X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fstrstr.c;h=e94cef7568b859859683370b0a710cb9c31d7f59;hb=a8df888bfdbd98882a6909821db496b1ef9f5b36;hp=77f24cbc93b7a50bbbb7419b187f2ebc0ae0143e;hpb=f49cdb3fcfccab4b4e56f08aa00b7df561951662;p=gnulib.git

diff --git a/lib/strstr.c b/lib/strstr.c
index 77f24cbc9..e94cef756 100644
--- a/lib/strstr.c
+++ b/lib/strstr.c
@@ -1,5 +1,6 @@
-/* strstr.c -- return the offset of one string within another
-   Copyright (C) 1989, 1990 Free Software Foundation, Inc.
+/* 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
@@ -13,32 +14,115 @@
 
    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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
 
-/* Written by Mike Rendell <michael@cs.mun.ca>.  */
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
 
-/* Return the starting address of string S2 in S1;
-   return 0 if it is not found. */
+/* Specification.  */
+#include "strstr.h"
 
+#include <stddef.h>  /* for NULL */
+
+#if HAVE_MBRTOWC
+# include "mbuiter.h"
+#endif
+
+/* Find the first occurrence of NEEDLE in HAYSTACK.  */
 char *
-strstr (s1, s2)
-     char *s1;
-     char *s2;
+strstr (const char *haystack, const char *needle)
 {
-  int i;
-  char *p1;
-  char *p2;
-  char *s = s1;
-
-  for (p2 = s2, i = 0; *s; p2 = s2, i++, s++)
+  /* 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)
     {
-      for (p1 = s; *p1 && *p2 && *p1 == *p2; p1++, p2++)
-	;
-      if (!*p2)
-	break;
+      mbui_iterator_t iter_needle;
+
+      mbui_init (iter_needle, needle);
+      if (mbui_avail (iter_needle))
+	{
+	  mbui_iterator_t iter_haystack;
+
+	  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 *) mbui_cur_ptr (iter_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;
     }
-  if (!*p2)
-    return s1 + i;
+  else
+#endif
+    {
+      if (*needle != '\0')
+	{
+	  /* Speed up the following searches of needle by caching its first
+	     character.  */
+	  char b = *needle++;
+
+	  for (;; haystack++)
+	    {
+	      if (*haystack == '\0')
+		/* No match.  */
+		return NULL;
+	      if (*haystack == b)
+		/* The first character matches.  */
+		{
+		  const char *rhaystack = haystack + 1;
+		  const char *rneedle = needle;
 
-  return 0;
+		  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;
+    }
 }