--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/brotli/c/common/shared_dictionary.c	Mon Sep 15 11:44:09 2025 +0200
@@ -0,0 +1,521 @@
+/* Copyright 2017 Google Inc. All Rights Reserved.
+
+   Distributed under MIT license.
+   See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
+*/
+
+/* Shared Dictionary definition and utilities. */
+
+#include <brotli/shared_dictionary.h>
+
+#include <memory.h>
+#include <stdlib.h>  /* malloc, free */
+#include <stdio.h>
+
+#include "dictionary.h"
+#include "platform.h"
+#include "shared_dictionary_internal.h"
+
+#if defined(__cplusplus) || defined(c_plusplus)
+extern "C" {
+#endif
+
+#if defined(BROTLI_EXPERIMENTAL)
+
+#define BROTLI_NUM_ENCODED_LENGTHS (SHARED_BROTLI_MAX_DICTIONARY_WORD_LENGTH \
+    - SHARED_BROTLI_MIN_DICTIONARY_WORD_LENGTH + 1)
+
+/* Max allowed by spec */
+#define BROTLI_MAX_SIZE_BITS 15u
+
+/* Returns BROTLI_TRUE on success, BROTLI_FALSE on failure. */
+static BROTLI_BOOL ReadBool(const uint8_t* encoded, size_t size, size_t* pos,
+    BROTLI_BOOL* result) {
+  uint8_t value;
+  size_t position = *pos;
+  if (position >= size) return BROTLI_FALSE;  /* past file end */
+  value = encoded[position++];
+  if (value > 1) return BROTLI_FALSE;  /* invalid bool */
+  *result = TO_BROTLI_BOOL(value);
+  *pos = position;
+  return BROTLI_TRUE;  /* success */
+}
+
+/* Returns BROTLI_TRUE on success, BROTLI_FALSE on failure. */
+static BROTLI_BOOL ReadUint8(const uint8_t* encoded, size_t size, size_t* pos,
+    uint8_t* result) {
+  size_t position = *pos;
+  if (position + sizeof(uint8_t) > size) return BROTLI_FALSE;
+  *result = encoded[position++];
+  *pos = position;
+  return BROTLI_TRUE;
+}
+
+/* Returns BROTLI_TRUE on success, BROTLI_FALSE on failure. */
+static BROTLI_BOOL ReadUint16(const uint8_t* encoded, size_t size, size_t* pos,
+    uint16_t* result) {
+  size_t position = *pos;
+  if (position + sizeof(uint16_t) > size) return BROTLI_FALSE;
+  *result = BROTLI_UNALIGNED_LOAD16LE(&encoded[position]);
+  position += 2;
+  *pos = position;
+  return BROTLI_TRUE;
+}
+
+/* Reads a varint into a uint32_t, and returns error if it's too large */
+/* Returns BROTLI_TRUE on success, BROTLI_FALSE on failure. */
+static BROTLI_BOOL ReadVarint32(const uint8_t* encoded, size_t size,
+    size_t* pos, uint32_t* result) {
+  int num = 0;
+  uint8_t byte;
+  *result = 0;
+  for (;;) {
+    if (*pos >= size) return BROTLI_FALSE;
+    byte = encoded[(*pos)++];
+    if (num == 4 && byte > 15) return BROTLI_FALSE;
+    *result |= (uint32_t)(byte & 127) << (num * 7);
+    if (byte < 128) return BROTLI_TRUE;
+    num++;
+  }
+}
+
+/* Returns the total length of word list. */
+static size_t BrotliSizeBitsToOffsets(const uint8_t* size_bits_by_length,
+    uint32_t* offsets_by_length) {
+  uint32_t pos = 0;
+  uint32_t i;
+  for (i = 0; i <= SHARED_BROTLI_MAX_DICTIONARY_WORD_LENGTH; i++) {
+    offsets_by_length[i] = pos;
+    if (size_bits_by_length[i] != 0) {
