Source code for google.appengine.api.files.file

#!/usr/bin/env python
#
# Copyright 2007 Google Inc.
#
# 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.
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"""Files API.

.. deprecated:: 1.8.1
   Use Google Cloud Storage Client library instead."""

from __future__ import with_statement



__all__ = [
           'ApiTemporaryUnavailableError',
           'BLOBSTORE_FILESYSTEM',
           'Error',
           'ExclusiveLockFailedError',
           'ExistenceError',
           'FileNotOpenedError',
           'FileTemporaryUnavailableError',
           'FILESYSTEMS',
           'FinalizationError',
           'GS_FILESYSTEM',
           'InvalidArgumentError',
           'InvalidFileNameError',
           'InvalidParameterError',
           'OperationNotSupportedError',
           'PermissionDeniedError',
           'ReadOnlyError',
           'SequenceKeyOutOfOrderError',
           'UnknownError',
           'UnsupportedContentTypeError',
           'UnsupportedOpenModeError',
           'WrongContentTypeError' ,
           'WrongOpenModeError',

           'RAW',
           'READ_BLOCK_SIZE',

           'delete',
           'finalize',
           'listdir',
           'open',
           'stat',

           'BufferedFile',
           ]

import os
import sys
import StringIO

from google.appengine.api import apiproxy_stub_map
from google.appengine.api.files import file_service_pb
from google.appengine.runtime import apiproxy_errors


BLOBSTORE_FILESYSTEM = 'blobstore'
GS_FILESYSTEM = 'gs'
FILESYSTEMS = (BLOBSTORE_FILESYSTEM, GS_FILESYSTEM)
READ_BLOCK_SIZE = 1024 * 512
_CREATION_HANDLE_PREFIX = 'writable:'
_DEFAULT_BUFFER_SIZE = 512 * 1024


