[PATCH] strverscmp: sync with glibc

[Paul Eggert]

Although this doesn't exactly synchronize with glibc
byte-for-byte, it makes the code behave the same as glibc.
* lib/strverscmp.c (S_I, S_F, S_Z): Now masks, not powers of 2.
(ISDIGIT): Remove, as glibc is sticking with isdigit, and the
difference shouldn't matter in practical use.  All uses changed
back to isdigit.
(__strverscmp, strverscmp): Use new glibc method for weak aliases.
(next_state): Now unsigned char array; redo elements.
(result_type): Now signed char array; redo elements.
(__strverscmp): Fix glibc bug 9913 by using new states.
* tests/test-strverscmp.c (main): Test glibc bug 9913.
---
 ChangeLog               |  15 +++++++
 lib/strverscmp.c        | 105 ++++++++++++++++++++----------------------------
 tests/test-strverscmp.c |  14 +++++++
 3 files changed, 73 insertions(+), 61 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index d694076..7d0cdbd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,18 @@
+2016-08-30  Paul Eggert  <address@hidden>
+
+       strverscmp: sync with glibc
+       Although this doesn't exactly synchronize with glibc
+       byte-for-byte, it makes the code behave the same as glibc.
+       * lib/strverscmp.c (S_I, S_F, S_Z): Now masks, not powers of 2.
+       (ISDIGIT): Remove, as glibc is sticking with isdigit, and the
+       difference shouldn't matter in practical use.  All uses changed
+       back to isdigit.
+       (__strverscmp, strverscmp): Use new glibc method for weak aliases.
+       (next_state): Now unsigned char array; redo elements.
+       (result_type): Now signed char array; redo elements.
+       (__strverscmp): Fix glibc bug 9913 by using new states.
+       * tests/test-strverscmp.c (main): Test glibc bug 9913.
+
 2016-08-29  Jim Meyering  <address@hidden>
 
        xalloc-oversized.h: port __builtin_mul_overflow change to GCC 6.2.0
diff --git a/lib/strverscmp.c b/lib/strverscmp.c
index bb04d6b..a23e47f 100644
--- a/lib/strverscmp.c
+++ b/lib/strverscmp.c
@@ -1,21 +1,21 @@
-/* Compare strings while treating digits numerically.  -*- coding: utf-8 -*-
-   Copyright (C) 1997, 2000, 2002, 2004, 2006, 2009-2016 Free Software
-   Foundation, Inc.
+/* Compare strings while treating digits characters numerically.
+   Copyright (C) 1997-2016 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Jean-François Bignolles <address@hidden>, 1997.
 
-   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 2, or (at your option)
-   any later version.
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
 
-   This program is distributed in the hope that it will be useful,
+   The GNU C Library 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.
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser 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/>.  */
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
 
 #if !_LIBC
 # include <config.h>
@@ -26,32 +26,16 @@
 
 /* states: S_N: normal, S_I: comparing integral part, S_F: comparing
            fractional parts, S_Z: idem but with leading Zeroes only */
-#define S_N    0x0
-#define S_I    0x4
-#define S_F    0x8
-#define S_Z    0xC
+#define  S_N    0x0
+#define  S_I    0x3
+#define  S_F    0x6
+#define  S_Z    0x9
 
 /* result_type: CMP: return diff; LEN: compare using len_diff/diff */
-#define CMP    2
-#define LEN    3
+#define  CMP    2
+#define  LEN    3
 
 
-/* ISDIGIT differs from isdigit, as follows:
-   - Its arg may be any int or unsigned int; it need not be an unsigned char
-     or EOF.
-   - It's typically faster.
-   POSIX says that only '0' through '9' are digits.  Prefer ISDIGIT to
-   isdigit unless it's important to use the locale's definition
-   of "digit" even when the host does not conform to POSIX.  */
-#define ISDIGIT(c) ((unsigned int) (c) - '0' <= 9)
-
-#undef __strverscmp
-#undef strverscmp
-
-#ifndef weak_alias
-# define __strverscmp strverscmp
-#endif
-
 /* Compare S1 and S2 as strings holding indices/version numbers,
    returning less than, equal to or greater than zero if S1 is less than,
    equal to or greater than S2 (for more info, see the texinfo doc).
@@ -66,30 +50,25 @@ __strverscmp (const char *s1, const char *s2)
   int state;
   int diff;
 
