diff options
Diffstat (limited to 'm4/regex.m4')
| -rw-r--r-- | m4/regex.m4 | 35 |
1 files changed, 34 insertions, 1 deletions
diff --git a/m4/regex.m4 b/m4/regex.m4 index 45a10490673..4a7257d8925 100644 --- a/m4/regex.m4 +++ b/m4/regex.m4 @@ -1,5 +1,5 @@ # regex.m4 -# serial 81 +# serial 82 dnl Copyright (C) 1996-2001, 2003-2026 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, @@ -318,6 +318,39 @@ AC_DEFUN([gl_REGEX], free (regs.end); } + /* These tests are derived from bug#68725, reported by + Ed Morton. The regex uses backrefs with optional groups + to detect palindromes. */ + { + regex_t re68725; + i = regcomp (&re68725, + "^(.?)(.?).?\\\\2\\\\1$", + REG_EXTENDED); + if (i) + result |= 64; + else + { + regmatch_t pm[3]; + /* "ab" is not a palindrome, so must not match + with $. */ + if (regexec (&re68725, "ab", 1, pm, 0) == 0) + result |= 64; + /* Without $, a shorter match (e.g., empty or "a") + is valid at position 0. Ensure set_regs retries + with a shorter match_last when the longest + structural match fails content validation. */ + regfree (&re68725); + i = regcomp (&re68725, + "^(.?)(.?).?\\\\2\\\\1", + REG_EXTENDED); + if (i) + result |= 64; + else if (regexec (&re68725, "ab", 3, pm, 0) != 0) + result |= 64; + regfree (&re68725); + } + } + #if 0 /* It would be nice to reject hosts whose regoff_t values are too narrow (including glibc on hosts with 64-bit ptrdiff_t and |