Compare commits

...
Author SHA1 Message Date
Niels Lohmann c403f93196 Sweep invalid UTF-8 at every position through dump()
Compare dump() of strings with ill-formed UTF-8 (stray continuation
bytes, invalid lead bytes, overlong encodings, surrogates, code points
above U+10FFFF, and sequences cut short by ASCII, a quote, a backslash,
a lead byte, or the end of the string) with an independent reference
serializer, for every error handler and with ensure_ascii on and off.
The pattern is put at every position of short strings to cross the
strides of the bulk scanners, and of longer ones to cross the end of the
512-byte string buffer.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-15 09:24:33 +02:00
Niels Lohmann e4eb7c2b0a Avoid raw string literals with backslashes in CHECK macros
MSVC's traditional preprocessor mis-lexes raw string literals inside
macro arguments and reports illegal escape sequences (C2017, C3850).

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 22:38:07 +02:00
Niels Lohmann 0299efb761 Escape characters below 0x60 from a table straight into the write buffer
When the bulk scanner in dump_escaped_impl() stops at a control
character, a quote or a backslash, that byte used to go through the
UTF-8 decoder and a switch that wrote the escape byte by byte into
string_buffer, which was then copied into write_buffer at the next run.

A byte below 0x60 at a character boundary is a complete code point, so
it now skips the decoder: its escape sequence comes from a 96-entry
table of 8-byte rows (sequence padded with zeros, length in the last
byte), and all 8 bytes are copied straight into write_buffer with one
room check. The check sits inside the existing character-boundary
block, so it runs once per scanner stop and not once per byte; testing
every byte cost about 6% on twitter.json with ensure_ascii.

The switch in the decoder's accept branch lost its cases for
characters below 0x60, which can no longer reach it.

Output is byte-identical. The string-buffer boundary tests now use
\u-escaped non-ASCII characters, since simple escapes no longer reach
string_buffer, and a new test case checks every ASCII character at
every position against a reference escaper.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 09:16:40 +02:00
3 changed files with 864 additions and 160 deletions

No files matched your search

+157 -68
View File
@@ -772,6 +772,33 @@ class serializer
break; break;
} }
} }
// A byte below 0x60 is a complete code point and needs no
// UTF-8 decoding. The scanner stops only at a control
// character, a quote, or a backslash in that range, so look up
// its escape sequence and write all 8 bytes of the table entry
// straight into the write buffer; only the length stored in the
// last byte of the entry is kept.
if (data[i] < 0x60)
{
// emit any bytes still pending in string_buffer first to
// preserve output order
if (bytes != 0)
{
put_buffer(string_buffer, bytes);
bytes = 0;
}
const auto& escape = ascii_escapes()[data[i]];
if (JSON_HEDLEY_UNLIKELY(write_buffer.size() - write_buffer_pos < escape.size()))
{
flush();
}
std::memcpy(write_buffer.data() + write_buffer_pos, escape.data(), escape.size());
write_buffer_pos += static_cast<std::size_t>(escape[7]);
bytes_after_last_accept = 0;
undumped_chars = 0;
continue;
}
} }
const auto byte = static_cast<std::uint8_t>(s[i]); const auto byte = static_cast<std::uint8_t>(s[i]);
@@ -780,71 +807,21 @@ class serializer
{ {
case UTF8_ACCEPT: // decode found a new code point case UTF8_ACCEPT: // decode found a new code point
{ {
switch (codepoint) // the code point is at least 0x60 (smaller ones are handled
// above) and is not printable ASCII (which the scanner
// copies): it is DEL (0x7F) under EnsureAscii or a non-ASCII
// character
if (EnsureAscii)
{ {
case 0x08: // backspace JSON_ASSERT(codepoint >= 0x7F);
if (error_handler == error_handler_t::keep)
{ {
string_buffer[bytes++] = '\\'; // this character was buffered as raw bytes below
string_buffer[bytes++] = 'b'; // in case it turned out to be part of an
break; // ill-formed sequence (which is kept as is); now
} // that it decoded to a well-formed code point,
// undo that and \u-escape it like any other
case 0x09: // horizontal tab // character instead
{
string_buffer[bytes++] = '\\';
string_buffer[bytes++] = 't';
break;
}
case 0x0A: // newline
{
string_buffer[bytes++] = '\\';
string_buffer[bytes++] = 'n';
break;
}
case 0x0C: // formfeed
{
string_buffer[bytes++] = '\\';
string_buffer[bytes++] = 'f';
break;
}
case 0x0D: // carriage return
{
string_buffer[bytes++] = '\\';
string_buffer[bytes++] = 'r';
break;
}
case 0x22: // quotation mark
{
string_buffer[bytes++] = '\\';
string_buffer[bytes++] = '"';
break;
}
case 0x5C: // reverse solidus
{
string_buffer[bytes++] = '\\';
string_buffer[bytes++] = '\\';
break;
}
default:
{
// escape control characters (0x00..0x1F) or, if
// EnsureAscii parameter is used, non-ASCII characters
if ((codepoint <= 0x1F) || (EnsureAscii && (codepoint >= 0x7F)))
{
if (EnsureAscii && error_handler == error_handler_t::keep)
{
// this character was buffered as raw bytes
// below in case it turned out to be part of
// an ill-formed sequence (which is kept as
// is); now that it decoded to a well-formed
// code point, undo that and \u-escape it
// like any other character instead
bytes = bytes_after_last_accept; bytes = bytes_after_last_accept;
} }
if (codepoint <= 0xFFFF) if (codepoint <= 0xFFFF)
@@ -859,13 +836,10 @@ class serializer
} }
else else
{ {
// copy byte to buffer (all previous bytes // copy byte to buffer (all previous bytes of the
// been copied have in default case above) // sequence have been copied in the default case below)
string_buffer[bytes++] = s[i]; string_buffer[bytes++] = s[i];
} }
break;
}
}
// write buffer and reset index; there must be 13 bytes // write buffer and reset index; there must be 13 bytes
// left, as this is the maximal number of bytes to be // left, as this is the maximal number of bytes to be
@@ -1253,6 +1227,121 @@ class serializer
} }
} }
/*!
@brief the JSON form of each character below 0x60
Entry c holds the escape sequence of character c - the short form for
\\b, \\t, \\n, \\f, \\r, \\" and \\\\, \\u00xx for the other control characters -
or c itself if it needs no escaping, padded with zeros to 7 bytes. The last
byte is the length of the sequence. The 8 bytes of an entry are copied at
once, so writing an escape needs neither a branch nor a byte-wise loop.
