1 files changed, 60 insertions, 23 deletions

diff --git a/gnu/usr.bin/grep/dfa.c b/gnu/usr.bin/grep/dfa.c
index ffbb751b9f5e..21329bc0a6a8 100644
--- a/gnu/usr.bin/grep/dfa.c
+++ b/gnu/usr.bin/grep/dfa.c
@@ -2747,7 +2747,8 @@ transit_state (struct dfa *d, int s, unsigned char const **pp)
    match needs to be verified by a backtracking matcher.  Otherwise
    we store a 0 in *backref. */
 size_t
-dfaexec (struct dfa *d, char const *begin, size_t size, int *backref)
+dfaexec (struct dfa *d, char const *begin, size_t size, int *backref,
+	 struct mb_cache *mb_cache)
 {
   register int s;	/* Current state. */
   register unsigned char const *p; /* Current input character. */
@@ -2779,43 +2780,79 @@ dfaexec (struct dfa *d, char const *begin, size_t size, int *backref)
 #ifdef MBS_SUPPORT
   if (MB_CUR_MAX > 1)
     {
-      int remain_bytes, i;
       buf_begin = begin;
       buf_end = end;
-
-      /* initialize mblen_buf, and inputwcs.  */
-      MALLOC(mblen_buf, unsigned char, end - (unsigned char const *)begin + 2);
-      MALLOC(inputwcs, wchar_t, end - (unsigned char const *)begin + 2);
-      memset(&mbs, 0, sizeof(mbstate_t));
-      remain_bytes = 0;
-      for (i = 0; i < end - (unsigned char const *)begin + 1; i++)
+      if (mb_cache && mb_cache->mblen_buf && mb_cache->wcs_buf &&
+	  begin > mb_cache->orig_buf &&
+	  (begin + size) <= (mb_cache->orig_buf + mb_cache->len))
+	{
+	  /* The cache can help us. */
+	  MALLOC(mblen_buf, unsigned char, size + 2);
+	  MALLOC(inputwcs, wchar_t, size + 2);
+	  memcpy (mblen_buf,
+		  mb_cache->mblen_buf + (begin - mb_cache->orig_buf),
+		  (size + 2) * sizeof (unsigned char));
+	  memcpy (inputwcs,
+		  mb_cache->wcs_buf + (begin - mb_cache->orig_buf),
+		  (size + 2) * sizeof (wchar_t));
+	  mblen_buf[size + 1] = 0;
+	  inputwcs[size + 1] = 0;
+	}
+      else
 	{
-	  if (remain_bytes == 0)
+	  int remain_bytes, i;
+
+	  /* initialize mblen_buf, and inputwcs.  */
+	  MALLOC(mblen_buf, unsigned char, end - (unsigned char const *)begin + 2);
+	  MALLOC(inputwcs, wchar_t, end - (unsigned char const *)begin + 2);
+	  memset(&mbs, 0, sizeof(mbstate_t));
+	  remain_bytes = 0;
+	  for (i = 0; i < end - (unsigned char const *)begin + 1; i++)
 	    {
-	      remain_bytes
-		= mbrtowc(inputwcs + i, begin + i,
-			  end - (unsigned char const *)begin - i + 1, &mbs);
-	      if (remain_bytes <= 1)
+	      if (remain_bytes == 0)
 		{
-		  remain_bytes = 0;
-		  inputwcs[i] = (wchar_t)begin[i];
-		  mblen_buf[i] = 0;
+		  remain_bytes
+		    = mbrtowc(inputwcs + i, begin + i,
+			      end - (unsigned char const *)begin - i + 1, &mbs);
+		  if (remain_bytes <= 1)
+		    {
+		      remain_bytes = 0;
+		      inputwcs[i] = (wchar_t)begin[i];
+		      mblen_buf[i] = 0;
+		    }
+		  else
+		    {
+		      mblen_buf[i] = remain_bytes;
+		      remain_bytes--;
+		    }
 		}
 	      else
 		{
 		  mblen_buf[i] = remain_bytes;
+		  inputwcs[i] = 0;
 		  remain_bytes--;
 		}
 	    }
-	  else
+	  mblen_buf[i] = 0;
+	  inputwcs[i] = 0; /* sentinel */
+
+	  if (mb_cache)
 	    {
-	      mblen_buf[i] = remain_bytes;
-	      inputwcs[i] = 0;
-	      remain_bytes--;
+	      /* Populate the cache. */
+	      mb_cache->len = size;
+	      mb_cache->orig_buf = begin;
+	      if (mb_cache->mblen_buf)
+		      free (mb_cache->mblen_buf);
+	      if (mb_cache->wcs_buf)
+		      free (mb_cache->wcs_buf);
+	      MALLOC(mb_cache->mblen_buf, unsigned char, size + 2);
+	      MALLOC(mb_cache->wcs_buf, wchar_t, size + 2);
+	      memcpy (mb_cache->mblen_buf, mblen_buf,
+		      (size + 2) * sizeof (unsigned char));
+	      memcpy (mb_cache->wcs_buf, inputwcs,
+		      (size + 2) * sizeof (wchar_t));
 	    }
 	}
-      mblen_buf[i] = 0;
-      inputwcs[i] = 0; /* sentinel */
     }
 #endif /* MBS_SUPPORT */