Library/Implementation/HTUU.c

/*
 * $LynxId: HTUU.c,v 1.11 2010/09/21 23:55:12 tom Exp $
 *
 * MODULE							HTUU.c
 *			UUENCODE AND UUDECODE
 *
 * ACKNOWLEDGEMENT:
 *	This code is taken from rpem distribution, and was originally
 *	written by Mark Riordan.
 *
 * AUTHORS:
 *	MR	Mark Riordan	riordanmr@clvax1.cl.msu.edu
 *	AL	Ari Luotonen	luotonen@dxcern.cern.ch
 *
 * HISTORY:
 *	Added as part of the WWW library and edited to conform
 *	with the WWW project coding standards by:	AL  5 Aug 1993
 *	Originally written by:				MR 12 Aug 1990
 *	Original header text:
 * -------------------------------------------------------------
 *  File containing routines to convert a buffer
 *  of bytes to/from RFC 1113 printable encoding format.
 *
 *  This technique is similar to the familiar Unix uuencode
 *  format in that it maps 6 binary bits to one ASCII
 *  character (or more aptly, 3 binary bytes to 4 ASCII
 *  characters).  However, RFC 1113 does not use the same
 *  mapping to printable characters as uuencode.
 *
 *  Mark Riordan   12 August 1990 and 17 Feb 1991.
 *  This code is hereby placed in the public domain.
 * -------------------------------------------------------------
 */

#include <HTUtils.h>
#include <HTUU.h>

#include <LYLeaks.h>

static char six2pr[64] =
{
    'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
    'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
    'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
    'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
};

static unsigned char pr2six[256];

/*--- function HTUU_encode -----------------------------------------------
 *
 * Encode a single line of binary data to a standard format that
 * uses only printing ASCII characters (but takes up 33% more bytes).
 *
 *    Entry    bufin    points to a buffer of bytes.  If nbytes is not
 *                      a multiple of three, then the byte just beyond
 *                      the last byte in the buffer must be 0.
 *             nbytes   is the number of bytes in that buffer.
 *                      This cannot be more than 48.
 *             bufcoded points to an output buffer.  Be sure that this
 *                      can hold at least 1 + (4*nbytes)/3 characters.
 *
 *    Exit     bufcoded contains the coded line.  The first 4*nbytes/3 bytes
 *                      contain printing ASCII characters representing
 *                      those binary bytes.  This may include one or
 *                      two '=' characters used as padding at the end.
 *                      The last byte is a zero byte.
 *             Returns the number of ASCII characters in "bufcoded".
 */
int HTUU_encode(unsigned char *bufin,
		size_t nbytes,
		char *bufcoded)
{
/* ENC is the basic 1 character encoding function to make a char printing */
#define ENC(c) six2pr[c]

    register char *outptr = bufcoded;
    size_t i;

    /* This doesn't seem to be needed (AL):   register unsigned char *inptr  = bufin; */

    for (i = 0; i < nbytes; i += 3) {
	*(outptr++) = ENC(*bufin >> 2);		/* c1 */
	*(outptr++) = ENC(((*bufin << 4) & 060) | ((bufin[1] >> 4) & 017));	/*c2 */
	*(outptr++) = ENC(((bufin[1] << 2) & 074) | ((bufin[2] >> 6) & 03));	/*c3 */
	*(outptr++) = ENC(bufin[2] & 077);	/* c4 */

	bufin += 3;
    }

    /* If nbytes was not a multiple of 3, then we have encoded too
     * many characters.  Adjust appropriately.
     */
    if (i == nbytes + 1) {
	/* There were only 2 bytes in that last group */
	outptr[-1] = '=';
    } else if (i == nbytes + 2) {
	/* There was only 1 byte in that last group */
	outptr[-1] = '=';
	outptr[-2] = '=';
    }
    *outptr = '\0';
    return (int) (outptr - bufcoded);
}

