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/*
* Copyright © 2022 Behdad Esfahbod
*
* This is part of HarfBuzz, a text shaping library.
*
* Permission is hereby granted, without written agreement and without
* license or royalty fees, to use, copy, modify, and distribute this
* software and its documentation for any purpose, provided that the
* above copyright notice and the following two paragraphs appear in
* all copies of this software.
*
* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*
* Google Author(s): Behdad Esfahbod
*/
#include "hb.hh"
#ifndef HB_NO_BUFFER_VERIFY
#include "hb-buffer.hh"
#define BUFFER_VERIFY_ERROR "buffer verify error: "
static inline void
buffer_verify_error (hb_buffer_t *buffer,
hb_font_t *font,
const char *fmt,
...) HB_PRINTF_FUNC(3, 4);
static inline void
buffer_verify_error (hb_buffer_t *buffer,
hb_font_t *font,
const char *fmt,
...)
{
va_list ap;
va_start (ap, fmt);
if (buffer->messaging ())
{
buffer->message_impl (font, fmt, ap);
}
else
{
fprintf (stderr, "harfbuzz ");
vfprintf (stderr, fmt, ap);
fprintf (stderr, "\n");
}
va_end (ap);
}
static bool
buffer_verify_monotone (hb_buffer_t *buffer,
hb_font_t *font)
{
/* Check that clusters are monotone. */
if (buffer->cluster_level == HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES ||
buffer->cluster_level == HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS)
{
bool is_forward = HB_DIRECTION_IS_FORWARD (hb_buffer_get_direction (buffer));
unsigned int num_glyphs;
hb_glyph_info_t *info = hb_buffer_get_glyph_infos (buffer, &num_glyphs);
for (unsigned int i = 1; i < num_glyphs; i++)
if (info[i-1].cluster != info[i].cluster &&
(info[i-1].cluster < info[i].cluster) != is_forward)
{
buffer_verify_error (buffer, font, BUFFER_VERIFY_ERROR "clusters are not monotone.");
return false;
}
}
return true;
}
static bool
buffer_verify_unsafe_to_break (hb_buffer_t *buffer,
hb_buffer_t *text_buffer,
hb_font_t *font,
const hb_feature_t *features,
unsigned int num_features,
const char * const *shapers)
{
if (buffer->cluster_level != HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES &&
buffer->cluster_level != HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS)
{
/* Cannot perform this check without monotone clusters. */
return true;
}
/* Check that breaking up shaping at safe-to-break is indeed safe. */
hb_buffer_t *fragment = hb_buffer_create_similar (buffer);
hb_buffer_set_flags (fragment, hb_buffer_get_flags (fragment) & ~HB_BUFFER_FLAG_VERIFY);
hb_buffer_t *reconstruction = hb_buffer_create_similar (buffer);
hb_buffer_set_flags (reconstruction, hb_buffer_get_flags (reconstruction) & ~HB_BUFFER_FLAG_VERIFY);
unsigned int num_glyphs;
hb_glyph_info_t *info = hb_buffer_get_glyph_infos (buffer, &num_glyphs);
unsigned int num_chars;
hb_glyph_info_t *text = hb_buffer_get_glyph_infos (text_buffer, &num_chars);
/* Chop text and shape fragments. */
bool forward = HB_DIRECTION_IS_FORWARD (hb_buffer_get_direction (buffer));
unsigned int start = 0;
unsigned int text_start = forward ? 0 : num_chars;
unsigned int text_end = text_start;
for (unsigned int end = 1; end < num_glyphs + 1; end++)
{
if (end < num_glyphs &&
(info[end].cluster == info[end-1].cluster ||
info[end-(forward?0:1)].mask & HB_GLYPH_FLAG_UNSAFE_TO_BREAK))
continue;
/* Shape segment corresponding to glyphs start..end. */
if (end == num_glyphs)
{
if (forward)
text_end = num_chars;
else
text_start = 0;
}
else
{
if (forward)
{
unsigned int cluster = info[end].cluster;
while (text_end < num_chars && text[text_end].cluster < cluster)
text_end++;
}
else
{
unsigned int cluster = info[end - 1].cluster;
while (text_start && text[text_start - 1].cluster >= cluster)
text_start--;
}
}
assert (text_start < text_end);
if (0)
