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quotprinenco.c

/*
 *    fhist - file history and comparison tools
 *    Copyright (C) 2000, 2002 Peter Miller;
 *    All rights reserved.
 *
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
 *
 * MANIFEST: functions for reading input and encoding it as quoted printable
 */

#include <error.h>
#include <input/quotprinenco.h>
#include <input/private.h>
#include <trace.h>


typedef struct input_quoted_printable_encode_ty input_quoted_printable_encode_ty;
struct input_quoted_printable_encode_ty
{
      input_ty    inherited;
      input_ty    *fp;
      int         state;
      int         c1;
      int         column;
      int         delete_on_close;
};


static void
destruct(input_ty *p)
{
      input_quoted_printable_encode_ty *this;

      trace(("input_quoted_printable_encode::destruct()\n{\n"));
      this = (input_quoted_printable_encode_ty *)p;
      input_pushback_transfer(this->fp, p);
      if (this->delete_on_close)
            input_delete(this->fp);
      this->fp = 0; /* paranoia */
      trace(("}\n"));
}


static int
hex(int n)
{
      return "0123456789ABCDEF"[n & 15];
}


static int
get(input_ty *p)
{
      input_quoted_printable_encode_ty *this;
      int         c;

      trace(("input_quoted_printable_encode::get()\n{\n"));
      this = (input_quoted_printable_encode_ty *)p;
      switch (this->state)
      {
      case 1:
            /*
             * we have given half of a '=' '\n' sequence.
             * Give the secoind byte, and resume normal
             */
            c = '\n';
            this->column = 0;
            this->state = 0;
            break;

      case 3:
            /*
             * we  have seen end of file without a newline
             * we have sent '=', now send '\n'
             */
            c = '\n';
            this->state = 4;
            break;
      
      case 4:
            /*
             * we have seen end of file
             */
            c = -1;
            break;

      case 5:
            /*
             * we have seen a newline
             * following end of file does NOT need a '=' '\n' sequence
             */
            c = input_getc(this->fp);
            if (c < 0)
            {
                  this->state = 4;
                  break;
            }
            this->state = 0;
            goto normal;

      case 6:
            /*
             * we have seen an unprintable character
             * we have sent the '=' synbol
             * now send the first hex byte
             */
            c = hex(this->c1 >> 4);
            this->state = 7;
            break;

      case 7:
            /*
             * we have seen an unprintable character
             * we have sent the '=' synbol
             * we have sent the first hex byte
             * now send the second hex byte
             * and the resume normal processing
             */
            c = hex(this->c1);
            this->state = 0;
            break;

      default:
            /*
             * Normal processing.
             * Actually case 0, but this cobvers a multitude of sins.
             */
            if (this->column >= 500)
            {
                  c = '=';
                  this->state = 1;
                  break;
            }
            c = input_getc(this->fp);
            if (c < 0)
            {
                  this->state = 3;
                  this->column = 0;
                  c = '=';
                  break;
            }
            normal:
            if (c == '\n')
            {
                  this->column = 0;
                  this->state = 5;
                  break;
            }
            if (c == '\t')
            {
                  this->column = (this->column + 8) & 7;
                  break;
            }
            if (c == 0 || c == '=' || c == '\r')
            {
                  this->column += 3;
                  this->c1 = c;
                  this->state = 6;
                  c = '=';
                  break;
            }
            this->column++;
            break;
      }
      trace(("}\n"));
      return c;
}


static long
itell(input_ty *fp)
{
      input_quoted_printable_encode_ty    *this;

      this = (input_quoted_printable_encode_ty *)fp;
      return input_ftell(this->fp);
}


static const char *
name(input_ty *p)
{
      input_quoted_printable_encode_ty    *this;

      trace(("input_quoted_printable_encode::name\n"));
      this = (input_quoted_printable_encode_ty *)p;
      return input_name(this->fp);
}


static long
length(input_ty *p)
{
      trace(("input_quoted_printable_encode::length => -1\n"));
      return -1;
}


static input_vtbl_ty vtbl =
{
      sizeof(input_quoted_printable_encode_ty),
      destruct,
      input_generic_read,
      get,
      itell,
      name,
      length,
};


input_ty *
input_quoted_printable_encode(input_ty *fp, int delete_on_close)
{
      input_ty    *result;
      input_quoted_printable_encode_ty    *this;

      trace(("input_quoted_printable_encode(fp = %08lX)\n{\n", (long)fp));
      result = input_new(&vtbl);
      this = (input_quoted_printable_encode_ty *)result;
      this->fp = fp;
      this->column = 0;
      this->state = 0;
      this->c1 = 0;
      this->delete_on_close = delete_on_close;
      trace(("return %08lX\n", (long)result));
      trace(("}\n"));
      return result;
}

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