[docs]class Error(Exception): """Base error class for this module."""
[docs]class UnsupportedOpenModeError(Error): """Unsupported file open mode was specified."""
[docs]class UnsupportedContentTypeError(Error): """Specified file content type is not supported by this api."""
[docs]class InvalidArgumentError(Error): """Function argument has invalid value."""
[docs]class FinalizationError(Error): """File is in wrong finalization state."""
[docs]class ExistenceError(Error): """File is in wrong existence state."""
[docs]class UnknownError(Error): """Unknown unexpected io error occured."""
[docs]class SequenceKeyOutOfOrderError(Error): """Sequence key specified is out of order. Attributes: last_sequence_key: last sequence key which was written to the file. """ def __init__(self, last_sequence_key, cause=None): Error.__init__(self, cause) self.last_sequence_key = last_sequence_key
[docs]class InvalidFileNameError(Error): """File name is invalid."""
[docs]class FileNotOpenedError(Error): """File was not opened."""
[docs]class ReadOnlyError(Error): """File is read-only mode."""
[docs]class WrongContentTypeError(Error): """File has a different content type."""
[docs]class WrongOpenModeError(Error): """Incorrect file open mode."""
[docs]class OperationNotSupportedError(Error): """Incorrect file open mode."""
[docs]class PermissionDeniedError(Error): """Application doesn't have permissions to perform the operation."""
[docs]class ApiTemporaryUnavailableError(Error): """Files API is temporary unavailable. Request should be retried soon."""
[docs]class FileTemporaryUnavailableError(Error): """File is temporary unavailable. Request should be retried soon."""
[docs]class InvalidParameterError(Error): """Parameter specified in Create() call is invalid."""
[docs]class ExclusiveLockFailedError(Error): """Exclusive lock can't be obtained."""
RAW = file_service_pb.FileContentType.RAW def _raise_app_error(e): """Convert RPC error into api-specific exception.""" if (e.application_error in [file_service_pb.FileServiceErrors.EXISTENCE_ERROR, file_service_pb.FileServiceErrors.EXISTENCE_ERROR_METADATA_NOT_FOUND, file_service_pb.FileServiceErrors.EXISTENCE_ERROR_METADATA_FOUND, file_service_pb.FileServiceErrors.EXISTENCE_ERROR_SHARDING_MISMATCH, file_service_pb.FileServiceErrors.EXISTENCE_ERROR_OBJECT_NOT_FOUND, file_service_pb.FileServiceErrors.EXISTENCE_ERROR_BUCKET_NOT_FOUND, ]): raise ExistenceError(e) elif (e.application_error == file_service_pb.FileServiceErrors.API_TEMPORARILY_UNAVAILABLE): raise ApiTemporaryUnavailableError(e) elif (e.application_error == file_service_pb.FileServiceErrors.FINALIZATION_ERROR): raise FinalizationError(e) elif (e.application_error == file_service_pb.FileServiceErrors.IO_ERROR): raise UnknownError(e) elif (e.application_error == file_service_pb.FileServiceErrors.SEQUENCE_KEY_OUT_OF_ORDER): raise SequenceKeyOutOfOrderError(e.error_detail, e) elif (e.application_error == file_service_pb.FileServiceErrors.INVALID_FILE_NAME): raise InvalidFileNameError(e) elif (e.application_error == file_service_pb.FileServiceErrors.FILE_NOT_OPENED): raise FileNotOpenedError(e) elif (e.application_error == file_service_pb.FileServiceErrors.READ_ONLY): raise ReadOnlyError(e) elif (e.application_error == file_service_pb.FileServiceErrors.WRONG_CONTENT_TYPE): raise WrongContentTypeError(e) elif (e.application_error == file_service_pb.FileServiceErrors.WRONG_OPEN_MODE): raise WrongOpenModeError(e) elif (e.application_error == file_service_pb.FileServiceErrors.OPERATION_NOT_SUPPORTED): raise OperationNotSupportedError(e) elif (e.application_error == file_service_pb.FileServiceErrors.PERMISSION_DENIED): raise PermissionDeniedError(e) elif (e.application_error == file_service_pb.FileServiceErrors.FILE_TEMPORARILY_UNAVAILABLE): raise FileTemporaryUnavailableError(e) elif (e.application_error == file_service_pb.FileServiceErrors.INVALID_PARAMETER): raise InvalidParameterError(e) elif (e.application_error == file_service_pb.FileServiceErrors.EXCLUSIVE_LOCK_FAILED): raise ExclusiveLockFailedError(e) raise Error(e) def _create_rpc(deadline): """Create RPC object for file service. Args: deadling: Request deadline in seconds. """ return apiproxy_stub_map.UserRPC('file', deadline) def _make_call(method, request, response, deadline=30): """Perform File RPC call. Args: method: Service method name as string. request: Request protocol buffer. response: Response protocol buffer. deadline: Request deadline in seconds. Raises: Error or it's descendant if any File API specific error has happened. """ rpc = _create_rpc(deadline=deadline) rpc.make_call(method, request, response) rpc.wait() try: rpc.check_success() except apiproxy_errors.ApplicationError, e: _raise_app_error(e) class _File(object): """File object. File object must be obtained by open() function and closed by its close() method. It supports scoped closing by with operator. """ def __init__(self, filename, mode, content_type, exclusive_lock): """Constructor. Args: filename: File's name as string. content_type: File's content type. Value from FileContentType.ContentType enum. """ self._filename = filename self._closed = False self._content_type = content_type self._mode = mode self._exclusive_lock = exclusive_lock self._offset = 0 self._open() def close(self, finalize=False): """Close file. Args: finalize: Specifies if file should