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gh-91700: Validate the group number in conditional expression in RE (GH-91702)

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In expression (?(group)...) an appropriate re.error is now
raised if the group number refers to not defined group.

Previously it raised RuntimeError: invalid SRE code.
This commit is contained in:
Serhiy Storchaka 2022-04-22 19:53:10 +03:00 • committed by GitHub
parent 6ccfa31421
commit 48ec61a89a
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3 changed files with 16 additions and 0 deletions
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10
Lib/re/_parser.py
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@ -77,6 +77,7 @@ class State:
self.groupdict = {}
self.groupwidths = [None] # group 0
self.lookbehindgroups = None
self.grouprefpos = {}
@property
def groups(self):
return len(self.groupwidths)
@ -795,6 +796,10 @@ def _parse(source, state, verbose, nested, first=False):
if condgroup >= MAXGROUPS:
msg = "invalid group reference %d" % condgroup
raise source.error(msg, len(condname) + 1)
if condgroup not in state.grouprefpos:
state.grouprefpos[condgroup] = (
source.tell() - len(condname) - 1
)
state.checklookbehindgroup(condgroup, source)
item_yes = _parse(source, state, verbose, nested + 1)
if source.match("|"):
@ -975,6 +980,11 @@ def parse(str, flags=0, state=None):
assert source.next == ")"
raise source.error("unbalanced parenthesis")
for g in p.state.grouprefpos:
if g >= p.state.groups:
msg = "invalid group reference %d" % g
raise error(msg, str, p.state.grouprefpos[g])
if flags & SRE_FLAG_DEBUG:
p.dump()