--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2008-10-03  Kamil Dudka  <kdudka@redhat.com>
+
+	filevercmp: new module
+	* lib/filevercmp.h: New function filevercmp comparing version strings.
+	* lib/filevercmp.c: Implementation of filevercmp function.
+	* modules/filevercmp: Module metadata.
+	* tests/test-filevercmp.c: Unit test for new module.
+	* modules/filevercmp-tests: Unit test metadata.
+	* MODULES.html.sh: Add filevercmp module.
+
 2008-10-03  Bruno Haible  <bruno@clisp.org>
 
 	* lib/c-ctype.h: Add comment.

--- a/MODULES.html.sh
+++ b/MODULES.html.sh
@@ -1856,6 +1856,7 @@
   func_module readtokens
   func_module readtokens0
   func_module strverscmp
+  func_module filevercmp
   func_end_table
 
   element="Support for systems lacking ISO C 99"

new file mode 100644
--- /dev/null
+++ b/lib/filevercmp.c
@@ -0,0 +1,154 @@
+/*
+   Copyright (C) 1995 Ian Jackson <iwj10@cus.cam.ac.uk>
+   Copyright (C) 2001 Anthony Towns <aj@azure.humbug.org.au>
+   Copyright (C) 2008 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+
+#include <config.h>
+#include "filevercmp.h"
+
+#include <sys/types.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <c-ctype.h>
+#include <limits.h>
+
+/* Match a file suffix defined by this regular expression:
+   /(\.[A-Za-z][A-Za-z0-9]*)*$/
+   Scan the string *STR and return a pointer to the matching suffix, or
+   NULL if not found.  Upon return, *STR points to terminating NUL.  */
+static const char *
+match_suffix (const char **str)
+{
+  const char *match = NULL;
+  bool read_alpha = false;
+  while (**str)
+    {
+      if (read_alpha)
+        {
+          read_alpha = false;
+          if (!c_isalpha (**str))
+            match = NULL;
+        }
+      else if ('.' == **str)
+        {
+          read_alpha = true;
+          if (!match)
+            match = *str;
+        }
+      else if (!c_isalnum (**str))
+        match = NULL;
+      (*str)++;
+    }
+  return match;
+}
+
+/* verrevcmp helper function */
+static inline int
+order (unsigned char c)
+{
+  if (c_isdigit (c))
+    return 0;
+  else if (c_isalpha (c))
+    return c;
+  else if (c == '~')
+    return -1;
+  else
+    return (int) c + UCHAR_MAX + 1;
+}
+
+/* slightly modified verrevcmp function from dpkg
+   S1, S2 - compared string
+   S1_LEN, S2_LEN - length of strings to be scanned
+
+   This implements the algorithm for comparison of version strings
+   specified by Debian and now widely adopted.  The detailed
+   specification can be found in the Debian Policy Manual in the
+   section on the `Version' control field.  This version of the code
+   implements that from s5.6.12 of Debian Policy v3.8.0.1
+   http://www.debian.org/doc/debian-policy/ch-controlfields.html#s-f-Version */
+static int
+verrevcmp (const char *s1, size_t s1_len, const char *s2, size_t s2_len)
+{
+  size_t s1_pos = 0;
+  size_t s2_pos = 0;
+  while (s1_pos < s1_len || s2_pos < s2_len)
+    {
+      int first_diff = 0;
+      while ((s1_pos < s1_len && !c_isdigit (s1[s1_pos]))
+	     || (s2_pos < s2_len && !c_isdigit (s2[s2_pos])))
+	{
+	  int s1_c = (s1_pos == s1_len) ? 0 : order (s1[s1_pos]);
+	  int s2_c = (s2_pos == s2_len) ? 0 : order (s2[s2_pos]);
+	  if (s1_c != s2_c)
+	    return s1_c - s2_c;
+	  s1_pos++;
+	  s2_pos++;
+	}
+      while (s1[s1_pos] == '0')
+	s1_pos++;
+      while (s2[s2_pos] == '0')
+	s2_pos++;
+      while (c_isdigit (s1[s1_pos]) && c_isdigit (s2[s2_pos]))
+	{
+	  if (!first_diff)
+	    first_diff = s1[s1_pos] - s2[s2_pos];
+	  s1_pos++;
+	  s2_pos++;
+	}
+      if (c_isdigit (s1[s1_pos]))
+	return 1;
+      if (c_isdigit (s2[s2_pos]))
+	return -1;
+      if (first_diff)
+	return first_diff;
+    }
+  return 0;
+}
+
+/* Compare version strings S1 and S2.
+   See filevercmp.h for function description.  */
+int
+filevercmp (const char *s1, const char *s2)
+{
+  const char *s1_pos = s1;
+  const char *s2_pos = s2;
+  const char *s1_suffix, *s2_suffix;
+  size_t s1_len, s2_len;
+  int result;
+
+  /* easy comparison to see if strings are identical */
+  int simple_cmp = strcmp (s1, s2);
+  if (simple_cmp == 0)
+    return 0;
+
+  /* "cut" file suffixes */
+  s1_suffix = match_suffix (&s1_pos);
+  s2_suffix = match_suffix (&s2_pos);
+  s1_len = (s1_suffix ? s1_suffix : s1_pos) - s1;
+  s2_len = (s2_suffix ? s2_suffix : s2_pos) - s2;
+
+  /* restore file suffixes if strings are identical after "cut" */
+  if ((s1_suffix || s2_suffix) && (s1_len == s2_len)
+      && 0 == strncmp (s1, s2, s1_len))
+    {
+      s1_len = s1_pos - s1;
+      s2_len = s2_pos - s2;
+    }
+
+  result = verrevcmp (s1, s1_len, s2, s2_len);
+  return result == 0 ? simple_cmp : result;
+}