be finalized upon closing. """ if self._closed: return self._closed = True request = file_service_pb.CloseRequest() response = file_service_pb.CloseResponse() request.set_filename(self._filename) request.set_finalize(finalize) self._make_rpc_call_with_retry('Close', request, response) def __enter__(self): return self def __exit__(self, atype, value, traceback): self.close() def write(self, data, sequence_key=None): """Write data to file. Args: data: Data to be written to the file. For RAW files it should be a string or byte sequence. sequence_key: Sequence key to use for write. Is used for RAW files only. File API infrastructure ensures that sequence_key are monotonically increasing. If sequence key less than previous one is used, a SequenceKeyOutOfOrderError exception with last recorded sequence key will be raised. If part of already written content is lost due to infrastructure failure, last_sequence_key will point to last successfully written key. Raises: SequenceKeyOutOfOrderError: Raised when passed sequence keys are not monotonically increasing. InvalidArgumentError: Raised when wrong object type is apssed in as data. Error: Error or its descendants are raised when other error has happened. """ if self._content_type == RAW: request = file_service_pb.AppendRequest() response = file_service_pb.AppendResponse() request.set_filename(self._filename) request.set_data(data) if sequence_key: request.set_sequence_key(sequence_key) self._make_rpc_call_with_retry('Append', request, response) else: raise UnsupportedContentTypeError( 'Unsupported content type: %s' % self._content_type) def tell(self): """Return file's current position. Is valid only when file is opened for read. """ self._verify_read_mode() return self._offset def seek(self, offset, whence=os.SEEK_SET): """Set the file's current position. Args: offset: seek offset as number. whence: seek mode. Supported modes are os.SEEK_SET (absolute seek), and os.SEEK_CUR (seek relative to the current position) and os.SEEK_END (seek relative to the end, offset should be negative). """ self._verify_read_mode() if whence == os.SEEK_SET: self._offset = offset elif whence == os.SEEK_CUR: self._offset += offset elif whence == os.SEEK_END: file_stat = self.stat() self._offset = file_stat.st_size + offset else: raise InvalidArgumentError('Whence mode %d is not supported', whence) def read(self, size=None): """Read data from RAW file. Args: size: Number of bytes to read as integer. Actual number of bytes read might be less than specified, but it's never 0 unless current offset is at the end of the file. If it is None, then file is read until the end. Returns: A string with data read. """ self._verify_read_mode() if self._content_type != RAW: raise UnsupportedContentTypeError( 'Unsupported content type: %s' % self._content_type) buf = StringIO.StringIO() original_offset = self._offset try: if size is None: size = sys.maxint while size > 0: request = file_service_pb.ReadRequest() response = file_service_pb.ReadResponse() request.set_filename(self._filename) request.set_pos(self._offset) request.set_max_bytes(min(READ_BLOCK_SIZE, size)) self._make_rpc_call_with_retry('Read', request, response) chunk = response.data() self._offset += len(chunk) if len(chunk) == 0: break buf.write(chunk) size -= len(chunk) return buf.getvalue() except: self._offset = original_offset raise finally: buf.close() def _verify_read_mode(self): if self._mode not in ('r', 'rb'): raise WrongOpenModeError('File is opened for write.') def _open(self): request = file_service_pb.OpenRequest() response = file_service_pb.OpenResponse() request.set_filename(self._filename) request.set_exclusive_lock(self._exclusive_lock) request.set_content_type(self._content_type) if self._mode in ('a', 'ab'): request.set_open_mode(file_service_pb.OpenRequest.APPEND) elif self._mode in ('r', 'rb'): request.set_open_mode(file_service_pb.OpenRequest.READ) else: raise UnsupportedOpenModeError('Unsupported open mode: %s', self._mode) self._make_rpc_call_with_retry('Open', request, response) def _make_rpc_call_with_retry(self, method, request, response): try: _make_call(method, request, response) except (ApiTemporaryUnavailableError, FileTemporaryUnavailableError): if method == 'Open': _make_call(method, request, response) return if self._exclusive_lock: raise self._open() _make_call(method, request, response) def stat(self): """Get status of a finalized file. Returns: a _FileStat object similar to that returned by python's os.stat(path). Throws: FinalizationError if file is not finalized. """ self._verify_read_mode() request = file_service_pb.StatRequest() response = file_service_pb.StatResponse() request.set_filename(self._filename) _make_call('Stat', request, response) if response.stat_size() == 0: raise ExistenceError("File %s not found." % self._filename) if response.stat_size() > 1: raise ValueError( "Requested stat for one file. Got more than one response.") file_stat_pb = response.stat(0) file_stat = _FileStat() file_stat.filename = file_stat_pb.filename() file_stat.finalized = file_stat_pb.finalized() file_stat.st_size = file_stat_pb.length() file_stat.st_mtime = file_stat_pb.mtime() file_stat.st_ctime = file_stat_pb.ctime() return file_stat
