Back to index

glibc  2.9
Defines | Enumerations | Functions | Variables
punycode.c File Reference
#include <string.h>
#include "punycode.h"

Go to the source code of this file.

Defines

#define basic(cp)   ((punycode_uint)(cp) < 0x80)
#define delim(cp)   ((cp) == delimiter)
#define flagged(bcp)   ((punycode_uint)(bcp) - 65 < 26)

Enumerations

enum  {
  base = 36, tmin = 1, tmax = 26, skew = 38,
  damp = 700, initial_bias = 72, initial_n = 0x80, delimiter = 0x2D
}

Functions

static punycode_uint decode_digit (punycode_uint cp)
static char encode_digit (punycode_uint d, int flag)
static char encode_basic (punycode_uint bcp, int flag)
static punycode_uint adapt (punycode_uint delta, punycode_uint numpoints, int firsttime)
int punycode_encode (size_t input_length, const punycode_uint input[], const unsigned char case_flags[], size_t *output_length, char output[])
 punycode_encode: : The number of code points in the array and the number of flags in the array.
int punycode_decode (size_t input_length, const char input[], size_t *output_length, punycode_uint output[], unsigned char case_flags[])
 punycode_decode: : The number of ASCII code points in the array.

Variables

static const punycode_uint maxint = -1

Define Documentation

#define basic (   cp)    ((punycode_uint)(cp) < 0x80)

Definition at line 74 of file punycode.c.

#define delim (   cp)    ((cp) == delimiter)

Definition at line 77 of file punycode.c.

#define flagged (   bcp)    ((punycode_uint)(bcp) - 65 < 26)

Definition at line 108 of file punycode.c.


Enumeration Type Documentation

anonymous enum
Enumerator:
base 
tmin 
tmax 
skew 
damp 
initial_bias 
initial_n 
delimiter 

Definition at line 68 of file punycode.c.

{ base = 36, tmin = 1, tmax = 26, skew = 38, damp = 700,
  initial_bias = 72, initial_n = 0x80, delimiter = 0x2D
};

Function Documentation

static punycode_uint adapt ( punycode_uint  delta,
punycode_uint  numpoints,
int  firsttime 
) [static]

Definition at line 132 of file punycode.c.

{
  punycode_uint k;

  delta = firsttime ? delta / damp : delta >> 1;
  /* delta >> 1 is a faster way of doing delta / 2 */
  delta += delta / numpoints;

  for (k = 0; delta > ((base - tmin) * tmax) / 2; k += base)
    {
      delta /= base - tmin;
    }

  return k + (base - tmin + 1) * delta / (delta + skew);
}

Here is the caller graph for this function:

static punycode_uint decode_digit ( punycode_uint  cp) [static]

Definition at line 84 of file punycode.c.

{
  return cp - 48 < 10 ? cp - 22 : cp - 65 < 26 ? cp - 65 :
    cp - 97 < 26 ? cp - 97 : base;
}

Here is the caller graph for this function:

static char encode_basic ( punycode_uint  bcp,
int  flag 
) [static]

Definition at line 117 of file punycode.c.

{
  bcp -= (bcp - 97 < 26) << 5;
  return bcp + ((!flag && (bcp - 65 < 26)) << 5);
}

Here is the caller graph for this function:

static char encode_digit ( punycode_uint  d,
int  flag 
) [static]

Definition at line 97 of file punycode.c.

{
  return d + 22 + 75 * (d < 26) - ((flag != 0) << 5);
  /*  0..25 map to ASCII a..z or A..Z */
  /* 26..35 map to ASCII 0..9         */
}

Here is the caller graph for this function:

int punycode_decode ( size_t  input_length,
const char  input[],
size_t output_length,
punycode_uint  output[],
unsigned char  case_flags[] 
)

punycode_decode: : The number of ASCII code points in the array.

