X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fmbsstr.c;h=24cff25dab2c667e8ff8fdb47bd649bd34d91d5e;hb=43593319b31e6b0175b8eec4433bac744959822d;hp=420be08436a3876ec34f941839ad104d8c56029d;hpb=bffe05f44cce9d4f948bb1286097cea293a067f6;p=gnulib.git

diff --git a/lib/mbsstr.c b/lib/mbsstr.c
index 420be0843..24cff25da 100644
--- a/lib/mbsstr.c
+++ b/lib/mbsstr.c
@@ -1,5 +1,5 @@
 /* Searching in a string.
-   Copyright (C) 2005-2007 Free Software Foundation, Inc.
+   Copyright (C) 2005-2013 Free Software Foundation, Inc.
    Written by Bruno Haible <bruno@clisp.org>, 2005.
 
    This program is free software: you can redistribute it and/or modify
@@ -24,147 +24,33 @@
 #include <stddef.h>  /* for NULL, in case a nonstandard string.h lacks it */
 
 #include "malloca.h"
-#if HAVE_MBRTOWC
-# include "mbuiter.h"
-#endif
+#include "mbuiter.h"
+
+/* Knuth-Morris-Pratt algorithm.  */
+#define UNIT unsigned char
+#define CANON_ELEMENT(c) c
+#include "str-kmp.h"
 
 /* Knuth-Morris-Pratt algorithm.
    See http://en.wikipedia.org/wiki/Knuth-Morris-Pratt_algorithm
-   Return a boolean indicating success.  */
-
-static bool
-knuth_morris_pratt_unibyte (const char *haystack, const char *needle,
-			    const char **resultp)
-{
-  size_t m = strlen (needle);
-
-  /* Allocate the table.  */
-  size_t *table = (size_t *) nmalloca (m, sizeof (size_t));
-  if (table == NULL)
-    return false;
-  /* Fill the table.
-     For 0 < i < m:
-       0 < table[i] <= i is defined such that
-       forall 0 < x < table[i]: needle[x..i-1] != needle[0..i-1-x],
-       and table[i] is as large as possible with this property.
-     This implies:
-     1) For 0 < i < m:
-          If table[i] < i,
-          needle[table[i]..i-1] = needle[0..i-1-table[i]].
-     2) For 0 < i < m:
-          rhaystack[0..i-1] == needle[0..i-1]
-          and exists h, i <= h < m: rhaystack[h] != needle[h]
-          implies
-          forall 0 <= x < table[i]: rhaystack[x..x+m-1] != needle[0..m-1].
-     table[0] remains uninitialized.  */
-  {
-    size_t i, j;
-
-    /* i = 1: Nothing to verify for x = 0.  */
-    table[1] = 1;
-    j = 0;
-
-    for (i = 2; i < m; i++)
-      {
-	/* Here: j = i-1 - table[i-1].
-	   The inequality needle[x..i-1] != needle[0..i-1-x] is known to hold
-	   for x < table[i-1], by induction.
-	   Furthermore, if j>0: needle[i-1-j..i-2] = needle[0..j-1].  */
-	unsigned char b = (unsigned char) needle[i - 1];
-
-	for (;;)
-	  {
-	    /* Invariants: The inequality needle[x..i-1] != needle[0..i-1-x]
-	       is known to hold for x < i-1-j.
-	       Furthermore, if j>0: needle[i-1-j..i-2] = needle[0..j-1].  */
-	    if (b == (unsigned char) needle[j])
-	      {
-		/* Set table[i] := i-1-j.  */
-		table[i] = i - ++j;
-		break;
-	      }
-	    /* The inequality needle[x..i-1] != needle[0..i-1-x] also holds
-	       for x = i-1-j, because
-	         needle[i-1] != needle[j] = needle[i-1-x].  */
-	    if (j == 0)
-	      {
-		/* The inequality holds for all possible x.  */
-		table[i] = i;
-		break;
-	      }
-	    /* The inequality needle[x..i-1] != needle[0..i-1-x] also holds
-	       for i-1-j < x < i-1-j+table[j], because for these x:
-		 needle[x..i-2]
-		 = needle[x-(i-1-j)..j-1]
-		 != needle[0..j-1-(x-(i-1-j))]  (by definition of table[j])
-		    = needle[0..i-2-x],
-	       hence needle[x..i-1] != needle[0..i-1-x].
-	       Furthermore
-		 needle[i-1-j+table[j]..i-2]
-		 = needle[table[j]..j-1]
-		 = needle[0..j-1-table[j]]  (by definition of table[j]).  */
-	    j = j - table[j];
-	  }
-	/* Here: j = i - table[i].  */
-      }
-  }
-
-  /* Search, using the table to accelerate the processing.  */
-  {
-    size_t j;
-    const char *rhaystack;
-    const char *phaystack;
-
-    *resultp = NULL;
-    j = 0;
-    rhaystack = haystack;
-    phaystack = haystack;
-    /* Invariant: phaystack = rhaystack + j.  */
-    while (*phaystack != '\0')
-      if ((unsigned char) needle[j] == (unsigned char) *phaystack)
-	{
-	  j++;
-	  phaystack++;
-	  if (j == m)
-	    {
-	      /* The entire needle has been found.  */
-	      *resultp = rhaystack;
-	      break;
-	    }
-	}
-      else if (j > 0)
-	{
-	  /* Found a match of needle[0..j-1], mismatch at needle[j].  */
-	  rhaystack += table[j];
-	  j -= table[j];
-	}
-      else
-	{
-	  /* Found a mismatch at needle[0] already.  */
-	  rhaystack++;
-	  phaystack++;
-	}
-  }
-
-  freea (table);
-  return true;
-}
-
-#if HAVE_MBRTOWC
+   Return a boolean indicating success:
+   Return true and set *RESULTP if the search was completed.
+   Return false if it was aborted because not enough memory was available.  */
 static bool
 knuth_morris_pratt_multibyte (const char *haystack, const char *needle,
-			      const char **resultp)
+                              const char **resultp)
 {
   size_t m = mbslen (needle);
   mbchar_t *needle_mbchars;
   size_t *table;
 
