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/*
* Copyright (c) 2016 Julien Palard.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*/
#include "is_utf8.h"
/*
Check if the given unsigned char * is a valid utf-8 sequence.
Return value :
If the string is valid utf-8, 0 is returned.
Else the position, starting from 1, is returned.
Source:
http://www.unicode.org/versions/Unicode7.0.0/UnicodeStandard-7.0.pdf
page 124, 3.9 "Unicode Encoding Forms", "UTF-8"
Table 3-7. Well-Formed UTF-8 Byte Sequences
-----------------------------------------------------------------------------
| Code Points | First Byte | Second Byte | Third Byte | Fourth Byte |
| U+0000..U+007F | 00..7F | | | |
| U+0080..U+07FF | C2..DF | 80..BF | | |
| U+0800..U+0FFF | E0 | A0..BF | 80..BF | |
| U+1000..U+CFFF | E1..EC | 80..BF | 80..BF | |
| U+D000..U+D7FF | ED | 80..9F | 80..BF | |
| U+E000..U+FFFF | EE..EF | 80..BF | 80..BF | |
| U+10000..U+3FFFF | F0 | 90..BF | 80..BF | 80..BF |
| U+40000..U+FFFFF | F1..F3 | 80..BF | 80..BF | 80..BF |
| U+100000..U+10FFFF | F4 | 80..8F | 80..BF | 80..BF |
-----------------------------------------------------------------------------
Returns the first erroneous byte position, and give in
`faulty_bytes` the number of actually existing bytes taking part in this error.
*/
int is_utf8(unsigned char *str, size_t len, char **message, int *faulty_bytes)
{
size_t i = 0;
*message = NULL;
*faulty_bytes = 0;
while (i < len)
{
if (str[i] <= 0x7F) /* 00..7F */
{
i += 1;
}
else if (str[i] >= 0xC2 && str[i] <= 0xDF) /* C2..DF 80..BF */
{
if (i + 1 < len) /* Expect a 2nd byte */
{
if (str[i + 1] < 0x80 || str[i + 1] > 0xBF)
{
*message = "After a first byte between C2 and DF, expecting a 2nd byte between 80 and BF";
*faulty_bytes = 2;
return i;
}
}
else
{
*message = "After a first byte between C2 and DF, expecting a 2nd byte.";
*faulty_bytes = 1;
return i;
}
i += 2;
}
else if (str[i] == 0xE0) /* E0 A0..BF 80..BF */
{
if (i + 2 < len) /* Expect a 2nd and 3rd byte */
{
if (str[i + 1] < 0xA0 || str[i + 1] > 0xBF)
{
*message = "After a first byte of E0, expecting a 2nd byte between A0 and BF.";
*faulty_bytes = 2;
return i;
}
if (str[i + 2] < 0x80 || str[i + 2] > 0xBF)
{
*message = "After a first byte of E0, expecting a 3nd byte between 80 and BF.";
*faulty_bytes = 3;
return i;
}
}
else
{
*message = "After a first byte of E0, expecting two following bytes.";
*faulty_bytes = 1;
return i;
}
i += 3;
}
else if (str[i] >= 0xE1 && str[i] <= 0xEC) /* E1..EC 80..BF 80..BF */
{
if (i + 2 < len) /* Expect a 2nd and 3rd byte */
{
if (str[i + 1] < 0x80 || str[i + 1] > 0xBF)
{
*message = "After a first byte between E1 and EC, expecting the 2nd byte between 80 and BF.";
*faulty_bytes = 2;
return i;
}
if (str[i + 2] < 0x80 || str[i + 2] > 0xBF)
{
*message = "After a first byte between E1 and EC, expecting the 3rd byte between 80 and BF.";
*faulty_bytes = 3;
return i;
}
}
else
{
*message = "After a first byte between E1 and EC, expecting two following bytes.";
*faulty_bytes = 1;
return i;
}
i += 3;
}
else if (str[i] == 0xED) /* ED 80..9F 80..BF */
{
if (i + 2 < len) /* Expect a 2nd and 3rd byte */
{
if (str[i + 1] < 0x80 || str[i + 1] > 0x9F)
{
*message = "After a first byte of ED, expecting 2nd byte between 80 and 9F.";
