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Optimize lit_is_valid_utf8_string (#4762)

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JerryScript-DCO-1.0-Signed-off-by: Gergo Csizi csgergo92@gmail.com
This commit is contained in:
Gergo Csizi
2021-10-20 15:45:47 +02:00
committed by GitHub
parent 4e8d6344a8
commit c446871214
2 changed files with 85 additions and 59 deletions
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jerry-core/lit/lit-strings.c
+49 -59
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@@ -17,6 +17,15 @@
#include "jrt-libc-includes.h"
#define LIT_UTF8_SURROGATE_MARKER 0xed /**< utf8 surrogate marker */
#define LIT_UTF8_HIGH_SURROGATE_MIN 0xa0 /**< utf8 high surrogate minimum */
#define LIT_UTF8_HIGH_SURROGATE_MAX 0xaf /**< utf8 high surrogate maximum */
#define LIT_UTF8_LOW_SURROGATE_MIN 0xb0 /**< utf8 low surrogate minimum */
#define LIT_UTF8_LOW_SURROGATE_MAX 0xbf /**< utf8 low surrogate maximum */
#define LIT_UTF8_1_BYTE_MAX 0xf4 /**< utf8 one byte max */
#define LIT_UTF8_2_BYTE_MAX 0x8f /**< utf8 two byte max */
#define LIT_UTF8_VALID_TWO_BYTE_START 0xc2 /**< utf8 two byte start */
/**
* Validate utf-8 string
*
@@ -31,89 +40,70 @@ lit_is_valid_utf8_string (const lit_utf8_byte_t *utf8_buf_p, /**< utf-8 string *
lit_utf8_size_t buf_size, /**< string size */
bool is_strict) /**< true if surrogate pairs are not allowed */
{
lit_utf8_size_t idx = 0;
const unsigned char *end = buf_size + utf8_buf_p;
bool is_prev_code_point_high_surrogate = false;
while (idx < buf_size)
const unsigned char *idx = (const unsigned char *) utf8_buf_p;
while (idx < end)
{
lit_utf8_byte_t c = utf8_buf_p[idx++];
if ((c & LIT_UTF8_1_BYTE_MASK) == LIT_UTF8_1_BYTE_MARKER)
const uint8_t first_byte = *idx++;
if (first_byte < LIT_UTF8_EXTRA_BYTE_MARKER)
{
is_prev_code_point_high_surrogate = false;
continue;
}
lit_code_point_t code_point = 0;
lit_code_point_t min_code_point = 0;
lit_utf8_size_t extra_bytes_count;
if ((c & LIT_UTF8_2_BYTE_MASK) == LIT_UTF8_2_BYTE_MARKER)
if (first_byte < LIT_UTF8_VALID_TWO_BYTE_START || idx >= end)
{
extra_bytes_count = 1;
min_code_point = LIT_UTF8_2_BYTE_CODE_POINT_MIN;
code_point = ((uint32_t) (c & LIT_UTF8_LAST_5_BITS_MASK));
}
else if ((c & LIT_UTF8_3_BYTE_MASK) == LIT_UTF8_3_BYTE_MARKER)
{
extra_bytes_count = 2;
min_code_point = LIT_UTF8_3_BYTE_CODE_POINT_MIN;
code_point = ((uint32_t) (c & LIT_UTF8_LAST_4_BITS_MASK));
}
else if ((c & LIT_UTF8_4_BYTE_MASK) == LIT_UTF8_4_BYTE_MARKER)
{
extra_bytes_count = 3;
min_code_point = LIT_UTF8_4_BYTE_CODE_POINT_MIN;
code_point = ((uint32_t) (c & LIT_UTF8_LAST_3_BITS_MASK));
}
else
{
/* utf-8 string could not contain 5- and 6-byte sequences. */
return false;
}
if (idx + extra_bytes_count > buf_size)
const uint8_t second_byte = *idx++;
if ((second_byte & LIT_UTF8_EXTRA_BYTE_MASK) != LIT_UTF8_EXTRA_BYTE_MARKER)
{
/* utf-8 string breaks in the middle */
return false;
}
for (lit_utf8_size_t offset = 0; offset < extra_bytes_count; ++offset)
if (first_byte < LIT_UTF8_3_BYTE_MARKER)
{
c = utf8_buf_p[idx + offset];
if ((c & LIT_UTF8_EXTRA_BYTE_MASK) != LIT_UTF8_EXTRA_BYTE_MARKER)
continue;
}
if (idx >= end || (*idx++ & LIT_UTF8_EXTRA_BYTE_MASK) != LIT_UTF8_EXTRA_BYTE_MARKER)
{
return false;
}
if (first_byte < LIT_UTF8_4_BYTE_MARKER)
{
if (first_byte == LIT_UTF8_3_BYTE_MARKER && (second_byte & LIT_UTF8_2_BYTE_MASK) == LIT_UTF8_EXTRA_BYTE_MARKER)
{
/* invalid continuation byte */
return false;
}
code_point <<= LIT_UTF8_BITS_IN_EXTRA_BYTES;
code_point |= (c & LIT_UTF8_LAST_6_BITS_MASK);
}
if (code_point < min_code_point
|| code_point > LIT_UNICODE_CODE_POINT_MAX)
{
/* utf-8 string doesn't encode valid unicode code point */
return false;
}
if (is_strict)
{
is_prev_code_point_high_surrogate = false;
if (code_point >= LIT_UTF16_HIGH_SURROGATE_MIN
&& code_point <= LIT_UTF16_HIGH_SURROGATE_MAX)
if (is_strict
&& first_byte == LIT_UTF8_SURROGATE_MARKER
&& second_byte >= LIT_UTF8_HIGH_SURROGATE_MIN
&& second_byte <= LIT_UTF8_HIGH_SURROGATE_MAX
&& idx + 3 <= end
&& idx[0] == LIT_UTF8_SURROGATE_MARKER
&& idx[1] >= LIT_UTF8_LOW_SURROGATE_MIN
&& idx[1] <= LIT_UTF8_LOW_SURROGATE_MAX)
{
is_prev_code_point_high_surrogate = true;
}
else if (code_point >= LIT_UTF16_LOW_SURROGATE_MIN
&& code_point <= LIT_UTF16_LOW_SURROGATE_MAX
&& is_prev_code_point_high_surrogate)
{
/* sequence of high and low surrogate is not allowed */
return false;
}
continue;
}
idx += extra_bytes_count;
if (idx >= end
|| first_byte > LIT_UTF8_1_BYTE_MAX
|| (first_byte == LIT_UTF8_4_BYTE_MARKER && second_byte <= LIT_UTF8_EXTRA_BYTE_MARKER)
|| (first_byte == LIT_UTF8_1_BYTE_MAX && second_byte > LIT_UTF8_2_BYTE_MAX)
|| (*idx++ & LIT_UTF8_EXTRA_BYTE_MASK) != LIT_UTF8_EXTRA_BYTE_MARKER)
{
return false;
}
}
return true;