git_remote_helpers/git/git.py

   1 #!/usr/bin/env python
   2
   3 """Functionality for interacting with Git repositories.
   4
   5 This module provides classes for interfacing with a Git repository.
   6 """
   7
   8 import os
   9 import re
  10 import time
  11 from binascii import hexlify
  12 from cStringIO import StringIO
  13 import unittest
  14
  15 from git_remote_helpers.util import debug, error, die, start_command, run_command
  16
  17
  18 def get_git_dir ():
  19     """Return the path to the GIT_DIR for this repo."""
  20     args = ("git", "rev-parse", "--git-dir")
  21     exit_code, output, errors = run_command(args)
  22     if exit_code:
  23         die("Failed to retrieve git dir")
  24     assert not errors
  25     return output.strip()
  26
  27
  28 def parse_git_config ():
  29     """Return a dict containing the parsed version of 'git config -l'."""
  30     exit_code, output, errors = run_command(("git", "config", "-z", "-l"))
  31     if exit_code:
  32         die("Failed to retrieve git configuration")
  33     assert not errors
  34     return dict([e.split('\n', 1) for e in output.split("\0") if e])
  35
  36
  37 def git_config_bool (value):
  38     """Convert the given git config string value to True or False.
  39
  40     Raise ValueError if the given string was not recognized as a
  41     boolean value.
  42
  43     """
  44     norm_value = str(value).strip().lower()
  45     if norm_value in ("true", "1", "yes", "on", ""):
  46         return True
  47     if norm_value in ("false", "0", "no", "off", "none"):
  48         return False
  49     raise ValueError("Failed to parse '%s' into a boolean value" % (value))
  50
  51
  52 def valid_git_ref (ref_name):
  53     """Return True iff the given ref name is a valid git ref name."""
  54     # The following is a reimplementation of the git check-ref-format
  55     # command.  The rules were derived from the git check-ref-format(1)
  56     # manual page.  This code should be replaced by a call to
  57     # check_ref_format() in the git library, when such is available.
  58     if ref_name.endswith('/') or \
  59        ref_name.startswith('.') or \
  60        ref_name.count('/.') or \
  61        ref_name.count('..') or \
  62        ref_name.endswith('.lock'):
  63         return False
  64     for c in ref_name:
  65         if ord(c) < 0x20 or ord(c) == 0x7f or c in " ~^:?*[":
  66             return False
  67     return True
  68
  69
  70 class GitObjectFetcher(object):
  71
  72     """Provide parsed access to 'git cat-file --batch'.
  73
  74     This provides a read-only interface to the Git object database.
  75
  76     """
  77
  78     def __init__ (self):
  79         """Initiate a 'git cat-file --batch' session."""
  80         self.queue = []  # List of object names to be submitted
  81         self.in_transit = None  # Object name currently in transit
  82
  83         # 'git cat-file --batch' produces binary output which is likely
  84         # to be corrupted by the default "rU"-mode pipe opened by
  85         # start_command.  (Mode == "rU" does universal new-line
  86         # conversion, which mangles carriage returns.) Therefore, we
  87         # open an explicitly binary-safe pipe for transferring the
  88         # output from 'git cat-file --batch'.
  89         pipe_r_fd, pipe_w_fd = os.pipe()
  90         pipe_r = os.fdopen(pipe_r_fd, "rb")
  91         pipe_w = os.fdopen(pipe_w_fd, "wb")
  92         self.proc = start_command(("git", "cat-file", "--batch"),
  93                                   stdout = pipe_w)
  94         self.f = pipe_r
  95
  96     def __del__ (self):
  97         """Verify completed communication with 'git cat-file --batch'."""
  98         assert not self.queue
  99         assert self.in_transit is None
 100         self.proc.stdin.close()
 101         assert self.proc.wait() == 0  # Zero exit code
 102         assert self.f.read() == ""  # No remaining output
 103
 104     def _submit_next_object (self):
 105         """Submit queue items to the 'git cat-file --batch' process.
 106
 107         If there are items in the queue, and there is currently no item
 108         currently in 'transit', then pop the first item off the queue,
 109         and submit it.
 110
 111         """
 112         if self.queue and self.in_transit is None:
 113             self.in_transit = self.queue.pop(0)
 114             print >> self.proc.stdin, self.in_transit[0]
 115
 116     def push (self, obj, callback):
 117         """Push the given object name onto the queue.