*/
static const std::array<std::array<char, 8>, 0x60>& ascii_escapes() noexcept
{
static const std::array<std::array<char, 8>, 0x60> escapes =
{
{
{{'\\', 'u', '0', '0', '0', '0', 0, 6}}, // 0x00
{{'\\', 'u', '0', '0', '0', '1', 0, 6}}, // 0x01
{{'\\', 'u', '0', '0', '0', '2', 0, 6}}, // 0x02
{{'\\', 'u', '0', '0', '0', '3', 0, 6}}, // 0x03
{{'\\', 'u', '0', '0', '0', '4', 0, 6}}, // 0x04
{{'\\', 'u', '0', '0', '0', '5', 0, 6}}, // 0x05
{{'\\', 'u', '0', '0', '0', '6', 0, 6}}, // 0x06
{{'\\', 'u', '0', '0', '0', '7', 0, 6}}, // 0x07
{{'\\', 'b', 0, 0, 0, 0, 0, 2}}, // 0x08
{{'\\', 't', 0, 0, 0, 0, 0, 2}}, // 0x09
{{'\\', 'n', 0, 0, 0, 0, 0, 2}}, // 0x0A
{{'\\', 'u', '0', '0', '0', 'b', 0, 6}}, // 0x0B
{{'\\', 'f', 0, 0, 0, 0, 0, 2}}, // 0x0C
{{'\\', 'r', 0, 0, 0, 0, 0, 2}}, // 0x0D
{{'\\', 'u', '0', '0', '0', 'e', 0, 6}}, // 0x0E
{{'\\', 'u', '0', '0', '0', 'f', 0, 6}}, // 0x0F
{{'\\', 'u', '0', '0', '1', '0', 0, 6}}, // 0x10
{{'\\', 'u', '0', '0', '1', '1', 0, 6}}, // 0x11
{{'\\', 'u', '0', '0', '1', '2', 0, 6}}, // 0x12
{{'\\', 'u', '0', '0', '1', '3', 0, 6}}, // 0x13
{{'\\', 'u', '0', '0', '1', '4', 0, 6}}, // 0x14
{{'\\', 'u', '0', '0', '1', '5', 0, 6}}, // 0x15
{{'\\', 'u', '0', '0', '1', '6', 0, 6}}, // 0x16
{{'\\', 'u', '0', '0', '1', '7', 0, 6}}, // 0x17
{{'\\', 'u', '0', '0', '1', '8', 0, 6}}, // 0x18
{{'\\', 'u', '0', '0', '1', '9', 0, 6}}, // 0x19
{{'\\', 'u', '0', '0', '1', 'a', 0, 6}}, // 0x1A
{{'\\', 'u', '0', '0', '1', 'b', 0, 6}}, // 0x1B
{{'\\', 'u', '0', '0', '1', 'c', 0, 6}}, // 0x1C
{{'\\', 'u', '0', '0', '1', 'd', 0, 6}}, // 0x1D
{{'\\', 'u', '0', '0', '1', 'e', 0, 6}}, // 0x1E
{{'\\', 'u', '0', '0', '1', 'f', 0, 6}}, // 0x1F
{{' ', 0, 0, 0, 0, 0, 0, 1}}, // 0x20
{{'!', 0, 0, 0, 0, 0, 0, 1}}, // 0x21
{{'\\', '"', 0, 0, 0, 0, 0, 2}}, // 0x22
{{'#', 0, 0, 0, 0, 0, 0, 1}}, // 0x23
{{'$', 0, 0, 0, 0, 0, 0, 1}}, // 0x24
{{'%', 0, 0, 0, 0, 0, 0, 1}}, // 0x25
{{'&', 0, 0, 0, 0, 0, 0, 1}}, // 0x26
{{'\'', 0, 0, 0, 0, 0, 0, 1}}, // 0x27
{{'(', 0, 0, 0, 0, 0, 0, 1}}, // 0x28
{{')', 0, 0, 0, 0, 0, 0, 1}}, // 0x29
{{'*', 0, 0, 0, 0, 0, 0, 1}}, // 0x2A
{{'+', 0, 0, 0, 0, 0, 0, 1}}, // 0x2B
{{',', 0, 0, 0, 0, 0, 0, 1}}, // 0x2C
{{'-', 0, 0, 0, 0, 0, 0, 1}}, // 0x2D
{{'.', 0, 0, 0, 0, 0, 0, 1}}, // 0x2E
{{'/', 0, 0, 0, 0, 0, 0, 1}}, // 0x2F
{{'0', 0, 0, 0, 0, 0, 0, 1}}, // 0x30
{{'1', 0, 0, 0, 0, 0, 0, 1}}, // 0x31
{{'2', 0, 0, 0, 0, 0, 0, 1}}, // 0x32
{{'3', 0, 0, 0, 0, 0, 0, 1}}, // 0x33
{{'4', 0, 0, 0, 0, 0, 0, 1}}, // 0x34
{{'5', 0, 0, 0, 0, 0, 0, 1}}, // 0x35
{{'6', 0, 0, 0, 0, 0, 0, 1}}, // 0x36
{{'7', 0, 0, 0, 0, 0, 0, 1}}, // 0x37
{{'8', 0, 0, 0, 0, 0, 0, 1}}, // 0x38
{{'9', 0, 0, 0, 0, 0, 0, 1}}, // 0x39
{{':', 0, 0, 0, 0, 0, 0, 1}}, // 0x3A
{{';', 0, 0, 0, 0, 0, 0, 1}}, // 0x3B
{{'<', 0, 0, 0, 0, 0, 0, 1}}, // 0x3C
{{'=', 0, 0, 0, 0, 0, 0, 1}}, // 0x3D
{{'>', 0, 0, 0, 0, 0, 0, 1}}, // 0x3E
{{'?', 0, 0, 0, 0, 0, 0, 1}}, // 0x3F
{{'@', 0, 0, 0, 0, 0, 0, 1}}, // 0x40
{{'A', 0, 0, 0, 0, 0, 0, 1}}, // 0x41
{{'B', 0, 0, 0, 0, 0, 0, 1}}, // 0x42
{{'C', 0, 0, 0, 0, 0, 0, 1}}, // 0x43
{{'D', 0, 0, 0, 0, 0, 0, 1}}, // 0x44
{{'E', 0, 0, 0, 0, 0, 0, 1}}, // 0x45
{{'F', 0, 0, 0, 0, 0, 0, 1}}, // 0x46
{{'G', 0, 0, 0, 0, 0, 0, 1}}, // 0x47
{{'H', 0, 0, 0, 0, 0, 0, 1}}, // 0x48
{{'I', 0, 0, 0, 0, 0, 0, 1}}, // 0x49
{{'J', 0, 0, 0, 0, 0, 0, 1}}, // 0x4A
{{'K', 0, 0, 0, 0, 0, 0, 1}}, // 0x4B
{{'L', 0, 0, 0, 0, 0, 0, 1}}, // 0x4C
{{'M', 0, 0, 0, 0, 0, 0, 1}}, // 0x4D
{{'N', 0, 0, 0, 0, 0, 0, 1}}, // 0x4E
{{'O', 0, 0, 0, 0, 0, 0, 1}}, // 0x4F
{{'P', 0, 0, 0, 0, 0, 0, 1}}, // 0x50
{{'Q', 0, 0, 0, 0, 0, 0, 1}}, // 0x51
{{'R', 0, 0, 0, 0, 0, 0, 1}}, // 0x52
{{'S', 0, 0, 0, 0, 0, 0, 1}}, // 0x53
{{'T', 0, 0, 0, 0, 0, 0, 1}}, // 0x54
{{'U', 0, 0, 0, 0, 0, 0, 1}}, // 0x55
{{'V', 0, 0, 0, 0, 0, 0, 1}}, // 0x56
{{'W', 0, 0, 0, 0, 0, 0, 1}}, // 0x57
{{'X', 0, 0, 0, 0, 0, 0, 1}}, // 0x58
{{'Y', 0, 0, 0, 0, 0, 0, 1}}, // 0x59
{{'Z', 0, 0, 0, 0, 0, 0, 1}}, // 0x5A
{{'[', 0, 0, 0, 0, 0, 0, 1}}, // 0x5B
{{'\\', '\\', 0, 0, 0, 0, 0, 2}}, // 0x5C