+      pos += i << size_bits_by_length[i];
+    }
+  }
+  return pos;
+}
+
+static BROTLI_BOOL ParseWordList(size_t size, const uint8_t* encoded,
+    size_t* pos, BrotliDictionary* out) {
+  size_t offset;
+  size_t i;
+  size_t position = *pos;
+  if (position + BROTLI_NUM_ENCODED_LENGTHS > size) {
+    return BROTLI_FALSE;
+  }
+
+  memset(out->size_bits_by_length, 0, SHARED_BROTLI_MIN_DICTIONARY_WORD_LENGTH);
+  memcpy(out->size_bits_by_length + SHARED_BROTLI_MIN_DICTIONARY_WORD_LENGTH,
+      &encoded[position], BROTLI_NUM_ENCODED_LENGTHS);
+  for (i = SHARED_BROTLI_MIN_DICTIONARY_WORD_LENGTH;
+      i <= SHARED_BROTLI_MAX_DICTIONARY_WORD_LENGTH; i++) {
+    if (out->size_bits_by_length[i] > BROTLI_MAX_SIZE_BITS) {
+      return BROTLI_FALSE;
+    }
+  }
+  position += BROTLI_NUM_ENCODED_LENGTHS;
+  offset = BrotliSizeBitsToOffsets(
+      out->size_bits_by_length, out->offsets_by_length);
+
+  out->data = &encoded[position];
+  out->data_size = offset;
+  position += offset;
+  if (position > size) return BROTLI_FALSE;
+  *pos = position;
+  return BROTLI_TRUE;
+}
+
+/* Computes the cutOffTransforms of a BrotliTransforms which already has the
+   transforms data correctly filled in. */
+static void ComputeCutoffTransforms(BrotliTransforms* transforms) {
+  uint32_t i;
+  for (i = 0; i < BROTLI_TRANSFORMS_MAX_CUT_OFF + 1; i++) {
+    transforms->cutOffTransforms[i] = -1;
+  }
+  for (i = 0; i < transforms->num_transforms; i++) {
+    const uint8_t* prefix = BROTLI_TRANSFORM_PREFIX(transforms, i);
+    uint8_t type = BROTLI_TRANSFORM_TYPE(transforms, i);
+    const uint8_t* suffix = BROTLI_TRANSFORM_SUFFIX(transforms, i);
+    if (type <= BROTLI_TRANSFORM_OMIT_LAST_9 && *prefix == 0 && *suffix == 0 &&
+        transforms->cutOffTransforms[type] == -1) {
+      transforms->cutOffTransforms[type] = (int16_t)i;
+    }
+  }
+}
+
+static BROTLI_BOOL ParsePrefixSuffixTable(size_t size, const uint8_t* encoded,
+    size_t* pos, BrotliTransforms* out, uint16_t* out_table,
+    size_t* out_table_size) {
+  size_t position = *pos;
+  size_t offset = 0;
+  size_t stringlet_count = 0;  /* NUM_PREFIX_SUFFIX */
+  size_t data_length = 0;
+
+  /* PREFIX_SUFFIX_LENGTH */
+  if (!ReadUint16(encoded, size, &position, &out->prefix_suffix_size)) {
+    return BROTLI_FALSE;
+  }
+  data_length = out->prefix_suffix_size;
+
+  /* Must at least have space for null terminator. */
+  if (data_length < 1) return BROTLI_FALSE;
+  out->prefix_suffix = &encoded[position];
+  if (position + data_length >= size) return BROTLI_FALSE;
+  while (BROTLI_TRUE) {
+    /* STRING_LENGTH */
+    size_t stringlet_len = encoded[position + offset];
+    out_table[stringlet_count] = (uint16_t)offset;
+    stringlet_count++;
+    offset++;
+    if (stringlet_len == 0) {
+      if (offset == data_length) {
+        break;
+      } else {
+        return BROTLI_FALSE;
+      }
+    }
+    if (stringlet_count > 255) return BROTLI_FALSE;
