1 """Mailcap file handling. See RFC 1524."""
2
3 import os
4 import warnings
5 import re
6
7 __all__ = ["getcaps","findmatch"]
8
9
10 _DEPRECATION_MSG = ('The {name} module is deprecated and will be removed in '
11 'Python {remove}. See the mimetypes module for an '
12 'alternative.')
13 warnings._deprecated(__name__, _DEPRECATION_MSG, remove=(3, 13))
14
15
16 def lineno_sort_key(entry):
17 # Sort in ascending order, with unspecified entries at the end
18 if 'lineno' in entry:
19 return 0, entry['lineno']
20 else:
21 return 1, 0
22
23 _find_unsafe = re.compile(r'[^\xa1-\U0010FFFF\w@+=:,./-]').search
24
25 class ESC[4;38;5;81mUnsafeMailcapInput(ESC[4;38;5;149mWarning):
26 """Warning raised when refusing unsafe input"""
27
28
29 # Part 1: top-level interface.
30
31 def getcaps():
32 """Return a dictionary containing the mailcap database.
33
34 The dictionary maps a MIME type (in all lowercase, e.g. 'text/plain')
35 to a list of dictionaries corresponding to mailcap entries. The list
36 collects all the entries for that MIME type from all available mailcap
37 files. Each dictionary contains key-value pairs for that MIME type,
38 where the viewing command is stored with the key "view".
39
40 """
41 caps = {}
42 lineno = 0
43 for mailcap in listmailcapfiles():
44 try:
45 fp = open(mailcap, 'r')
46 except OSError:
47 continue
48 with fp:
49 morecaps, lineno = _readmailcapfile(fp, lineno)
50 for key, value in morecaps.items():
51 if not key in caps:
52 caps[key] = value
53 else:
54 caps[key] = caps[key] + value
55 return caps
56
57 def listmailcapfiles():
58 """Return a list of all mailcap files found on the system."""
59 # This is mostly a Unix thing, but we use the OS path separator anyway
60 if 'MAILCAPS' in os.environ:
61 pathstr = os.environ['MAILCAPS']
62 mailcaps = pathstr.split(os.pathsep)
63 else:
64 if 'HOME' in os.environ:
65 home = os.environ['HOME']
66 else:
67 # Don't bother with getpwuid()
68 home = '.' # Last resort
69 mailcaps = [home + '/.mailcap', '/etc/mailcap',
70 '/usr/etc/mailcap', '/usr/local/etc/mailcap']
71 return mailcaps
72
73
74 # Part 2: the parser.
75 def readmailcapfile(fp):
76 """Read a mailcap file and return a dictionary keyed by MIME type."""
77 warnings.warn('readmailcapfile is deprecated, use getcaps instead',
78 DeprecationWarning, 2)
79 caps, _ = _readmailcapfile(fp, None)
80 return caps
81
82
83 def _readmailcapfile(fp, lineno):
84 """Read a mailcap file and return a dictionary keyed by MIME type.
85
86 Each MIME type is mapped to an entry consisting of a list of
87 dictionaries; the list will contain more than one such dictionary
88 if a given MIME type appears more than once in the mailcap file.
89 Each dictionary contains key-value pairs for that MIME type, where
90 the viewing command is stored with the key "view".
91 """
92 caps = {}
93 while 1:
94 line = fp.readline()
95 if not line: break
96 # Ignore comments and blank lines
97 if line[0] == '#' or line.strip() == '':
98 continue
99 nextline = line
100 # Join continuation lines
101 while nextline[-2:] == '\\\n':
102 nextline = fp.readline()
103 if not nextline: nextline = '\n'
104 line = line[:-2] + nextline
105 # Parse the line
106 key, fields = parseline(line)
107 if not (key and fields):
108 continue
109 if lineno is not None:
110 fields['lineno'] = lineno
111 lineno += 1
112 # Normalize the key
113 types = key.split('/')
114 for j in range(len(types)):
115 types[j] = types[j].strip()
116 key = '/'.join(types).lower()
117 # Update the database
118 if key in caps:
119 caps[key].append(fields)
120 else:
121 caps[key] = [fields]
122 return caps, lineno
123
124 def parseline(line):
125 """Parse one entry in a mailcap file and return a dictionary.
126
127 The viewing command is stored as the value with the key "view",
128 and the rest of the fields produce key-value pairs in the dict.
129 """
130 fields = []
131 i, n = 0, len(line)
132 while i < n:
133 field, i = parsefield(line, i, n)
134 fields.append(field)
135 i = i+1 # Skip semicolon
136 if len(fields) < 2:
137 return None, None
138 key, view, rest = fields[0], fields[1], fields[2:]
139 fields = {'view': view}
140 for field in rest:
141 i = field.find('=')
142 if i < 0:
143 fkey = field
144 fvalue = ""
145 else:
146 fkey = field[:i].strip()
147 fvalue = field[i+1:].strip()
148 if fkey in fields:
149 # Ignore it
150 pass
151 else:
152 fields[fkey] = fvalue
153 return key, fields
154
155 def parsefield(line, i, n):
156 """Separate one key-value pair in a mailcap entry."""