{{']', 0, 0, 0, 0, 0, 0, 1}}, // 0x5D
{{'^', 0, 0, 0, 0, 0, 0, 1}}, // 0x5E
{{'_', 0, 0, 0, 0, 0, 0, 1}}, // 0x5F
}
};
return escapes;
}
/*! /*!
* @brief write a lowercase "\\uXXXX" escape sequence into @a string_buffer * @brief write a lowercase "\\uXXXX" escape sequence into @a string_buffer
* *
+157 -68
View File
@@ -27087,6 +27087,33 @@ class serializer
break; break;
} }
} }
// A byte below 0x60 is a complete code point and needs no
// UTF-8 decoding. The scanner stops only at a control
// character, a quote, or a backslash in that range, so look up
// its escape sequence and write all 8 bytes of the table entry
// straight into the write buffer; only the length stored in the
// last byte of the entry is kept.
if (data[i] < 0x60)
{
// emit any bytes still pending in string_buffer first to
// preserve output order
if (bytes != 0)
{
put_buffer(string_buffer, bytes);
bytes = 0;
}
const auto& escape = ascii_escapes()[data[i]];
if (JSON_HEDLEY_UNLIKELY(write_buffer.size() - write_buffer_pos < escape.size()))
{
flush();
}
std::memcpy(write_buffer.data() + write_buffer_pos, escape.data(), escape.size());
write_buffer_pos += static_cast<std::size_t>(escape[7]);
bytes_after_last_accept = 0;
undumped_chars = 0;
continue;
}
} }
const auto byte = static_cast<std::uint8_t>(s[i]); const auto byte = static_cast<std::uint8_t>(s[i]);
@@ -27095,71 +27122,21 @@ class serializer
{ {
case UTF8_ACCEPT: // decode found a new code point case UTF8_ACCEPT: // decode found a new code point
{ {
switch (codepoint) // the code point is at least 0x60 (smaller ones are handled
// above) and is not printable ASCII (which the scanner
// copies): it is DEL (0x7F) under EnsureAscii or a non-ASCII
// character
if (EnsureAscii)
{ {
case 0x08: // backspace JSON_ASSERT(codepoint >= 0x7F);
if (error_handler == error_handler_t::keep)
{ {
string_buffer[bytes++] = '\\'; // this character was buffered as raw bytes below
string_buffer[bytes++] = 'b'; // in case it turned out to be part of an
break; // ill-formed sequence (which is kept as is); now
} // that it decoded to a well-formed code point,
// undo that and \u-escape it like any other
case 0x09: // horizontal tab // character instead
{
string_buffer[bytes++] = '\\';
string_buffer[bytes++] = 't';
break;
}
case 0x0A: // newline
{
string_buffer[bytes++] = '\\';
string_buffer[bytes++] = 'n';
break;
}
case 0x0C: // formfeed
{
string_buffer[bytes++] = '\\';
string_buffer[bytes++] = 'f';
break;
}
case 0x0D: // carriage return
{
string_buffer[bytes++] = '\\';
string_buffer[bytes++] = 'r';
break;
}
case 0x22: // quotation mark
{
string_buffer[bytes++] = '\\';
string_buffer[bytes++] = '"';
break;
}
case 0x5C: // reverse solidus
{
string_buffer[bytes++] = '\\';
string_buffer[bytes++] = '\\';
break;
}
default:
{
// escape control characters (0x00..0x1F) or, if
// EnsureAscii parameter is used, non-ASCII characters
if ((codepoint <= 0x1F) || (EnsureAscii && (codepoint >= 0x7F)))
{
if (EnsureAscii && error_handler == error_handler_t::keep)
{
// this character was buffered as raw bytes
// below in case it turned out to be part of
// an ill-formed sequence (which is kept as
// is); now that it decoded to a well-formed
// code point, undo that and \u-escape it
// like any other character instead
bytes = bytes_after_last_accept; bytes = bytes_after_last_accept;
} }
if (codepoint <= 0xFFFF) if (codepoint <= 0xFFFF)
@@ -27174,13 +27151,10 @@ class serializer
} }
else else
{ {
// copy byte to buffer (all previous bytes // copy byte to buffer (all previous bytes of the
// been copied have in default case above) // sequence have been copied in the default case below)
string_buffer[bytes++] = s[i]; string_buffer[bytes++] = s[i];
} }
break;
}
}
// write buffer and reset index; there must be 13 bytes // write buffer and reset index; there must be 13 bytes
// left, as this is the maximal number of bytes to be // left, as this is the maximal number of bytes to be
@@ -27568,6 +27542,121 @@ class serializer
} }
} }
/*!