   /* Allocate room for needle_mbchars and the table.  */
-  char *memory = (char *) nmalloca (m, sizeof (mbchar_t) + sizeof (size_t));
+  void *memory = nmalloca (m, sizeof (mbchar_t) + sizeof (size_t));
+  void *table_memory;
   if (memory == NULL)
     return false;
-  needle_mbchars = (mbchar_t *) memory;
-  table = (size_t *) (memory + m * sizeof (mbchar_t));
+  needle_mbchars = memory;
+  table = table_memory = needle_mbchars + m;
 
   /* Fill needle_mbchars.  */
   {
@@ -200,46 +86,46 @@ knuth_morris_pratt_multibyte (const char *haystack, const char *needle,
 
     for (i = 2; i < m; i++)
       {
-	/* Here: j = i-1 - table[i-1].
-	   The inequality needle[x..i-1] != needle[0..i-1-x] is known to hold
-	   for x < table[i-1], by induction.
-	   Furthermore, if j>0: needle[i-1-j..i-2] = needle[0..j-1].  */
-	mbchar_t *b = &needle_mbchars[i - 1];
-
-	for (;;)
-	  {
-	    /* Invariants: The inequality needle[x..i-1] != needle[0..i-1-x]
-	       is known to hold for x < i-1-j.
-	       Furthermore, if j>0: needle[i-1-j..i-2] = needle[0..j-1].  */
-	    if (mb_equal (*b, needle_mbchars[j]))
-	      {
-		/* Set table[i] := i-1-j.  */
-		table[i] = i - ++j;
-		break;
-	      }
-	    /* The inequality needle[x..i-1] != needle[0..i-1-x] also holds
-	       for x = i-1-j, because
-	         needle[i-1] != needle[j] = needle[i-1-x].  */
-	    if (j == 0)
-	      {
-		/* The inequality holds for all possible x.  */
-		table[i] = i;
-		break;
-	      }
-	    /* The inequality needle[x..i-1] != needle[0..i-1-x] also holds
-	       for i-1-j < x < i-1-j+table[j], because for these x:
-		 needle[x..i-2]
-		 = needle[x-(i-1-j)..j-1]
-		 != needle[0..j-1-(x-(i-1-j))]  (by definition of table[j])
-		    = needle[0..i-2-x],
-	       hence needle[x..i-1] != needle[0..i-1-x].
-	       Furthermore
-		 needle[i-1-j+table[j]..i-2]
-		 = needle[table[j]..j-1]
-		 = needle[0..j-1-table[j]]  (by definition of table[j]).  */
-	    j = j - table[j];
-	  }
-	/* Here: j = i - table[i].  */
+        /* Here: j = i-1 - table[i-1].
+           The inequality needle[x..i-1] != needle[0..i-1-x] is known to hold
+           for x < table[i-1], by induction.
+           Furthermore, if j>0: needle[i-1-j..i-2] = needle[0..j-1].  */
+        mbchar_t *b = &needle_mbchars[i - 1];
+
+        for (;;)
+          {
+            /* Invariants: The inequality needle[x..i-1] != needle[0..i-1-x]
+               is known to hold for x < i-1-j.
+               Furthermore, if j>0: needle[i-1-j..i-2] = needle[0..j-1].  */
+            if (mb_equal (*b, needle_mbchars[j]))
+              {
+                /* Set table[i] := i-1-j.  */
+                table[i] = i - ++j;
+                break;
+              }
