git学习--commit-msg缺失导致的missing Change-Id问题分析

一.简介

commit-msg hook

这个hook由’git commit’触发, 且可以通过

--no-verify

来略过.它接受一个参数, 包含commit msg的文件的路径.如果以非0状态退出, ‘git commit’ 将会被取消.这个hook可以用于修改message(信息)文件, 用来匹配项目的规范格式(如果有的话).也可以用于校验commit msg,并在必要时拒绝提交.缺省的’commit-msg’ hook, 当启用时,将检查重复的”Signed-off-by”行, 如果找到,则取消commit.

二.问题情景

当执行git add “file”添加到暂存器，然后执行git commit提交到本地库的时候，git需要在commit的时候在日志中写入一个唯一标识提交的SHA-1值，即是Change-Id值. git commit时会调用commit_msg脚本检查提交信息，以便在git push的时候能正常推送到远程库。此时调用默认目录下的commit_msg钩子脚本，默认目录为“.git/hooks/commit_msg”. 如果此目录下无commit_msg脚本则commit时提交日志中无ChangeId信息，则在git push的时候出错，无法正常吧改动上传到远程服务器。

如下为git push提交不成功出现的错误信息：

[分离头指针 fbea87a] 测试
1 file changed, 0 insertions(+), 0 deletions(-)
create mode 100644 ttt
HostName@TianTian-Dev-81222:~/Work/test/test0$ git push origin HEAD:refs/for/master
Counting objects: 3, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (2/2), done.
Writing objects: 100% (2/2), 223 bytes, done.
Total 2 (delta 0), reused 0 (delta 0)
remote: Processing changes: refs: 1, done
remote: ERROR: missing Change-Id in commit message footer
remote: Suggestion for commit message:
remote: ttt
remote:
remote: Change-Id: Ifbea87a6358d55a189528a5f501492c37bdfec21
remote:
remote: Hint: To automatically insert Change-Id, install the hook:
remote:   gitdir=$(git rev-parse --git-dir); scp -p -P 29418 HostName@192.168.77.11:hooks/commit-msg ${gitdir}/hooks/
remote:
remote:
To ssh://HostName@192.168.77.11:29418/test/test0
! [remote rejected] HEAD -> refs/for/master (missing Change-Id in commit message footer)
error: 无法推送一些引用到 'ssh://HostName@192.168.77.11:29418/test/test0'

三.解决方法

方法一：临时解决

1> 复制Change-Id: Ifbea87a6358d55a189528a5f501492c37bdfec21

2> 执行 gitdir=$(git rev-parse --git-dir); scp -p -P 29418 HostName@192.168.77.11:hooks/commit-msg ${gitdir}/hooks/  从服务器拷贝commit-msg脚本到.git/hooks/目录下

3> 执行git commit --amend重新修复提交，把第一步中的Change-Id: Ifbea87a6358d55a189528a5f501492c37bdfec21黏贴到提交日志的下一行。

4> 重新执行git push推送本地改动到远程服务器

方法二：永久解决

存放一个全局的钩子脚本配置，commit-msg可以从服务器上拷贝，也可以用已有仓库的commit-msg脚本。本方法采用脚本一次性解决。脚本命名为commit_msg_hook.sh,只要执行一次脚本然后重启shell生效。当用户运行git commit提交代码的时候会自动调用commit-msg脚本在提交日志中自动放入Change-Id信息，不在需要手工写入。脚本内容如下：

SERVER_PORT="29418"
###gerrit服务器ip地址，根据具体情况更改
SERVER_IP="192.168.77.11"
mkdir -p ~/.git_template/hooks
scp -p -P "$SERVER_PORT" "$SERVER_IP":hooks/commit-msg ~/.git_template/hooks
chmod u+x ~/.git_template/hooks/commit-msg
git config --global init.templatedir ~/.git_template
这里写代码片二.

四.commit_msg脚本解析

########################################

BEGIN： gerrit version v2.10版本的commit_msg钩子脚本如下：

########################################

#!/bin/sh
# From Gerrit Code Review 2.10
#
# 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.
#

unset GREP_OPTIONS

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

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

if test "false" = "`git config --bool --get gerrit.createChangeId`"
then
return
fi

# Does Change-Id: already exist? if so, exit (no change).
###grep参数-i, --ignore-case 忽略大小写方式查找以“Change-Id:”开头字符串###
if grep -i '^Change-Id:' "$MSG" >/dev/null
then
return
fi

id=`_gen_ChangeId`

###$$：Shell本身的PID（ProcessID）###
T="$MSG.tmp.$$"
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.
###awk的next用法在处理逐行读取文本方面很强大，next逐行读取文本###
/^#/ { 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 / {
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

########################################

END

########################################