printf("start %d end %d text start %d end %d\n", start, end, text_start, text_end);
hb_buffer_clear_contents (fragment);
hb_buffer_flags_t flags = hb_buffer_get_flags (fragment);
if (0 < text_start)
flags = (hb_buffer_flags_t) (flags & ~HB_BUFFER_FLAG_BOT);
if (text_end < num_chars)
flags = (hb_buffer_flags_t) (flags & ~HB_BUFFER_FLAG_EOT);
hb_buffer_set_flags (fragment, flags);
hb_buffer_append (fragment, text_buffer, text_start, text_end);
if (!hb_shape_full (font, fragment, features, num_features, shapers))
{
buffer_verify_error (buffer, font, BUFFER_VERIFY_ERROR "shaping failed while shaping fragment.");
hb_buffer_destroy (reconstruction);
hb_buffer_destroy (fragment);
return false;
}
hb_buffer_append (reconstruction, fragment, 0, -1);
start = end;
if (forward)
text_start = text_end;
else
text_end = text_start;
}
bool ret = true;
hb_buffer_diff_flags_t diff = hb_buffer_diff (reconstruction, buffer, (hb_codepoint_t) -1, 0);
if (diff)
{
buffer_verify_error (buffer, font, BUFFER_VERIFY_ERROR "unsafe-to-break test failed.");
ret = false;
/* Return the reconstructed result instead so it can be inspected. */
hb_buffer_set_length (buffer, 0);
hb_buffer_append (buffer, reconstruction, 0, -1);
}
hb_buffer_destroy (reconstruction);
hb_buffer_destroy (fragment);
return ret;
}
static bool
buffer_verify_unsafe_to_concat (hb_buffer_t *buffer,
hb_buffer_t *text_buffer,
hb_font_t *font,
const hb_feature_t *features,
unsigned int num_features,
const char * const *shapers)
{
if (buffer->cluster_level != HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES &&
buffer->cluster_level != HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS)
{
/* Cannot perform this check without monotone clusters. */
return true;
}
/* Check that shuffling up text before shaping at safe-to-concat points
* is indeed safe. */
/* This is what we do:
*
* 1. We shape text once. Then segment the text at all the safe-to-concat
* points;
*
* 2. Then we create two buffers, one containing all the even segments and
* one all the odd segments.
*
* 3. Because all these segments were safe-to-concat at both ends, we
* expect that concatenating them and shaping should NOT change the
* shaping results of each segment. As such, we expect that after
* shaping the two buffers, we still get cluster boundaries at the
* segment boundaries, and that those all are safe-to-concat points.
* Moreover, that there are NOT any safe-to-concat points within the
* segments.
*
* 4. Finally, we reconstruct the shaping results of the original text by
* simply interleaving the shaping results of the segments from the two
* buffers, and assert that the total shaping results is the same as
* the one from original buffer in step 1.
*/
hb_buffer_t *fragments[2] {hb_buffer_create_similar (buffer),
hb_buffer_create_similar (buffer)};
hb_buffer_set_flags (fragments[0], hb_buffer_get_flags (fragments[0]) & ~HB_BUFFER_FLAG_VERIFY);
hb_buffer_set_flags (fragments[1], hb_buffer_get_flags (fragments[1]) & ~HB_BUFFER_FLAG_VERIFY);
hb_buffer_t *reconstruction = hb_buffer_create_similar (buffer);
hb_buffer_set_flags (reconstruction, hb_buffer_get_flags (reconstruction) & ~HB_BUFFER_FLAG_VERIFY);
hb_segment_properties_t props;
hb_buffer_get_segment_properties (buffer, &props);
hb_buffer_set_segment_properties (fragments[0], &props);
hb_buffer_set_segment_properties (fragments[1], &props);
hb_buffer_set_segment_properties (reconstruction, &props);
unsigned num_glyphs;
hb_glyph_info_t *info = hb_buffer_get_glyph_infos (buffer, &num_glyphs);
unsigned num_chars;
hb_glyph_info_t *text = hb_buffer_get_glyph_infos (text_buffer, &num_chars);
bool forward = HB_DIRECTION_IS_FORWARD (hb_buffer_get_direction (buffer));
if (!forward)
hb_buffer_reverse (buffer);
/*
* Split text into segments and collect into to fragment streams.