+            /* The inequality needle[x..i-1] != needle[0..i-1-x] also holds
+               for x = i-1-j, because
+                 needle[i-1] != needle[j] = needle[i-1-x].  */
+            if (j == 0)
+              {
+                /* The inequality holds for all possible x.  */
+                table[i] = i;
+                break;
+              }
+            /* The inequality needle[x..i-1] != needle[0..i-1-x] also holds
+               for i-1-j < x < i-1-j+table[j], because for these x:
+                 needle[x..i-2]
+                 = needle[x-(i-1-j)..j-1]
+                 != needle[0..j-1-(x-(i-1-j))]  (by definition of table[j])
+                    = needle[0..i-2-x],
+               hence needle[x..i-1] != needle[0..i-1-x].
+               Furthermore
+                 needle[i-1-j+table[j]..i-2]
+                 = needle[table[j]..j-1]
+                 = needle[0..j-1-table[j]]  (by definition of table[j]).  */
+            j = j - table[j];
+          }
+        /* Here: j = i - table[i].  */
       }
   }
 
@@ -256,42 +142,41 @@ knuth_morris_pratt_multibyte (const char *haystack, const char *needle,
     /* Invariant: phaystack = rhaystack + j.  */
     while (mbui_avail (phaystack))
       if (mb_equal (needle_mbchars[j], mbui_cur (phaystack)))
-	{
-	  j++;
-	  mbui_advance (phaystack);
-	  if (j == m)
-	    {
-	      /* The entire needle has been found.  */
-	      *resultp = mbui_cur_ptr (rhaystack);
-	      break;
-	    }
-	}
+        {
+          j++;
+          mbui_advance (phaystack);
+          if (j == m)
+            {
+              /* The entire needle has been found.  */
+              *resultp = mbui_cur_ptr (rhaystack);
+              break;
+            }
+        }
       else if (j > 0)
-	{
-	  /* Found a match of needle[0..j-1], mismatch at needle[j].  */
-	  size_t count = table[j];
-	  j -= count;
-	  for (; count > 0; count--)
-	    {
-	      if (!mbui_avail (rhaystack))
-		abort ();
-	      mbui_advance (rhaystack);
-	    }
-	}
+        {
+          /* Found a match of needle[0..j-1], mismatch at needle[j].  */
+          size_t count = table[j];
+          j -= count;
+          for (; count > 0; count--)
+            {
+              if (!mbui_avail (rhaystack))
+                abort ();
+              mbui_advance (rhaystack);
+            }
+        }
       else
-	{
-	  /* Found a mismatch at needle[0] already.  */
-	  if (!mbui_avail (rhaystack))
-	    abort ();
-	  mbui_advance (rhaystack);
-	  mbui_advance (phaystack);
-	}
+        {
+          /* Found a mismatch at needle[0] already.  */
+          if (!mbui_avail (rhaystack))
+            abort ();
+          mbui_advance (rhaystack);
+          mbui_advance (phaystack);
+        }
   }
 