@brief the JSON form of each character below 0x60
Entry c holds the escape sequence of character c - the short form for
\\b, \\t, \\n, \\f, \\r, \\" and \\\\, \\u00xx for the other control characters -
or c itself if it needs no escaping, padded with zeros to 7 bytes. The last
byte is the length of the sequence. The 8 bytes of an entry are copied at
once, so writing an escape needs neither a branch nor a byte-wise loop.
*/
static const std::array<std::array<char, 8>, 0x60>& ascii_escapes() noexcept
{
static const std::array<std::array<char, 8>, 0x60> escapes =
{
{
{{'\\', 'u', '0', '0', '0', '0', 0, 6}}, // 0x00
{{'\\', 'u', '0', '0', '0', '1', 0, 6}}, // 0x01
{{'\\', 'u', '0', '0', '0', '2', 0, 6}}, // 0x02
{{'\\', 'u', '0', '0', '0', '3', 0, 6}}, // 0x03
{{'\\', 'u', '0', '0', '0', '4', 0, 6}}, // 0x04
{{'\\', 'u', '0', '0', '0', '5', 0, 6}}, // 0x05
{{'\\', 'u', '0', '0', '0', '6', 0, 6}}, // 0x06
{{'\\', 'u', '0', '0', '0', '7', 0, 6}}, // 0x07
{{'\\', 'b', 0, 0, 0, 0, 0, 2}}, // 0x08
{{'\\', 't', 0, 0, 0, 0, 0, 2}}, // 0x09
{{'\\', 'n', 0, 0, 0, 0, 0, 2}}, // 0x0A
{{'\\', 'u', '0', '0', '0', 'b', 0, 6}}, // 0x0B
{{'\\', 'f', 0, 0, 0, 0, 0, 2}}, // 0x0C
{{'\\', 'r', 0, 0, 0, 0, 0, 2}}, // 0x0D
{{'\\', 'u', '0', '0', '0', 'e', 0, 6}}, // 0x0E
{{'\\', 'u', '0', '0', '0', 'f', 0, 6}}, // 0x0F
{{'\\', 'u', '0', '0', '1', '0', 0, 6}}, // 0x10
{{'\\', 'u', '0', '0', '1', '1', 0, 6}}, // 0x11
{{'\\', 'u', '0', '0', '1', '2', 0, 6}}, // 0x12
{{'\\', 'u', '0', '0', '1', '3', 0, 6}}, // 0x13
{{'\\', 'u', '0', '0', '1', '4', 0, 6}}, // 0x14
{{'\\', 'u', '0', '0', '1', '5', 0, 6}}, // 0x15
{{'\\', 'u', '0', '0', '1', '6', 0, 6}}, // 0x16
{{'\\', 'u', '0', '0', '1', '7', 0, 6}}, // 0x17
{{'\\', 'u', '0', '0', '1', '8', 0, 6}}, // 0x18
{{'\\', 'u', '0', '0', '1', '9', 0, 6}}, // 0x19
{{'\\', 'u', '0', '0', '1', 'a', 0, 6}}, // 0x1A
{{'\\', 'u', '0', '0', '1', 'b', 0, 6}}, // 0x1B
{{'\\', 'u', '0', '0', '1', 'c', 0, 6}}, // 0x1C
{{'\\', 'u', '0', '0', '1', 'd', 0, 6}}, // 0x1D
{{'\\', 'u', '0', '0', '1', 'e', 0, 6}}, // 0x1E
{{'\\', 'u', '0', '0', '1', 'f', 0, 6}}, // 0x1F
{{' ', 0, 0, 0, 0, 0, 0, 1}}, // 0x20
{{'!', 0, 0, 0, 0, 0, 0, 1}}, // 0x21
{{'\\', '"', 0, 0, 0, 0, 0, 2}}, // 0x22
{{'#', 0, 0, 0, 0, 0, 0, 1}}, // 0x23
{{'$', 0, 0, 0, 0, 0, 0, 1}}, // 0x24
{{'%', 0, 0, 0, 0, 0, 0, 1}}, // 0x25
{{'&', 0, 0, 0, 0, 0, 0, 1}}, // 0x26
{{'\'', 0, 0, 0, 0, 0, 0, 1}}, // 0x27
{{'(', 0, 0, 0, 0, 0, 0, 1}}, // 0x28
{{')', 0, 0, 0, 0, 0, 0, 1}}, // 0x29
{{'*', 0, 0, 0, 0, 0, 0, 1}}, // 0x2A
{{'+', 0, 0, 0, 0, 0, 0, 1}}, // 0x2B
{{',', 0, 0, 0, 0, 0, 0, 1}}, // 0x2C
{{'-', 0, 0, 0, 0, 0, 0, 1}}, // 0x2D
{{'.', 0, 0, 0, 0, 0, 0, 1}}, // 0x2E
{{'/', 0, 0, 0, 0, 0, 0, 1}}, // 0x2F
{{'0', 0, 0, 0, 0, 0, 0, 1}}, // 0x30
{{'1', 0, 0, 0, 0, 0, 0, 1}}, // 0x31
{{'2', 0, 0, 0, 0, 0, 0, 1}}, // 0x32
{{'3', 0, 0, 0, 0, 0, 0, 1}}, // 0x33
{{'4', 0, 0, 0, 0, 0, 0, 1}}, // 0x34
{{'5', 0, 0, 0, 0, 0, 0, 1}}, // 0x35
{{'6', 0, 0, 0, 0, 0, 0, 1}}, // 0x36
{{'7', 0, 0, 0, 0, 0, 0, 1}}, // 0x37
{{'8', 0, 0, 0, 0, 0, 0, 1}}, // 0x38
{{'9', 0, 0, 0, 0, 0, 0, 1}}, // 0x39
{{':', 0, 0, 0, 0, 0, 0, 1}}, // 0x3A
{{';', 0, 0, 0, 0, 0, 0, 1}}, // 0x3B
{{'<', 0, 0, 0, 0, 0, 0, 1}}, // 0x3C
{{'=', 0, 0, 0, 0, 0, 0, 1}}, // 0x3D
{{'>', 0, 0, 0, 0, 0, 0, 1}}, // 0x3E
{{'?', 0, 0, 0, 0, 0, 0, 1}}, // 0x3F
{{'@', 0, 0, 0, 0, 0, 0, 1}}, // 0x40
{{'A', 0, 0, 0, 0, 0, 0, 1}}, // 0x41
{{'B', 0, 0, 0, 0, 0, 0, 1}}, // 0x42
{{'C', 0, 0, 0, 0, 0, 0, 1}}, // 0x43
{{'D', 0, 0, 0, 0, 0, 0, 1}}, // 0x44
{{'E', 0, 0, 0, 0, 0, 0, 1}}, // 0x45
{{'F', 0, 0, 0, 0, 0, 0, 1}}, // 0x46
{{'G', 0, 0, 0, 0, 0, 0, 1}}, // 0x47
{{'H', 0, 0, 0, 0, 0, 0, 1}}, // 0x48
{{'I', 0, 0, 0, 0, 0, 0, 1}}, // 0x49
{{'J', 0, 0, 0, 0, 0, 0, 1}}, // 0x4A
{{'K', 0, 0, 0, 0, 0, 0, 1}}, // 0x4B
{{'L', 0, 0, 0, 0, 0, 0, 1}}, // 0x4C
{{'M', 0, 0, 0, 0, 0, 0, 1}}, // 0x4D
{{'N', 0, 0, 0, 0, 0, 0, 1}}, // 0x4E
{{'O', 0, 0, 0, 0, 0, 0, 1}}, // 0x4F
{{'P', 0, 0, 0, 0, 0, 0, 1}}, // 0x50
{{'Q', 0, 0, 0, 0, 0, 0, 1}}, // 0x51