+    offset += stringlet_len;
+    if (offset >= data_length) return BROTLI_FALSE;
+  }
+
+  position += data_length;
+  *pos = position;
+  *out_table_size = (uint16_t)stringlet_count;
+  return BROTLI_TRUE;
+}
+
+static BROTLI_BOOL ParseTransformsList(size_t size, const uint8_t* encoded,
+    size_t* pos, BrotliTransforms* out, uint16_t* prefix_suffix_table,
+    size_t* prefix_suffix_count) {
+  uint32_t i;
+  BROTLI_BOOL has_params = BROTLI_FALSE;
+  BROTLI_BOOL prefix_suffix_ok = BROTLI_FALSE;
+  size_t position = *pos;
+  size_t stringlet_cnt = 0;
+  if (position >= size) return BROTLI_FALSE;
+
+  prefix_suffix_ok = ParsePrefixSuffixTable(
+      size, encoded, &position, out, prefix_suffix_table, &stringlet_cnt);
+  if (!prefix_suffix_ok) return BROTLI_FALSE;
+  out->prefix_suffix_map = prefix_suffix_table;
+  *prefix_suffix_count = stringlet_cnt;
+
+  out->num_transforms = encoded[position++];
+  out->transforms = &encoded[position];
+  position += (size_t)out->num_transforms * 3;
+  if (position > size) return BROTLI_FALSE;
+  /* Check for errors and read extra parameters. */
+  for (i = 0; i < out->num_transforms; i++) {
+    uint8_t prefix_id = BROTLI_TRANSFORM_PREFIX_ID(out, i);
+    uint8_t type = BROTLI_TRANSFORM_TYPE(out, i);
+    uint8_t suffix_id = BROTLI_TRANSFORM_SUFFIX_ID(out, i);
+    if (prefix_id >= stringlet_cnt) return BROTLI_FALSE;
+    if (type >= BROTLI_NUM_TRANSFORM_TYPES) return BROTLI_FALSE;
+    if (suffix_id >= stringlet_cnt) return BROTLI_FALSE;
+    if (type == BROTLI_TRANSFORM_SHIFT_FIRST ||
+        type == BROTLI_TRANSFORM_SHIFT_ALL) {
+      has_params = BROTLI_TRUE;
+    }
+  }
+  if (has_params) {
+    out->params = &encoded[position];
+    position += (size_t)out->num_transforms * 2;
+    if (position > size) return BROTLI_FALSE;
+    for (i = 0; i < out->num_transforms; i++) {
+      uint8_t type = BROTLI_TRANSFORM_TYPE(out, i);
+      if (type != BROTLI_TRANSFORM_SHIFT_FIRST &&
+          type != BROTLI_TRANSFORM_SHIFT_ALL) {
+        if (out->params[i * 2] != 0 || out->params[i * 2 + 1] != 0) {
+          return BROTLI_FALSE;
+        }
+      }
+    }
+  } else {
+    out->params = NULL;
+  }
+  ComputeCutoffTransforms(out);
+  *pos = position;
+  return BROTLI_TRUE;
+}
+
+static BROTLI_BOOL DryParseDictionary(const uint8_t* encoded,
+    size_t size, uint32_t* num_prefix, BROTLI_BOOL* is_custom_static_dict) {
+  size_t pos = 0;
+  uint32_t chunk_size = 0;
+  uint8_t num_word_lists;
+  uint8_t num_transform_lists;
+  *is_custom_static_dict = BROTLI_FALSE;
+  *num_prefix = 0;
+
+  /* Skip magic header bytes. */
+  pos += 2;
+
+  /* LZ77_DICTIONARY_LENGTH */
+  if (!ReadVarint32(encoded, size, &pos, &chunk_size)) return BROTLI_FALSE;
+  if (chunk_size != 0) {
+    /* This limitation is not specified but the 32-bit Brotli decoder for now */
+    if (chunk_size > 1073741823) return BROTLI_FALSE;
+    *num_prefix = 1;
+    if (pos + chunk_size > size) return BROTLI_FALSE;
