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/* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 "apr.h"
#include "apr_private.h"
#include "apr_errno.h"
#include "apr_arch_utf8.h"
/* Implementation of RFC 3629, "UTF-8, a transformation format of ISO 10646"
* with particular attention to canonical translation forms (see section 10
* "Security Considerations" of the RFC for more info).
*
* Since several architectures including Windows support unicode, with utf-16
* used as the actual storage conventions by that archicture, these functions
* exist to transform or validate utf-16 strings into APR's 'char' type
* convention. It is left up to the operating system to determine the
* validitity of the string, e.g. normative forms, in the context of
* its native language support. Other file systems which support filename
* characters of 0x80-0xff but have no explicit requirement for Unicode
* will find this function useful only for validating the character sequences
* and rejecting poorly encoded utf-8 sequences.
*
* len utf-4 range (hex) utf-8 octet sequence (binary)
* 1:2 00000000-0000007F 0xxxxxxx
* 2:2 00000080-000007FF 110XXXXx 10xxxxxx
* 3:2 00000800-0000FFFF 1110XXXX 10Xxxxxx 10xxxxxx
* 4:4 00010000-001FFFFF 11110XXX 10XXxxxx 10xxxxxx 10xxxxxx
* 00200000-03FFFFFF 111110XX 10XXXxxx 10xxxxxx 10xxxxxx 10xxxxxx
* 04000000-7FFFFFFF 1111110X 10XXXXxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
*
* One of the X bits must be 1 to avoid overlong representation in utf-8.
*
* For conversion into utf-16, the 4th form is limited in range to 0010 FFFF,
* and the final two forms are used only by full utf-32, per RFC 3629;
*
* "Pairs of UCS-2 values between D800 and DFFF (surrogate pairs in
* Unicode parlance), being actually UCS-4 characters transformed
* through UTF-16, need special treatment: the UTF-16 transformation
* must be undone, yielding a UCS-4 character that is then transformed
* as above."
*
* From RFC2781 UTF-16: the compressed ISO 10646 encoding bitmask
*
* U' = U - 0x10000
* U' = 00000000 0000yyyy yyyyyyxx xxxxxxxx
* W1 = 110110yy yyyyyyyy
* W2 = 110111xx xxxxxxxx
* Max U' = 0000 00001111 11111111 11111111
* Max U = 0000 00010000 11111111 11111111
*
* Also note ISO/IEC 10646:2014 Clause 9.4: "Because surrogate code points
* are not UCS scalar values, UTF-32 code units in the range
* 0000 D800-0000 DFFF are ill-formed" for future reference in adding any
* utf-32 accessor functions.
*
* Len is the table above is a mapping of bytes used for utf-8:utf-16 values,
* which results in these conclusions of maximum allocations;
*
* apr_conv_utf8_to_utf16 out bytes:sizeof(in) * 1 <= Req <= sizeof(in) * 2
* apr_conv_utf16_to_utf8 out words:sizeof(in) / 2 <= Req <= sizeof(in) * 3 / 2
*/
APR_DECLARE(apr_status_t) apr_conv_utf8_to_utf16(const char *in,
apr_size_t *inbytes,
apr_wchar_t *out,
apr_size_t *outwords)
{
apr_int64_t newch, mask;
apr_size_t expect, eating;
int ch;
while (*inbytes && *outwords)
{
ch = (unsigned char)(*in++);
if (!(ch & 0200)) {
/* US-ASCII-7 plain text
*/
--*inbytes;
--*outwords;
*(out++) = ch;
}
else
{
if ((ch & 0300) != 0300) {
/* Multibyte Continuation is out of place
*/
return APR_EINVAL;
}
else
{
/* Multibyte Sequence Lead Character
*
* Compute the expected bytes while adjusting
* or lead byte and leading zeros mask.