{{'R', 0, 0, 0, 0, 0, 0, 1}}, // 0x52
{{'S', 0, 0, 0, 0, 0, 0, 1}}, // 0x53
{{'T', 0, 0, 0, 0, 0, 0, 1}}, // 0x54
{{'U', 0, 0, 0, 0, 0, 0, 1}}, // 0x55
{{'V', 0, 0, 0, 0, 0, 0, 1}}, // 0x56
{{'W', 0, 0, 0, 0, 0, 0, 1}}, // 0x57
{{'X', 0, 0, 0, 0, 0, 0, 1}}, // 0x58
{{'Y', 0, 0, 0, 0, 0, 0, 1}}, // 0x59
{{'Z', 0, 0, 0, 0, 0, 0, 1}}, // 0x5A
{{'[', 0, 0, 0, 0, 0, 0, 1}}, // 0x5B
{{'\\', '\\', 0, 0, 0, 0, 0, 2}}, // 0x5C
{{']', 0, 0, 0, 0, 0, 0, 1}}, // 0x5D
{{'^', 0, 0, 0, 0, 0, 0, 1}}, // 0x5E
{{'_', 0, 0, 0, 0, 0, 0, 1}}, // 0x5F
}
};
return escapes;
}
/*! /*!
* @brief write a lowercase "\\uXXXX" escape sequence into @a string_buffer * @brief write a lowercase "\\uXXXX" escape sequence into @a string_buffer
* *
+550 -24
View File
@@ -20,8 +20,11 @@
using nlohmann::json; using nlohmann::json;
#include <array> #include <array>
#include <cstdint>
#include <sstream> #include <sstream>
#include <iomanip> #include <iomanip>
#include <string>
#include <vector>
#include "test_utils.hpp" #include "test_utils.hpp"
@@ -923,66 +926,68 @@ TEST_CASE("serialization boundary values for the string buffer")
// mid-string once fewer than 13 bytes remain (`string_buffer.size() - bytes // mid-string once fewer than 13 bytes remain (`string_buffer.size() - bytes
// < 13`), 13 being one more than the most a single code point can ever // < 13`), 13 being one more than the most a single code point can ever
// write at once (a surrogate pair: two back-to-back "\uXXXX" escapes, 12 // write at once (a surrogate pair: two back-to-back "\uXXXX" escapes, 12
// bytes). Every write into string_buffer that this check protects happens // bytes). Characters below 0x60 (control characters, '"' and '\\') are
// in steps of 2 (a simple "\\x" escape) or 6 (one "\uXXXX" unit), so // escaped straight into the write buffer and never reach string_buffer, so
// `bytes` only ever takes even values at the point the check runs - the // under ensure_ascii it fills in steps of 6 (one "\uXXXX" unit for a
// tightest values actually reachable are therefore 498 (512 - 498 == 14, // character below U+10000) or 12 (a surrogate pair). With 2-byte characters
// one simple escape away from the threshold) and 500 (512 - 500 == 12, // such as U+00E4, `bytes` takes multiples of 6 at the point the check runs;
// where the flush fires immediately and resets bytes to 0). // the tightest values reachable are therefore 498 (512 - 498 == 14, after
// 83 characters) and 504 (512 - 504 == 8, after 84 characters, where the
// flush fires immediately and resets bytes to 0).
SECTION("a run of 2-byte escapes lands bytes on, and one step past, the flush threshold") SECTION("a run of 6-byte escapes lands bytes on, and one step past, the flush threshold")
{ {
for (const int count : for (const int count :
{ {
249, 250, 251 83, 84, 85
}) })
{ {
CAPTURE(count) CAPTURE(count)
const json j = std::string(static_cast<std::size_t>(count), '\n'); std::string umlauts;
std::string expected = "\""; std::string expected = "\"";
for (int i = 0; i < count; ++i) for (int i = 0; i < count; ++i)
{ {
expected += "\\n"; umlauts += "\xC3\xA4";
expected += "\\u00e4";
} }
expected += '"'; expected += '"';
CHECK(j.dump() == expected); CHECK(json(umlauts).dump(-1, ' ', true) == expected);
} }
} }
SECTION("an ASCII prefix leaves the tightest reachable margin before a 12-byte surrogate pair") SECTION("a prefix leaves the tightest reachable margin before a 12-byte surrogate pair")
{ {
// U+1F600 (the "\xF0\x9F\x98\x80" UTF-8 bytes) is dumped under // U+1F600 (the "\xF0\x9F\x98\x80" UTF-8 bytes) is dumped under
// ensure_ascii as the 12-byte surrogate pair "\ud83d\ude00"; that // ensure_ascii as the 12-byte surrogate pair "\ud83d\ude00"; that
// write happens in a single step with no intermediate flush check, so // write happens in a single step with no intermediate flush check, so
// it is the write most exposed by an off-by-one in the "< 13" guard. // it is the write most exposed by an off-by-one in the "< 13" guard.