: An array of ASCII code points (0..7F). : The caller passes in the maximum number of code points that it can receive into the array (which is also the maximum number of flags that it can receive into the array, if is not a NULL pointer). On successful return it will contain the number of code points actually output (which is also the number of flags actually output, if case_flags is not a null pointer). The decoder will never need to output more code points than the number of ASCII code points in the input, because of the way the encoding is defined. The number of code points output cannot exceed the maximum possible value of a punycode_uint, even if the supplied is greater than that. : An array of code points like the input argument of punycode_encode() (see above). : A NULL pointer (if the flags are not needed by the caller) or an array of boolean values parallel to the array. Nonzero (true, flagged) suggests that the corresponding Unicode character be forced to uppercase by the caller (if possible), and zero (false, unflagged) suggests that it be forced to lowercase (if possible). ASCII code points (0..7F) are output already in the proper case, but their flags will be set appropriately so that applying the flags would be harmless.

Converts Punycode to a sequence of code points (presumed to be Unicode code points).

Return value: The return value can be any of the punycode_status values defined above. If not punycode_success, then , , and might contain garbage.

Definition at line 337 of file punycode.c.

{
  punycode_uint n, out, i, max_out, bias, oldi, w, k, digit, t;
  size_t b, j, in;

  /* Initialize the state: */

  n = initial_n;
  out = i = 0;
  max_out = *output_length > maxint ? maxint
    : (punycode_uint) * output_length;
  bias = initial_bias;

  /* Handle the basic code points:  Let b be the number of input code */
  /* points before the last delimiter, or 0 if there is none, then    */
  /* copy the first b code points to the output.                      */

  for (b = j = 0; j < input_length; ++j)
    if (delim (input[j]))
      b = j;
  if (b > max_out)
    return punycode_big_output;

  for (j = 0; j < b; ++j)
    {
      if (case_flags)
       case_flags[out] = flagged (input[j]);
      if (!basic (input[j]))
       return punycode_bad_input;
      output[out++] = input[j];
    }

  /* Main decoding loop:  Start just after the last delimiter if any  */
  /* basic code points were copied; start at the beginning otherwise. */

  for (in = b > 0 ? b + 1 : 0; in < input_length; ++out)
    {

      /* in is the index of the next ASCII code point to be consumed, */
      /* and out is the number of code points in the output array.    */

      /* Decode a generalized variable-length integer into delta,  */
      /* which gets added to i.  The overflow checking is easier   */
      /* if we increase i as we go, then subtract off its starting */
      /* value at the end to obtain delta.                         */

      for (oldi = i, w = 1, k = base;; k += base)
       {
         if (in >= input_length)
           return punycode_bad_input;
         digit = decode_digit (input[in++]);
         if (digit >= base)
           return punycode_bad_input;
         if (digit > (maxint - i) / w)
           return punycode_overflow;
         i += digit * w;
         t = k <= bias /* + tmin */ ? tmin :     /* +tmin not needed */
           k >= bias + tmax ? tmax : k - bias;
         if (digit < t)
           break;
         if (w > maxint / (base - t))
           return punycode_overflow;
         w *= (base - t);
       }

      bias = adapt (i - oldi, out + 1, oldi == 0);

      /* i was supposed to wrap around from out+1 to 0,   */
      /* incrementing n each time, so we'll fix that now: */

      if (i / (out + 1) > maxint - n)
       return punycode_overflow;
      n += i / (out + 1);
      i %= (out + 1);

      /* Insert n at position i of the output: */

      /* not needed for Punycode: */
      /* if (basic(n)) return punycode_invalid_input; */
      if (out >= max_out)
       return punycode_big_output;

      if (case_flags)
       {
         memmove (case_flags + i + 1, case_flags + i, out - i);
         /* Case of last ASCII code point determines case flag: */
         case_flags[i] = flagged (input[in - 1]);
       }

      memmove (output + i + 1, output + i, (out - i) * sizeof *output);
      output[i++] = n;
    }

  *output_length = (size_t) out;
  /* cannot overflow because out <= old value of *output_length */
  return punycode_success;
}

Here is the call graph for this function:

Here is the caller graph for this function:

int punycode_encode ( size_t  input_length,
const punycode_uint  input[],
const unsigned char  case_flags[],
size_t output_length,
char  output[] 
)

punycode_encode: : The number of code points in the array and the number of flags in the array.

