lib: Add PCRE2 support

Some results:

```
====
PCRE
====
% ./a.out "^65001" "65001"
comparing: ^65001 / 65001

ret status: 0
[14:31] donatas-pc donatas /home/donatas
% ./a.out "^65001_" "65001"
comparing: ^65001_ / 65001

ret status: 0

=====
PCRE2
=====
% ./a.out "^65001" "65001"
comparing: ^65001 / 65001

ret status: 0
[14:30] donatas-pc donatas /home/donatas
% ./a.out "^65001_" "65001"
comparing: ^65001_ / 65001

ret status: 1
```

Seems that if using PCRE2, we need to escape outer `()` chars and `|`. Sounds
like a bug.
But this is only with some older PCRE2 versions. With >= 10.36, I wasn't able
to reproduce this, everything is fine and working as expected.

Adding _FRR_PCRE2_POSIX definition because pcre2posix.h does not have
include's guard.

Signed-off-by: Donatas Abraitis <donatas@opensourcerouting.org>

8 files changed, 64 insertions, 15 deletions

diff --git a/bgpd/bgp_regex.h b/bgpd/bgp_regex.h
index 43ebb9ac9..e07b7f911 100644
--- a/bgpd/bgp_regex.h
+++ b/bgpd/bgp_regex.h
@@ -18,19 +18,24 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
-#ifndef _QUAGGA_BGP_REGEX_H
-#define _QUAGGA_BGP_REGEX_H
+#ifndef _FRR_BGP_REGEX_H
+#define _FRR_BGP_REGEX_H
 
 #include <zebra.h>
 
-#ifdef HAVE_LIBPCREPOSIX
+#ifdef HAVE_LIBPCRE2_POSIX
+#ifndef _FRR_PCRE2_POSIX
+#define _FRR_PCRE2_POSIX
+#include <pcre2posix.h>
+#endif /* _FRR_PCRE2_POSIX */
+#elif defined(HAVE_LIBPCREPOSIX)
 #include <pcreposix.h>
 #else
 #include <regex.h>
-#endif /* HAVE_LIBPCREPOSIX */
+#endif /* HAVE_LIBPCRE2_POSIX */
 
 extern void bgp_regex_free(regex_t *regex);
 extern regex_t *bgp_regcomp(const char *str);
 extern int bgp_regexec(regex_t *regex, struct aspath *aspath);
 
-#endif /* _QUAGGA_BGP_REGEX_H */
+#endif /* _FRR_BGP_REGEX_H */
diff --git a/bgpd/bgp_routemap.c b/bgpd/bgp_routemap.c
index aff09206e..b736e6c38 100644
--- a/bgpd/bgp_routemap.c
+++ b/bgpd/bgp_routemap.c
@@ -30,11 +30,16 @@
 #include "log.h"
 #include "frrlua.h"
 #include "frrscript.h"
-#ifdef HAVE_LIBPCREPOSIX
+#ifdef HAVE_LIBPCRE2_POSIX
+#ifndef _FRR_PCRE2_POSIX
+#define _FRR_PCRE2_POSIX
+#include <pcre2posix.h>
+#endif /* _FRR_PCRE2_POSIX */
+#elif defined(HAVE_LIBPCREPOSIX)
 #include <pcreposix.h>
 #else
 #include <regex.h>
-#endif /* HAVE_LIBPCREPOSIX */
+#endif /* HAVE_LIBPCRE2_POSIX */
 #include "buffer.h"
 #include "sockunion.h"
 #include "hash.h"
diff --git a/configure.ac b/configure.ac
index 1a481ecd7..97c8ca451 100644
--- a/configure.ac
+++ b/configure.ac
@@ -712,6 +712,8 @@ AC_ARG_ENABLE([cpu-time],
   AS_HELP_STRING([--disable-cpu-time], [disable cpu usage data gathering]))
 AC_ARG_ENABLE([pcreposix],
   AS_HELP_STRING([--enable-pcreposix], [enable using PCRE Posix libs for regex functions]))
+AC_ARG_ENABLE([pcre2posix],
+  AS_HELP_STRING([--enable-pcre2posix], [enable using PCRE2 Posix libs for regex functions]))
 AC_ARG_ENABLE([fpm],
   AS_HELP_STRING([--enable-fpm], [enable Forwarding Plane Manager support]))
 AC_ARG_ENABLE([werror],
@@ -1659,6 +1661,16 @@ if test "$enable_pcreposix" = "yes"; then
 fi
 AC_SUBST([HAVE_LIBPCREPOSIX])
 
+dnl ---------------------------
+dnl check system has PCRE2 regexp
+dnl ---------------------------
+if test "$enable_pcre2posix" = "yes"; then
+  AC_CHECK_LIB([pcre2-posix], [regexec], [], [
+    AC_MSG_ERROR([--enable-pcre2posix given but unable to find libpcre2-posix])
+  ])
+fi
+AC_SUBST([HAVE_LIBPCRE2_POSIX])
+
 dnl ##########################################################################
 dnl test "$enable_clippy_only" != "yes"
 fi
diff --git a/doc/user/installation.rst b/doc/user/installation.rst
index ba35facf2..8f89c6c4f 100644
--- a/doc/user/installation.rst
+++ b/doc/user/installation.rst
@@ -368,6 +368,13 @@ options from the list below.
 