 118
 119         The given callback function will at some point in the future
 120         be called exactly once with the following arguments:
 121         - self - this GitObjectFetcher instance
 122         - obj  - the object name provided to push()
 123         - sha1 - the SHA1 of the object, if 'None' obj is missing
 124         - t    - the type of the object (tag/commit/tree/blob)
 125         - size - the size of the object in bytes
 126         - data - the object contents
 127
 128         """
 129         self.queue.append((obj, callback))
 130         self._submit_next_object()  # (Re)start queue processing
 131
 132     def process_next_entry (self):
 133         """Read the next entry off the queue and invoke callback."""
 134         obj, cb = self.in_transit
 135         self.in_transit = None
 136         header = self.f.readline()
 137         if header == "%s missing\n" % (obj):
 138             cb(self, obj, None, None, None, None)
 139             return
 140         sha1, t, size = header.split(" ")
 141         assert len(sha1) == 40
 142         assert t in ("tag", "commit", "tree", "blob")
 143         assert size.endswith("\n")
 144         size = int(size.strip())
 145         data = self.f.read(size)
 146         assert self.f.read(1) == "\n"
 147         cb(self, obj, sha1, t, size, data)
 148         self._submit_next_object()
 149
 150     def process (self):
 151         """Process the current queue until empty."""
 152         while self.in_transit is not None:
 153             self.process_next_entry()
 154
 155     # High-level convenience methods:
 156
 157     def get_sha1 (self, objspec):
 158         """Return the SHA1 of the object specified by 'objspec'.
 159
 160         Return None if 'objspec' does not specify an existing object.
 161
 162         """
 163         class _ObjHandler(object):
 164             """Helper class for getting the returned SHA1."""
 165             def __init__ (self, parser):
 166                 self.parser = parser
 167                 self.sha1 = None
 168
 169             def __call__ (self, parser, obj, sha1, t, size, data):
 170                 # FIXME: Many unused arguments. Could this be cheaper?
 171                 assert parser == self.parser
 172                 self.sha1 = sha1
 173
 174         handler = _ObjHandler(self)
 175         self.push(objspec, handler)
 176         self.process()
 177         return handler.sha1
 178
 179     def open_obj (self, objspec):
 180         """Return a file object wrapping the contents of a named object.
 181
 182         The caller is responsible for calling .close() on the returned
 183         file object.
 184
 185         Raise KeyError if 'objspec' does not exist in the repo.
 186
 187         """
 188         class _ObjHandler(object):
 189             """Helper class for parsing the returned git object."""
 190             def __init__ (self, parser):
 191                 """Set up helper."""
 192                 self.parser = parser
 193                 self.contents = StringIO()
 194                 self.err = None
 195
 196             def __call__ (self, parser, obj, sha1, t, size, data):
 197                 """Git object callback (see GitObjectFetcher documentation)."""
 198                 assert parser == self.parser
 199                 if not sha1:  # Missing object
 200                     self.err = "Missing object '%s'" % obj
 201                 else:
 202                     assert size == len(data)
 203                     self.contents.write(data)
 204
 205         handler = _ObjHandler(self)
 206         self.push(objspec, handler)
 207         self.process()
 208         if handler.err:
 209             raise KeyError(handler.err)
 210         handler.contents.seek(0)
 211         return handler.contents
 212
 213     def walk_tree (self, tree_objspec, callback, prefix = ""):
 214         """Recursively walk the given Git tree object.
 215
 216         Recursively walk all subtrees of the given tree object, and
 217         invoke the given callback passing three arguments:
 218         (path, mode, data) with the path, permission bits, and contents
 219         of all the blobs found in the entire tree structure.
 220
 221         """
 222         class _ObjHandler(object):
 223             """Helper class for walking a git tree structure."""
 224             def __init__ (self, parser, cb, path, mode = None):
 225                 """Set up helper."""
 226                 self.parser = parser
 227                 self.cb = cb
 228                 self.path = path
 229                 self.mode = mode
 230                 self.err = None
 231
 232             def parse_tree (self, treedata):
 233                 """Parse tree object data, yield tree entries.
 234
 235                 Each tree entry is a 3-tuple (mode, sha1, path)
 236
 237                 self.path is prepended to all paths yielded
 238                 from this method.
