Reject an empty quoted abbreviation in the C zoneinfo parser

Author: tonghuaroot

Lib/test/test_zoneinfo/test_zoneinfo.py

@@ -1149,6 +1149,9 @@ def test_invalid_tzstr(self):
             "AB C3",
             " A B 3",
             "AAA4BB B,J60/2,J300/2",  # Embedded whitespace in DST
+            # Empty quoted abbreviation
+            "<>5",
+            "AAA4<>,M3.2.0/2,M11.1.0/3",
             "PST8PDT,M3.2.0/2",  # Only one transition rule
             # Invalid offset hours
             "AAA168",

Misc/NEWS.d/next/Library/2026-06-26-13-39-11.gh-issue-152248.N2Rmaf.rst

@@ -1,4 +1,3 @@
-Fix the pure-Python :mod:`zoneinfo` parser accepting an unquoted POSIX TZ
-abbreviation that contains characters other than ASCII letters (for example an
-embedded space), which the C implementation already rejects. Patch by
-tonghuaroot.
+Make the C and pure-Python :mod:`zoneinfo` parsers validate POSIX TZ
+abbreviations consistently, rejecting unquoted abbreviations with non-letter
+characters and empty quoted abbreviations (``<>``). Patch by tonghuaroot.

Modules/_zoneinfo.c

@@ -1762,6 +1762,9 @@ parse_abbr(const char **p, PyObject **abbr)
             ptr++;
         }
         str_end = ptr;
+        if (str_end == str_start) {
+            return -1;
+        }
         ptr++;
     }
     else {