From 61002ea45309851a61de2650b599baee3f2df1f9 Mon Sep 17 00:00:00 2001
From: Christopher Krah <48338417+chrikrah@users.noreply.github.com>
Date: Mon, 2 Nov 2026 19:31:06 +0100
Subject: [PATCH] pofile: Unescape the C escapes GNU gettext writes

GNU xgettext and msgcat write BEL, BS, FF and VT inside PO strings as
\a, \b, \f and \v. read_po only decoded \n, \r, \t, \\ and \", so these
four stayed as a backslash and a letter, and a catalog compiled by
Babel looked the message up under the wrong msgid.

Signed-off-by: Christopher Krah <48338417+chrikrah@users.noreply.github.com>
---
 babel/messages/pofile.py      | 13 ++++---------
 tests/messages/test_pofile.py | 14 ++++++++++++++
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/babel/messages/pofile.py b/babel/messages/pofile.py
index e3b99e4b6..63401f10d 100644
--- a/babel/messages/pofile.py
+++ b/babel/messages/pofile.py
@@ -26,7 +26,8 @@
     from _typeshed import SupportsWrite
 
 
-_unescape_re = re.compile(r'\\([\\trn"])')
+_unescape_re = re.compile(r'\\([\\abfnrtv"])')
+_unescape_map = {'a': '\a', 'b': '\b', 'f': '\f', 'n': '\n', 'r': '\r', 't': '\t', 'v': '\v'}
 
 
 def unescape(string: str) -> str:
@@ -42,14 +43,8 @@ def unescape(string: str) -> str:
 
     def replace_escapes(match):
         m = match.group(1)
-        if m == 'n':
-            return '\n'
-        elif m == 't':
-            return '\t'
-        elif m == 'r':
-            return '\r'
-        # m is \ or "
-        return m
+        # m is a letter of a C escape, or \ or "
+        return _unescape_map.get(m, m)
 
     if "\\" not in string:  # Fast path: there's nothing to unescape
         return string[1:-1]
diff --git a/tests/messages/test_pofile.py b/tests/messages/test_pofile.py
index 1b753eac8..14db8182f 100644
--- a/tests/messages/test_pofile.py
+++ b/tests/messages/test_pofile.py
@@ -87,6 +87,20 @@ def test_unescape_of_quoted_newline():
     assert pofile.unescape(r'"\\n"') == '\\n'
 
 
+def test_unescape_of_c_escapes():
+    # GNU xgettext and msgcat write these control characters as C escapes
+    assert pofile.unescape(r'"\a\b\f\n\r\t\v"') == '\a\b\f\n\r\t\v'
+
+
+def test_read_po_unescapes_vertical_tab():
+    buf = StringIO(r'''
+msgid "col1\vcol2"
+msgstr "Spalte1\vSpalte2"
+''')
+    catalog = pofile.read_po(buf)
+    assert catalog.get('col1\vcol2').string == 'Spalte1\vSpalte2'
+
+
 def test_denormalize_on_msgstr_without_empty_first_line():
     # handle irregular multi-line msgstr (no "" as first line)
     # gracefully (#171)