 239
 240                 """
 241                 while treedata:
 242                     mode = int(treedata[:6], 10)
 243                     # Turn 100xxx into xxx
 244                     if mode > 100000:
 245                         mode -= 100000
 246                     assert treedata[6] == " "
 247                     i = treedata.find("\0", 7)
 248                     assert i > 0
 249                     path = treedata[7:i]
 250                     sha1 = hexlify(treedata[i + 1: i + 21])
 251                     yield (mode, sha1, self.path + path)
 252                     treedata = treedata[i + 21:]
 253
 254             def __call__ (self, parser, obj, sha1, t, size, data):
 255                 """Git object callback (see GitObjectFetcher documentation)."""
 256                 assert parser == self.parser
 257                 if not sha1:  # Missing object
 258                     self.err = "Missing object '%s'" % (obj)
 259                     return
 260                 assert size == len(data)
 261                 if t == "tree":
 262                     if self.path:
 263                         self.path += "/"
 264                     # Recurse into all blobs and subtrees
 265                     for m, s, p in self.parse_tree(data):
 266                         parser.push(s,
 267                                     self.__class__(self.parser, self.cb, p, m))
 268                 elif t == "blob":
 269                     self.cb(self.path, self.mode, data)
 270                 else:
 271                     raise ValueError("Unknown object type '%s'" % (t))
 272
 273         self.push(tree_objspec, _ObjHandler(self, callback, prefix))
 274         self.process()
 275
 276
 277 class GitRefMap(object):
 278
 279     """Map Git ref names to the Git object names they currently point to.
 280
 281     Behaves like a dictionary of Git ref names -> Git object names.
 282
 283     """
 284
 285     def __init__ (self, obj_fetcher):
 286         """Create a new Git ref -> object map."""
 287         self.obj_fetcher = obj_fetcher
 288         self._cache = {}  # dict: refname -> objname
 289
 290     def _load (self, ref):
 291         """Retrieve the object currently bound to the given ref.
 292
 293         The name of the object pointed to by the given ref is stored
 294         into this mapping, and also returned.
 295
 296         """
 297         if ref not in self._cache:
 298             self._cache[ref] = self.obj_fetcher.get_sha1(ref)
 299         return self._cache[ref]
 300
 301     def __contains__ (self, refname):
 302         """Return True if the given refname is present in this cache."""
 303         return bool(self._load(refname))
 304
 305     def __getitem__ (self, refname):
 306         """Return the git object name pointed to by the given refname."""
 307         commit = self._load(refname)
 308         if commit is None:
 309             raise KeyError("Unknown ref '%s'" % (refname))
 310         return commit
 311
 312     def get (self, refname, default = None):
 313         """Return the git object name pointed to by the given refname."""
 314         commit = self._load(refname)
 315         if commit is None:
 316             return default
 317         return commit
 318
 319
 320 class GitFICommit(object):
 321
 322     """Encapsulate the data in a Git fast-import commit command."""
 323
 324     SHA1RE = re.compile(r'^[0-9a-f]{40}$')
 325
 326     @classmethod
 327     def parse_mode (cls, mode):
 328         """Verify the given git file mode, and return it as a string."""
 329         assert mode in (644, 755, 100644, 100755, 120000)
 330         return "%i" % (mode)
 331
 332     @classmethod
 333     def parse_objname (cls, objname):
 334         """Return the given object name (or mark number) as a string."""
 335         if isinstance(objname, int):  # Object name is a mark number
 336             assert objname > 0
 337             return ":%i" % (objname)
 338
 339         # No existence check is done, only checks for valid format
 340         assert cls.SHA1RE.match(objname)  # Object name is valid SHA1
 341         return objname
 342
 343     @classmethod
 344     def quote_path (cls, path):
 345         """Return a quoted version of the given path."""
 346         path = path.replace("\\", "\\\\")
 347         path = path.replace("\n", "\\n")
 348         path = path.replace('"', '\\"')
 349         return '"%s"' % (path)
 350
 351     @classmethod
 352     def parse_path (cls, path):
 353         """Verify that the given path is valid, and quote it, if needed."""