*faulty_bytes = 2;
return i;
}
if (str[i + 2] < 0x80 || str[i + 2] > 0xBF)
{
*message = "After a first byte of ED, expecting 3rd byte between 80 and BF.";
*faulty_bytes = 3;
return i;
}
}
else
{
*message = "After a first byte of ED, expecting two following bytes.";
*faulty_bytes = 1;
return i;
}
i += 3;
}
else if (str[i] >= 0xEE && str[i] <= 0xEF) /* EE..EF 80..BF 80..BF */
{
if (i + 2 < len) /* Expect a 2nd and 3rd byte */
{
if (str[i + 1] < 0x80 || str[i + 1] > 0xBF)
{
*message = "After a first byte between EE and EF, expecting 2nd byte between 80 and BF.";
*faulty_bytes = 2;
return i;
}
if (str[i + 2] < 0x80 || str[i + 2] > 0xBF)
{
*message = "After a first byte between EE and EF, expecting 3rd byte between 80 and BF.";
*faulty_bytes = 3;
return i;
}
}
else
{
*message = "After a first byte between EE and EF, two following bytes.";
*faulty_bytes = 1;
return i;
}
i += 3;
}
else if (str[i] == 0xF0) /* F0 90..BF 80..BF 80..BF */
{
if (i + 3 < len) /* Expect a 2nd, 3rd 3th byte */
{
if (str[i + 1] < 0x90 || str[i + 1] > 0xBF)
{
*message = "After a first byte of F0, expecting 2nd byte between 90 and BF.";
*faulty_bytes = 2;
return i;
}
if (str[i + 2] < 0x80 || str[i + 2] > 0xBF)
{
*message = "After a first byte of F0, expecting 3rd byte between 80 and BF.";
*faulty_bytes = 3;
return i;
}
if (str[i + 3] < 0x80 || str[i + 3] > 0xBF)
{
*message = "After a first byte of F0, expecting 4th byte between 80 and BF.";
*faulty_bytes = 4;
return i;
}
}
else
{
*message = "After a first byte of F0, expecting three following bytes.";
*faulty_bytes = 1;
return i;
}
i += 4;
}
else if (str[i] >= 0xF1 && str[i] <= 0xF3) /* F1..F3 80..BF 80..BF 80..BF */
{
if (i + 3 < len) /* Expect a 2nd, 3rd 3th byte */
{
if (str[i + 1] < 0x80 || str[i + 1] > 0xBF)
{
*message = "After a first byte of F1, F2, or F3, expecting a 2nd byte between 80 and BF.";
*faulty_bytes = 2;
return i;
}
if (str[i + 2] < 0x80 || str[i + 2] > 0xBF)
{
*message = "After a first byte of F1, F2, or F3, expecting a 3rd byte between 80 and BF.";
*faulty_bytes = 3;
return i;
}
if (str[i + 3] < 0x80 || str[i + 3] > 0xBF)
{
*message = "After a first byte of F1, F2, or F3, expecting a 4th byte between 80 and BF.";
*faulty_bytes = 4;
return i;
}
}
else
{
*message = "After a first byte of F1, F2, or F3, expecting three following bytes.";
*faulty_bytes = 1;
return i;
}
i += 4;
}
else if (str[i] == 0xF4) /* F4 80..8F 80..BF 80..BF */
{
if (i + 3 < len) /* Expect a 2nd, 3rd 3th byte */
{
if (str[i + 1] < 0x80 || str[i + 1] > 0x8F)
{
*message = "After a first byte of F4, expecting 2nd byte between 80 and 8F.";
*faulty_bytes = 2;
return i;
}
if (str[i + 2] < 0x80 || str[i + 2] > 0xBF)
{
*message = "After a first byte of F4, expecting 3rd byte between 80 and BF.";
*faulty_bytes = 3;
return i;
}
if (str[i + 3] < 0x80 || str[i + 3] > 0xBF)
{
*message = "After a first byte of F4, expecting 4th byte between 80 and BF.";
*faulty_bytes = 4;
return i;
}
}
else
{
*message = "After a first byte of F4, expecting three following bytes.";
*faulty_bytes = 1;
return i;
}
i += 4;
}
else
{
*message = "Expecting bytes in the following ranges: 00..7F C2..F4.";
*faulty_bytes = 1;
return i;
}
}
message = NULL;
return 0;
}
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