   freea (memory);
   return true;
 }
-#endif
 
 /* Find the first occurrence of the character string NEEDLE in the character
    string HAYSTACK.  Return NULL if NEEDLE is not found in HAYSTACK.  */
@@ -303,196 +188,196 @@ mbsstr (const char *haystack, const char *needle)
        - 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;
 
       mbui_init (iter_needle, needle);
       if (mbui_avail (iter_needle))
-	{
-	  /* Minimizing the worst-case complexity:
-	     Let n = mbslen(haystack), m = mbslen(needle).
-	     The naïve algorithm is O(n*m) worst-case.
-	     The Knuth-Morris-Pratt algorithm is O(n) worst-case but it needs a
-	     memory allocation.
-	     To achieve linear complexity and yet amortize the cost of the
-	     memory allocation, we activate the Knuth-Morris-Pratt algorithm
-	     only once the naïve algorithm has already run for some time; more
-	     precisely, when
-	       - the outer loop count is >= 10,
-	       - the average number of comparisons per outer loop is >= 5,
-	       - the total number of comparisons is >= m.
-	     But we try it only once.  If the memory allocation attempt failed,
-	     we don't retry it.  */
-	  bool try_kmp = true;
-	  size_t outer_loop_count = 0;
-	  size_t comparison_count = 0;
-	  size_t last_ccount = 0;		   /* last comparison count */
-	  mbui_iterator_t iter_needle_last_ccount; /* = needle + last_ccount */
-
-	  mbui_iterator_t iter_haystack;
-
-	  mbui_init (iter_needle_last_ccount, needle);
-	  mbui_init (iter_haystack, haystack);
-	  for (;; mbui_advance (iter_haystack))
-	    {
-	      if (!mbui_avail (iter_haystack))
-		/* No match.  */
-		return NULL;
-
-	      /* See whether it's advisable to use an asymptotically faster
-		 algorithm.  */
-	      if (try_kmp
-		  && outer_loop_count >= 10
-		  && comparison_count >= 5 * outer_loop_count)
-		{
-		  /* See if needle + comparison_count now reaches the end of
-		     needle.  */
-		  size_t count = comparison_count - last_ccount;
-		  for (;
-		       count > 0 && mbui_avail (iter_needle_last_ccount);
-		       count--)
-		    mbui_advance (iter_needle_last_ccount);
-		  last_ccount = comparison_count;
-		  if (!mbui_avail (iter_needle_last_ccount))
-		    {
-		      /* Try the Knuth-Morris-Pratt algorithm.  */
-		      const char *result;
-		      bool success =
-			knuth_morris_pratt_multibyte (haystack, needle,
-						      &result);
-		      if (success)
-			return (char *) result;
-		      try_kmp = false;
-		    }
-		}
-
-	      outer_loop_count++;
-	      comparison_count++;
-	      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;
-		      comparison_count++;
-		      if (!mb_equal (mbui_cur (rhaystack), mbui_cur (rneedle)))
-			/* Nothing in this round.  */
-			break;
-		    }
-		}
-	    }
-	}
+        {
+          /* Minimizing the worst-case complexity:
+             Let n = mbslen(haystack), m = mbslen(needle).
+             The naïve algorithm is O(n*m) worst-case.
+             The Knuth-Morris-Pratt algorithm is O(n) worst-case but it needs a
+             memory allocation.
+             To achieve linear complexity and yet amortize the cost of the
+             memory allocation, we activate the Knuth-Morris-Pratt algorithm
+             only once the naïve algorithm has already run for some time; more
+             precisely, when
+               - the outer loop count is >= 10,
+               - the average number of comparisons per outer loop is >= 5,
+               - the total number of comparisons is >= m.
+             But we try it only once.  If the memory allocation attempt failed,
+             we don't retry it.  */
+          bool try_kmp = true;
+          size_t outer_loop_count = 0;
+          size_t comparison_count = 0;
+          size_t last_ccount = 0;                  /* last comparison count */
+          mbui_iterator_t iter_needle_last_ccount; /* = needle + last_ccount */
