1/*
2                            __  __            _
3                         ___\ \/ /_ __   __ _| |_
4                        / _ \\  /| '_ \ / _` | __|
5                       |  __//  \| |_) | (_| | |_
6                        \___/_/\_\ .__/ \__,_|\__|
7                                 |_| XML parser
8
9   Copyright (c) 1997-2000 Thai Open Source Software Center Ltd
10   Copyright (c) 2000-2017 Expat development team
11   Licensed under the MIT license:
12
13   Permission is  hereby granted,  free of charge,  to any  person obtaining
14   a  copy  of  this  software   and  associated  documentation  files  (the
15   "Software"),  to  deal in  the  Software  without restriction,  including
16   without  limitation the  rights  to use,  copy,  modify, merge,  publish,
17   distribute, sublicense, and/or sell copies of the Software, and to permit
18   persons  to whom  the Software  is  furnished to  do so,  subject to  the
19   following conditions:
20
21   The above copyright  notice and this permission notice  shall be included
22   in all copies or substantial portions of the Software.
23
24   THE  SOFTWARE  IS  PROVIDED  "AS  IS",  WITHOUT  WARRANTY  OF  ANY  KIND,
25   EXPRESS  OR IMPLIED,  INCLUDING  BUT  NOT LIMITED  TO  THE WARRANTIES  OF
26   MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
27   NO EVENT SHALL THE AUTHORS OR  COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
28   DAMAGES OR  OTHER LIABILITY, WHETHER  IN AN  ACTION OF CONTRACT,  TORT OR
29   OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
30   USE OR OTHER DEALINGS IN THE SOFTWARE.
31*/
32
33#define CHARSET_MAX 41
34
35static const char *
36getTok(const char **pp) {
37  enum { inAtom, inString, init, inComment };
38  int state = init;
39  const char *tokStart = 0;
40  for (;;) {
41    switch (**pp) {
42    case '\0':
43      return 0;
44    case ' ':
45    case '\r':
46    case '\t':
47    case '\n':
48      if (state == inAtom)
49        return tokStart;
50      break;
51    case '(':
52      if (state == inAtom)
53        return tokStart;
54      if (state != inString)
55        state++;
56      break;
57    case ')':
58      if (state > init)
59        --state;
60      else if (state != inString)
61        return 0;
62      break;
63    case ';':
64    case '/':
65    case '=':
66      if (state == inAtom)
67        return tokStart;
68      if (state == init)
69        return (*pp)++;
70      break;
71    case '\\':
72      ++*pp;
73      if (**pp == '\0')
74        return 0;
75      break;
76    case '"':
77      switch (state) {
78      case inString:
79        ++*pp;
80        return tokStart;
81      case inAtom:
82        return tokStart;
83      case init:
84        tokStart = *pp;
85        state = inString;
86        break;
87      }
88      break;
89    default:
90      if (state == init) {
91        tokStart = *pp;
92        state = inAtom;
93      }
94      break;
95    }
96    ++*pp;
97  }
98  /* not reached */
99}
100
101/* key must be lowercase ASCII */
102
103static int
104matchkey(const char *start, const char *end, const char *key) {
105  if (! start)
106    return 0;
107  for (; start != end; start++, key++)
108    if (*start != *key && *start != 'A' + (*key - 'a'))
109      return 0;
110  return *key == '\0';
111}
112
113void
114getXMLCharset(const char *buf, char *charset) {
115  const char *next, *p;
116
117  charset[0] = '\0';
118  next = buf;
119  p = getTok(&next);
120  if (matchkey(p, next, "text"))
121    strcpy(charset, "us-ascii");
122  else if (! matchkey(p, next, "application"))
123    return;
124  p = getTok(&next);
125  if (! p || *p != '/')
126    return;
127  p = getTok(&next);
128  if (matchkey(p, next, "xml"))
129    isXml = 1;
130  p = getTok(&next);
131  while (p) {
132    if (*p == ';') {
133      p = getTok(&next);
134      if (matchkey(p, next, "charset")) {
135        p = getTok(&next);
136        if (p && *p == '=') {
137          p = getTok(&next);
138          if (p) {
139            char *s = charset;
140            if (*p == '"') {
141              while (++p != next - 1) {
142                if (*p == '\\')
143                  ++p;
144                if (s == charset + CHARSET_MAX - 1) {
145                  charset[0] = '\0';
146                  break;
147                }
148                *s++ = *p;
149              }
150              *s++ = '\0';
151            } else {
152              if (next - p > CHARSET_MAX - 1)
153                break;
154              while (p != next)
155                *s++ = *p++;
156              *s = 0;
157              break;
158            }
159          }
160        }
161      }
162    } else
163      p = getTok(&next);
164  }
165}
166
167int
168main(int argc, char **argv) {
169  char buf[CHARSET_MAX];
170  getXMLCharset(argv[1], buf);
171  printf("charset = \"%s\"\n", buf);
172  return 0;
173}
174