [ "STABLE_MIN_VER" -ge "$min" ]; then
		return 1
	fi

	# No version tag, unsure, or version tag is older than ours
	return 0
}

function do_one {
	for i in $(git log --no-merges --format="%H" $1 $2 | tac); do
		subj=$(git log -1 --format="%s" $i)

		# Let's grab the mainline commit id, this is useful if the version tag
		# doesn't exist in the commit we're looking at but exists upstream.
		orig_cmt=$(git log --no-merges --format="%H" -F --grep "$subj" origin/master | tail -n1)

		# If the commit doesn't apply for us, skip it
		check_relevant $orig_cmt
		if [ $? -eq "0" ]; then
			continue
		fi

		pick_one $i
		if [ $? -gt 0 ] ; then
			echo "Cherry pick failed. Fix, commit (or reset) and exit."
			/bin/sh
			continue
		fi

		# If we didn't find the commit upstream then this must be a custom commit
		# in the given tree - make sure the user checks this commit.
		if [ "$orig_cmt" = "" ] ; then
			msg="Custom"
			orig_cmt=$(git rev-parse HEAD)
			echo "Custom commit, please double-check!"
			/bin/sh
		fi
		stable-make-pretty $orig_cmt $msg
	done
}

if [ "$#" -ne 1 ] && [ "$#" -ne 2 ]; then
        echo "Usage: stable steal-commits <commit range> [branch]"
        exit 1
fi

do_one $1 $2