git-merge-fredrik.py

   1 #!/usr/bin/python
   2
   3 import sys, math, random, os, re, signal, tempfile, stat, errno, traceback
   4 from heapq import heappush, heappop
   5 from sets import Set
   6
   7 sys.path.append('@@GIT_PYTHON_PATH@@')
   8 from gitMergeCommon import *
   9
  10 alwaysWriteTree = False
  11
  12 # The actual merge code
  13 # ---------------------
  14
  15 def merge(h1, h2, branch1Name, branch2Name, graph, callDepth=0):
  16     '''Merge the commits h1 and h2, return the resulting virtual
  17     commit object and a flag indicating the cleaness of the merge.'''
  18     assert(isinstance(h1, Commit) and isinstance(h2, Commit))
  19     assert(isinstance(graph, Graph))
  20
  21     def infoMsg(*args):
  22         sys.stdout.write('  '*callDepth)
  23         printList(args)
  24     infoMsg('Merging:')
  25     infoMsg(h1)
  26     infoMsg(h2)
  27     sys.stdout.flush()
  28
  29     ca = getCommonAncestors(graph, h1, h2)
  30     infoMsg('found', len(ca), 'common ancestor(s):')
  31     for x in ca:
  32         infoMsg(x)
  33     sys.stdout.flush()
  34
  35     Ms = ca[0]
  36     for h in ca[1:]:
  37         [Ms, ignore] = merge(Ms, h,
  38                              'Temporary shared merge branch 1',
  39                              'Temporary shared merge branch 2',
  40                              graph, callDepth+1)
  41         assert(isinstance(Ms, Commit))
  42
  43     if callDepth == 0:
  44         if len(ca) > 1:
  45             runProgram(['git-read-tree', h1.tree()])
  46             runProgram(['git-update-cache', '-q', '--refresh'])
  47         # Use the original index if we only have one common ancestor
  48
  49         updateWd = True
  50         if alwaysWriteTree:
  51             cleanCache = True
  52         else:
  53             cleanCache = False
  54     else:
  55         runProgram(['git-read-tree', h1.tree()])
  56         updateWd = False
  57         cleanCache = True
  58
  59     [shaRes, clean] = mergeTrees(h1.tree(), h2.tree(), Ms.tree(),
  60                                  branch1Name, branch2Name,
  61                                  cleanCache, updateWd)
  62
  63     if clean or cleanCache:
  64         res = Commit(None, [h1, h2], tree=shaRes)
  65         graph.addNode(res)
  66     else:
  67         res = None
  68
  69     return [res, clean]
  70
  71 getFilesRE = re.compile('([0-9]+) ([a-z0-9]+) ([0-9a-f]{40})\t(.*)')
  72 def getFilesAndDirs(tree):
  73     files = Set()
  74     dirs = Set()
  75     out = runProgram(['git-ls-tree', '-r', '-z', tree])
  76     for l in out.split('\0'):
  77         m = getFilesRE.match(l)
  78         if m:
  79             if m.group(2) == 'tree':
  80                 dirs.add(m.group(4))
  81             elif m.group(2) == 'blob':
  82                 files.add(m.group(4))
  83
  84     return [files, dirs]
  85
  86 class CacheEntry:
  87     def __init__(self, path):
  88         class Stage:
  89             def __init__(self):
  90                 self.sha1 = None
  91                 self.mode = None
  92
  93         self.stages = [Stage(), Stage(), Stage()]
  94         self.path = path
  95
  96 unmergedRE = re.compile('^([0-9]+) ([0-9a-f]{40}) ([1-3])\t(.*)$')
  97 def unmergedCacheEntries():
  98     '''Create a dictionary mapping file names to CacheEntry
  99     objects. The dictionary contains one entry for every path with a
 100     non-zero stage entry.'''
