contrib/devtools/github-merge.py

   1 #!/usr/bin/env python3
   2 # Copyright (c) 2016-2017 Bitcoin Core Developers
   3 # Distributed under the MIT software license, see the accompanying
   4 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
   5
   6 # This script will locally construct a merge commit for a pull request on a
   7 # github repository, inspect it, sign it and optionally push it.
   8
   9 # The following temporary branches are created/overwritten and deleted:
  10 # * pull/$PULL/base (the current master we're merging onto)
  11 # * pull/$PULL/head (the current state of the remote pull request)
  12 # * pull/$PULL/merge (github's merge)
  13 # * pull/$PULL/local-merge (our merge)
  14
  15 # In case of a clean merge that is accepted by the user, the local branch with
  16 # name $BRANCH is overwritten with the merged result, and optionally pushed.
  17 from __future__ import division,print_function,unicode_literals
  18 import os
  19 from sys import stdin,stdout,stderr
  20 import argparse
  21 import hashlib
  22 import subprocess
  23 import json,codecs
  24 try:
  25     from urllib.request import Request,urlopen
  26 except:
  27     from urllib2 import Request,urlopen
  28
  29 # External tools (can be overridden using environment)
  30 GIT = os.getenv('GIT','git')
  31 BASH = os.getenv('BASH','bash')
  32
  33 # OS specific configuration for terminal attributes
  34 ATTR_RESET = ''
  35 ATTR_PR = ''
  36 COMMIT_FORMAT = '%h %s (%an)%d'
  37 if os.name == 'posix': # if posix, assume we can use basic terminal escapes
  38     ATTR_RESET = '\033[0m'
  39     ATTR_PR = '\033[1;36m'
  40     COMMIT_FORMAT = '%C(bold blue)%h%Creset %s %C(cyan)(%an)%Creset%C(green)%d%Creset'
  41
  42 def git_config_get(option, default=None):
  43     '''
  44     Get named configuration option from git repository.
  45     '''
  46     try:
  47         return subprocess.check_output([GIT,'config','--get',option]).rstrip().decode('utf-8')
  48     except subprocess.CalledProcessError as e:
  49         return default
  50
  51 def retrieve_pr_info(repo,pull):
  52     '''
  53     Retrieve pull request information from github.
  54     Return None if no title can be found, or an error happens.
  55     '''
  56     try:
  57         req = Request("https://api.github.com/repos/"+repo+"/pulls/"+pull)
  58         result = urlopen(req)
  59         reader = codecs.getreader('utf-8')
  60         obj = json.load(reader(result))
  61         return obj
  62     except Exception as e:
  63         print('Warning: unable to retrieve pull information from github: %s' % e)
  64         return None
  65
  66 def ask_prompt(text):
  67     print(text,end=" ",file=stderr)
  68     stderr.flush()
  69     reply = stdin.readline().rstrip()
  70     print("",file=stderr)
  71     return reply
  72
  73 def get_symlink_files():
  74     files = sorted(subprocess.check_output([GIT, 'ls-tree', '--full-tree', '-r', 'HEAD']).splitlines())
  75     ret = []
  76     for f in files:
  77         if (int(f.decode('utf-8').split(" ")[0], 8) & 0o170000) == 0o120000:
  78             ret.append(f.decode('utf-8').split("\t")[1])
  79     return ret
  80
  81 def tree_sha512sum(commit='HEAD'):
  82     # request metadata for entire tree, recursively
  83     files = []
  84     blob_by_name = {}
  85     for line in subprocess.check_output([GIT, 'ls-tree', '--full-tree', '-r', commit]).splitlines():
  86         name_sep = line.index(b'\t')
  87         metadata = line[:name_sep].split() # perms, 'blob', blobid
  88         assert(metadata[1] == b'blob')
  89         name = line[name_sep+1:]
  90         files.append(name)
  91         blob_by_name[name] = metadata[2]
  92
  93     files.sort()
  94     # open connection to git-cat-file in batch mode to request data for all blobs
  95     # this is much faster than launching it per file
  96     p = subprocess.Popen([GIT, 'cat-file', '--batch'], stdout=subprocess.PIPE, stdin=subprocess.PIPE)
  97     overall = hashlib.sha512()
  98     for f in files:
  99         blob = blob_by_name[f]
 100         # request blob
 101         p.stdin.write(blob + b'\n')
 102         p.stdin.flush()
 103         # read header: blob, "blob", size
 104         reply = p.stdout.readline().split()
 105         assert(reply[0] == blob and reply[1] == b'blob')
 106         size = int(reply[2])
 107         # hash the blob data
 108         intern = hashlib.sha512()
 109         ptr = 0
 110         while ptr < size:
 111             bs = min(65536, size - ptr)
 112             piece = p.stdout.read(bs)
 113             if len(piece) == bs:
 114                 intern.update(piece)
 115             else:
 116                 raise IOError('Premature EOF reading git cat-file output')
 117             ptr += bs
 118         dig = intern.hexdigest()
 119         assert(p.stdout.read(1) == b'\n') # ignore LF that follows blob data
 120         # update overall hash with file hash
 121         overall.update(dig.encode("utf-8"))
 122         overall.update("  ".encode("utf-8"))
 123         overall.update(f)
 124         overall.update("\n".encode("utf-8"))
 125     p.stdin.close()
 126     if p.wait():
 127         raise IOError('Non-zero return value executing git cat-file')
 128     return overall.hexdigest()
 129
 130 def print_merge_details(pull, title, branch, base_branch, head_branch):
 131     print('%s#%s%s %s %sinto %s%s' % (ATTR_RESET+ATTR_PR,pull,ATTR_RESET,title,ATTR_RESET+ATTR_PR,branch,ATTR_RESET))
 132     subprocess.check_call([GIT,'log','--graph','--topo-order','--pretty=format:'+COMMIT_FORMAT,base_branch+'..'+head_branch])
 133
 134 def parse_arguments():
 135     epilog = '''
 136         In addition, you can set the following git configuration variables:
 137         githubmerge.repository (mandatory),
 138         user.signingkey (mandatory),
 139         githubmerge.host (default: git@github.com),
 140         githubmerge.branch (no default),
 141         githubmerge.testcmd (default: none).
 142     '''
 143     parser = argparse.ArgumentParser(description='Utility to merge, sign and push github pull requests',
 144             epilog=epilog)
 145     parser.add_argument('pull', metavar='PULL', type=int, nargs=1,
 146         help='Pull request ID to merge')
 147     parser.add_argument('branch', metavar='BRANCH', type=str, nargs='?',
 148         default=None, help='Branch to merge against (default: githubmerge.branch setting, or base branch for pull, or \'master\')')
 149     return parser.parse_args()
 150
 151 def main():
 152     # Extract settings from git repo
 153     repo = git_config_get('githubmerge.repository')
 154     host = git_config_get('githubmerge.host','git@github.com')
 155     opt_branch = git_config_get('githubmerge.branch',None)
 156     testcmd = git_config_get('githubmerge.testcmd')
 157     signingkey = git_config_get('user.signingkey')
 158     if repo is None:
 159         print("ERROR: No repository configured. Use this command to set:", file=stderr)
 160         print("git config githubmerge.repository <owner>/<repo>", file=stderr)
 161         exit(1)
 162     if signingkey is None:
 163         print("ERROR: No GPG signing key set. Set one using:",file=stderr)
 164         print("git config --global user.signingkey <key>",file=stderr)
 165         exit(1)
 166
 167     host_repo = host+":"+repo # shortcut for push/pull target
 168
 169     # Extract settings from command line
 170     args = parse_arguments()
 171     pull = str(args.pull[0])
 172
 173     # Receive pull information from github
 174     info = retrieve_pr_info(repo,pull)
 175     if info is None:
 176         exit(1)
 177     title = info['title'].strip()
 178     # precedence order for destination branch argument:
 179     #   - command line argument
 180     #   - githubmerge.branch setting
 181     #   - base branch for pull (as retrieved from github)
 182     #   - 'master'
 183     branch = args.branch or opt_branch or info['base']['ref'] or 'master'
 184
 185     # Initialize source branches
 186     head_branch = 'pull/'+pull+'/head'