-  /* Symbol(s)    0       [1-9]   others  (padding)
-     Transition   (10) 0  (01) d  (00) x  (11) -   */
-  static const unsigned int next_state[] =
+  /* Symbol(s)    0       [1-9]   others
+     Transition   (10) 0  (01) d  (00) x   */
+  static const unsigned char next_state[] =
   {
-      /* state    x    d    0    - */
-      /* S_N */  S_N, S_I, S_Z, S_N,
-      /* S_I */  S_N, S_I, S_I, S_I,
-      /* S_F */  S_N, S_F, S_F, S_F,
-      /* S_Z */  S_N, S_F, S_Z, S_Z
+      /* state    x    d    0  */
+      /* S_N */  S_N, S_I, S_Z,
+      /* S_I */  S_N, S_I, S_I,
+      /* S_F */  S_N, S_F, S_F,
+      /* S_Z */  S_N, S_F, S_Z
   };
 
-  static const int result_type[] =
+  static const signed char result_type[] =
   {
-      /* state   x/x  x/d  x/0  x/-  d/x  d/d  d/0  d/-
-                 0/x  0/d  0/0  0/-  -/x  -/d  -/0  -/- */
-
-      /* S_N */  CMP, CMP, CMP, CMP, CMP, LEN, CMP, CMP,
-                 CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
-      /* S_I */  CMP, -1,  -1,  CMP,  1,  LEN, LEN, CMP,
-                  1,  LEN, LEN, CMP, CMP, CMP, CMP, CMP,
-      /* S_F */  CMP, CMP, CMP, CMP, CMP, LEN, CMP, CMP,
-                 CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
-      /* S_Z */  CMP,  1,   1,  CMP, -1,  CMP, CMP, CMP,
-                 -1,  CMP, CMP, CMP
+      /* state   x/x  x/d  x/0  d/x  d/d  d/0  0/x  0/d  0/0  */
+
+      /* S_N */  CMP, CMP, CMP, CMP, LEN, CMP, CMP, CMP, CMP,
+      /* S_I */  CMP, -1,  -1,  +1,  LEN, LEN, +1,  LEN, LEN,
+      /* S_F */  CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
+      /* S_Z */  CMP, +1,  +1,  -1,  CMP, CMP, -1,  CMP, CMP
   };
 
   if (p1 == p2)
@@ -98,17 +77,20 @@ __strverscmp (const char *s1, const char *s2)
   c1 = *p1++;
   c2 = *p2++;
   /* Hint: '0' is a digit too.  */
-  state = S_N | ((c1 == '0') + (ISDIGIT (c1) != 0));
+  state = S_N + ((c1 == '0') + (isdigit (c1) != 0));
 
-  while ((diff = c1 - c2) == 0 && c1 != '\0')
+  while ((diff = c1 - c2) == 0)
     {
+      if (c1 == '\0')
+        return diff;
+
       state = next_state[state];
       c1 = *p1++;
       c2 = *p2++;
-      state |= (c1 == '0') + (ISDIGIT (c1) != 0);
+      state += (c1 == '0') + (isdigit (c1) != 0);
     }
 
-  state = result_type[state << 2 | ((c2 == '0') + (ISDIGIT (c2) != 0))];
+  state = result_type[state * 3 + (((c2 == '0') + (isdigit (c2) != 0)))];
 
   switch (state)
     {
@@ -116,16 +98,17 @@ __strverscmp (const char *s1, const char *s2)
       return diff;
 
     case LEN:
-      while (ISDIGIT (*p1++))
-        if (!ISDIGIT (*p2++))
+      while (isdigit (*p1++))
+        if (!isdigit (*p2++))
           return 1;
 
-      return ISDIGIT (*p2) ? -1 : diff;
+      return isdigit (*p2) ? -1 : diff;
 
     default:
       return state;
     }
 }
 #ifdef weak_alias
+libc_hidden_def (__strverscmp)
 weak_alias (__strverscmp, strverscmp)
 #endif
diff --git a/tests/test-strverscmp.c b/tests/test-strverscmp.c
index e5a6bb1..0cafe08 100644
--- a/tests/test-strverscmp.c
+++ b/tests/test-strverscmp.c
@@ -41,5 +41,19 @@ main (void)
   ASSERT (strverscmp ("09", "0") < 0);
   ASSERT (strverscmp ("9", "10") < 0);
   ASSERT (strverscmp ("0a", "0") > 0);
+
+  /* From glibc bug 9913.  */
+  {
+    static char const a[] = "B0075022800016.gbp.corp.com";
+    static char const b[] = "B007502280067.gbp.corp.com";
+    static char const c[] = "B007502357019.GBP.CORP.COM";
+    ASSERT (strverscmp (a, b) < 0);
+    ASSERT (strverscmp (b, c) < 0);
+    ASSERT (strverscmp (a, c) < 0);
+    ASSERT (strverscmp (b, a) > 0);
+    ASSERT (strverscmp (c, b) > 0);
+    ASSERT (strverscmp (c, a) > 0);
+  }
+
   return 0;
 }
-- 
2.7.4