kc3-lang/libxkbcommon/src/utf8.c

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• Hash : 183761ac
  Author :
  Date : 2023-05-13T17:26:24
  

  Do not interpret nor emit invalid Unicode encoding forms Surrogates are invalid in both UTF-32 and UTF-8. See https://www.unicode.org/versions/Unicode15.0.0/ch03.pdf#G28875 and https://www.unicode.org/versions/Unicode15.0.0/ch03.pdf#G31703

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• src/utf8.c

• /*
   * Copyright © 2012 Intel Corporation
   * Copyright © 2014 Ran Benita <ran234@gmail.com>
   *
   * Permission is hereby granted, free of charge, to any person obtaining a
   * copy of this software and associated documentation files (the "Software"),
   * to deal in the Software without restriction, including without limitation
   * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   * and/or sell copies of the Software, and to permit persons to whom the
   * Software is furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice (including the next
   * paragraph) shall be included in all copies or substantial portions of the
   * Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
   * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
   * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
   * DEALINGS IN THE SOFTWARE.
   *
   * Author: Rob Bradford <rob@linux.intel.com>
   */
  
  #include "config.h"
  
  #include <stddef.h>
  #include <stdbool.h>
  #include <inttypes.h>
  
  #include "utf8.h"
  
  /* Conformant encoding form conversion from UTF-32 to UTF-8.
   *
   * See https://www.unicode.org/versions/Unicode15.0.0/ch03.pdf#G28875
   * for further details.
  */
  int
  utf32_to_utf8(uint32_t unichar, char *buffer)
  {
      int count, shift, length;
      uint8_t head;
  
      if (unichar <= 0x007f) {
          buffer[0] = unichar;
          buffer[1] = '\0';
          return 2;
      }
      else if (unichar <= 0x07FF) {
          length = 2;
          head = 0xc0;
      }
      /* Handle surrogates */
      else if (0xd800 <= unichar && unichar <= 0xdfff) {
          goto ill_formed_code_unit_subsequence;
      }
      else if (unichar <= 0xffff) {
          length = 3;
          head = 0xe0;
      }
      else if (unichar <= 0x10ffff) {
          length = 4;
          head = 0xf0;
      }
      else {
          goto ill_formed_code_unit_subsequence;
      }
  
      for (count = length - 1, shift = 0; count > 0; count--, shift += 6)
          buffer[count] = 0x80 | ((unichar >> shift) & 0x3f);
  
      buffer[0] = head | ((unichar >> shift) & 0x3f);
      buffer[length] = '\0';
  
      return length + 1;
  
  ill_formed_code_unit_subsequence:
      buffer[0] = '\0';
      return 0;
  }
  
  bool
  is_valid_utf8(const char *ss, size_t len)
  {
      size_t i = 0;
      size_t tail_bytes = 0;
      const uint8_t *s = (const uint8_t *) ss;
  
      /* This beauty is from:
       *  The Unicode Standard Version 6.2 - Core Specification, Table 3.7
       *  https://www.unicode.org/versions/Unicode6.2.0/ch03.pdf#G7404
       * We can optimize if needed. */
      while (i < len)
      {
          if (s[i] <= 0x7F) {
              tail_bytes = 0;
          }
          else if (s[i] >= 0xC2 && s[i] <= 0xDF) {
              tail_bytes = 1;
          }
          else if (s[i] == 0xE0) {
              i++;
              if (i >= len || !(s[i] >= 0xA0 && s[i] <= 0xBF))
                  return false;
              tail_bytes = 1;
          }
          else if (s[i] >= 0xE1 && s[i] <= 0xEC) {
              tail_bytes = 2;
          }
          else if (s[i] == 0xED) {
              i++;
              if (i >= len || !(s[i] >= 0x80 && s[i] <= 0x9F))
                  return false;
              tail_bytes = 1;
          }
          else if (s[i] >= 0xEE && s[i] <= 0xEF) {
              tail_bytes = 2;
          }
          else if (s[i] == 0xF0) {
              i++;
              if (i >= len || !(s[i] >= 0x90 && s[i] <= 0xBF))
                  return false;
              tail_bytes = 2;
          }
          else if (s[i] >= 0xF1 && s[i] <= 0xF3) {
              tail_bytes = 3;
          }
          else if (s[i] == 0xF4) {
              i++;
              if (i >= len || !(s[i] >= 0x80 && s[i] <= 0x8F))
                  return false;
              tail_bytes = 2;
          }
          else {
              return false;
          }
  
          i++;
  
          while (i < len && tail_bytes > 0 && s[i] >= 0x80 && s[i] <= 0xBF) {
              i++;
              tail_bytes--;
          }
  
          if (tail_bytes != 0)
              return false;
      }
  
      return true;
  }
  

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