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gh-91760: More strict rules for numerical group references and group names in RE (GH-91792)

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Only sequence of ASCII digits is now accepted as a numerical reference.
The group name in bytes patterns and replacement strings can now only
contain ASCII letters and digits and underscore.
This commit is contained in:
Serhiy Storchaka 2022-05-08 19:19:29 +03:00 • committed by GitHub
parent 7b024e3a3f
commit a84a56d80f
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GPG key ID: 4AEE18F83AFDEB23
5 changed files with 62 additions and 91 deletions
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40
Lib/re/_parser.py
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@ -291,17 +291,13 @@ class Tokenizer:
msg = msg.encode('ascii', 'backslashreplace').decode('ascii')
return error(msg, self.string, self.tell() - offset)
def checkgroupname(self, name, offset, nested):
def checkgroupname(self, name, offset):
if not (self.istext or name.isascii()):
msg = "bad character in group name %a" % name
raise self.error(msg, len(name) + offset)
if not name.isidentifier():
msg = "bad character in group name %r" % name
raise self.error(msg, len(name) + offset)
if not (self.istext or name.isascii()):
import warnings
warnings.warn(
"bad character in group name %a at position %d" %
(name, self.tell() - len(name) - offset),
DeprecationWarning, stacklevel=nested + 7
)
def _class_escape(source, escape):
# handle escape code inside character class
@ -717,11 +713,11 @@ def _parse(source, state, verbose, nested, first=False):
if sourcematch("<"):
# named group: skip forward to end of name
name = source.getuntil(">", "group name")
source.checkgroupname(name, 1, nested)
source.checkgroupname(name, 1)
elif sourcematch("="):
# named backreference
name = source.getuntil(")", "group name")
source.checkgroupname(name, 1, nested)
source.checkgroupname(name, 1)
gid = state.groupdict.get(name)
if gid is None:
msg = "unknown group name %r" % name
@ -782,20 +778,14 @@ def _parse(source, state, verbose, nested, first=False):
elif char == "(":
# conditional backreference group
condname = source.getuntil(")", "group name")
if condname.isidentifier():
source.checkgroupname(condname, 1, nested)
if not (condname.isdecimal() and condname.isascii()):
source.checkgroupname(condname, 1)
condgroup = state.groupdict.get(condname)
if condgroup is None:
msg = "unknown group name %r" % condname
raise source.error(msg, len(condname) + 1)
else:
try:
condgroup = int(condname)
if condgroup < 0:
raise ValueError
except ValueError:
msg = "bad character in group name %r" % condname
raise source.error(msg, len(condname) + 1) from None
condgroup = int(condname)
if not condgroup:
raise source.error("bad group number",
len(condname) + 1)
@ -1022,20 +1012,14 @@ def parse_template(source, state):
if not s.match("<"):
raise s.error("missing <")
name = s.getuntil(">", "group name")
if name.isidentifier():
s.checkgroupname(name, 1, -1)
if not (name.isdecimal() and name.isascii()):
s.checkgroupname(name, 1)
try:
index = groupindex[name]
except KeyError:
raise IndexError("unknown group name %r" % name) from None
else:
try:
index = int(name)
if index < 0:
raise ValueError
except ValueError:
raise s.error("bad character in group name %r" % name,
len(name) + 1) from None
index = int(name)
if index >= MAXGROUPS:
raise s.error("invalid group reference %d" % index,
len(name) + 1)