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+/*************************************************
+* Perl-Compatible Regular Expressions *
+*************************************************/
+
+/* PCRE is a library of functions to support regular expressions whose syntax
+and semantics are as close as possible to those of the Perl 5 language.
+
+ Written by Philip Hazel
+ Copyright (c) 1997-2013 University of Cambridge
+
+-----------------------------------------------------------------------------
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+ * Redistributions of source code must retain the above copyright notice,
+ this list of conditions and the following disclaimer.
+
+ * Redistributions in binary form must reproduce the above copyright
+ notice, this list of conditions and the following disclaimer in the
+ documentation and/or other materials provided with the distribution.
+
+ * Neither the name of the University of Cambridge nor the names of its
+ contributors may be used to endorse or promote products derived from
+ this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
+-----------------------------------------------------------------------------
+*/
+
+
+/* This module contains an internal function for validating UTF-16 character
+strings. */
+
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+/* Generate code with 16 bit character support. */
+#define COMPILE_PCRE16
+
+#include "pcre_internal.h"
+
+
+/*************************************************
+* Validate a UTF-16 string *
+*************************************************/
+
+/* This function is called (optionally) at the start of compile or match, to
+check that a supposed UTF-16 string is actually valid. The early check means
+that subsequent code can assume it is dealing with a valid string. The check
+can be turned off for maximum performance, but the consequences of supplying an
+invalid string are then undefined.
+
+From release 8.21 more information about the details of the error are passed
+back in the returned value:
+
+PCRE_UTF16_ERR0 No error
+PCRE_UTF16_ERR1 Missing low surrogate at the end of the string
+PCRE_UTF16_ERR2 Invalid low surrogate
+PCRE_UTF16_ERR3 Isolated low surrogate
+PCRE_UTF16_ERR4 Unused (was non-character)
+
+Arguments:
+ string points to the string
+ length length of string, or -1 if the string is zero-terminated
+ errp pointer to an error position offset variable
+
+Returns: = 0 if the string is a valid UTF-16 string
+ > 0 otherwise, setting the offset of the bad character
+*/
+
+int
+PRIV(valid_utf)(PCRE_PUCHAR string, int length, int *erroroffset)
+{
+#ifdef SUPPORT_UTF
+register PCRE_PUCHAR p;
+register pcre_uint32 c;
+
+if (length < 0)
+ {
+ for (p = string; *p != 0; p++);
+ length = p - string;
+ }
+
+for (p = string; length-- > 0; p++)
+ {
+ c = *p;
+
+ if ((c & 0xf800) != 0xd800)
+ {
+ /* Normal UTF-16 code point. Neither high nor low surrogate. */
+ }
+ else if ((c & 0x0400) == 0)
+ {
+ /* High surrogate. Must be a followed by a low surrogate. */
+ if (length == 0)
+ {
+ *erroroffset = p - string;
+ return PCRE_UTF16_ERR1;
+ }
+ p++;
+ length--;
+ if ((*p & 0xfc00) != 0xdc00)
+ {
+ *erroroffset = p - string;
+ return PCRE_UTF16_ERR2;
+ }
+ }
+ else
+ {
+ /* Isolated low surrogate. Always an error. */
+ *erroroffset = p - string;
+ return PCRE_UTF16_ERR3;
+ }
+ }
+
+#else /* SUPPORT_UTF */
+(void)(string); /* Keep picky compilers happy */
+(void)(length);
+(void)(erroroffset);
+#endif /* SUPPORT_UTF */
+
+return PCRE_UTF16_ERR0; /* This indicates success */
+}
+
+/* End of pcre16_valid_utf16.c */