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Implement a safer and more predictable interpolation approach.

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Closes SF bug #511737.
This commit is contained in:
Fred Drake 2002-10-25 21:52:00 +00:00
parent 98e3b29b59
commit 0eebd5cef9
3 changed files with 74 additions and 1 deletions
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48
Lib/ConfigParser.py
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@ -538,3 +538,51 @@ class ConfigParser(RawConfigParser):
if value.find("%(") != -1:
raise InterpolationDepthError(option, section, rawval)
return value
class SafeConfigParser(ConfigParser):
def _interpolate(self, section, option, rawval, vars):
# do the string interpolation
L = []
self._interpolate_some(option, L, rawval, section, vars, 1)
return ''.join(L)
_interpvar_match = re.compile(r"%\(([^)]+)\)s").match
def _interpolate_some(self, option, accum, rest, section, map, depth):
if depth > MAX_INTERPOLATION_DEPTH:
raise InterpolationDepthError(option, section, rest)
while rest:
p = rest.find("%")
if p < 0:
accum.append(rest)
return
if p > 0:
accum.append(rest[:p])
rest = rest[p:]
# p is no longer used
c = rest[1:2]
if c == "%":
accum.append("%")
rest = rest[2:]
elif c == "(":
m = self._interpvar_match(rest)
if m is None:
raise InterpolationSyntaxError(
"bad interpolation variable syntax at: %r" % rest)
var = m.group(1)
rest = rest[m.end():]
try:
v = map[var]
except KeyError:
raise InterpolationError(
"no value found for %r" % var)
if "%" in v:
self._interpolate_some(option, accum, v,
section, map, depth + 1)
else:
accum.append(v)
else:
raise InterpolationSyntaxError(
"'%' must be followed by '%' or '('")