[docs]def open(filename, mode='r', content_type=RAW, exclusive_lock=False, buffering=0): """Open a file. Args: filename: A name of the file as string. mode: File open mode. Either 'a' or 'r'. content_type: File's content type. Value from FileContentType.ContentType enum. exclusive_lock: If file should be exclusively locked. All other exclusive lock attempts will file until file is correctly closed. buffering: optional argument similar to the one in Python's open. It specifies the file's desired buffer size: 0 means unbuffered, positive value means use a buffer of that size, any negative value means the default size. Only read buffering is supported. Returns: File object. Raises: InvalidArgumentError: Raised when given illegal argument value or type. """ if not filename: raise InvalidArgumentError('Filename is empty') if not isinstance(filename, basestring): raise InvalidArgumentError('Filename should be a string but is %s (%s)' % (filename.__class__, filename)) if content_type != RAW: raise InvalidArgumentError('Invalid content type') if not (isinstance(buffering, int) or isinstance(buffering, long)): raise InvalidArgumentError('buffering should be an int but is %s' % buffering) if mode == 'r' or mode == 'rb': if buffering > 0: return BufferedFile(filename, buffering) elif buffering < 0: return BufferedFile(filename, _DEFAULT_BUFFER_SIZE) return _File(filename, mode=mode, content_type=content_type, exclusive_lock=exclusive_lock)
[docs]def listdir(path, **kwargs): """Return a sorted list of filenames (matching a pattern) in the given path. Only Google Cloud Storage paths are supported in current implementation. Args: path: a Google Cloud Storage path of "/gs/bucketname" form. kwargs: other keyword arguments to be relayed to Google Cloud Storage. This can be used to select certain files with names matching a pattern. See google.appengine.api.files.gs.listdir for details. Returns: a list containing filenames (matching a pattern) from the given path. Sorted by Python String. """ from google.appengine.api.files import gs if not isinstance(path, basestring): raise InvalidArgumentError('path should be a string, but is %s(%r)' % (path.__class__.__name__, path)) if path.startswith(gs._GS_PREFIX): return gs.listdir(path, kwargs) else: raise InvalidFileNameError('Unsupported path: %s' % path)
[docs]def finalize(filename, content_type=RAW): """Finalize a file. Args: filename: File name as string. content_type: File's content type. Value from FileContentType.ContentType enum. """ if not filename: raise InvalidArgumentError('Filename is empty') if not isinstance(filename, basestring): raise InvalidArgumentError('Filename should be a string') if content_type != RAW: raise InvalidArgumentError('Invalid content type') try: f = open(filename, 'a', exclusive_lock=True, content_type=content_type) f.close(finalize=True) except FinalizationError: pass
class _FileStat(object): """_FileStat contains file attributes. Attributes: filename: the uploaded filename of the file; finalized: whether the file is finalized. This is always true by now; st_size: number of bytes of the file; st_ctime: creation time; st_mtime: modification time. """ def __init__(self): self.filename = None self.finalized = True self.st_size = None self.st_ctime = None self.st_mtime = None
[docs]def stat(filename): """Get status of a finalized file given it's full path filename. Returns: a _FileStat object similar to that returned by python's os.stat(path). Throws: FinalizationError if file is not finalized. """ if not filename: raise InvalidArgumentError('Filename is empty') if not isinstance(filename, basestring): raise InvalidArgumentError('Filename should be a string') with open(filename, 'r') as f: return f.stat()
def _create(filesystem, content_type=RAW, filename=None, params=None): """Create a file. Args: filesystem: File system to create a file at as string. content_type: File content type. filename: Requested file name as string. Some file system require this to be filled in, some require it to be None. params: {string: string} dict of file parameters. Each filesystem interprets them differently. """ if not filesystem: raise InvalidArgumentError('Filesystem is empty') if not isinstance(filesystem, basestring): raise InvalidArgumentError('Filesystem should be a string') if content_type != RAW: raise InvalidArgumentError('Invalid content type') request = file_service_pb.CreateRequest() response = file_service_pb.CreateResponse() request.set_filesystem(filesystem) request.set_content_type(content_type) if filename: if not isinstance(filename, basestring): raise InvalidArgumentError('Filename should be a string') request.set_filename(filename) if params: if not isinstance(params, dict): raise InvalidArgumentError('Parameters should be a dictionary') for k,v in params.items(): param = request.add_parameters() param.set_name(k) param.set_value(v) _make_call('Create', request, response) return response.filename() def __checkIsFinalizedName(filename): """Check if a filename is finalized. A filename is finalized when it has creation handle prefix, which is the same for both blobstore and gs files. Args: filename: a gs or blobstore filename that starts with '/gs/' or '/blobstore/' Raises: InvalidFileNameError: raised when filename is finalized. """ if filename.split('/')[2].startswith(_CREATION_HANDLE_PREFIX): raise InvalidFileNameError('File %s should have finalized filename' % filename)