 187     base_branch = 'pull/'+pull+'/base'
 188     merge_branch = 'pull/'+pull+'/merge'
 189     local_merge_branch = 'pull/'+pull+'/local-merge'
 190
 191     devnull = open(os.devnull,'w')
 192     try:
 193         subprocess.check_call([GIT,'checkout','-q',branch])
 194     except subprocess.CalledProcessError as e:
 195         print("ERROR: Cannot check out branch %s." % (branch), file=stderr)
 196         exit(3)
 197     try:
 198         subprocess.check_call([GIT,'fetch','-q',host_repo,'+refs/pull/'+pull+'/*:refs/heads/pull/'+pull+'/*'])
 199     except subprocess.CalledProcessError as e:
 200         print("ERROR: Cannot find pull request #%s on %s." % (pull,host_repo), file=stderr)
 201         exit(3)
 202     try:
 203         subprocess.check_call([GIT,'log','-q','-1','refs/heads/'+head_branch], stdout=devnull, stderr=stdout)
 204     except subprocess.CalledProcessError as e:
 205         print("ERROR: Cannot find head of pull request #%s on %s." % (pull,host_repo), file=stderr)
 206         exit(3)
 207     try:
 208         subprocess.check_call([GIT,'log','-q','-1','refs/heads/'+merge_branch], stdout=devnull, stderr=stdout)
 209     except subprocess.CalledProcessError as e:
 210         print("ERROR: Cannot find merge of pull request #%s on %s." % (pull,host_repo), file=stderr)
 211         exit(3)
 212     try:
 213         subprocess.check_call([GIT,'fetch','-q',host_repo,'+refs/heads/'+branch+':refs/heads/'+base_branch])
 214     except subprocess.CalledProcessError as e:
 215         print("ERROR: Cannot find branch %s on %s." % (branch,host_repo), file=stderr)
 216         exit(3)
 217     subprocess.check_call([GIT,'checkout','-q',base_branch])
 218     subprocess.call([GIT,'branch','-q','-D',local_merge_branch], stderr=devnull)
 219     subprocess.check_call([GIT,'checkout','-q','-b',local_merge_branch])
 220
 221     try:
 222         # Go up to the repository's root.
 223         toplevel = subprocess.check_output([GIT,'rev-parse','--show-toplevel']).strip()
 224         os.chdir(toplevel)
 225         # Create unsigned merge commit.
 226         if title:
 227             firstline = 'Merge #%s: %s' % (pull,title)
 228         else:
 229             firstline = 'Merge #%s' % (pull,)
 230         message = firstline + '\n\n'
 231         message += subprocess.check_output([GIT,'log','--no-merges','--topo-order','--pretty=format:%h %s (%an)',base_branch+'..'+head_branch]).decode('utf-8')
 232         try:
 233             subprocess.check_call([GIT,'merge','-q','--commit','--no-edit','--no-ff','-m',message.encode('utf-8'),head_branch])
 234         except subprocess.CalledProcessError as e:
 235             print("ERROR: Cannot be merged cleanly.",file=stderr)
 236             subprocess.check_call([GIT,'merge','--abort'])
 237             exit(4)
 238         logmsg = subprocess.check_output([GIT,'log','--pretty=format:%s','-n','1']).decode('utf-8')
 239         if logmsg.rstrip() != firstline.rstrip():
 240             print("ERROR: Creating merge failed (already merged?).",file=stderr)
 241             exit(4)
 242
 243         symlink_files = get_symlink_files()
 244         for f in symlink_files:
 245             print("ERROR: File %s was a symlink" % f)
 246         if len(symlink_files) > 0:
 247             exit(4)
 248
 249         # Put tree SHA512 into the message
 250         try:
 251             first_sha512 = tree_sha512sum()
 252             message += '\n\nTree-SHA512: ' + first_sha512
 253         except subprocess.CalledProcessError as e:
 254             printf("ERROR: Unable to compute tree hash")
 255             exit(4)
 256         try:
 257             subprocess.check_call([GIT,'commit','--amend','-m',message.encode('utf-8')])
 258         except subprocess.CalledProcessError as e:
 259             printf("ERROR: Cannot update message.",file=stderr)
 260             exit(4)
 261
 262         print_merge_details(pull, title, branch, base_branch, head_branch)
 263         print()
 264
 265         # Run test command if configured.