+    pos += chunk_size;
+  }
+
+  if (!ReadUint8(encoded, size, &pos, &num_word_lists)) {
+    return BROTLI_FALSE;
+  }
+  if (!ReadUint8(encoded, size, &pos, &num_transform_lists)) {
+    return BROTLI_FALSE;
+  }
+
+  if (num_word_lists > 0 || num_transform_lists > 0) {
+    *is_custom_static_dict = BROTLI_TRUE;
+  }
+
+  return BROTLI_TRUE;
+}
+
+static BROTLI_BOOL ParseDictionary(const uint8_t* encoded, size_t size,
+    BrotliSharedDictionary* dict) {
+  uint32_t i;
+  size_t pos = 0;
+  uint32_t chunk_size = 0;
+  size_t total_prefix_suffix_count = 0;
+  size_t trasform_list_start[SHARED_BROTLI_NUM_DICTIONARY_CONTEXTS];
+  uint16_t temporary_prefix_suffix_table[256];
+
+  /* Skip magic header bytes. */
+  pos += 2;
+
+  /* LZ77_DICTIONARY_LENGTH */
+  if (!ReadVarint32(encoded, size, &pos, &chunk_size)) return BROTLI_FALSE;
+  if (chunk_size != 0) {
+    if (pos + chunk_size > size) return BROTLI_FALSE;
+    dict->prefix_size[dict->num_prefix] = chunk_size;
+    dict->prefix[dict->num_prefix] = &encoded[pos];
+    dict->num_prefix++;
+    /* LZ77_DICTIONARY_LENGTH bytes. */
+    pos += chunk_size;
+  }
+
+  /* NUM_WORD_LISTS */
+  if (!ReadUint8(encoded, size, &pos, &dict->num_word_lists)) {
+    return BROTLI_FALSE;
+  }
+  if (dict->num_word_lists > SHARED_BROTLI_NUM_DICTIONARY_CONTEXTS) {
+    return BROTLI_FALSE;
+  }
+
+  if (dict->num_word_lists != 0) {
+    dict->words_instances = (BrotliDictionary*)dict->alloc_func(
+        dict->memory_manager_opaque,
+        dict->num_word_lists * sizeof(*dict->words_instances));
+    if (!dict->words_instances) return BROTLI_FALSE;  /* OOM */
+  }
+  for (i = 0; i < dict->num_word_lists; i++) {
+    if (!ParseWordList(size, encoded, &pos, &dict->words_instances[i])) {
+      return BROTLI_FALSE;
+    }
+  }
+
+  /* NUM_TRANSFORM_LISTS */
+  if (!ReadUint8(encoded, size, &pos, &dict->num_transform_lists)) {
+    return BROTLI_FALSE;
+  }
+  if (dict->num_transform_lists > SHARED_BROTLI_NUM_DICTIONARY_CONTEXTS) {
+    return BROTLI_FALSE;
+  }
+
+  if (dict->num_transform_lists != 0) {
+    dict->transforms_instances = (BrotliTransforms*)dict->alloc_func(
+        dict->memory_manager_opaque,
+        dict->num_transform_lists * sizeof(*dict->transforms_instances));
+    if (!dict->transforms_instances) return BROTLI_FALSE;  /* OOM */
+  }
+  for (i = 0; i < dict->num_transform_lists; i++) {
+    BROTLI_BOOL ok = BROTLI_FALSE;
+    size_t prefix_suffix_count = 0;
+    trasform_list_start[i] = pos;
+    dict->transforms_instances[i].prefix_suffix_map =
+        temporary_prefix_suffix_table;
+    ok = ParseTransformsList(
+        size, encoded, &pos, &dict->transforms_instances[i],
+        temporary_prefix_suffix_table, &prefix_suffix_count);
+    if (!ok) return BROTLI_FALSE;
+    total_prefix_suffix_count += prefix_suffix_count;
+  }
+  if (total_prefix_suffix_count != 0) {
+    dict->prefix_suffix_maps = (uint16_t*)dict->alloc_func(