*/
{
unsigned fragment_idx = 0;
unsigned start = 0;
unsigned text_start = 0;
unsigned text_end = 0;
for (unsigned end = 1; end < num_glyphs + 1; end++)
{
if (end < num_glyphs &&
(info[end].cluster == info[end-1].cluster ||
info[end].mask & HB_GLYPH_FLAG_UNSAFE_TO_CONCAT))
continue;
/* Accumulate segment corresponding to glyphs start..end. */
if (end == num_glyphs)
text_end = num_chars;
else
{
unsigned cluster = info[end].cluster;
while (text_end < num_chars && text[text_end].cluster < cluster)
text_end++;
}
assert (text_start < text_end);
if (0)
printf("start %d end %d text start %d end %d\n", start, end, text_start, text_end);
#if 0
hb_buffer_flags_t flags = hb_buffer_get_flags (fragment);
if (0 < text_start)
flags = (hb_buffer_flags_t) (flags & ~HB_BUFFER_FLAG_BOT);
if (text_end < num_chars)
flags = (hb_buffer_flags_t) (flags & ~HB_BUFFER_FLAG_EOT);
hb_buffer_set_flags (fragment, flags);
#endif
hb_buffer_append (fragments[fragment_idx], text_buffer, text_start, text_end);
start = end;
text_start = text_end;
fragment_idx = 1 - fragment_idx;
}
}
bool ret = true;
hb_buffer_diff_flags_t diff;
/*
* Shape the two fragment streams.
*/
if (!hb_shape_full (font, fragments[0], features, num_features, shapers))
{
buffer_verify_error (buffer, font, BUFFER_VERIFY_ERROR "shaping failed while shaping fragment.");
ret = false;
goto out;
}
if (!hb_shape_full (font, fragments[1], features, num_features, shapers))
{
buffer_verify_error (buffer, font, BUFFER_VERIFY_ERROR "shaping failed while shaping fragment.");
ret = false;
goto out;
}
if (!forward)
{
hb_buffer_reverse (fragments[0]);
hb_buffer_reverse (fragments[1]);
}
/*
* Reconstruct results.
*/
{
unsigned fragment_idx = 0;
unsigned fragment_start[2] {0, 0};
unsigned fragment_num_glyphs[2];
hb_glyph_info_t *fragment_info[2];
for (unsigned i = 0; i < 2; i++)
fragment_info[i] = hb_buffer_get_glyph_infos (fragments[i], &fragment_num_glyphs[i]);
while (fragment_start[0] < fragment_num_glyphs[0] ||
fragment_start[1] < fragment_num_glyphs[1])
{
unsigned fragment_end = fragment_start[fragment_idx] + 1;
while (fragment_end < fragment_num_glyphs[fragment_idx] &&
(fragment_info[fragment_idx][fragment_end].cluster == fragment_info[fragment_idx][fragment_end - 1].cluster ||
fragment_info[fragment_idx][fragment_end].mask & HB_GLYPH_FLAG_UNSAFE_TO_CONCAT))
fragment_end++;
hb_buffer_append (reconstruction, fragments[fragment_idx], fragment_start[fragment_idx], fragment_end);
fragment_start[fragment_idx] = fragment_end;
fragment_idx = 1 - fragment_idx;
}
}
if (!forward)
{
hb_buffer_reverse (buffer);
hb_buffer_reverse (reconstruction);
}
/*
* Diff results.
*/
diff = hb_buffer_diff (reconstruction, buffer, (hb_codepoint_t) -1, 0);
if (diff)
{
buffer_verify_error (buffer, font, BUFFER_VERIFY_ERROR "unsafe-to-concat test failed.");
ret = false;
/* Return the reconstructed result instead so it can be inspected. */
hb_buffer_set_length (buffer, 0);
hb_buffer_append (buffer, reconstruction, 0, -1);
}
out:
hb_buffer_destroy (reconstruction);
hb_buffer_destroy (fragments[0]);
hb_buffer_destroy (fragments[1]);
return ret;
}
bool
hb_buffer_t::verify (hb_buffer_t *text_buffer,
hb_font_t *font,
const hb_feature_t *features,
unsigned int num_features,
const char * const *shapers)
{
bool ret = true;
if (!buffer_verify_monotone (this, font))
ret = false;
if (!buffer_verify_unsafe_to_break (this, text_buffer, font, features, num_features, shapers))
ret = false;
if ((flags & HB_BUFFER_FLAG_PRODUCE_UNSAFE_TO_CONCAT) != 0 &&
!buffer_verify_unsafe_to_concat (this, text_buffer, font, features, num_features, shapers))
ret = false;
if (!ret)
{
unsigned len = text_buffer->len;
hb_vector_t<char> bytes;
if (likely (bytes.resize (len * 10 + 16)))
{
hb_buffer_serialize_unicode (text_buffer,
0, len,
bytes.arrayZ, bytes.length,
&len,
HB_BUFFER_SERIALIZE_FORMAT_TEXT,
HB_BUFFER_SERIALIZE_FLAG_NO_CLUSTERS);
buffer_verify_error (this, font, BUFFER_VERIFY_ERROR "text was: %s.", bytes.arrayZ);
}
}
return ret;
}
#endif