 354         assert not isinstance(path, int)  # Cannot be a mark number
 355
 356         # These checks verify the rules on the fast-import man page
 357         assert not path.count("//")
 358         assert not path.endswith("/")
 359         assert not path.startswith("/")
 360         assert not path.count("/./")
 361         assert not path.count("/../")
 362         assert not path.endswith("/.")
 363         assert not path.endswith("/..")
 364         assert not path.startswith("./")
 365         assert not path.startswith("../")
 366
 367         if path.count('"') + path.count('\n') + path.count('\\'):
 368             return cls.quote_path(path)
 369         return path
 370
 371     def __init__ (self, name, email, timestamp, timezone, message):
 372         """Create a new Git fast-import commit, with the given metadata."""
 373         self.name = name
 374         self.email = email
 375         self.timestamp = timestamp
 376         self.timezone = timezone
 377         self.message = message
 378         self.pathops = []  # List of path operations in this commit
 379
 380     def modify (self, mode, blobname, path):
 381         """Add a file modification to this Git fast-import commit."""
 382         self.pathops.append(("M",
 383                              self.parse_mode(mode),
 384                              self.parse_objname(blobname),
 385                              self.parse_path(path)))
 386
 387     def delete (self, path):
 388         """Add a file deletion to this Git fast-import commit."""
 389         self.pathops.append(("D", self.parse_path(path)))
 390
 391     def copy (self, path, newpath):
 392         """Add a file copy to this Git fast-import commit."""
 393         self.pathops.append(("C",
 394                              self.parse_path(path),
 395                              self.parse_path(newpath)))
 396
 397     def rename (self, path, newpath):
 398         """Add a file rename to this Git fast-import commit."""
 399         self.pathops.append(("R",
 400                              self.parse_path(path),
 401                              self.parse_path(newpath)))
 402
 403     def note (self, blobname, commit):
 404         """Add a note object to this Git fast-import commit."""
 405         self.pathops.append(("N",
 406                              self.parse_objname(blobname),
 407                              self.parse_objname(commit)))
 408
 409     def deleteall (self):
 410         """Delete all files in this Git fast-import commit."""
 411         self.pathops.append("deleteall")
 412
 413
 414 class TestGitFICommit(unittest.TestCase):
 415
 416     """GitFICommit selftests."""
 417
 418     def test_basic (self):
 419         """GitFICommit basic selftests."""
 420
 421         def expect_fail (method, data):
 422             """Verify that the method(data) raises an AssertionError."""
 423             try:
 424                 method(data)
 425             except AssertionError:
 426                 return
 427             raise AssertionError("Failed test for invalid data '%s(%s)'" %
 428                                  (method.__name__, repr(data)))
 429
 430     def test_parse_mode (self):
 431         """GitFICommit.parse_mode() selftests."""
 432         self.assertEqual(GitFICommit.parse_mode(644), "644")
 433         self.assertEqual(GitFICommit.parse_mode(755), "755")
 434         self.assertEqual(GitFICommit.parse_mode(100644), "100644")
 435         self.assertEqual(GitFICommit.parse_mode(100755), "100755")
 436         self.assertEqual(GitFICommit.parse_mode(120000), "120000")
 437         self.assertRaises(AssertionError, GitFICommit.parse_mode, 0)
 438         self.assertRaises(AssertionError, GitFICommit.parse_mode, 123)
 439         self.assertRaises(AssertionError, GitFICommit.parse_mode, 600)
 440         self.assertRaises(AssertionError, GitFICommit.parse_mode, "644")
 441         self.assertRaises(AssertionError, GitFICommit.parse_mode, "abc")
 442
 443     def test_parse_objname (self):
 444         """GitFICommit.parse_objname() selftests."""
 445         self.assertEqual(GitFICommit.parse_objname(1), ":1")
 446         self.assertRaises(AssertionError, GitFICommit.parse_objname, 0)
 447         self.assertRaises(AssertionError, GitFICommit.parse_objname, -1)
 448         self.assertEqual(GitFICommit.parse_objname("0123456789" * 4),
 449                          "0123456789" * 4)
 450         self.assertEqual(GitFICommit.parse_objname("2468abcdef" * 4),
 451                          "2468abcdef" * 4)
 452         self.assertRaises(AssertionError, GitFICommit.parse_objname,
 453                           "abcdefghij" * 4)
 454
 455     def test_parse_path (self):
 456         """GitFICommit.parse_path() selftests."""
