mongo-ruby-driver/ext/cbson/encoding_helpers.c

119 lines
4.4 KiB
C

/*
* Copyright 2009-2010 10gen, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "encoding_helpers.h"
/*
* Portions Copyright 2001 Unicode, Inc.
*
* Disclaimer
*
* This source code is provided as is by Unicode, Inc. No claims are
* made as to fitness for any particular purpose. No warranties of any
* kind are expressed or implied. The recipient agrees to determine
* applicability of information provided. If this file has been
* purchased on magnetic or optical media from Unicode, Inc., the
* sole remedy for any claim will be exchange of defective media
* within 90 days of receipt.
*
* Limitations on Rights to Redistribute This Code
*
* Unicode, Inc. hereby grants the right to freely use the information
* supplied in this file in the creation of products supporting the
* Unicode Standard, and to make copies of this file in any form
* for internal or external distribution as long as this notice
* remains attached.
*/
/*
* Index into the table below with the first byte of a UTF-8 sequence to
* get the number of trailing bytes that are supposed to follow it.
*/
static const char trailingBytesForUTF8[256] = {
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, 3,3,3,3,3,3,3,3,4,4,4,4,5,5,5,5
};
/* --------------------------------------------------------------------- */
/*
* Utility routine to tell whether a sequence of bytes is legal UTF-8.
* This must be called with the length pre-determined by the first byte.
* The length can be set by:
* length = trailingBytesForUTF8[*source]+1;
* and the sequence is illegal right away if there aren't that many bytes
* available.
* If presented with a length > 4, this returns 0. The Unicode
* definition of UTF-8 goes up to 4-byte sequences.
*/
static unsigned char isLegalUTF8(const unsigned char* source, int length) {
unsigned char a;
const unsigned char* srcptr = source + length;
switch (length) {
default: return 0;
/* Everything else falls through when "true"... */
case 4: if ((a = (*--srcptr)) < 0x80 || a > 0xBF) return 0;
case 3: if ((a = (*--srcptr)) < 0x80 || a > 0xBF) return 0;
case 2: if ((a = (*--srcptr)) > 0xBF) return 0;
switch (*source) {
/* no fall-through in this inner switch */
case 0xE0: if (a < 0xA0) return 0; break;
case 0xF0: if (a < 0x90) return 0; break;
case 0xF4: if (a > 0x8F) return 0; break;
default: if (a < 0x80) return 0;
}
case 1: if (*source >= 0x80 && *source < 0xC2) return 0;
if (*source > 0xF4) return 0;
}
return 1;
}
result_t check_string(const unsigned char* string, const long length,
const char check_utf8, const char check_null) {
int position = 0;
/* By default we go character by character. Will be different for checking
* UTF-8 */
int sequence_length = 1;
if (!check_utf8 && !check_null) {
return VALID;
}
while (position < length) {
if (check_null && *(string + position) == 0) {
return HAS_NULL;
}
if (check_utf8) {
sequence_length = trailingBytesForUTF8[*(string + position)] + 1;
if ((position + sequence_length) > length) {
return NOT_UTF_8;
}
if (!isLegalUTF8(string + position, sequence_length)) {
return NOT_UTF_8;
}
}
position += sequence_length;
}
return VALID;
}