summaryrefslogtreecommitdiff
path: root/kmime/kmime_charfreq.cpp
blob: 3ec6d05dc27ce2e49b84fc30735166c64bd3f3dd (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
/*
  kmime_charfreq.cpp

  KMime, the KDE Internet mail/usenet news message library.
  Copyright (c) 2001-2002 Marc Mutz <mutz@kde.org>

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Library General Public
  License as published by the Free Software Foundation; either
  version 2 of the License, or (at your option) any later version.

  This library 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
  Library General Public License for more details.

  You should have received a copy of the GNU Library General Public License
  along with this library; see the file COPYING.LIB.  If not, write to
  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  Boston, MA 02110-1301, USA.
*/

/**
  @file
  This file is part of the API for handling MIME data and
  defines the CharFreq class.

  @brief
  Defines the CharFreq class.

  @authors Marc Mutz \<mutz@kde.org\>
*/

#include "kmime_charfreq.h"

using namespace KMime;

/**
 * Private class that helps to provide binary compatibility between releases.
 * @internal
 */
//@cond PRIVATE
//class KMime::CharFreq::Private
//{
//  public:
//};
//@endcond

CharFreq::CharFreq( const QByteArray &buf )
  : mNUL( 0 ),
    mCTL( 0 ),
    mCR( 0 ), mLF( 0 ),
    mCRLF( 0 ),
    mPrintable( 0 ),
    mEightBit( 0 ),
    mTotal( 0 ),
    mLineMin( 0xffffffff ),
    mLineMax( 0 ),
    mTrailingWS( false ),
    mLeadingFrom( false )
{
  if ( !buf.isEmpty() ) {
    count( buf.data(), buf.size() );
  }
}

CharFreq::CharFreq( const char *buf, size_t len )
  : mNUL( 0 ),
    mCTL( 0 ),
    mCR( 0 ), mLF( 0 ),
    mCRLF( 0 ),
    mPrintable( 0 ),
    mEightBit( 0 ),
    mTotal( 0 ),
    mLineMin( 0xffffffff ),
    mLineMax( 0 ),
    mTrailingWS( false ),
    mLeadingFrom( false )
{
  if ( buf && len > 0 ) {
    count( buf, len );
  }
}

//@cond PRIVATE
static inline bool isWS( char ch )
{
  return ( ch == '\t' || ch == ' ' );
}
//@endcond

void CharFreq::count( const char *it, size_t len )
{
  const char *end = it + len;
  uint currentLineLength = 0;
  // initialize the prevChar with LF so that From_ detection works w/o
  // special-casing:
  char prevChar = '\n';
  char prevPrevChar = 0;

  for ( ; it != end ; ++it ) {
    ++currentLineLength;
    switch ( *it ) {
    case '\0': ++mNUL; break;
    case '\r': ++mCR;  break;
    case '\n': ++mLF;
      if ( prevChar == '\r' ) {
        --currentLineLength; ++mCRLF;
      }
      if ( currentLineLength >= mLineMax ) {
        mLineMax = currentLineLength-1;
      }
      if ( currentLineLength <= mLineMin ) {
        mLineMin = currentLineLength-1;
      }
      if ( !mTrailingWS ) {
        if ( isWS( prevChar ) ||
             ( prevChar == '\r' && isWS( prevPrevChar ) ) ) {
          mTrailingWS = true;
        }
      }
      currentLineLength = 0;
      break;
    case 'F': // check for lines starting with From_ if not found already:
      if ( !mLeadingFrom ) {
        if ( prevChar == '\n' && end - it >= 5 &&
             !qstrncmp( "From ", it, 5 ) ) {
          mLeadingFrom = true;
        }
      }
      ++mPrintable;
      break;
    default:
    {
      uchar c = *it;
      if ( c == '\t' || ( c >= ' ' && c <= '~' ) ) {
        ++mPrintable;
      } else if ( c == 127 || c < ' ' ) {
        ++mCTL;
      } else {
        ++mEightBit;
      }
    }
    }
    prevPrevChar = prevChar;
    prevChar = *it;
  }

  // consider the length of the last line
  if ( currentLineLength >= mLineMax ) {
    mLineMax = currentLineLength;
  }
  if ( currentLineLength <= mLineMin ) {
    mLineMin = currentLineLength;
  }

  // check whether the last character is tab or space
  if ( isWS( prevChar ) ) {
    mTrailingWS = true;
  }

  mTotal = len;
}

bool CharFreq::isEightBitData() const
{
  return type() == EightBitData;
}

bool CharFreq::isEightBitText() const
{
  return type() == EightBitText;
}

bool CharFreq::isSevenBitData() const
{
  return type() == SevenBitData;
}

bool CharFreq::isSevenBitText() const
{
  return type() == SevenBitText;
}

bool CharFreq::hasTrailingWhitespace() const
{
  return mTrailingWS;
}

bool CharFreq::hasLeadingFrom() const
{
  return mLeadingFrom;
}

CharFreq::Type CharFreq::type() const
{
#if 0
  qDebug( "Total: %d; NUL: %d; CTL: %d;\n"
          "CR: %d; LF: %d; CRLF: %d;\n"
          "lineMin: %d; lineMax: %d;\n"
          "printable: %d; eightBit: %d;\n"
          "trailing whitespace: %s;\n"
          "leading 'From ': %s;\n",
          total, NUL, CTL, CR, LF, CRLF, lineMin, lineMax,
          printable, eightBit,
          mTrailingWS ? "yes" : "no" , mLeadingFrom ? "yes" : "no" );
#endif
  if ( mNUL ) { // must be binary
    return Binary;
  }

  // doesn't contain NUL's:
  if ( mEightBit ) {
    if ( mLineMax > 988 ) {
      return EightBitData; // not allowed in 8bit
    }
    if ( ( mLF != mCRLF && mCRLF > 0 ) || mCR != mCRLF || controlCodesRatio() > 0.2 ) {
      return EightBitData;
    }
    return EightBitText;
  }

  // doesn't contain NUL's, nor 8bit chars:
  if ( mLineMax > 988 ) {
    return SevenBitData;
  }
  if ( ( mLF != mCRLF && mCRLF > 0 ) || mCR != mCRLF || controlCodesRatio() > 0.2 ) {
    return SevenBitData;
  }

  // no NUL, no 8bit chars, no excessive CTLs and no lines > 998 chars:
  return SevenBitText;
}

float CharFreq::printableRatio() const
{
  if ( mTotal ) {
    return float(mPrintable) / float(mTotal);
  } else {
    return 0;
  }
}

float CharFreq::controlCodesRatio() const
{
  if ( mTotal ) {
    return float(mCTL) / float(mTotal);
  } else {
    return 0;
  }
}