+
+          mbui_iterator_t iter_haystack;
+
+          mbui_init (iter_needle_last_ccount, needle);
+          mbui_init (iter_haystack, haystack);
+          for (;; mbui_advance (iter_haystack))
+            {
+              if (!mbui_avail (iter_haystack))
+                /* No match.  */
+                return NULL;
+
+              /* See whether it's advisable to use an asymptotically faster
+                 algorithm.  */
+              if (try_kmp
+                  && outer_loop_count >= 10
+                  && comparison_count >= 5 * outer_loop_count)
+                {
+                  /* See if needle + comparison_count now reaches the end of
+                     needle.  */
+                  size_t count = comparison_count - last_ccount;
+                  for (;
+                       count > 0 && mbui_avail (iter_needle_last_ccount);
+                       count--)
+                    mbui_advance (iter_needle_last_ccount);
+                  last_ccount = comparison_count;
+                  if (!mbui_avail (iter_needle_last_ccount))
+                    {
+                      /* Try the Knuth-Morris-Pratt algorithm.  */
+                      const char *result;
+                      bool success =
+                        knuth_morris_pratt_multibyte (haystack, needle,
+                                                      &result);
+                      if (success)
+                        return (char *) result;
+                      try_kmp = false;
+                    }
+                }
+
+              outer_loop_count++;
+              comparison_count++;
+              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;
+                      comparison_count++;
+                      if (!mb_equal (mbui_cur (rhaystack), mbui_cur (rneedle)))
+                        /* Nothing in this round.  */
+                        break;
+                    }
+                }
+            }
+        }
       else
-	return (char *) haystack;
+        return (char *) haystack;
     }
   else
-#endif
     {
       if (*needle != '\0')
-	{
-	  /* Minimizing the worst-case complexity:
-	     Let n = strlen(haystack), m = strlen(needle).
-	     The naïve algorithm is O(n*m) worst-case.
-	     The Knuth-Morris-Pratt algorithm is O(n) worst-case but it needs a
-	     memory allocation.
-	     To achieve linear complexity and yet amortize the cost of the
-	     memory allocation, we activate the Knuth-Morris-Pratt algorithm
-	     only once the naïve algorithm has already run for some time; more
-	     precisely, when
-	       - the outer loop count is >= 10,
-	       - the average number of comparisons per outer loop is >= 5,
-	       - the total number of comparisons is >= m.
-	     But we try it only once.  If the memory allocation attempt failed,
-	     we don't retry it.  */
-	  bool try_kmp = true;
-	  size_t outer_loop_count = 0;
-	  size_t comparison_count = 0;
-	  size_t last_ccount = 0;		   /* last comparison count */
-	  const char *needle_last_ccount = needle; /* = needle + last_ccount */
-
-	  /* Speed up the following searches of needle by caching its first
-	     character.  */
-	  char b = *needle++;
-
-	  for (;; haystack++)
-	    {
-	      if (*haystack == '\0')
-		/* No match.  */
-		return NULL;
-
-	      /* See whether it's advisable to use an asymptotically faster
-		 algorithm.  */
-	      if (try_kmp
-		  && outer_loop_count >= 10
-		  && comparison_count >= 5 * outer_loop_count)
-		{
-		  /* See if needle + comparison_count now reaches the end of
-		     needle.  */
-		  if (needle_last_ccount != NULL)
-		    {
-		      needle_last_ccount +=
-			strnlen (needle_last_ccount,
-				 comparison_count - last_ccount);
-		      if (*needle_last_ccount == '\0')
-			needle_last_ccount = NULL;
-		      last_ccount = comparison_count;
-		    }
-		  if (needle_last_ccount == NULL)
-		    {