157 start = i
158 while i < n:
159 c = line[i]
160 if c == ';':
161 break
162 elif c == '\\':
163 i = i+2
164 else:
165 i = i+1
166 return line[start:i].strip(), i
167
168
169 # Part 3: using the database.
170
171 def findmatch(caps, MIMEtype, key='view', filename="/dev/null", plist=[]):
172 """Find a match for a mailcap entry.
173
174 Return a tuple containing the command line, and the mailcap entry
175 used; (None, None) if no match is found. This may invoke the
176 'test' command of several matching entries before deciding which
177 entry to use.
178
179 """
180 if _find_unsafe(filename):
181 msg = "Refusing to use mailcap with filename %r. Use a safe temporary filename." % (filename,)
182 warnings.warn(msg, UnsafeMailcapInput)
183 return None, None
184 entries = lookup(caps, MIMEtype, key)
185 # XXX This code should somehow check for the needsterminal flag.
186 for e in entries:
187 if 'test' in e:
188 test = subst(e['test'], filename, plist)
189 if test is None:
190 continue
191 if test and os.system(test) != 0:
192 continue
193 command = subst(e[key], MIMEtype, filename, plist)
194 if command is not None:
195 return command, e
196 return None, None
197
198 def lookup(caps, MIMEtype, key=None):
199 entries = []
200 if MIMEtype in caps:
201 entries = entries + caps[MIMEtype]
202 MIMEtypes = MIMEtype.split('/')
203 MIMEtype = MIMEtypes[0] + '/*'
204 if MIMEtype in caps:
205 entries = entries + caps[MIMEtype]
206 if key is not None:
207 entries = [e for e in entries if key in e]
208 entries = sorted(entries, key=lineno_sort_key)
209 return entries
210
211 def subst(field, MIMEtype, filename, plist=[]):
212 # XXX Actually, this is Unix-specific
213 res = ''
214 i, n = 0, len(field)
215 while i < n:
216 c = field[i]; i = i+1
217 if c != '%':
218 if c == '\\':
219 c = field[i:i+1]; i = i+1
220 res = res + c
221 else:
222 c = field[i]; i = i+1
223 if c == '%':
224 res = res + c
225 elif c == 's':
226 res = res + filename
227 elif c == 't':
228 if _find_unsafe(MIMEtype):
229 msg = "Refusing to substitute MIME type %r into a shell command." % (MIMEtype,)
230 warnings.warn(msg, UnsafeMailcapInput)
231 return None
232 res = res + MIMEtype
233 elif c == '{':
234 start = i
235 while i < n and field[i] != '}':
236 i = i+1
237 name = field[start:i]
238 i = i+1
239 param = findparam(name, plist)
240 if _find_unsafe(param):
241 msg = "Refusing to substitute parameter %r (%s) into a shell command" % (param, name)
242 warnings.warn(msg, UnsafeMailcapInput)
243 return None
244 res = res + param
245 # XXX To do:
246 # %n == number of parts if type is multipart/*
247 # %F == list of alternating type and filename for parts
248 else:
249 res = res + '%' + c
250 return res
251
252 def findparam(name, plist):
253 name = name.lower() + '='
254 n = len(name)
255 for p in plist:
256 if p[:n].lower() == name:
257 return p[n:]
258 return ''
259
260
261 # Part 4: test program.
262
263 def test():
264 import sys
265 caps = getcaps()
266 if not sys.argv[1:]:
267 show(caps)
268 return
269 for i in range(1, len(sys.argv), 2):
270 args = sys.argv[i:i+2]
271 if len(args) < 2:
272 print("usage: mailcap [MIMEtype file] ...")
273 return
274 MIMEtype = args[0]
275 file = args[1]
276 command, e = findmatch(caps, MIMEtype, 'view', file)
277 if not command:
278 print("No viewer found for", type)
279 else:
280 print("Executing:", command)
281 sts = os.system(command)
282 sts = os.waitstatus_to_exitcode(sts)
283 if sts:
284 print("Exit status:", sts)
285
286 def show(caps):
287 print("Mailcap files:")
288 for fn in listmailcapfiles(): print("\t" + fn)
289 print()
290 if not caps: caps = getcaps()
291 print("Mailcap entries:")
292 print()
293 ckeys = sorted(caps)
294 for type in ckeys:
295 print(type)
296 entries = caps[type]
297 for e in entries:
298 keys = sorted(e)
299 for k in keys:
300 print(" %-15s" % k, e[k])
301 print()
302
303 if __name__ == '__main__':
304 test()