+        dict->memory_manager_opaque,
+        total_prefix_suffix_count * sizeof(*dict->prefix_suffix_maps));
+    if (!dict->prefix_suffix_maps) return BROTLI_FALSE;  /* OOM */
+  }
+  total_prefix_suffix_count = 0;
+  for (i = 0; i < dict->num_transform_lists; i++) {
+    size_t prefix_suffix_count = 0;
+    size_t position = trasform_list_start[i];
+    uint16_t* prefix_suffix_map =
+      &dict->prefix_suffix_maps[total_prefix_suffix_count];
+    BROTLI_BOOL ok = ParsePrefixSuffixTable(
+        size, encoded, &position, &dict->transforms_instances[i],
+        prefix_suffix_map, &prefix_suffix_count);
+    if (!ok) return BROTLI_FALSE;
+    dict->transforms_instances[i].prefix_suffix_map = prefix_suffix_map;
+    total_prefix_suffix_count += prefix_suffix_count;
+  }
+
+  if (dict->num_word_lists != 0 || dict->num_transform_lists != 0) {
+    if (!ReadUint8(encoded, size, &pos, &dict->num_dictionaries)) {
+      return BROTLI_FALSE;
+    }
+    if (dict->num_dictionaries == 0 ||
+        dict->num_dictionaries > SHARED_BROTLI_NUM_DICTIONARY_CONTEXTS) {
+      return BROTLI_FALSE;
+    }
+    for (i = 0; i < dict->num_dictionaries; i++) {
+      uint8_t words_index;
+      uint8_t transforms_index;
+      if (!ReadUint8(encoded, size, &pos, &words_index)) {
+        return BROTLI_FALSE;
+      }
+      if (words_index > dict->num_word_lists) return BROTLI_FALSE;
+      if (!ReadUint8(encoded, size, &pos, &transforms_index)) {
+        return BROTLI_FALSE;
+      }
+      if (transforms_index > dict->num_transform_lists) return BROTLI_FALSE;
+      dict->words[i] = words_index == dict->num_word_lists ?
+          BrotliGetDictionary() : &dict->words_instances[words_index];
+      dict->transforms[i] = transforms_index == dict->num_transform_lists ?
+          BrotliGetTransforms(): &dict->transforms_instances[transforms_index];
+    }
+    /* CONTEXT_ENABLED */
+    if (!ReadBool(encoded, size, &pos, &dict->context_based)) {
+      return BROTLI_FALSE;
+    }
+
+    /* CONTEXT_MAP */
+    if (dict->context_based) {
+      for (i = 0; i < SHARED_BROTLI_NUM_DICTIONARY_CONTEXTS; i++) {
+        if (!ReadUint8(encoded, size, &pos, &dict->context_map[i])) {
+          return BROTLI_FALSE;
+        }
+        if (dict->context_map[i] >= dict->num_dictionaries) {
+          return BROTLI_FALSE;
+        }
+      }
+    }
+  } else {
+    dict->context_based = BROTLI_FALSE;
+    dict->num_dictionaries = 1;
+    dict->words[0] = BrotliGetDictionary();
+    dict->transforms[0] = BrotliGetTransforms();
+  }
+
+  return BROTLI_TRUE;
+}
+
+/* Decodes shared dictionary and verifies correctness.
+   Returns BROTLI_TRUE if dictionary is valid, BROTLI_FALSE otherwise.
+   The BrotliSharedDictionary must already have been initialized. If the
+   BrotliSharedDictionary already contains data, compound dictionaries
+   will be appended, but an error will be returned if it already has
+   custom words or transforms.