 101
 102     lines = runProgram(['git-ls-files', '-z', '--unmerged']).split('\0')
 103     lines.pop()
 104
 105     res = {}
 106     for l in lines:
 107         m = unmergedRE.match(l)
 108         if m:
 109             mode = int(m.group(1), 8)
 110             sha1 = m.group(2)
 111             stage = int(m.group(3)) - 1
 112             path = m.group(4)
 113
 114             if res.has_key(path):
 115                 e = res[path]
 116             else:
 117                 e = CacheEntry(path)
 118                 res[path] = e
 119
 120             e.stages[stage].mode = mode
 121             e.stages[stage].sha1 = sha1
 122         else:
 123             die('Error: Merge program failed: Unexpected output from', \
 124                 'git-ls-files:', l)
 125     return res
 126
 127 def mergeTrees(head, merge, common, branch1Name, branch2Name,
 128                cleanCache, updateWd):
 129     '''Merge the trees 'head' and 'merge' with the common ancestor
 130     'common'. The name of the head branch is 'branch1Name' and the name of
 131     the merge branch is 'branch2Name'. Return a tuple (tree, cleanMerge)
 132     where tree is the resulting tree and cleanMerge is True iff the
 133     merge was clean.'''
 134
 135     assert(isSha(head) and isSha(merge) and isSha(common))
 136
 137     if common == merge:
 138         print 'Already uptodate!'
 139         return [head, True]
 140
 141     if updateWd:
 142         updateArg = '-u'
 143     else:
 144         updateArg = '-i'
 145     runProgram(['git-read-tree', updateArg, '-m', common, head, merge])
 146     cleanMerge = True
 147
 148     [tree, code] = runProgram('git-write-tree', returnCode=True)
 149     tree = tree.rstrip()
 150     if code != 0:
 151         [files, dirs] = getFilesAndDirs(head)
 152         [filesM, dirsM] = getFilesAndDirs(merge)
 153         files.union_update(filesM)
 154         dirs.union_update(dirsM)
 155
 156         cleanMerge = True
 157         entries = unmergedCacheEntries()
 158         for name in entries:
 159             if not processEntry(entries[name], branch1Name, branch2Name,
 160                                 files, dirs, cleanCache, updateWd):
 161                 cleanMerge = False
 162
 163         if cleanMerge or cleanCache:
 164             tree = runProgram('git-write-tree').rstrip()
 165         else:
 166             tree = None
 167     else:
 168         cleanMerge = True
 169
 170     return [tree, cleanMerge]
 171
 172 def processEntry(entry, branch1Name, branch2Name, files, dirs,
 173                  cleanCache, updateWd):
 174     '''Merge one cache entry. 'files' is a Set with the files in both of
 175     the heads that we are going to merge. 'dirs' contains the
 176     corresponding data for directories. If 'cleanCache' is True no
 177     non-zero stages will be left in the cache for the path
 178     corresponding to the entry 'entry'.'''
 179
 180 # cleanCache == True  => Don't leave any non-stage 0 entries in the cache.
 181 #               False => Leave unmerged entries
 182
 183 # updateWd  == True  => Update the working directory to correspond to the cache
 184 #              False => Leave the working directory unchanged
 185
 186 # clean     == True  => non-conflict case
 187 #              False => conflict case
 188
 189 # If cleanCache == False then the cache shouldn't be updated if clean == False
 190
 191     def updateFile(clean, sha, mode, path):
 192         if cleanCache or (not cleanCache and clean):
 193             runProgram(['git-update-cache', '--add', '--cacheinfo',
 194                         '0%o' % mode, sha, path])
 195
 196         if updateWd:
 197             prog = ['git-cat-file', 'blob', sha]
 198             if stat.S_ISREG(mode):
 199                 try:
 200                     os.unlink(path)
 201                 except OSError:
 202                     pass
 203                 if mode & 0100:
 204                     mode = 0777
 205                 else:
 206                     mode = 0666
 207                 fd = os.open(path, os.O_WRONLY | os.O_TRUNC | os.O_CREAT, mode)
 208                 proc = subprocess.Popen(prog, stdout=fd)
 209                 proc.wait()
 210                 os.close(fd)
