1 import os
2 import sysconfig
3
4
5 def reset_tzpath(to=None):
6 global TZPATH
7
8 tzpaths = to
9 if tzpaths is not None:
10 if isinstance(tzpaths, (str, bytes)):
11 raise TypeError(
12 f"tzpaths must be a list or tuple, "
13 + f"not {type(tzpaths)}: {tzpaths!r}"
14 )
15
16 if not all(map(os.path.isabs, tzpaths)):
17 raise ValueError(_get_invalid_paths_message(tzpaths))
18 base_tzpath = tzpaths
19 else:
20 env_var = os.environ.get("PYTHONTZPATH", None)
21 if env_var is not None:
22 base_tzpath = _parse_python_tzpath(env_var)
23 else:
24 base_tzpath = _parse_python_tzpath(
25 sysconfig.get_config_var("TZPATH")
26 )
27
28 TZPATH = tuple(base_tzpath)
29
30
31 def _parse_python_tzpath(env_var):
32 if not env_var:
33 return ()
34
35 raw_tzpath = env_var.split(os.pathsep)
36 new_tzpath = tuple(filter(os.path.isabs, raw_tzpath))
37
38 # If anything has been filtered out, we will warn about it
39 if len(new_tzpath) != len(raw_tzpath):
40 import warnings
41
42 msg = _get_invalid_paths_message(raw_tzpath)
43
44 warnings.warn(
45 "Invalid paths specified in PYTHONTZPATH environment variable. "
46 + msg,
47 InvalidTZPathWarning,
48 )
49
50 return new_tzpath
51
52
53 def _get_invalid_paths_message(tzpaths):
54 invalid_paths = (path for path in tzpaths if not os.path.isabs(path))
55
56 prefix = "\n "
57 indented_str = prefix + prefix.join(invalid_paths)
58
59 return (
60 "Paths should be absolute but found the following relative paths:"
61 + indented_str
62 )
63
64
65 def find_tzfile(key):
66 """Retrieve the path to a TZif file from a key."""
67 _validate_tzfile_path(key)
68 for search_path in TZPATH:
69 filepath = os.path.join(search_path, key)
70 if os.path.isfile(filepath):
71 return filepath
72
73 return None
74
75
76 _TEST_PATH = os.path.normpath(os.path.join("_", "_"))[:-1]
77
78
79 def _validate_tzfile_path(path, _base=_TEST_PATH):
80 if os.path.isabs(path):
81 raise ValueError(
82 f"ZoneInfo keys may not be absolute paths, got: {path}"
83 )
84
85 # We only care about the kinds of path normalizations that would change the
86 # length of the key - e.g. a/../b -> a/b, or a/b/ -> a/b. On Windows,
87 # normpath will also change from a/b to a\b, but that would still preserve
88 # the length.
89 new_path = os.path.normpath(path)
90 if len(new_path) != len(path):
91 raise ValueError(
92 f"ZoneInfo keys must be normalized relative paths, got: {path}"
93 )
94
95 resolved = os.path.normpath(os.path.join(_base, new_path))
96 if not resolved.startswith(_base):
97 raise ValueError(
98 f"ZoneInfo keys must refer to subdirectories of TZPATH, got: {path}"
99 )
100
101
102 del _TEST_PATH
103
104
105 def available_timezones():
106 """Returns a set containing all available time zones.
107
108 .. caution::
109
110 This may attempt to open a large number of files, since the best way to
111 determine if a given file on the time zone search path is to open it
112 and check for the "magic string" at the beginning.
113 """
114 from importlib import resources
115
116 valid_zones = set()
117
118 # Start with loading from the tzdata package if it exists: this has a
119 # pre-assembled list of zones that only requires opening one file.
120 try:
121 with resources.files("tzdata").joinpath("zones").open("r") as f:
122 for zone in f:
123 zone = zone.strip()
124 if zone:
125 valid_zones.add(zone)
126 except (ImportError, FileNotFoundError):
127 pass
128
129 def valid_key(fpath):
130 try:
131 with open(fpath, "rb") as f:
132 return f.read(4) == b"TZif"
133 except Exception: # pragma: nocover
134 return False
135
136 for tz_root in TZPATH:
137 if not os.path.exists(tz_root):
138 continue
139
140 for root, dirnames, files in os.walk(tz_root):
141 if root == tz_root:
142 # right/ and posix/ are special directories and shouldn't be
143 # included in the output of available zones
144 if "right" in dirnames:
145 dirnames.remove("right")
146 if "posix" in dirnames:
147 dirnames.remove("posix")
148
149 for file in files:
150 fpath = os.path.join(root, file)
151
152 key = os.path.relpath(fpath, start=tz_root)
153 if os.sep != "/": # pragma: nocover
154 key = key.replace(os.sep, "/")
155
156 if not key or key in valid_zones:
157 continue
158
159 if valid_key(fpath):
160 valid_zones.add(key)
161
162 if "posixrules" in valid_zones:
163 # posixrules is a special symlink-only time zone where it exists, it
164 # should not be included in the output
165 valid_zones.remove("posixrules")
166
167 return valid_zones
168
169
170 class ESC[4;38;5;81mInvalidTZPathWarning(ESC[4;38;5;149mRuntimeWarning):
171 """Warning raised if an invalid path is specified in PYTHONTZPATH."""
172
173
174 TZPATH = ()
175 reset_tzpath()