/*--- function HTUU_decode ------------------------------------------------
 *
 * Decode an ASCII-encoded buffer back to its original binary form.
 *
 *    Entry    bufcoded    points to a uuencoded string.  It is
 *                         terminated by any character not in
 *                         the printable character table six2pr, but
 *                         leading whitespace is stripped.
 *             bufplain    points to the output buffer; must be big
 *                         enough to hold the decoded string (generally
 *                         shorter than the encoded string) plus
 *                         as many as two extra bytes used during
 *                         the decoding process.
 *             outbufsize  is the maximum number of bytes that
 *                         can fit in bufplain.
 *
 *    Exit     Returns the number of binary bytes decoded.
 *             bufplain    contains these bytes.
 */
int HTUU_decode(char *bufcoded,
		unsigned char *bufplain,
		int outbufsize)
{
/* single character decode */
#define DEC(c) pr2six[(int)c]
#define MAXVAL 63

    static int first = 1;

    int nbytesdecoded, j;
    register char *bufin;
    register unsigned char *bufout = bufplain;
    register int nprbytes;

    /* If this is the first call, initialize the mapping table.
     * This code should work even on non-ASCII machines.
     */
    if (first) {
	first = 0;
	for (j = 0; j < 256; j++)
	    pr2six[j] = MAXVAL + 1;

	for (j = 0; j < 64; j++)
	    pr2six[UCH(six2pr[j])] = UCH(j);
#if 0
      /* *INDENT-OFF* */
      pr2six['A']= 0; pr2six['B']= 1; pr2six['C']= 2; pr2six['D']= 3;
      pr2six['E']= 4; pr2six['F']= 5; pr2six['G']= 6; pr2six['H']= 7;
      pr2six['I']= 8; pr2six['J']= 9; pr2six['K']=10; pr2six['L']=11;
      pr2six['M']=12; pr2six['N']=13; pr2six['O']=14; pr2six['P']=15;
      pr2six['Q']=16; pr2six['R']=17; pr2six['S']=18; pr2six['T']=19;
      pr2six['U']=20; pr2six['V']=21; pr2six['W']=22; pr2six['X']=23;
      pr2six['Y']=24; pr2six['Z']=25; pr2six['a']=26; pr2six['b']=27;
      pr2six['c']=28; pr2six['d']=29; pr2six['e']=30; pr2six['f']=31;
      pr2six['g']=32; pr2six['h']=33; pr2six['i']=34; pr2six['j']=35;
      pr2six['k']=36; pr2six['l']=37; pr2six['m']=38; pr2six['n']=39;
      pr2six['o']=40; pr2six['p']=41; pr2six['q']=42; pr2six['r']=43;
      pr2six['s']=44; pr2six['t']=45; pr2six['u']=46; pr2six['v']=47;
      pr2six['w']=48; pr2six['x']=49; pr2six['y']=50; pr2six['z']=51;
      pr2six['0']=52; pr2six['1']=53; pr2six['2']=54; pr2six['3']=55;
      pr2six['4']=56; pr2six['5']=57; pr2six['6']=58; pr2six['7']=59;
      pr2six['8']=60; pr2six['9']=61; pr2six['+']=62; pr2six['/']=63;
      /* *INDENT-ON* */

#endif
    }

    /* Strip leading whitespace. */

    while (*bufcoded == ' ' || *bufcoded == '\t')
	bufcoded++;

    /* Figure out how many characters are in the input buffer.
     * If this would decode into more bytes than would fit into
     * the output buffer, adjust the number of input bytes downwards.
     */
    bufin = bufcoded;
    while (pr2six[UCH(*(bufin++))] <= MAXVAL) ;
    nprbytes = (int) (bufin - bufcoded - 1);
    nbytesdecoded = ((nprbytes + 3) / 4) * 3;
    if (nbytesdecoded > outbufsize) {
	nprbytes = (outbufsize * 4) / 3;
    }

    bufin = bufcoded;

    while (nprbytes > 0) {
	*(bufout++) = UCH((DEC(bufin[0]) << 2) | (DEC(bufin[1]) >> 4));
	*(bufout++) = UCH((DEC(bufin[1]) << 4) | (DEC(bufin[2]) >> 2));
	*(bufout++) = UCH((DEC(bufin[2]) << 6) | (DEC(bufin[3])));
	bufin += 4;
	nprbytes -= 4;
    }

    if (nprbytes & 03) {
	if (pr2six[(int) bufin[-2]] > MAXVAL) {
	    nbytesdecoded -= 2;
	} else {
	    nbytesdecoded -= 1;
	}
    }

    return (nbytesdecoded);
}