--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/harfbuzz/src/hb-buffer-verify.cc	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,439 @@
+/*
+ * 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_flags_t (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_flags_t (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;
+    }
+    else if (!fragment->successful || fragment->shaping_failed)
+    {
+      hb_buffer_destroy (reconstruction);
+      hb_buffer_destroy (fragment);
+      return true;
+    }
+    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 & ~HB_BUFFER_DIFF_FLAG_GLYPH_FLAGS_MISMATCH)
+  {
+    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_flags_t (hb_buffer_get_flags (fragments[0]) & ~HB_BUFFER_FLAG_VERIFY)));
+  hb_buffer_set_flags (fragments[1], (hb_buffer_flags_t (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_flags_t (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;
+  }
+  else if (!fragments[0]->successful || fragments[0]->shaping_failed)
+  {
+    ret = true;
+    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;
+  }
+  else if (!fragments[1]->successful || fragments[1]->shaping_failed)
+  {
+    ret = true;
+    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 & ~HB_BUFFER_DIFF_FLAG_GLYPH_FLAGS_MISMATCH)
+  {
+    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)
+  {
+#ifndef HB_NO_BUFFER_SERIALIZE
+    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);
+    }
+#endif
+  }
+  return ret;
+}
+
+
+#endif