-		      /* Try the Knuth-Morris-Pratt algorithm.  */
-		      const char *result;
-		      bool success =
-			knuth_morris_pratt_unibyte (haystack, needle - 1,
-						    &result);
-		      if (success)
-			return (char *) result;
-		      try_kmp = false;
-		    }
-		}
-
-	      outer_loop_count++;
-	      comparison_count++;
-	      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;
-		      comparison_count++;
-		      if (*rhaystack != *rneedle)
-			/* Nothing in this round.  */
-			break;
-		    }
-		}
-	    }
-	}
+        {
+          /* Minimizing the worst-case complexity:
+             Let n = strlen(haystack), m = strlen(needle).
+             The naïve algorithm is O(n*m) worst-case.
+             The Knuth-Morris-Pratt algorithm is O(n) worst-case but it needs a
+             memory allocation.
+             To achieve linear complexity and yet amortize the cost of the
+             memory allocation, we activate the Knuth-Morris-Pratt algorithm
+             only once the naïve algorithm has already run for some time; more
+             precisely, when
+               - the outer loop count is >= 10,
+               - the average number of comparisons per outer loop is >= 5,
+               - the total number of comparisons is >= m.
+             But we try it only once.  If the memory allocation attempt failed,
+             we don't retry it.  */
+          bool try_kmp = true;
+          size_t outer_loop_count = 0;
+          size_t comparison_count = 0;
+          size_t last_ccount = 0;                  /* last comparison count */
+          const char *needle_last_ccount = needle; /* = needle + last_ccount */
+
+          /* Speed up the following searches of needle by caching its first
+             character.  */
+          char b = *needle++;
+
+          for (;; haystack++)
+            {
+              if (*haystack == '\0')
+                /* No match.  */
+                return NULL;
+
+              /* See whether it's advisable to use an asymptotically faster
+                 algorithm.  */
+              if (try_kmp
+                  && outer_loop_count >= 10
+                  && comparison_count >= 5 * outer_loop_count)
+                {
+                  /* See if needle + comparison_count now reaches the end of
+                     needle.  */
+                  if (needle_last_ccount != NULL)
+                    {
+                      needle_last_ccount +=
+                        strnlen (needle_last_ccount,
+                                 comparison_count - last_ccount);
+                      if (*needle_last_ccount == '\0')
+                        needle_last_ccount = NULL;
+                      last_ccount = comparison_count;
+                    }
+                  if (needle_last_ccount == NULL)
+                    {
+                      /* Try the Knuth-Morris-Pratt algorithm.  */
+                      const unsigned char *result;
+                      bool success =
+                        knuth_morris_pratt ((const unsigned char *) haystack,
+                                            (const unsigned char *) (needle - 1),
+                                            strlen (needle - 1),
+                                            &result);
+                      if (success)
+                        return (char *) result;
+                      try_kmp = false;
+                    }
+                }
+
+              outer_loop_count++;
+              comparison_count++;
+              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;
+                      comparison_count++;
+                      if (*rhaystack != *rneedle)
+                        /* Nothing in this round.  */
+                        break;
+                    }
+                }
+            }
+        }
       else
-	return (char *) haystack;
+        return (char *) haystack;
     }
 }