 211             elif stat.S_ISLNK(mode):
 212                 linkTarget = runProgram(prog)
 213                 os.symlink(linkTarget, path)
 214             else:
 215                 assert(False)
 216             runProgram(['git-update-cache', '--', path])
 217
 218     def removeFile(clean, path):
 219         if cleanCache or (not cleanCache and clean):
 220             runProgram(['git-update-cache', '--force-remove', '--', path])
 221
 222         if updateWd:
 223             try:
 224                 os.unlink(path)
 225             except OSError, e:
 226                 if e.errno != errno.ENOENT and e.errno != errno.EISDIR:
 227                     raise
 228
 229     def uniquePath(path, branch):
 230         newPath = path + '_' + branch
 231         suffix = 0
 232         while newPath in files or newPath in dirs:
 233             suffix += 1
 234             newPath = path + '_' + branch + '_' + str(suffix)
 235         files.add(newPath)
 236         return newPath
 237
 238     debug('processing', entry.path, 'clean cache:', cleanCache,
 239           'wd:', updateWd)
 240
 241     cleanMerge = True
 242
 243     path = entry.path
 244     oSha = entry.stages[0].sha1
 245     oMode = entry.stages[0].mode
 246     aSha = entry.stages[1].sha1
 247     aMode = entry.stages[1].mode
 248     bSha = entry.stages[2].sha1
 249     bMode = entry.stages[2].mode
 250
 251     assert(oSha == None or isSha(oSha))
 252     assert(aSha == None or isSha(aSha))
 253     assert(bSha == None or isSha(bSha))
 254
 255     assert(oMode == None or type(oMode) is int)
 256     assert(aMode == None or type(aMode) is int)
 257     assert(bMode == None or type(bMode) is int)
 258
 259     if (oSha and (not aSha or not bSha)):
 260     #
 261     # Case A: Deleted in one
 262     #
 263         if (not aSha     and not bSha) or \
 264            (aSha == oSha and not bSha) or \
 265            (not aSha     and bSha == oSha):
 266     # Deleted in both or deleted in one and unchanged in the other
 267             if aSha:
 268                 print 'Removing ' + path
 269             removeFile(True, path)
 270         else:
 271     # Deleted in one and changed in the other
 272             cleanMerge = False
 273             if not aSha:
 274                 print 'CONFLICT (del/mod): "' + path + '" deleted in', \
 275                       branch1Name, 'and modified in', branch2Name, \
 276                       '. Version', branch2Name, ' of "' + path + \
 277                       '" left in tree'
 278                 mode = bMode
 279                 sha = bSha
 280             else:
 281                 print 'CONFLICT (mod/del): "' + path + '" deleted in', \
 282                       branch2Name, 'and modified in', branch1Name + \
 283                       '. Version', branch1Name, 'of "' + path + \
 284                       '" left in tree'
 285                 mode = aMode
 286                 sha = aSha
 287
 288             updateFile(False, sha, mode, path)
 289
 290     elif (not oSha and aSha     and not bSha) or \
 291          (not oSha and not aSha and bSha):
 292     #
 293     # Case B: Added in one.
 294     #
 295         if aSha:
 296             addBranch = branch1Name
 297             otherBranch = branch2Name
 298             mode = aMode
 299             sha = aSha
 300             conf = 'file/dir'
 301         else:
 302             addBranch = branch2Name
 303             otherBranch = branch1Name
 304             mode = bMode
 305             sha = bSha
 306             conf = 'dir/file'
 307
 308         if path in dirs:
 309             cleanMerge = False
 310             newPath = uniquePath(path, addBranch)
 311             print 'CONFLICT (' + conf + \
 312                   '): There is a directory with name "' + path + '" in', \
 313                   otherBranch + '. Adding "' + path + '" as "' + newPath + '"'
 314
 315             removeFile(False, path)
 316             path = newPath
 317         else:
 318             print 'Adding "' + path + '"'
 319
 320         updateFile(True, sha, mode, path)
 321
 322     elif not oSha and aSha and bSha:
 323     #
 324     # Case C: Added in both (check for same permissions).
