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GeezerVison is showing github.com — GitPython/gitdb/gitdb/util.py at main · gitpython-developers/GitPython Expand file tree/ Copy pathutil.pyMore file actions 398 lines (311 loc) · 12 KB / Copy pathutil.pyFile metadata and controls398 lines (311 loc) · 12 KB 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 # Copyright (C) 2010, 2011 Sebastian Thiel ([email protected]) and contributors # # This module is part of GitDB and is released under # the New BSD License: https://opensource.org/license/bsd-3-clause/ import binascii import os import mmap import sys import time import errno from io import BytesIO from smmap import ( StaticWindowMapManager, SlidingWindowMapManager, SlidingWindowMapBuffer ) # initialize our global memory manager instance # Use it to free cached (and unused) resources. mman = SlidingWindowMapManager() # END handle mman import hashlib try: from struct import unpack_from except ImportError: from struct import unpack, calcsize __calcsize_cache = dict() def unpack_from(fmt, data, offset=0): try: size = __calcsize_cache[fmt] except KeyError: size = calcsize(fmt) __calcsize_cache[fmt] = size # END exception handling return unpack(fmt, data[offset: offset + size]) # END own unpack_from implementation #{ Aliases hex_to_bin = binascii.a2b_hex bin_to_hex = binascii.b2a_hex # errors ENOENT = errno.ENOENT # os shortcuts exists = os.path.exists mkdir = os.mkdir chmod = os.chmod isdir = os.path.isdir isfile = os.path.isfile rename = os.rename dirname = os.path.dirname basename = os.path.basename join = os.path.join read = os.read write = os.write close = os.close fsync = os.fsync def _retry(func, *args, **kwargs): # Wrapper around functions, that are problematic on "Windows". Sometimes # the OS or someone else has still a handle to the file if sys.platform == "win32": for _ in range(10): try: return func(*args, **kwargs) except Exception: time.sleep(0.1) return func(*args, **kwargs) else: return func(*args, **kwargs) def remove(*args, **kwargs): return _retry(os.remove, *args, **kwargs) # Backwards compatibility imports from gitdb.const import ( NULL_BIN_SHA, NULL_HEX_SHA ) #} END Aliases #{ compatibility stuff ... class _RandomAccessBytesIO: """Wrapper to provide required functionality in case memory maps cannot or may not be used. This is only really required in python 2.4""" __slots__ = '_sio' def __init__(self, buf=''): self._sio = BytesIO(buf) def __getattr__(self, attr): return getattr(self._sio, attr) def __len__(self): return len(self.getvalue()) def __getitem__(self, i): return self.getvalue()[i] def __getslice__(self, start, end): return self.getvalue()[start:end] def byte_ord(b): """ Return the integer representation of the byte string. This supports Python 3 byte arrays as well as standard strings. """ try: return ord(b) except TypeError: return b #} END compatibility stuff ... #{ Routines def make_sha(source=b''): """A python2.4 workaround for the sha/hashlib module fiasco **Note** From the dulwich project """ try: return hashlib.sha1(source) except NameError: import sha sha1 = sha.sha(source) return sha1 def allocate_memory(size): """:return: a file-protocol accessible memory block of the given size""" if size == 0: return _RandomAccessBytesIO(b'') # END handle empty chunks gracefully try: return mmap.mmap(-1, size) # read-write by default except OSError: # setup real memory instead # this of course may fail if the amount of memory is not available in # one chunk - would only be the case in python 2.4, being more likely on # 32 bit systems. return _RandomAccessBytesIO(b"\0" * size) # END handle memory allocation def file_contents_ro(fd, stream=False, allow_mmap=True): """:return: read-only contents of the file represented by the file descriptor fd :param fd: file descriptor opened for reading :param stream: if False, random access is provided, otherwise the stream interface is provided. :param allow_mmap: if True, its allowed to map the contents into memory, which allows large files to be handled and accessed efficiently. The file-descriptor will change its position if this is False""" try: if allow_mmap: # supports stream and random access try: return mmap.mmap(fd, 0, access=mmap.ACCESS_READ) except OSError: # python 2.4 issue, 0 wants to be the actual size return mmap.mmap(fd, os.fstat(fd).st_size, access=mmap.ACCESS_READ) # END handle python 2.4 except OSError: pass # END exception handling # read manually contents = os.read(fd, os.fstat(fd).st_size) if stream: return _RandomAccessBytesIO(contents) return contents def file_contents_ro_filepath(filepath, stream=False, allow_mmap=True, flags=0): """Get the file contents at filepath as fast as possible :return: random access compatible memory of the given filepath :param stream: see ``file_contents_ro`` :param allow_mmap: see ``file_contents_ro`` :param flags: additional flags to pass to os.open :raise OSError: If the file could not be opened **Note** for now we don't try to use O_NOATIME directly as the right value needs to be shared per database in fact. It only makes a real difference for loose object databases anyway, and they use it with the help of the ``flags`` parameter""" fd = os.open(filepath, os.O_RDONLY | getattr(os, 'O_BINARY', 0) | flags) try: return file_contents_ro(fd, stream, allow_mmap) finally: close(fd) # END assure file is closed