: An array of code points. They are presumed to be Unicode code points, but that is not strictly REQUIRED. The array contains code points, not code units. UTF-16 uses code units D800 through DFFF to refer to code points 10000..10FFFF. The code points D800..DFFF do not occur in any valid Unicode string. The code points that can occur in Unicode strings (0..D7FF and E000..10FFFF) are also called Unicode scalar values. : A NULL pointer or an array of boolean values parallel to the array. Nonzero (true, flagged) suggests that the corresponding Unicode character be forced to uppercase after being decoded (if possible), and zero (false, unflagged) suggests that it be forced to lowercase (if possible). ASCII code points (0..7F) are encoded literally, except that ASCII letters are forced to uppercase or lowercase according to the corresponding case flags. If is a NULL pointer then ASCII letters are left as they are, and other code points are treated as unflagged. : The caller passes in the maximum number of ASCII code points that it can receive. On successful return it will contain the number of ASCII code points actually output. : An array of ASCII code points. It is not null-terminated; it will contain zeros if and only if the contains zeros. (Of course the caller can leave room for a terminator and add one if needed.)

Converts a sequence of code points (presumed to be Unicode code points) to Punycode.

Return value: The return value can be any of the punycode_status values defined above except punycode_bad_input. If not punycode_success, then and might contain garbage.

Definition at line 188 of file punycode.c.

{
  punycode_uint input_len, n, delta, h, b, bias, j, m, q, k, t;
  size_t out, max_out;

  /* The Punycode spec assumes that the input length is the same type */
  /* of integer as a code point, so we need to convert the size_t to  */
  /* a punycode_uint, which could overflow.                           */

  if (input_length > maxint)
    return punycode_overflow;
  input_len = (punycode_uint) input_length;

  /* Initialize the state: */

  n = initial_n;
  delta = 0;
  out = 0;
  max_out = *output_length;
  bias = initial_bias;

  /* Handle the basic code points: */

  for (j = 0; j < input_len; ++j)
    {
      if (basic (input[j]))
       {
         if (max_out - out < 2)
           return punycode_big_output;
         output[out++] = case_flags ?
           encode_basic (input[j], case_flags[j]) : (char) input[j];
       }
      /* else if (input[j] < n) return punycode_bad_input; */
      /* (not needed for Punycode with unsigned code points) */
    }

  h = b = (punycode_uint) out;
  /* cannot overflow because out <= input_len <= maxint */

  /* h is the number of code points that have been handled, b is the  */
  /* number of basic code points, and out is the number of ASCII code */
  /* points that have been output.                                    */

  if (b > 0)
    output[out++] = delimiter;

  /* Main encoding loop: */

  while (h < input_len)
    {
      /* All non-basic code points < n have been     */
      /* handled already.  Find the next larger one: */

      for (m = maxint, j = 0; j < input_len; ++j)
       {
         /* if (basic(input[j])) continue; */
         /* (not needed for Punycode) */
         if (input[j] >= n && input[j] < m)
           m = input[j];
       }

      /* Increase delta enough to advance the decoder's    */
      /* <n,i> state to <m,0>, but guard against overflow: */

      if (m - n > (maxint - delta) / (h + 1))
       return punycode_overflow;
      delta += (m - n) * (h + 1);
      n = m;

      for (j = 0; j < input_len; ++j)
       {
         /* Punycode does not need to check whether input[j] is basic: */
         if (input[j] < n /* || basic(input[j]) */ )
           {
             if (++delta == 0)
              return punycode_overflow;
           }

         if (input[j] == n)
           {
             /* Represent delta as a generalized variable-length integer: */

             for (q = delta, k = base;; k += base)
              {
                if (out >= max_out)
                  return punycode_big_output;
                t = k <= bias /* + tmin */ ? tmin :     /* +tmin not needed */
                  k >= bias + tmax ? tmax : k - bias;
                if (q < t)
                  break;
                output[out++] = encode_digit (t + (q - t) % (base - t), 0);
                q = (q - t) / (base - t);
              }

             output[out++] = encode_digit (q, case_flags && case_flags[j]);
             bias = adapt (delta, h + 1, h == b);
             delta = 0;
             ++h;
           }
       }

      ++delta, ++n;
    }

  *output_length = out;
  return punycode_success;
}

Here is the call graph for this function:

Here is the caller graph for this function:


Variable Documentation

const punycode_uint maxint = -1 [static]

Definition at line 126 of file punycode.c.