*/
mask = 0340;
expect = 1;
while ((ch & mask) == mask) {
mask |= mask >> 1;
if (++expect > 3) /* (or 5 for a utf-32 code point) */
return APR_EINVAL;
}
newch = ch & ~mask;
eating = expect + 1;
if (*inbytes <= expect)
return APR_INCOMPLETE;
/* Reject values of excessive leading 0 bits
* utf-8 _demands_ the shortest possible byte length
*/
if (expect == 1) {
if (!(newch & 0036))
return APR_EINVAL;
}
else {
/* Reject values of excessive leading 0 bits
*/
if (!newch && !((unsigned char)*in & 0077 & (mask << 1)))
return APR_EINVAL;
if (expect == 2) {
/* Reject values D800-DFFF when not utf-16 encoded
*/
if (newch == 0015 && ((unsigned char)*in & 0040))
return APR_EINVAL;
}
else if (expect == 3) {
/* Short circuit values > 110000
*/
if (newch > 4)
return APR_EINVAL;
if (newch == 4 && ((unsigned char)*in & 0060))
return APR_EINVAL;
}
}
/* Where the boolean (expect > 2) is true, we will need
* an extra word for the output.
*/
if (*outwords < (apr_size_t)(expect > 2) + 1)
break; /* buffer full */
while (expect--)
{
/* Multibyte Continuation must be legal */
if (((ch = (unsigned char)*(in++)) & 0300) != 0200)
return APR_EINVAL;
newch <<= 6;
newch |= (ch & 0077);
}
*inbytes -= eating;
/* newch is now a true utf-32 character
*
* now we need to fold to utf-16
*/
if (newch < 0x10000)
{
--*outwords;
*(out++) = (apr_wchar_t) newch;
}
else
{
*outwords -= 2;
newch -= 0x10000;
*(out++) = (apr_wchar_t) (0xD800 | (newch >> 10));
*(out++) = (apr_wchar_t) (0xDC00 | (newch & 0x03FF));
}
}
}
}
/* Buffer full 'errors' aren't errors, the client must inspect both
* the inbytes and outwords values
*/
return APR_SUCCESS;
}
APR_DECLARE(apr_status_t) apr_conv_utf16_to_utf8(const apr_wchar_t *in,
apr_size_t *inwords,
char *out,
apr_size_t *outbytes)
{
apr_int64_t newch, require;
apr_size_t need;
char *invout;
int ch;
while (*inwords && *outbytes)
{
ch = (unsigned short)(*in++);
if (ch < 0x80)
{
--*inwords;
--*outbytes;
*(out++) = (unsigned char) ch;
}
else
{
if ((ch & 0xFC00) == 0xDC00) {
/* Invalid Leading utf-16 Multiword Continuation Character
*/
return APR_EINVAL;
}
if ((ch & 0xFC00) == 0xD800) {
/* Leading utf-16 Multiword Character
*/
if (*inwords < 2) {
/* Missing utf-16 Multiword Continuation Character
*/
return APR_INCOMPLETE;
}
if (((unsigned short)(*in) & 0xFC00) != 0xDC00) {
/* Invalid utf-16 Multiword Continuation Character
*/
return APR_EINVAL;
}
newch = (ch & 0x03FF) << 10 | ((unsigned short)(*in++) & 0x03FF);
newch += 0x10000;
}
else {
/* utf-16 Single Word Character
*/
newch = ch;
}
/* Determine the absolute minimum utf-8 bytes required
*/
require = newch >> 11;
need = 1;
while (require)
require >>= 5, ++need;
if (need >= *outbytes)
break; /* Insufficient buffer */
*inwords -= (need > 2) + 1;
*outbytes -= need + 1;
/* Compute the utf-8 characters in last to first order,
* calculating the lead character length bits along the way.
*/
ch = 0200;
out += need + 1;
invout = out;
while (need--) {
ch |= ch >> 1;
*(--invout) = (unsigned char)(0200 | (newch & 0077));
newch >>= 6;
}
/* Compute the lead utf-8 character and move the dest offset
*/
*(--invout) = (unsigned char)(ch | newch);
}
}
/* Buffer full 'errors' aren't errors, the client must inspect both
* the inwords and outbytes values
*/
return APR_SUCCESS;
}
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