def sliding_ro_buffer(filepath, flags=0): """ :return: a buffer compatible object which uses our mapped memory manager internally ready to read the whole given filepath""" return SlidingWindowMapBuffer(mman.make_cursor(filepath), flags=flags) def to_hex_sha(sha): """:return: hexified version of sha""" if len(sha) == 40: return sha return bin_to_hex(sha) def to_bin_sha(sha): if len(sha) == 20: return sha return hex_to_bin(sha) #} END routines #{ Utilities class LazyMixin: """ Base class providing an interface to lazily retrieve attribute values upon first access. If slots are used, memory will only be reserved once the attribute is actually accessed and retrieved the first time. All future accesses will return the cached value as stored in the Instance's dict or slot. """ __slots__ = tuple() def __getattr__(self, attr): """ Whenever an attribute is requested that we do not know, we allow it to be created and set. Next time the same attribute is requested, it is simply returned from our dict/slots. """ self._set_cache_(attr) # will raise in case the cache was not created return object.__getattribute__(self, attr) def _set_cache_(self, attr): """ This method should be overridden in the derived class. It should check whether the attribute named by attr can be created and cached. Do nothing if you do not know the attribute or call your subclass The derived class may create as many additional attributes as it deems necessary in case a git command returns more information than represented in the single attribute.""" pass class LockedFD: """ This class facilitates a safe read and write operation to a file on disk. If we write to 'file', we obtain a lock file at 'file.lock' and write to that instead. If we succeed, the lock file will be renamed to overwrite the original file. When reading, we obtain a lock file, but to prevent other writers from succeeding while we are reading the file. This type handles error correctly in that it will assure a consistent state on destruction. **note** with this setup, parallel reading is not possible""" __slots__ = ("_filepath", '_fd', '_write') def __init__(self, filepath): """Initialize an instance with the givne filepath""" self._filepath = filepath self._fd = None self._write = None # if True, we write a file def __del__(self): # will do nothing if the file descriptor is already closed if self._fd is not None: self.rollback() def _lockfilepath(self): return "%s.lock" % self._filepath def open(self, write=False, stream=False): """ Open the file descriptor for reading or writing, both in binary mode. :param write: if True, the file descriptor will be opened for writing. Other wise it will be opened read-only. :param stream: if True, the file descriptor will be wrapped into a simple stream object which supports only reading or writing :return: fd to read from or write to. It is still maintained by this instance and must not be closed directly :raise IOError: if the lock could not be retrieved :raise OSError: If the actual file could not be opened for reading **note** must only be called once""" if self._write is not None: raise AssertionError("Called %s multiple times" % self.open) self._write = write # try to open the lock file binary = getattr(os, 'O_BINARY', 0) lockmode = os.O_WRONLY | os.O_CREAT | os.O_EXCL | binary try: fd = os.open(self._lockfilepath(), lockmode, int("600", 8)) if not write: os.close(fd) else: self._fd = fd # END handle file descriptor except OSError as e: raise OSError("Lock at %r could not be obtained" % self._lockfilepath()) from e # END handle lock retrieval # open actual file if required if self._fd is None: # we could specify exclusive here, as we obtained the lock anyway try: self._fd = os.open(self._filepath, os.O_RDONLY | binary) except: # assure we release our lockfile remove(self._lockfilepath()) raise # END handle lockfile # END open descriptor for reading if stream: # need delayed import from gitdb.stream import FDStream return FDStream(self._fd) else: return self._fd # END handle stream def commit(self): """When done writing, call this function to commit your changes into the actual file. The file descriptor will be closed, and the lockfile handled. **Note** can be called multiple times""" self._end_writing(successful=True) def rollback(self): """Abort your operation without any changes. The file descriptor will be closed, and the lock released. **Note** can be called multiple times""" self._end_writing(successful=False) def _end_writing(self, successful=True): """Handle the lock according to the write mode """ if self._write is None: raise AssertionError("Cannot end operation if it wasn't started yet") if self._fd is None: return os.close(self._fd) self._fd = None lockfile = self._lockfilepath() if self._write and successful: # on windows, rename does not silently overwrite the existing one if sys.platform == "win32": if isfile(self._filepath): remove(self._filepath) # END remove if exists # END win32 special handling os.rename(lockfile, self._filepath) # assure others can at least read the file - the tmpfile left it at rw-- # We may also write that file, on windows that boils down to a remove- # protection as well chmod(self._filepath, int("644", 8)) else: # just delete the file so far, we failed remove(lockfile) # END successful handling #} END utilities |
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