// A prefix of 249 newlines leaves exactly 14 bytes of headroom // A prefix of 83 U+00E4 characters leaves exactly 14 bytes of headroom
// (512 - 498), the smallest margin the guard ever actually allows // (512 - 498), the smallest margin the guard ever actually allows
// into a new code point; 250 newlines instead trigger the guard's own // into a new code point; 84 characters instead trigger the guard's own
// flush first, so the emoji starts from a freshly emptied (512-byte) // flush first, so the emoji starts from a freshly emptied (512-byte)
// buffer, and 251 repeats that with one more escape already past the // buffer, and 85 repeats that with one more escape already past the
// reset. Together they cover the margin the guard allows landing on, // reset. Together they cover the margin the guard allows landing on,
// one step before, and one step after - all must still produce the // one step before, and one step after - all must still produce the
// identical, correct escapes. // identical, correct escapes.
for (const int prefix_count : for (const int prefix_count :
{ {
249, 250, 251 83, 84, 85
}) })
{ {
CAPTURE(prefix_count) CAPTURE(prefix_count)
const std::string prefix(static_cast<std::size_t>(prefix_count), '\n'); std::string prefix;
const std::string emoji = "\xF0\x9F\x98\x80";
const json j = prefix + emoji;
std::string expected_prefix; std::string expected_prefix;
for (int i = 0; i < prefix_count; ++i) for (int i = 0; i < prefix_count; ++i)
{ {
expected_prefix += "\\n"; prefix += "\xC3\xA4";
expected_prefix += "\\u00e4";
} }
const std::string emoji = "\xF0\x9F\x98\x80";
const json j = prefix + emoji;
// newline escaping does not depend on ensure_ascii: only the // without ensure_ascii, the whole string is copied unchanged
// emoji differs (raw UTF-8 bytes vs. a \u-escaped surrogate pair)
std::string expected_raw = "\""; std::string expected_raw = "\"";
expected_raw += expected_prefix; expected_raw += prefix;
expected_raw += emoji; expected_raw += emoji;
expected_raw += '"'; expected_raw += '"';
std::string expected_ascii = "\""; std::string expected_ascii = "\"";
@@ -1027,3 +1032,524 @@ TEST_CASE("serialization boundary values for the string buffer")
} }
} }
} }
namespace
{
// appends the escaped form of the ASCII character c to out; written
// independently of the table in serializer::ascii_escapes()
void append_escaped_ascii(std::string& out, const char c, const bool ensure_ascii)
{
const auto byte = static_cast<unsigned char>(c);
switch (byte)
{
case '\b':
out += "\\b";
break;
case '\t':
out += "\\t";
break;
case '\n':
out += "\\n";
break;
case '\f':
out += "\\f";
break;
case '\r':
out += "\\r";
break;
case '"':
out += "\\\"";
break;
case '\\':
out += "\\\\";
break;
default:
if (byte < 0x20 || (ensure_ascii && byte == 0x7F))
{
// byte < 0x80, so the first two hex digits are 0
const char* const hex = "0123456789abcdef";
out += "\\u00";
out += hex[byte >> 4U];
out += hex[byte & 0x0FU];
}
else
{
out += c;
}
break;
}
}
// reference escaper for ASCII strings
std::string reference_escape_ascii(const std::string& s, const bool ensure_ascii)
{
std::string result = "\"";
for (const char c : s)
{
append_escaped_ascii(result, c, ensure_ascii);
}
result += '"';
return result;
}
} // namespace
TEST_CASE("characters below 0x60 are escaped from a table straight into the write buffer")
{
SECTION("every ASCII character at every position")
{
// lengths up to 17 cover the 8-byte strides of the bulk scanner on
// both sides of the character, so the scanner stops at it from every
// offset
for (std::size_t length = 1; length <= 17; ++length)
{
for (std::size_t pos = 0; pos < length; ++pos)
{
for (unsigned int c = 0; c < 0x80; ++c)
{
std::string s(length, 'a');
s[pos] = static_cast<char>(c);
CAPTURE(length)
CAPTURE(pos)
CAPTURE(c)
const json j = s;
CHECK(j.dump(-1, ' ', false) == reference_escape_ascii(s, false));
CHECK(j.dump(-1, ' ', true) == reference_escape_ascii(s, true));
}
}
}
}
SECTION("runs of escaped characters")
{
std::string s;
for (unsigned int c = 0; c < 0x20; ++c)
{
s += static_cast<char>(c);
}
s += R"("\"\)";
CHECK(json(s).dump() == reference_escape_ascii(s, false));
CHECK(json(s).dump(-1, ' ', true) == reference_escape_ascii(s, true));
}
SECTION("escapes straddle the end of the write buffer")
{
// the 8-byte store of a table entry needs room for all 8 bytes, even
// when the escape itself is shorter; a prefix of k plain characters
// shifts the 6-byte escapes across every offset of the 1024-byte
// write buffer
for (std::size_t k = 0; k < 8; ++k)
{
CAPTURE(k)
const std::string s = std::string(k, 'a') + std::string(400, '\x01');
CHECK(json(s).dump() == reference_escape_ascii(s, false));
CHECK(json::array({s, s}).dump() == "[" + reference_escape_ascii(s, false) + "," + reference_escape_ascii(s, false) + "]");
}
}
SECTION("pending \\u escapes of non-ASCII characters are written first")
{
// under ensure_ascii, U+00E4 is \u-escaped into the string buffer;
// a following escape from the table must not overtake it
const json j = "\xC3\xA4\n\xC3\xA4\"\xF0\x9F\x98\x80\\";
CHECK(j.dump(-1, ' ', true) == "\"\\u00e4\\n\\u00e4\\\"\\ud83d\\ude00\\\\\"");
CHECK(j.dump(-1, ' ', false) == "\"\xC3\xA4\\n\xC3\xA4\\\"\xF0\x9F\x98\x80\\\\\"");
}
SECTION("escapes after invalid UTF-8 for every error handler")
{
const json j = "a\xFF\n\xC3\"";
CHECK_THROWS_WITH_AS(utils::ignore_return_value(j.dump()), "[json.exception.type_error.316] invalid UTF-8 byte at index 1: 0xFF", json::type_error&);
CHECK(j.dump(-1, ' ', false, json::error_handler_t::ignore) == "\"a\\n\\\"\"");
CHECK(j.dump(-1, ' ', true, json::error_handler_t::ignore) == "\"a\\n\\\"\"");
CHECK(j.dump(-1, ' ', false, json::error_handler_t::replace) == "\"a\xEF\xBF\xBD\\n\xEF\xBF\xBD\\\"\"");
CHECK(j.dump(-1, ' ', true, json::error_handler_t::replace) == "\"a\\ufffd\\n\\ufffd\\\"\"");
