/usr/lib/python3/dist-packages/postgresql/configfile.py is in python3-postgresql 1.1.0-1build1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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# .configfile
##
'PostgreSQL configuration file parser and editor functions.'
import sys
import os
from . import string as pg_str
from . import api as pg_api
quote = "'"
comment = '#'
def parse_line(line, equality = '=', comment = comment, quote = quote):
keyval = line.split(equality, 1)
if len(keyval) == 2:
key, val = keyval
prekey_len = 0
for c in key:
if not c.isspace() and c not in comment:
break
prekey_len += 1
key_len = 0
for c in key[prekey_len:]:
if not (c.isalpha() or c.isdigit() or c in '_'):
break
key_len += 1
# If non-whitespace exists after the key,
# it's a complex comment, so just bail out.
if key[prekey_len + key_len:].strip():
return
preval_len = 0
for c in val:
if not c.isspace() or c in '\n\r':
break
preval_len += 1
inquotes = False
escaped = False
val_len = 0
for i in range(preval_len, len(val)):
c = val[i]
if c == quote:
if inquotes is False:
inquotes = True
else:
if escaped is False:
# Peek ahead to see if it's escaped with another quote
escaped = (len(val) > i+1 and val[i+1] == quote)
if escaped is False:
inquotes = False
elif escaped is True:
# It *was* an escaped quote.
escaped = False
elif inquotes is False and (c.isspace() or c in comment):
break
val_len += 1
return (
# The key slice
slice(prekey_len, key_len + prekey_len),
# The value slice
slice(len(key) + 1 + preval_len, len(key) + 1 + preval_len + val_len)
)
def unquote(s, quote = quote):
"""
Unquote the string `s` if quoted.
"""
s = s.strip()
if not s.startswith(quote):
return s
return s[1:-1].replace(quote*2, quote)
def write_config(map, writer, keys = None):
'A configuration writer that will trample & merely write the settings'
if keys is None:
keys = map
for k in keys:
writer('='.join((k, map[k])) + os.linesep)
def alter_config(
map : "the configuration changes to make",
fo : "file object containing configuration lines(Iterable)",
keys : "the keys to change; defaults to map.keys()" = None
):
'Alters a configuration file without trampling on the existing structure'
if keys is None:
keys = list(map.keys())
# Normalize keys and map them back to
pkeys = {
k.lower().strip() : keys.index(k) for k in keys
}
lines = []
candidates = {}
i = -1
# Process lines in fo
for l in fo:
i += 1
lines.append(l)
pl = parse_line(l)
# "Bad" line? fuh-get-duh-bowt-it.
if pl is None:
continue
sk, sv = pl
k = l[sk].lower()
v = l[sv]
# It's a candidate?
if k in pkeys:
c = candidates.get(k)
if c is None:
candidates[k] = c = []
c.append((i, sk, sv))
# Simply insert the data somewhere for unfound keys.
for k in pkeys:
if k not in candidates:
key = keys[pkeys[k]]
val = map[key]
# Can't comment without an uncommented candidate.
if val is not None:
if not lines[-1].endswith(os.linesep):
lines[-1] = lines[-1] + os.linesep
lines.append("%s = '%s'" %(key, val.replace("'", "''")))
# Multiple lines may have the key, so make a decision based on the value.
for ck in candidates.keys():
to_set_key = keys[pkeys[ck]]
to_set_val = map[keys[pkeys[ck]]]
if to_set_val is None:
# Comment uncommented occurrences.
for cl in candidates[ck]:
line_num, sk, sv = cl
if comment not in lines[line_num][:sk.start]:
lines[line_num] = '#' + lines[line_num]
else:
# Manage occurrences.
# w_ is for winner.
# Now, a winner is elected for alteration. The winner
# is decided based on a two factors: commenting and value.
w_score = -1
w_commented = None
w_val = None
w_cl = None
for cl in candidates[ck]:
line_num, sk, sv = cl
l = lines[line_num]
lkey = l[sk]
lval = l[sv]
commented = (comment in l[:sk.start])
score = \
(not commented and 1 or 0) + \
(unquote(lval) == to_set_val and 2 or 0)
# So, if a line is not commented, and has equal
# values, then that's the winner. If a line is commented,
# and has a has equal values, it will succeed over a mere
# uncommented value.
if score > w_score:
if w_commented is False:
# It's now a loser, so comment it out if necessary.
lines[w_cl[0]] = '#' + lines[w_cl[0]]
w_score = score
w_commented = commented
w_val = lval
w_cl = cl
elif commented is False:
# Loser needs to be commented.
lines[line_num] = '#' + l
line_num, sk, sv = w_cl
l = lines[line_num]
if w_commented:
bol = ''
else:
bol = l[:sk.start]
post_val = l[sv.stop:]
# If there is post-value data, validate that it's commented.
if post_val and not post_val.isspace():
stripped_post_val = post_val.lstrip()
if not stripped_post_val.startswith(comment):
post_val = '%s%s%s' %(
# The whitespace before the uncommented visibles
post_val[0:len(post_val) - len(stripped_post_val)],
# A comment followed by the uncommented visibles
comment, stripped_post_val
)
# Everything is set as quoted as it's the only safe
# way to set something without delving into setting types.
lines[line_num] = \
bol + l[sk.start:sv.start] + \
"'%s'" %(to_set_val.replace("'", "''"),) + post_val
return lines
def read_config(iter, d = None, selector = None):
if d is None:
d = {}
for line in iter:
kv = parse_line(line)
if kv:
key = line[kv[0]]
if comment not in line[:kv[0].start] and \
(selector is None or selector(key)):
d[key] = unquote(line[kv[1]])
return d
class ConfigFile(pg_api.Settings):
"""
Provides a mapping interface to a configuration file.
Every action will cause the file to be wholly read, so using `update` to make
multiple changes is desirable.
"""
_e_factors = ('path',)
_e_label = 'CONFIGFILE'
def _e_metas(self):
yield (None, len(self.keys()))
def __init__(self, path, open = open):
self.path = path
self._open = open
self._store = []
self._restore = {}
def __repr__(self):
return "%s.%s(%r)" %(
type(self).__module__,
type(self).__name__,
self.path
)
def _save(self, lines : [str]):
with self._open(self.path, 'w') as cf:
for l in lines:
cf.write(l)
def __delitem__(self, k):
with self._open(self.path) as cf:
lines = alter_config({k : None}, cf)
self._save()
def __getitem__(self, k):
with self._open(self.path) as cfo:
return read_config(
cfo,
selector = k.__eq__
)[k]
def __setitem__(self, k, v):
self.update({k : v})
def __call__(self, **kw):
self._store.insert(0, kw)
def __context__(self):
return self
def __iter__(self):
return self.keys()
def __len__(self):
return len(list(self.keys()))
def __enter__(self):
res = self.getset(self._store[0].keys())
self.update(self._store[0])
del self._store[0]
self._restore.append(res)
def __exit__(self, exc, val, tb):
self._restored.update(self._restore[-1])
del self._restore[-1]
self.update(self._restored)
self._restored.clear()
return exc is None
def get(self, k, alt = None):
with self._open(self.path) as cf:
return read_config(cf, selector = k.__eq__).get(k, alt)
def keys(self):
return read_config(self._open(self.path)).keys()
def values(self):
return read_config(self._open(self.path)).values()
def items(self):
return read_config(self._open(self.path)).items()
def update(self, keyvals):
"""
Given a dictionary of settings, apply them to the cluster's
postgresql.conf.
"""
with self._open(self.path) as cf:
lines = alter_config(keyvals, cf)
self._save(lines)
def getset(self, keys):
"""
Get all the settings in the list of keys.
Returns a dictionary of those keys.
"""
keys = set(keys)
with self._open(self.path) as cfo:
cfg = read_config(
cfo,
selector = keys.__contains__
)
for x in (keys - set(cfg.keys())):
cfg[x] = None
return cfg
##
# vim: ts=3:sw=3:noet:
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