| paul@147 | 1 | #!/usr/bin/env python |
| paul@147 | 2 | |
| paul@147 | 3 | """ |
| paul@147 | 4 | Filesystem utilities. |
| paul@147 | 5 | |
| paul@147 | 6 | Copyright (C) 2014, 2015 Paul Boddie <paul@boddie.org.uk> |
| paul@147 | 7 | |
| paul@147 | 8 | This program is free software; you can redistribute it and/or modify it under |
| paul@147 | 9 | the terms of the GNU General Public License as published by the Free Software |
| paul@147 | 10 | Foundation; either version 3 of the License, or (at your option) any later |
| paul@147 | 11 | version. |
| paul@147 | 12 | |
| paul@147 | 13 | This program is distributed in the hope that it will be useful, but WITHOUT |
| paul@147 | 14 | ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS |
| paul@147 | 15 | FOR A PARTICULAR PURPOSE. See the GNU General Public License for more |
| paul@147 | 16 | details. |
| paul@147 | 17 | |
| paul@147 | 18 | You should have received a copy of the GNU General Public License along with |
| paul@147 | 19 | this program. If not, see <http://www.gnu.org/licenses/>. |
| paul@147 | 20 | """ |
| paul@147 | 21 | |
| paul@303 | 22 | import errno |
| paul@330 | 23 | from imiptools.config import DEFAULT_PERMISSIONS, DEFAULT_DIR_PERMISSIONS |
| paul@147 | 24 | from os.path import abspath, commonprefix, exists, join |
| paul@303 | 25 | from os import chmod, makedirs, mkdir, rmdir |
| paul@303 | 26 | from time import sleep, time |
| paul@147 | 27 | |
| paul@147 | 28 | def check_dir(base, dir): |
| paul@147 | 29 | return commonprefix([base, abspath(dir)]) == base |
| paul@147 | 30 | |
| paul@330 | 31 | def fix_permissions(filename, is_dir=False): |
| paul@147 | 32 | try: |
| paul@330 | 33 | chmod(filename, is_dir and DEFAULT_DIR_PERMISSIONS or DEFAULT_PERMISSIONS) |
| paul@147 | 34 | except OSError: |
| paul@147 | 35 | pass |
| paul@147 | 36 | |
| paul@356 | 37 | def make_path(base, parts): |
| paul@356 | 38 | for part in parts: |
| paul@356 | 39 | pathname = join(base, part) |
| paul@356 | 40 | if not exists(pathname): |
| paul@356 | 41 | mkdir(pathname) |
| paul@356 | 42 | fix_permissions(pathname, True) |
| paul@356 | 43 | base = pathname |
| paul@356 | 44 | |
| paul@147 | 45 | class FileBase: |
| paul@147 | 46 | |
| paul@147 | 47 | "Basic filesystem operations." |
| paul@147 | 48 | |
| paul@303 | 49 | lock_name = "__lock__" |
| paul@303 | 50 | |
| paul@147 | 51 | def __init__(self, store_dir): |
| paul@147 | 52 | self.store_dir = store_dir |
| paul@147 | 53 | if not exists(self.store_dir): |
| paul@356 | 54 | makedirs(self.store_dir) |
| paul@356 | 55 | fix_permissions(self.store_dir, True) |
| paul@147 | 56 | |
| paul@147 | 57 | def get_file_object(self, base, *parts): |
| paul@147 | 58 | pathname = join(base, *parts) |
| paul@147 | 59 | return check_dir(base, pathname) and pathname or None |
| paul@147 | 60 | |
| paul@147 | 61 | def get_object_in_store(self, *parts): |
| paul@147 | 62 | |
| paul@147 | 63 | """ |
| paul@147 | 64 | Return the name of any valid object stored within a hierarchy specified |
| paul@147 | 65 | by the given 'parts'. |
| paul@147 | 66 | """ |
| paul@147 | 67 | |
| paul@147 | 68 | parent = expected = self.store_dir |
| paul@147 | 69 | |
| paul@147 | 70 | for part in parts: |
| paul@147 | 71 | filename = self.get_file_object(expected, part) |
| paul@147 | 72 | if not filename: |
| paul@147 | 73 | return False |
| paul@147 | 74 | parent = expected |
| paul@147 | 75 | expected = filename |
| paul@147 | 76 | |
| paul@147 | 77 | if not exists(parent): |
| paul@356 | 78 | make_path(self.store_dir, parts[:-1]) |
| paul@147 | 79 | |
| paul@147 | 80 | return filename |
| paul@147 | 81 | |
| paul@303 | 82 | # Locking methods. |
| paul@303 | 83 | # This uses the directory creation method exploited by MoinMoin.util.lock. |
| paul@303 | 84 | # However, a simple single lock type mechanism is employed here. |
| paul@303 | 85 | |
| paul@303 | 86 | def get_lock_dir(self, *parts): |
| paul@303 | 87 | parts = parts and list(parts) or [] |
| paul@303 | 88 | parts.append(self.lock_name) |
| paul@303 | 89 | return self.get_object_in_store(*parts) |
| paul@303 | 90 | |
| paul@303 | 91 | def acquire_lock(self, timeout=None, *parts): |
| paul@303 | 92 | |
| paul@303 | 93 | """ |
| paul@303 | 94 | Acquire an exclusive lock on the directory or a path within it described |
| paul@303 | 95 | by 'parts'. |
| paul@303 | 96 | """ |
| paul@303 | 97 | |
| paul@303 | 98 | start = now = time() |
| paul@303 | 99 | |
| paul@303 | 100 | while not timeout or now - start < timeout: |
| paul@303 | 101 | try: |
| paul@303 | 102 | mkdir(self.get_lock_dir(*parts)) |
| paul@303 | 103 | break |
| paul@303 | 104 | except OSError, exc: |
| paul@303 | 105 | if exc.errno != errno.EEXIST: |
| paul@303 | 106 | raise |
| paul@303 | 107 | sleep(1) |
| paul@303 | 108 | now = time() |
| paul@303 | 109 | |
| paul@303 | 110 | def release_lock(self, *parts): |
| paul@303 | 111 | |
| paul@303 | 112 | """ |
| paul@303 | 113 | Release an acquired lock on the directory or a path within it described |
| paul@303 | 114 | by 'parts'. |
| paul@303 | 115 | """ |
| paul@303 | 116 | |
| paul@303 | 117 | try: |
| paul@303 | 118 | rmdir(self.get_lock_dir(*parts)) |
| paul@303 | 119 | except OSError, exc: |
| paul@303 | 120 | if exc.errno != errno.ENOENT: |
| paul@303 | 121 | raise |
| paul@303 | 122 | |
| paul@147 | 123 | # vim: tabstop=4 expandtab shiftwidth=4 |