    Turn on the usage of PCRE Posix libs for regex functionality.
 
+.. option:: --enable-pcre2posix
+
+   Turn on the usage of PCRE2 Posix libs for regex functionality.
+
+   PCRE2 versions <= 10.31 work a bit differently. We suggest using at least
+   >= 10.36.
+
 .. option:: --enable-rpath
 
    Set hardcoded rpaths in the executable [default=yes].
diff --git a/lib/frrstr.c b/lib/frrstr.c
index 1b98b224c..d66c6f8c1 100644
--- a/lib/frrstr.c
+++ b/lib/frrstr.c
@@ -23,11 +23,16 @@
 #include <string.h>
 #include <ctype.h>
 #include <sys/types.h>
-#ifdef HAVE_LIBPCREPOSIX
+#ifdef HAVE_LIBPCRE2_POSIX
+#ifndef _FRR_PCRE2_POSIX
+#define _FRR_PCRE2_POSIX
+#include <pcre2posix.h>
+#endif /* _FRR_PCRE2_POSIX */
+#elif defined(HAVE_LIBPCREPOSIX)
 #include <pcreposix.h>
 #else
 #include <regex.h>
-#endif /* HAVE_LIBPCREPOSIX */
+#endif /* HAVE_LIBPCRE2_POSIX */
 
 #include "frrstr.h"
 #include "memory.h"
diff --git a/lib/frrstr.h b/lib/frrstr.h
index d52d6a448..f0066d0fc 100644
--- a/lib/frrstr.h
+++ b/lib/frrstr.h
@@ -23,11 +23,16 @@
 
 #include <sys/types.h>
 #include <sys/types.h>
-#ifdef HAVE_LIBPCREPOSIX
+#ifdef HAVE_LIBPCRE2_POSIX
+#ifndef _FRR_PCRE2_POSIX
+#define _FRR_PCRE2_POSIX
+#include <pcre2posix.h>
+#endif /* _FRR_PCRE2_POSIX */
+#elif defined(HAVE_LIBPCREPOSIX)
 #include <pcreposix.h>
 #else
 #include <regex.h>
-#endif /* HAVE_LIBPCREPOSIX */
+#endif /* HAVE_LIBPCRE2_POSIX */
 #include <stdbool.h>
 
 #include "vector.h"
diff --git a/lib/vty.c b/lib/vty.c
index d524ae53c..5fe8d8247 100644
--- a/lib/vty.c
+++ b/lib/vty.c
@@ -24,11 +24,16 @@
 #include <lib/version.h>
 #include <sys/types.h>
 #include <sys/types.h>
-#ifdef HAVE_LIBPCREPOSIX
+#ifdef HAVE_LIBPCRE2_POSIX
+#ifndef _FRR_PCRE2_POSIX
+#define _FRR_PCRE2_POSIX
+#include <pcre2posix.h>
+#endif /* _FRR_PCRE2_POSIX */
+#elif defined(HAVE_LIBPCREPOSIX)
 #include <pcreposix.h>
 #else
 #include <regex.h>
-#endif /* HAVE_LIBPCREPOSIX */
+#endif /* HAVE_LIBPCRE2_POSIX */
 #include <stdio.h>
 
 #include "linklist.h"
diff --git a/lib/vty.h b/lib/vty.h
index 430579c5a..0b3fd2443 100644
--- a/lib/vty.h
+++ b/lib/vty.h
@@ -22,11 +22,16 @@
 #define _ZEBRA_VTY_H
 
 #include <sys/types.h>
-#ifdef HAVE_LIBPCREPOSIX
+#ifdef HAVE_LIBPCRE2_POSIX
+#ifndef _FRR_PCRE2_POSIX
+#define _FRR_PCRE2_POSIX
+#include <pcre2posix.h>
+#endif /* _FRR_PCRE2_POSIX */
+#elif defined(HAVE_LIBPCREPOSIX)
 #include <pcreposix.h>
 #else
 #include <regex.h>
-#endif /* HAVE_LIBPCREPOSIX */
+#endif /* HAVE_LIBPCRE2_POSIX */
 
 #include "thread.h"
 #include "log.h"