+   TODO(lode): link to RFC for shared brotli once published. */
+static BROTLI_BOOL DecodeSharedDictionary(
+    const uint8_t* encoded, size_t size, BrotliSharedDictionary* dict) {
+  uint32_t num_prefix = 0;
+  BROTLI_BOOL is_custom_static_dict = BROTLI_FALSE;
+  BROTLI_BOOL has_custom_static_dict =
+      dict->num_word_lists > 0 || dict->num_transform_lists > 0;
+
+  /* Check magic header bytes. */
+  if (size < 2) return BROTLI_FALSE;
+  if (encoded[0] != 0x91 || encoded[1] != 0) return BROTLI_FALSE;
+
+  if (!DryParseDictionary(encoded, size, &num_prefix, &is_custom_static_dict)) {
+    return BROTLI_FALSE;
+  }
+
+  if (num_prefix + dict->num_prefix > SHARED_BROTLI_MAX_COMPOUND_DICTS) {
+    return BROTLI_FALSE;
+  }
+
+  /* Cannot combine different static dictionaries, only prefix dictionaries */
+  if (has_custom_static_dict && is_custom_static_dict) return BROTLI_FALSE;
+
+  return ParseDictionary(encoded, size, dict);
+}
+
+#endif  /* BROTLI_EXPERIMENTAL */
+
+void BrotliSharedDictionaryDestroyInstance(
+    BrotliSharedDictionary* dict) {
+  if (!dict) {
+    return;
+  } else {
+    brotli_free_func free_func = dict->free_func;
+    void* opaque = dict->memory_manager_opaque;
+    /* Cleanup. */
+    free_func(opaque, dict->words_instances);
+    free_func(opaque, dict->transforms_instances);
+    free_func(opaque, dict->prefix_suffix_maps);
+    /* Self-destruction. */
+    free_func(opaque, dict);
+  }
+}
+
+BROTLI_BOOL BrotliSharedDictionaryAttach(
+    BrotliSharedDictionary* dict, BrotliSharedDictionaryType type,
+    size_t data_size, const uint8_t data[BROTLI_ARRAY_PARAM(data_size)]) {
+  if (!dict) {
+    return BROTLI_FALSE;
+  }
+#if defined(BROTLI_EXPERIMENTAL)
+  if (type == BROTLI_SHARED_DICTIONARY_SERIALIZED) {
+    return DecodeSharedDictionary(data, data_size, dict);
+  }
+#endif  /* BROTLI_EXPERIMENTAL */
+  if (type == BROTLI_SHARED_DICTIONARY_RAW) {
+    if (dict->num_prefix >= SHARED_BROTLI_MAX_COMPOUND_DICTS) {
+      return BROTLI_FALSE;
+    }
+    dict->prefix_size[dict->num_prefix] = data_size;
+    dict->prefix[dict->num_prefix] = data;
+    dict->num_prefix++;
+    return BROTLI_TRUE;
+  }
+  return BROTLI_FALSE;
+}
+
+BrotliSharedDictionary* BrotliSharedDictionaryCreateInstance(
+    brotli_alloc_func alloc_func, brotli_free_func free_func, void* opaque) {
+  BrotliSharedDictionary* dict = 0;
+  if (!alloc_func && !free_func) {
+    dict = (BrotliSharedDictionary*)malloc(sizeof(BrotliSharedDictionary));
+  } else if (alloc_func && free_func) {
+    dict = (BrotliSharedDictionary*)alloc_func(
+        opaque, sizeof(BrotliSharedDictionary));
+  }
+  if (dict == 0) {
+    return 0;
+  }
+
+  /* TODO(eustas): explicitly initialize all the fields? */
+  memset(dict, 0, sizeof(BrotliSharedDictionary));
+
+  dict->context_based = BROTLI_FALSE;
+  dict->num_dictionaries = 1;
+  dict->num_word_lists = 0;
+  dict->num_transform_lists = 0;
+
+  dict->words[0] = BrotliGetDictionary();
+  dict->transforms[0] = BrotliGetTransforms();
+
+  dict->alloc_func = alloc_func ? alloc_func : BrotliDefaultAllocFunc;
+  dict->free_func = free_func ? free_func : BrotliDefaultFreeFunc;
+  dict->memory_manager_opaque = opaque;
+
+  return dict;
+}
+
+#if defined(__cplusplus) || defined(c_plusplus)
+}  /* extern "C" */
+#endif