 325     #
 326         if aSha == bSha:
 327             if aMode != bMode:
 328                 cleanMerge = False
 329                 print 'CONFLICT: File "' + path + \
 330                       '" added identically in both branches,'
 331                 print 'CONFLICT: but permissions conflict', '0%o' % aMode, \
 332                       '->', '0%o' % bMode
 333                 print 'CONFLICT: adding with permission:', '0%o' % aMode
 334
 335                 updateFile(False, aSha, aMode, path)
 336             else:
 337                 # This case is handled by git-read-tree
 338                 assert(False)
 339         else:
 340             cleanMerge = False
 341             newPath1 = uniquePath(path, branch1Name)
 342             newPath2 = uniquePath(path, branch2Name)
 343             print 'CONFLICT (add/add): File "' + path + \
 344                   '" added non-identically in both branches.', \
 345                   'Adding "' + newPath1 + '" and "' + newPath2 + '" instead.'
 346             removeFile(False, path)
 347             updateFile(False, aSha, aMode, newPath1)
 348             updateFile(False, bSha, bMode, newPath2)
 349
 350     elif oSha and aSha and bSha:
 351     #
 352     # case D: Modified in both, but differently.
 353     #
 354         print 'Auto-merging', path
 355         orig = runProgram(['git-unpack-file', oSha]).rstrip()
 356         src1 = runProgram(['git-unpack-file', aSha]).rstrip()
 357         src2 = runProgram(['git-unpack-file', bSha]).rstrip()
 358         [out, ret] = runProgram(['merge',
 359                                  '-L', branch1Name + '/' + path,
 360                                  '-L', 'orig/' + path,
 361                                  '-L', branch2Name + '/' + path,
 362                                  src1, orig, src2], returnCode=True)
 363
 364         if aMode == oMode:
 365             mode = bMode
 366         else:
 367             mode = aMode
 368
 369         sha = runProgram(['git-hash-object', '-t', 'blob', '-w',
 370                           src1]).rstrip()
 371
 372         if ret != 0:
 373             cleanMerge = False
 374             print 'CONFLICT (content): Merge conflict in "' + path + '".'
 375             updateFile(False, sha, mode, path)
 376         else:
 377             updateFile(True, sha, mode, path)
 378
 379         os.unlink(orig)
 380         os.unlink(src1)
 381         os.unlink(src2)
 382     else:
 383         die("ERROR: Fatal merge failure, shouldn't happen.")
 384
 385     return cleanMerge
 386
 387 def usage():
 388     die('Usage:', sys.argv[0], ' <base>... -- <head> <remote>..')
 389
 390 # main entry point as merge strategy module
 391 # The first parameters up to -- are merge bases, and the rest are heads.
 392 # This strategy module figures out merge bases itself, so we only
 393 # get heads.
 394
 395 if len(sys.argv) < 4:
 396     usage()
 397
 398 for nextArg in xrange(1, len(sys.argv)):
 399     if sys.argv[nextArg] == '--':
 400         if len(sys.argv) != nextArg + 3:
 401             die('Not handling anything other than two heads merge.')
 402         try:
 403             h1 = firstBranch = sys.argv[nextArg + 1]
 404             h2 = secondBranch = sys.argv[nextArg + 2]
 405         except IndexError:
 406             usage()
 407         break
 408
 409 print 'Merging', h1, 'with', h2
 410
 411 try:
 412     h1 = runProgram(['git-rev-parse', '--verify', h1 + '^0']).rstrip()
 413     h2 = runProgram(['git-rev-parse', '--verify', h2 + '^0']).rstrip()
 414
 415     graph = buildGraph([h1, h2])
 416
 417     [res, clean] = merge(graph.shaMap[h1], graph.shaMap[h2],
 418                          firstBranch, secondBranch, graph)
 419
 420     print ''
 421 except:
 422     traceback.print_exc(None, sys.stderr)
 423     sys.exit(2)
 424
 425 if clean:
 426     sys.exit(0)
 427 else:
 428     print 'Automatic merge failed, fix up by hand'
 429     sys.exit(1)