 457         self.assertEqual(GitFICommit.parse_path("foo/bar"), "foo/bar")
 458         self.assertEqual(GitFICommit.parse_path("path/with\n and \" in it"),
 459                          '"path/with\\n and \\" in it"')
 460         self.assertRaises(AssertionError, GitFICommit.parse_path, 1)
 461         self.assertRaises(AssertionError, GitFICommit.parse_path, 0)
 462         self.assertRaises(AssertionError, GitFICommit.parse_path, -1)
 463         self.assertRaises(AssertionError, GitFICommit.parse_path, "foo//bar")
 464         self.assertRaises(AssertionError, GitFICommit.parse_path, "foo/bar/")
 465         self.assertRaises(AssertionError, GitFICommit.parse_path, "/foo/bar")
 466         self.assertRaises(AssertionError, GitFICommit.parse_path, "foo/./bar")
 467         self.assertRaises(AssertionError, GitFICommit.parse_path, "foo/../bar")
 468         self.assertRaises(AssertionError, GitFICommit.parse_path, "foo/bar/.")
 469         self.assertRaises(AssertionError, GitFICommit.parse_path, "foo/bar/..")
 470         self.assertRaises(AssertionError, GitFICommit.parse_path, "./foo/bar")
 471         self.assertRaises(AssertionError, GitFICommit.parse_path, "../foo/bar")
 472
 473
 474 class GitFastImport(object):
 475
 476     """Encapsulate communication with git fast-import."""
 477
 478     def __init__ (self, f, obj_fetcher, last_mark = 0):
 479         """Set up self to communicate with a fast-import process through f."""
 480         self.f = f  # File object where fast-import stream is written
 481         self.obj_fetcher = obj_fetcher  # GitObjectFetcher instance
 482         self.next_mark = last_mark + 1  # Next mark number
 483         self.refs = set()  # Keep track of the refnames we've seen
 484
 485     def comment (self, s):
 486         """Write the given comment in the fast-import stream."""
 487         assert "\n" not in s, "Malformed comment: '%s'" % (s)
 488         self.f.write("# %s\n" % (s))
 489
 490     def commit (self, ref, commitdata):
 491         """Make a commit on the given ref, with the given GitFICommit.
 492
 493         Return the mark number identifying this commit.
 494
 495         """
 496         self.f.write("""\
 497 commit %(ref)s
 498 mark :%(mark)i
 499 committer %(name)s <%(email)s> %(timestamp)i %(timezone)s
 500 data %(msgLength)i
 501 %(msg)s
 502 """ % {
 503     'ref': ref,
 504     'mark': self.next_mark,
 505     'name': commitdata.name,
 506     'email': commitdata.email,
 507     'timestamp': commitdata.timestamp,
 508     'timezone': commitdata.timezone,
 509     'msgLength': len(commitdata.message),
 510     'msg': commitdata.message,
 511 })
 512
 513         if ref not in self.refs:
 514             self.refs.add(ref)
 515             parent = ref + "^0"
 516             if self.obj_fetcher.get_sha1(parent):
 517                 self.f.write("from %s\n" % (parent))
 518
 519         for op in commitdata.pathops:
 520             self.f.write(" ".join(op))
 521             self.f.write("\n")
 522         self.f.write("\n")
 523         retval = self.next_mark
 524         self.next_mark += 1
 525         return retval
 526
 527     def blob (self, data):
 528         """Import the given blob.
 529
 530         Return the mark number identifying this blob.
 531
 532         """
 533         self.f.write("blob\nmark :%i\ndata %i\n%s\n" %
 534                      (self.next_mark, len(data), data))
 535         retval = self.next_mark
 536         self.next_mark += 1
 537         return retval
 538
 539     def reset (self, ref, objname):
 540         """Reset the given ref to point at the given Git object."""
 541         self.f.write("reset %s\nfrom %s\n\n" %
 542                      (ref, GitFICommit.parse_objname(objname)))
 543         if ref not in self.refs:
 544             self.refs.add(ref)
 545
 546
 547 class GitNotes(object):
 548
 549     """Encapsulate access to Git notes.
 550
 551     Simulates a dictionary of object name (SHA1) -> Git note mappings.
 552
 553     """
 554
 555     def __init__ (self, notes_ref, obj_fetcher):
 556         """Create a new Git notes interface, bound to the given notes ref."""