CHECK(j.dump(-1, ' ', false, json::error_handler_t::keep) == "\"a\xFF\\n\xC3\\\"\"");
CHECK(j.dump(-1, ' ', true, json::error_handler_t::keep) == "\"a\xFF\\n\xC3\\\"\"");
}
}
namespace
{
// expected result of dumping a string: the output, or (with
// error_handler_t::strict) the message of the type_error.316 exception
struct expected_dump
{
bool throws = false;
std::string text{}; // NOLINT(readability-redundant-member-init)
};
std::string upper_hex_byte(const unsigned char byte)
{
const char* const hex = "0123456789ABCDEF";
return std::string(1, hex[byte >> 4U]) + hex[byte & 0x0FU];
}
void append_u_escape(std::string& out, const std::uint32_t code_unit)
{
const char* const hex = "0123456789abcdef";
out += "\\u";
for (int shift = 12; shift >= 0; shift -= 4)
{
out += hex[(code_unit >> static_cast<unsigned int>(shift)) & 0x0FU];
}
}
void append_replacement_character(std::string& out, const bool ensure_ascii)
{
out += ensure_ascii ? "\\ufffd" : "\xEF\xBF\xBD";
}
// reference serializer for arbitrary byte strings, written from the documented
// behavior of dump() and independently of serializer::dump_escaped(): UTF-8 is
// decoded strictly (well-formed sequences as in Table 3-7 of the Unicode
// Standard), and each ill-formed sequence is handled as the error handler says
expected_dump reference_dump_string(const std::string& s, const bool ensure_ascii, const json::error_handler_t error_handler)
{
expected_dump result;
std::string& out = result.text;
out = "\"";
// handle the ill-formed bytes s[begin, end), of which s[index] is the byte
// that could not be decoded; returns false if an exception is expected
const auto ill_formed = [&](const std::size_t begin, const std::size_t end, const std::size_t index)
{
switch (error_handler)
{
case json::error_handler_t::strict:
result.throws = true;
out = "[json.exception.type_error.316] invalid UTF-8 byte at index " + std::to_string(index) + ": 0x" + upper_hex_byte(static_cast<unsigned char>(s[index]));
return false;
case json::error_handler_t::ignore:
break;
case json::error_handler_t::replace:
append_replacement_character(out, ensure_ascii);
break;
case json::error_handler_t::keep:
default:
// kept as is, even with ensure_ascii
out.append(s, begin, end - begin);
break;
}
return true;
};
std::size_t i = 0;
while (i < s.size())
{
const auto lead = static_cast<unsigned char>(s[i]);
if (lead < 0x80)
{
append_escaped_ascii(out, s[i], ensure_ascii);
++i;
continue;
}
// number of bytes of the sequence and the range of its second byte
std::size_t length = 0;
std::uint32_t code_point = 0;
unsigned char lower = 0x80;
unsigned char upper = 0xBF;
if (lead >= 0xC2 && lead <= 0xDF)
{
length = 2;
code_point = lead & 0x1FU;
}
else if (lead >= 0xE0 && lead <= 0xEF)
{
length = 3;
code_point = lead & 0x0FU;
lower = (lead == 0xE0) ? 0xA0 : 0x80; // no overlong encodings
upper = (lead == 0xED) ? 0x9F : 0xBF; // no surrogates
}
else if (lead >= 0xF0 && lead <= 0xF4)
{
length = 4;
code_point = lead & 0x07U;
lower = (lead == 0xF0) ? 0x90 : 0x80; // no overlong encodings
upper = (lead == 0xF4) ? 0x8F : 0xBF; // nothing above U+10FFFF
}
else
{
// a byte that cannot start a sequence is consumed
if (!ill_formed(i, i + 1, i))
{
return result;
}
++i;
continue;
}
std::size_t j = i + 1;
for (; j < i + length; ++j)
{
if (j == s.size())
{
// the string ends in the middle of the sequence
switch (error_handler)
{
case json::error_handler_t::strict:
result.throws = true;
out = "[json.exception.type_error.316] incomplete UTF-8 string; last byte: 0x" + upper_hex_byte(static_cast<unsigned char>(s.back()));
return result;
case json::error_handler_t::ignore:
break;
case json::error_handler_t::replace:
append_replacement_character(out, ensure_ascii);
break;
case json::error_handler_t::keep:
default:
out.append(s, i, s.size() - i);
break;
}
out += '"';
return result;
}
const auto byte = static_cast<unsigned char>(s[j]);
if (byte < lower || byte > upper)
{
break;
}
code_point = (code_point << 6U) | (byte & 0x3FU);
lower = 0x80;
upper = 0xBF;
}
if (j < i + length)
{
// the sequence was abandoned at s[j]; that byte is read again as
// the start of a new character
if (!ill_formed(i, j, j))
{
return result;
}
i = j;
continue;
}
if (!ensure_ascii)
{
out.append(s, i, length);
}
else if (code_point <= 0xFFFF)
{
append_u_escape(out, code_point);
}
else
{
append_u_escape(out, 0xD800U + ((code_point - 0x10000U) >> 10U));
append_u_escape(out, 0xDC00U + ((code_point - 0x10000U) & 0x3FFU));
}
i = j;
}
out += '"';
return result;
}
std::string hex_dump(const std::string& s)
{
std::string result;
for (const char c : s)
{
result += upper_hex_byte(static_cast<unsigned char>(c));
result += ' ';
}
return result;
}
// compares dump() of s with the reference for every error handler, with
// ensure_ascii on and off; CHECKs only on a mismatch to keep the sweep fast;
// error_handler_t::strict can be skipped where the position of the string
// buffer does not matter, as throwing is slow on some platforms
void check_dump_against_reference(const std::string& s, const bool with_strict = true)
{
const json j = s;
const std::array<json::error_handler_t, 4> error_handlers =
{
{
json::error_handler_t::strict, json::error_handler_t::ignore,
json::error_handler_t::replace, json::error_handler_t::keep
}
};
for (const auto error_handler : error_handlers)
{
if (!with_strict && error_handler == json::error_handler_t::strict)
{
continue;
}
for (const bool ensure_ascii :
{
false, true
})
{
const expected_dump expected = reference_dump_string(s, ensure_ascii, error_handler);
expected_dump actual;
int id = 0;
try
{
actual.text = j.dump(-1, ' ', ensure_ascii, error_handler);
}
catch (const json::exception& e)
{
actual.throws = true;
actual.text = e.what();
id = e.id;
}
