Improve string validation .. check for invalid unicode characters.

git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@22712 72102866-910b-0410-8b05-ffd578937521

Source/Additions/Unicode.m

@@ -1090,6 +1090,66 @@ int encode_cstrtoustr(unichar *dst, int dl, const char *src, int sl,
 }
 
 
+/**
+ * Function to check a block of data for validity as a unicode string and
+ * say whether it contains solely ASCII or solely Latin1 data.<br />
+ * Any leading BOM must already have been removed and the data must already
+ * be in native byte order.
+ */
+BOOL
+GSIsUnicode(const unichar *chars, unsigned length,
+  BOOL *isASCII, BOOL *isLatin1)
+{
+  unsigned	i = 0;
+  unichar	c;
+
+  *isASCII = YES;
+  *isLatin1 = YES;
+  while (i < length)
+    {
+      if ((c = chars[i++]) > 127)
+        {
+	  *isASCII = NO;
+	  i--;
+	  while (i < length)
+	    {
+	      if ((c = chars[i++]) > 255)
+		{
+		  *isLatin1 = NO;
+		  i--;
+		  while (i < length)
+		    {
+		      c = chars[i++];
+		      if (c == 0xfffe || c == 0xffff
+			|| (c >= 0xfdd0 && c <= 0xfdef))
+			{
+			  return NO;	// Non-characters.
+			}
+		      if (c >= 0xdc00 && c <= 0xdfff)
+		        {
+			  return NO;	// Second half of a surrogate pair.
+		        }
+		      if (c >= 0xd800 && c <= 0xdbff)
+		        {
+			  // First half of a surrogate pair.
+			  if (i >= length)
+			    {
+			      return NO;	// Second half missing
+			    }
+			  c = chars[i];
+			  if (c < 0xdc00 || c > 0xdfff)
+			    {
+			      return NO;	// Second half missing
+			    }
+			  i++;		// Step past second half
+		        }
+		    }
+		}
+	    }
+        }
+    }
+  return YES;
+}
 
 #define	GROW() \
 if (dst == 0) \