 557         self.notes_ref = notes_ref
 558         self.obj_fetcher = obj_fetcher  # Used to get objects from repo
 559         self.imports = []  # list: (objname, note data blob name) tuples
 560
 561     def __del__ (self):
 562         """Verify that self.commit_notes() was called before destruction."""
 563         if self.imports:
 564             error("Missing call to self.commit_notes().")
 565             error("%i notes are not committed!", len(self.imports))
 566
 567     def _load (self, objname):
 568         """Return the note data associated with the given git object.
 569
 570         The note data is returned in string form. If no note is found
 571         for the given object, None is returned.
 572
 573         """
 574         try:
 575             f = self.obj_fetcher.open_obj("%s:%s" % (self.notes_ref, objname))
 576             ret = f.read()
 577             f.close()
 578         except KeyError:
 579             ret = None
 580         return ret
 581
 582     def __getitem__ (self, objname):
 583         """Return the note contents associated with the given object.
 584
 585         Raise KeyError if given object has no associated note.
 586
 587         """
 588         blobdata = self._load(objname)
 589         if blobdata is None:
 590             raise KeyError("Object '%s' has no note" % (objname))
 591         return blobdata
 592
 593     def get (self, objname, default = None):
 594         """Return the note contents associated with the given object.
 595
 596         Return given default if given object has no associated note.
 597
 598         """
 599         blobdata = self._load(objname)
 600         if blobdata is None:
 601             return default
 602         return blobdata
 603
 604     def import_note (self, objname, data, gfi):
 605         """Tell git fast-import to store data as a note for objname.
 606
 607         This method uses the given GitFastImport object to create a
 608         blob containing the given note data.  Also an entry mapping the
 609         given object name to the created blob is stored until
 610         commit_notes() is called.
 611
 612         Note that this method only works if it is later followed by a
 613         call to self.commit_notes() (which produces the note commit
 614         that refers to the blob produced here).
 615
 616         """
 617         if not data.endswith("\n"):
 618             data += "\n"
 619         gfi.comment("Importing note for object %s" % (objname))
 620         mark = gfi.blob(data)
 621         self.imports.append((objname, mark))
 622
 623     def commit_notes (self, gfi, author, message):
 624         """Produce a git fast-import note commit for the imported notes.
 625
 626         This method uses the given GitFastImport object to create a
 627         commit on the notes ref, introducing the notes previously
 628         submitted to import_note().
 629
 630         """
 631         if not self.imports:
 632             return
 633         commitdata = GitFICommit(author[0], author[1],
 634                                  time.time(), "0000", message)
 635         for objname, blobname in self.imports:
 636             assert isinstance(objname, int) and objname > 0
 637             assert isinstance(blobname, int) and blobname > 0
 638             commitdata.note(blobname, objname)
 639         gfi.commit(self.notes_ref, commitdata)
 640         self.imports = []
 641
 642
 643 class GitCachedNotes(GitNotes):
 644
 645     """Encapsulate access to Git notes (cached version).
 646
 647     Only use this class if no caching is done at a higher level.
 648
 649     Simulates a dictionary of object name (SHA1) -> Git note mappings.
 650
 651     """
 652
 653     def __init__ (self, notes_ref, obj_fetcher):
 654         """Set up a caching wrapper around GitNotes."""
 655         GitNotes.__init__(self, notes_ref, obj_fetcher)
 656         self._cache = {}  # Cache: object name -> note data
 657
 658     def __del__ (self):
 659         """Verify that GitNotes' destructor is called."""
 660         GitNotes.__del__(self)
 661
 662     def _load (self, objname):
 663         """Extend GitNotes._load() with a local objname -> note cache."""
 664         if objname not in self._cache:
 665             self._cache[objname] = GitNotes._load(self, objname)
 666         return self._cache[objname]
 667
 668     def import_note (self, objname, data, gfi):
 669         """Extend GitNotes.import_note() with a local objname -> note cache."""
 670         if not data.endswith("\n"):
 671             data += "\n"
 672         assert objname not in self._cache
 673         self._cache[objname] = data
 674         GitNotes.import_note(self, objname, data, gfi)
 675
 676
 677 if __name__ == '__main__':
 678     unittest.main()