new file mode 100644
--- /dev/null
+++ b/lib/filevercmp.h
@@ -0,0 +1,42 @@
+/*
+   Copyright (C) 1995 Ian Jackson <iwj10@cus.cam.ac.uk>
+   Copyright (C) 2001 Anthony Towns <aj@azure.humbug.org.au>
+   Copyright (C) 2008 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+
+#ifndef FILEVERCMP_H
+#define FILEVERCMP_H
+
+/* Compare version strings:
+
+   This function compares strings S1 and S2:
+   1) By PREFIX in the same way as strcmp.
+   2) Then by VERSION (most similarly to version compare of Debian's dpkg).
+      Leading zeros in version numbers are ignored.
+   3) If both (PREFIX and  VERSION) are equal, strcmp function is used for
+      comparison. So this function can return 0 if (and only if) strings S1
+      and S2 are identical.
+
+   It returns number >0 for S1 > S2, 0 for S1 == S2 and number <0 for S1 < S2.
+
+   This function compares strings, in a way that if VER1 and VER2 are version
+   numbers and PREFIX and SUFFIX (SUFFIX defined as (\.[A-Za-z][A-Za-z0-9]*)*)
+   are strings then VER1 < VER2 implies filevercmp (PREFIX VER1 SUFFIX,
+   PREFIX VER2 SUFFIX) < 0.
+
+   This function is intended to be a replacement for strverscmp. */
+int filevercmp (const char *s1, const char *s2);
+
+#endif /* FILEVERCMP_H */

new file mode 100644
--- /dev/null
+++ b/modules/filevercmp
@@ -0,0 +1,26 @@
+Description:
+compare version strings and version-containing file names
+
+Files:
+lib/filevercmp.h
+lib/filevercmp.c
+
+Depends-on:
+c-ctype
+inline
+stdbool
+string
+
+configure.ac:
+
+Makefile.am:
+lib_SOURCES += filevercmp.c
+
+Include:
+"filevercmp.h"
+
+License:
+LGPL
+
+Maintainer:
+all

new file mode 100644
--- /dev/null
+++ b/modules/filevercmp-tests
@@ -0,0 +1,10 @@
+Files:
+tests/test-filevercmp.c
+
+Depends-on:
+
+configure.ac:
+
+Makefile.am:
+TESTS += test-filevercmp
+check_PROGRAMS += test-filevercmp

new file mode 100644
--- /dev/null
+++ b/tests/test-filevercmp.c
@@ -0,0 +1,95 @@
+/* Test of filevercmp() function.
+   Copyright (C) 2008 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+#include <config.h>
+
+#include "filevercmp.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#define ASSERT(expr) \
+  do									     \
+    {									     \
+      if (!(expr))							     \
+        {								     \
+          fprintf (stderr, "%s:%d: assertion failed\n", __FILE__, __LINE__); \
+          fflush (stderr);						     \
+          abort ();							     \
+        }								     \
+    }									     \
+  while (0)
+
+/* set of well sorted examples */
+static const char *const examples[] =
+{
+  "gcc-c++-10.fc9.tar.gz",
+  "gcc-c++-10.8.12-0.7rc2.fc9.tar.bz2",
+  "glibc-2-0.1.beta1.fc10.rpm",
+  "glibc-common-5-0.2.beta2.fc9.ebuild",
+  "glibc-common-5-0.2b.deb",
+  "glibc-common-11b.ebuild",
+  "glibc-common-11-0.6rc2.ebuild",
+  "libstdc++-0.5.8.11-0.7rc2.fc10.tar.gz",
+  "libstdc++-4a.fc8.tar.gz",
+  "libstdc++-4.10.4.20040204svn.rpm",
+  "libstdc++-devel-3.fc8.ebuild",
+  "libstdc++-devel-3a.fc9.tar.gz",
+  "libstdc++-devel-8.fc8.deb",
+  "libstdc++-devel-8.6.2-0.4b.fc8",
+  "nss_ldap-1-0.2b.fc9.tar.bz2",
+  "nss_ldap-1-0.6rc2.fc8.tar.gz",
+  "nss_ldap-1.0-0.1a.tar.gz",
+  "nss_ldap-10beta1.fc8.tar.gz",
+  "nss_ldap-10.11.8.6.20040204cvs.fc10.ebuild",
+  NULL
+};
+
+int
+main (int argc, char **argv)
+{
+  const char *const *i;
+
+  /* Following tests taken from test-strverscmp.c */
+  ASSERT (filevercmp ("", "") == 0);
+  ASSERT (filevercmp ("a", "a") == 0);
+  ASSERT (filevercmp ("a", "b") < 0);
+  ASSERT (filevercmp ("b", "a") > 0);
+  ASSERT (filevercmp ("a0", "a") > 0);
+  ASSERT (filevercmp ("00", "01") < 0);
+  ASSERT (filevercmp ("01", "010") < 0);
+  ASSERT (filevercmp ("9", "10") < 0);
+  ASSERT (filevercmp ("0a", "0") > 0);
+
+  /* compare each version string with each other - O(n^2) */
+  for (i = examples; *i; i++)
+    {
+      const char *const *j;
+      for (j = examples; *j; j++)
+	{
+	  int result = filevercmp (*i, *j);
+	  if (result < 0)
+	    ASSERT (i < j);
+	  else if (0 < result)
+	    ASSERT (j < i);
+	  else
+	    ASSERT (i == j);
+	}
+    }
+
+  return 0;
+}