if (actual.throws != expected.throws || actual.text != expected.text || (actual.throws && id != 316))
{
const std::string input = hex_dump(s);
CAPTURE(input)
CAPTURE(ensure_ascii)
CAPTURE(static_cast<int>(error_handler))
CHECK(actual.throws == expected.throws);
CHECK(actual.text == expected.text);
CHECK((!actual.throws || id == 316));
}
}
}
}
} // namespace
TEST_CASE("invalid UTF-8 at every position is handled like the reference")
{
// ill-formed byte sequences; those that end in a truncated sequence are
// also cut short by the filler that follows, or by the end of the string
const std::vector<std::string> patterns =
{
// stray continuation bytes
"\x80", "\xBF",
// bytes that cannot start a sequence
"\xC0", "\xC1", "\xF5", "\xF6", "\xF7", "\xF8", "\xF9", "\xFA", "\xFB", "\xFC", "\xFD", "\xFE", "\xFF",
// overlong encodings
"\xC0\xAF", "\xE0\x80\x80", "\xF0\x80\x80\x80",
// UTF-16 surrogates
"\xED\xA0\x80", "\xED\xBF\xBF",
// a code point above U+10FFFF
"\xF4\x90\x80\x80",
// sequences cut short by ASCII, a control character, a quote, a
// backslash, DEL, or the lead byte of a well-formed character
"\xC3" "a", "\xE2\x82" "\n", "\xE2\x82\"", "\xF0\x9F\x98\\", "\xC3\x7F", "\xC3\xC3\xA4", "\xE2\xF0\x9F\x98\x80",
// truncated sequences
"\xC3", "\xE2\x82", "\xF0\x9F\x98"
};
// well-formed characters of 1, 2, 3, and 4 bytes
const std::vector<std::string> fillers = {"a", "\xC3\xA4", "\xE2\x82\xAC", "\xF0\x9F\x98\x80"};
const auto make_string = [](const std::string & filler, const std::size_t before, const std::string & pattern, const std::size_t after)
{
std::string s;
for (std::size_t k = 0; k < before; ++k)
{
s += filler;
}
s += pattern;
for (std::size_t k = 0; k < after; ++k)
{
s += filler;
}
return s;
};
SECTION("the reference")
{
// the reference itself, against hand-written results
const std::string s = "a\xFF\n\xC3\"\xE0\x80\xF0\x9F\x98\x80\xE2\x82";
CHECK(reference_dump_string(s, false, json::error_handler_t::strict).text == "[json.exception.type_error.316] invalid UTF-8 byte at index 1: 0xFF");
CHECK(reference_dump_string(s.substr(2), false, json::error_handler_t::strict).text == "[json.exception.type_error.316] invalid UTF-8 byte at index 2: 0x22");
CHECK(reference_dump_string("\xF0\x9F\x98\x80\xE2\x82", true, json::error_handler_t::strict).text == "[json.exception.type_error.316] incomplete UTF-8 string; last byte: 0x82");
CHECK(reference_dump_string(s, false, json::error_handler_t::ignore).text == "\"a\\n\\\"\xF0\x9F\x98\x80\"");
CHECK(reference_dump_string(s, true, json::error_handler_t::ignore).text == "\"a\\n\\\"\\ud83d\\ude00\"");
CHECK(reference_dump_string(s, false, json::error_handler_t::replace).text == "\"a\xEF\xBF\xBD\\n\xEF\xBF\xBD\\\"\xEF\xBF\xBD\xEF\xBF\xBD\xF0\x9F\x98\x80\xEF\xBF\xBD\"");
CHECK(reference_dump_string(s, true, json::error_handler_t::replace).text == "\"a\\ufffd\\n\\ufffd\\\"\\ufffd\\ufffd\\ud83d\\ude00\\ufffd\"");
CHECK(reference_dump_string(s, false, json::error_handler_t::keep).text == "\"" + std::string("a\xFF\\n\xC3\\\"\xE0\x80\xF0\x9F\x98\x80\xE2\x82") + "\"");
CHECK(reference_dump_string(s, true, json::error_handler_t::keep).text == "\"" + std::string("a\xFF\\n\xC3\\\"\xE0\x80\\ud83d\\ude00\xE2\x82") + "\"");
check_dump_against_reference(s);
}
SECTION("short strings")
{
// strings of up to 17 bytes put the pattern at every offset of an
// 8-byte stride of the bulk scanners, with whole strides on both
// sides; lengths around 24, 32, and 40 bytes cross the 16- and 32-byte
// strides; error_handler_t::strict is checked for up to 17 bytes of
// ASCII and 8 bytes of other characters only, as throwing is slow on
// some platforms
for (const auto& filler : fillers)
{
for (std::size_t length = 0; length * filler.size() <= 40; ++length)
{
const std::size_t bytes = length * filler.size();
if (filler.size() == 1 && bytes > 17 && (bytes + 1) % 8 > 2)
{
continue;
}
for (std::size_t pos = 0; pos <= length; ++pos)
{
for (const auto& pattern : patterns)
{
check_dump_against_reference(make_string(filler, pos, pattern, length - pos), bytes <= (filler.size() == 1 ? 17 : 8));
}
}
}
}
}
SECTION("strings crossing the end of the string buffer")
{
// characters that are not copied in bulk go through a 512-byte string
// buffer that is written out once fewer than 13 bytes are left; with
// ensure_ascii, each 2-byte character takes 6 bytes of it and each
// 4-byte character 12, so the pattern meets the end of the buffer after
// about 84 or 42 characters (3-byte characters behave like 2-byte
// ones); plain ASCII, copied in bulk, is checked around 512 bytes;
// positions further away are sampled; error_handler_t::strict throws
// at the first ill-formed byte, regardless of the string buffer, and is
// covered above
for (const auto& filler : fillers)
{
if (filler.size() == 3)
{
continue;
}
const std::size_t escaped_size = filler.size() == 1 ? 1 : filler.size() * 3;
const std::size_t middle = 506 / escaped_size;
const std::size_t window = filler.size() == 1 ? 8 : 16;
for (std::size_t pos = 0; pos <= middle + window; pos += (pos + window >= middle) ? 1 : 29)
{
for (const std::size_t after :
{
std::size_t{0}, std::size_t{12}
})
{
for (const auto& pattern : patterns)
{
check_dump_against_reference(make_string(filler, pos, pattern, after), false);
}
}
}
}
}
SECTION("repeated invalid sequences at every offset of the string buffer")
{
// ill-formed sequences that are kept or replaced fill the string
// buffer without a bulk copy in between; a prefix of 0 to 12 bytes
// 0xFF (kept as 1 byte, replaced by 3 or 6) shifts them across every
// offset of the end of the buffer
for (const auto& pattern : patterns)
{
for (std::size_t shift = 0; shift <= 12; ++shift)
{
std::string s(shift, '\xFF');
while (s.size() < 600)
{
s += pattern;
}
check_dump_against_reference(s, shift == 0);
check_dump_against_reference(s + "\xF0\x9F\x98\x80", false);
}
}
}
}