gerrit-change-id

#!/bin/sh
# From Gerrit Code Review 2.5.1
#
# Part of Gerrit Code Review (http://code.google.com/p/gerrit/)
#
# Copyright (C) 2009 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

CHANGE_ID_AFTER="Bug|Issue|Story"
MSG="$1"

# Check for, and add if missing, a unique Change-Id
#
add_ChangeId() {
        clean_message=`sed -e '
                /^diff --git a\/.*/{
                        s///
                        q
                }
                /^Signed-off-by:/d
                /^#/d
        ' "$MSG" | git stripspace`
        if test -z "$clean_message"
        then
                return
        fi

        # Does Change-Id: already exist? if so, exit (no change).
        if grep -i '^Change-Id:' "$MSG" >/dev/null
        then
                return
        fi

        id=`_gen_ChangeId`
        T="$MSG.tmp.$$"
        AWK=awk
        if [ -x /usr/xpg4/bin/awk ]; then
                # Solaris AWK is just too broken
                AWK=/usr/xpg4/bin/awk
        fi

        # How this works:
        # - parse the commit message as (textLine+ blankLine*)*
        # - assume textLine+ to be a footer until proven otherwise
        # - exception: the first block is not footer (as it is the title)
        # - read textLine+ into a variable
        # - then count blankLines
        # - once the next textLine appears, print textLine+ blankLine* as these
        #   aren't footer
        # - in END, the last textLine+ block is available for footer parsing
        $AWK '
        BEGIN {
                # while we start with the assumption that textLine+
                # is a footer, the first block is not.
                isFooter = 0
                footerComment = 0
                blankLines = 0
        }

        # Skip lines starting with "#" without any spaces before it.
        /^#/ { next }

        # Skip the line starting with the diff command and everything after it,
        # up to the end of the file, assuming it is only patch data.
        # If more than one line before the diff was empty, strip all but one.
        /^diff --git a/ {
                blankLines = 0
                while (getline) { }
                next
        }

        # Count blank lines outside footer comments
        /^$/ && (footerComment == 0) {
                blankLines++
                next
        }

        # Catch footer comment
        /^\[[a-zA-Z0-9-]+:/ && (isFooter == 1) {
                footerComment = 1
        }

        /]$/ && (footerComment == 1) {
                footerComment = 2
        }

        # We have a non-blank line after blank lines. Handle this.
        (blankLines > 0) {
                print lines
                for (i = 0; i < blankLines; i++) {
                        print ""
                }

                lines = ""
                blankLines = 0
                isFooter = 1
                footerComment = 0
        }

        # Detect that the current block is not the footer
        (footerComment == 0) && (!/^\[?[a-zA-Z0-9-]+:/ || /^[a-zA-Z0-9-]+:\/\//) {
                isFooter = 0
        }

        {
                # We need this information about the current last comment line
                if (footerComment == 2) {
                        footerComment = 0
                }
                if (lines != "") {
                        lines = lines "\n";
                }
                lines = lines $0
        }

        # Footer handling:
        # If the last block is considered a footer, splice in the Change-Id at the
        # right place.
        # Look for the right place to inject Change-Id by considering
        # CHANGE_ID_AFTER. Keys listed in it (case insensitive) come first,
        # then Change-Id, then everything else (eg. Signed-off-by:).
        #
        # Otherwise just print the last block, a new line and the Change-Id as a
        # block of its own.
        END {
                unprinted = 1
                if (isFooter == 0) {
                        print lines "\n"
                        lines = ""
                }
                changeIdAfter = "^(" tolower("'"$CHANGE_ID_AFTER"'") "):"
                numlines = split(lines, footer, "\n")
                for (line = 1; line <= numlines; line++) {
                        if (unprinted && match(tolower(footer[line]), changeIdAfter) != 1) {
                                unprinted = 0
                                print "Change-Id: I'"$id"'"
                        }
                        print footer[line]
                }
                if (unprinted) {
                        print "Change-Id: I'"$id"'"
                }
        }' "$MSG" > $T && mv $T "$MSG" || rm -f $T
}
_gen_ChangeIdInput() {
        echo "tree `git write-tree`"
        if parent=`git rev-parse "HEAD^0" 2>/dev/null`
        then
                echo "parent $parent"
        fi
        echo "author `git var GIT_AUTHOR_IDENT`"
        echo "committer `git var GIT_COMMITTER_IDENT`"
        echo
        printf '%s' "$clean_message"
}
_gen_ChangeId() {
        _gen_ChangeIdInput |
        git hash-object -t commit --stdin
}


add_ChangeId