Make strstr() work in multibyte locales.

1 files changed, 106 insertions, 99 deletions

diff --git a/lib/strstr.c b/lib/strstr.c
index 8f82b4589c..5bd7cb4658 100644
--- a/lib/strstr.c
+++ b/lib/strstr.c
@@ -1,119 +1,126 @@
-/* Copyright (C) 1994, 1999, 2002-2003 Free Software Foundation, Inc.
-This file is part of the GNU C Library.
+/* Searching in a string.
+   Copyright (C) 2005 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2005.
 
-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.
+   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.
 
-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.
+   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.  */
-
-/*
- * My personal strstr() implementation that beats most other algorithms.
- * Until someone tells me otherwise, I assume that this is the
- * fastest implementation of strstr() in C.
- * I deliberately chose not to comment it.  You should have at least
- * as much fun trying to understand it, as I had to write it :-).
- *
- * Stephen R. van den Berg, berg@pool.informatik.rwth-aachen.de	*/
+   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.  */
 
 #if HAVE_CONFIG_H
 # include <config.h>
 #endif
 
-#include <string.h>
-
-typedef unsigned chartype;
+/* Specification.  */
+#include "strstr.h"
 
-#undef strstr
+#if HAVE_MBRTOWC
+# include "mbuiter.h"
+#endif
 
+/* Find the first occurrence of NEEDLE in HAYSTACK.  */
 char *
-strstr (const char *phaystack, const char *pneedle)
+strstr (const char *haystack, const char *needle)
 {
-  register const unsigned char *haystack, *needle;
-  register chartype b, c;
+  /* Be careful not to look at the entire extent of haystack or needle
+     until needed.  This is useful because of these two cases:
+       - haystack may be very long, and a match of needle found early,
+       - needle may be very long, and not even a short initial segment of
+         needle may be found in haystack.  */
+#if HAVE_MBRTOWC
+  if (MB_CUR_MAX > 1)
+    {
+      mbui_iterator_t iter_needle;
 
-  haystack = (const unsigned char *) phaystack;
-  needle = (const unsigned char *) pneedle;
+      mbui_init (iter_needle, needle);
+      if (mbui_avail (iter_needle))
+	{
+	  mbui_iterator_t iter_haystack;
 
-  b = *needle;
-  if (b != '\0')
+	  mbui_init (iter_haystack, haystack);
+	  for (;; mbui_advance (iter_haystack))
+	    {
+	      if (!mbui_avail (iter_haystack))
+		/* No match.  */
+		return NULL;
+
+	      if (mb_equal (mbui_cur (iter_haystack), mbui_cur (iter_needle)))
+		/* The first character matches.  */
+		{
+		  mbui_iterator_t rhaystack;
+		  mbui_iterator_t rneedle;
+
+		  memcpy (&rhaystack, &iter_haystack, sizeof (mbui_iterator_t));
+		  mbui_advance (rhaystack);
+
+		  mbui_init (rneedle, needle);
+		  if (!mbui_avail (rneedle))
+		    abort ();
+		  mbui_advance (rneedle);
+
+		  for (;; mbui_advance (rhaystack), mbui_advance (rneedle))
+		    {
+		      if (!mbui_avail (rneedle))
+			/* Found a match.  */
+			return (char *) haystack;
+		      if (!mbui_avail (rhaystack))
+			/* No match.  */
+			return NULL;
+		      if (!mb_equal (mbui_cur (rhaystack), mbui_cur (rneedle)))
+			/* Nothing in this round.  */
+			break;
+		    }
+		}
+	    }
+	}
+      else
+	return (char *) haystack;
+    }
+  else
+#endif
     {
-      haystack--;				/* possible ANSI violation */
-      do
+      if (*needle != '\0')
 	{
-	  c = *++haystack;
-	  if (c == '\0')
-	    goto ret0;
-	}
-      while (c != b);
+	  /* Speed up the following searches of needle by caching its first
+	     character.  */
+	  char b = *needle++;
 
-      c = *++needle;
-      if (c == '\0')
-	goto foundneedle;
-      ++needle;
-      goto jin;
-
-      for (;;)
-        {
-          register chartype a;
-	  register const unsigned char *rhaystack, *rneedle;
-
-	  do
+	  for (;; haystack++)
 	    {
-	      a = *++haystack;
-	      if (a == '\0')
-		goto ret0;
-	      if (a == b)
-		break;
-	      a = *++haystack;
-	      if (a == '\0')
-		goto ret0;
-shloop:;    }
-          while (a != b);
-
-jin:	  a = *++haystack;
-	  if (a == '\0')
-	    goto ret0;
-
-	  if (a != c)
-	    goto shloop;
-
-	  rhaystack = haystack-- + 1;
-	  rneedle = needle;
-	  a = *rneedle;
-
-	  if (*rhaystack == a)
-	    do
-	      {
-		if (a == '\0')
-		  goto foundneedle;
-		++rhaystack;
-		a = *++needle;
-		if (*rhaystack != a)
-		  break;
-		if (a == '\0')
-		  goto foundneedle;
-		++rhaystack;
-		a = *++needle;
-	      }
-	    while (*rhaystack == a);
-
-	  needle = rneedle;		   /* took the register-poor approach */
-
-	  if (a == '\0')
-	    break;
-        }
+	      if (*haystack == '\0')
+		/* No match.  */
+		return NULL;
+	      if (*haystack == b)
+		/* The first character matches.  */
+		{
+		  const char *rhaystack = haystack + 1;
+		  const char *rneedle = needle;
+
+		  for (;; rhaystack++, rneedle++)
+		    {
+		      if (*rneedle == '\0')
+			/* Found a match.  */
+			return (char *) haystack;
+		      if (*rhaystack == '\0')
+			/* No match.  */
+			return NULL;
+		      if (*rhaystack != *rneedle)
+			/* Nothing in this round.  */
+			break;
+		    }
+		}
+	    }
+	}
+      else
+	return (char *) haystack;
     }
-foundneedle:
-  return (char*) haystack;
-ret0:
-  return 0;
 }