[docs]def delete(*filenames): """Permanently delete files. Delete on non-finalized/non-existent files is a no-op. Args: filenames: finalized file names as strings. filename should has format "/gs/bucket/filename" or "/blobstore/blobkey". Raises: InvalidFileNameError: Raised when any filename is not of valid format or not a finalized name. IOError: Raised if any problem occurs contacting the backend system. """ from google.appengine.api.files import blobstore as files_blobstore from google.appengine.api.files import gs from google.appengine.ext import blobstore blobkeys = [] for filename in filenames: if not isinstance(filename, basestring): raise InvalidArgumentError('Filename should be a string, but is %s(%r)' % (filename.__class__.__name__, filename)) if filename.startswith(files_blobstore._BLOBSTORE_DIRECTORY): __checkIsFinalizedName(filename) blobkey = files_blobstore.get_blob_key(filename) if blobkey: blobkeys.append(blobkey) elif filename.startswith(gs._GS_PREFIX): __checkIsFinalizedName(filename) blobkeys.append(blobstore.create_gs_key(filename)) else: raise InvalidFileNameError('Filename should start with /%s or /%s' % (files_blobstore._BLOBSTORE_DIRECTORY, gs._GS_PREFIX)) try: blobstore.delete(blobkeys) except Exception, e: raise IOError('Blobstore failure.', e)
def _get_capabilities(): """Get files API capabilities. Returns: An instance of file_service_pb.GetCapabilitiesResponse. """ request = file_service_pb.GetCapabilitiesRequest() response = file_service_pb.GetCapabilitiesResponse() _make_call('GetCapabilities', request, response) return response
[docs]class BufferedFile(object): """BufferedFile is a file-like object reading underlying file in chunks.""" def __init__(self, filename, buffer_size=_DEFAULT_BUFFER_SIZE): """Constructor. Args: filename: the name of the file to read as string. buffer_size: buffer read size to use as int. """ self._filename = filename self._position = 0 self._buffer = '' self._buffer_pos = 0 self._buffer_size = buffer_size self._eof = False def __enter__(self): return self def __exit__(self, atype, value, traceback): self.close()
[docs] def close(self): self._buffer = '' self._eof = True self._buffer_pos = 0
[docs] def tell(self): """Return file's current position.""" return self._position
[docs] def read(self, size=None): """Read data from RAW file. Args: size: Number of bytes to read as integer. Actual number of bytes read is always equal to size unless end if file was reached. Returns: A string with data read. """ if size is None: size = sys.maxint data_list = [] while True: result = self.__readBuffer(size) data_list.append(result) size -= len(result) if size == 0 or self._eof: return ''.join(data_list) self.__refillBuffer()
[docs] def readline(self, size=-1): """Read one line delimited by '\n' from the file. A trailing newline character is kept in the string. It may be absent when a file ends with an incomplete line. If the size argument is non-negative, it specifies the maximum string size (counting the newline) to return. An empty string is returned only when EOF is encountered immediately. Args: size: Maximum number of bytes to read. If not specified, readline stops only on '\n' or EOF. Returns: The data read as a string. """ data_list = [] while True: if size < 0: end_pos = len(self._buffer) else: end_pos = self._buffer_pos + size newline_pos = self._buffer.find('\n', self._buffer_pos, end_pos) if newline_pos != -1: data_list.append(self.__readBuffer(newline_pos + 1 - self._buffer_pos)) return ''.join(data_list) else: result = self.__readBuffer(size) data_list.append(result) size -= len(result) if size == 0 or self._eof: return ''.join(data_list) self.__refillBuffer()
def __readBuffer(self, size): """Read chars from self._buffer. Args: size: number of chars to read. Read the entire buffer if negative. Returns: chars read in string. """ if size < 0: size = len(self._buffer) - self._buffer_pos result = self._buffer[self._buffer_pos:self._buffer_pos+size] self._position += len(result) self._buffer_pos += len(result) return result def __refillBuffer(self): """Refill _buffer with another read from source.""" with open(self._filename, 'r') as f: f.seek(self._position) data = f.read(self._buffer_size) self._eof = len(data) < self._buffer_size self._buffer = data self._buffer_pos = 0
[docs] def seek(self, offset, whence=os.SEEK_SET): """Set the file's current position. Args: offset: seek offset as number. whence: seek mode. Supported modes are os.SEEK_SET (absolute seek), os.SEEK_CUR (seek relative to the current position), and os.SEEK_END (seek relative to the end, offset should be negative). """ if whence == os.SEEK_SET: self._position = offset elif whence == os.SEEK_CUR: self._position += offset elif whence == os.SEEK_END: file_stat = stat(self._filename) self._position = file_stat.st_size + offset else: raise InvalidArgumentError('Whence mode %d is not supported', whence) self._buffer = '' self._buffer_pos = 0 self._eof = False
def _default_gs_bucket_name(): """Return the default Google Storage bucket name for the application. Returns: A string that is the default bucket name for the application. """ request = file_service_pb.GetDefaultGsBucketNameRequest() response = file_service_pb.GetDefaultGsBucketNameResponse() _make_call('GetDefaultGsBucketName', request, response) return response.default_gs_bucket_name()

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