 266         if testcmd:
 267             if subprocess.call(testcmd,shell=True):
 268                 print("ERROR: Running %s failed." % testcmd,file=stderr)
 269                 exit(5)
 270
 271             # Show the created merge.
 272             diff = subprocess.check_output([GIT,'diff',merge_branch+'..'+local_merge_branch])
 273             subprocess.check_call([GIT,'diff',base_branch+'..'+local_merge_branch])
 274             if diff:
 275                 print("WARNING: merge differs from github!",file=stderr)
 276                 reply = ask_prompt("Type 'ignore' to continue.")
 277                 if reply.lower() == 'ignore':
 278                     print("Difference with github ignored.",file=stderr)
 279                 else:
 280                     exit(6)
 281         else:
 282             # Verify the result manually.
 283             print("Dropping you on a shell so you can try building/testing the merged source.",file=stderr)
 284             print("Run 'git diff HEAD~' to show the changes being merged.",file=stderr)
 285             print("Type 'exit' when done.",file=stderr)
 286             if os.path.isfile('/etc/debian_version'): # Show pull number on Debian default prompt
 287                 os.putenv('debian_chroot',pull)
 288             subprocess.call([BASH,'-i'])
 289
 290         second_sha512 = tree_sha512sum()
 291         if first_sha512 != second_sha512:
 292             print("ERROR: Tree hash changed unexpectedly",file=stderr)
 293             exit(8)
 294
 295         # Sign the merge commit.
 296         print_merge_details(pull, title, branch, base_branch, head_branch)
 297         while True:
 298             reply = ask_prompt("Type 's' to sign off on the above merge, or 'x' to reject and exit.").lower()
 299             if reply == 's':
 300                 try:
 301                     subprocess.check_call([GIT,'commit','-q','--gpg-sign','--amend','--no-edit'])
 302                     break
 303                 except subprocess.CalledProcessError as e:
 304                     print("Error signing, exiting.",file=stderr)
 305                     exit(1)
 306             elif reply == 'x':
 307                 print("Not signing off on merge, exiting.",file=stderr)
 308                 exit(1)
 309
 310         # Put the result in branch.
 311         subprocess.check_call([GIT,'checkout','-q',branch])
 312         subprocess.check_call([GIT,'reset','-q','--hard',local_merge_branch])
 313     finally:
 314         # Clean up temporary branches.
 315         subprocess.call([GIT,'checkout','-q',branch])
 316         subprocess.call([GIT,'branch','-q','-D',head_branch],stderr=devnull)
 317         subprocess.call([GIT,'branch','-q','-D',base_branch],stderr=devnull)
 318         subprocess.call([GIT,'branch','-q','-D',merge_branch],stderr=devnull)
 319         subprocess.call([GIT,'branch','-q','-D',local_merge_branch],stderr=devnull)
 320
 321     # Push the result.
 322     while True:
 323         reply = ask_prompt("Type 'push' to push the result to %s, branch %s, or 'x' to exit without pushing." % (host_repo,branch)).lower()
 324         if reply == 'push':
 325             subprocess.check_call([GIT,'push',host_repo,'refs/heads/'+branch])
 326             break
 327         elif reply == 'x':
 328             exit(1)
 329
 330 if __name__ == '__main__':
 331     main()
 332