summaryrefslogtreecommitdiffstats
path: root/Lib/mailcap.py
blob: 0c0b19c47c5a1a82238c8cbe2d3489392e0131dd (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
253
"""Mailcap file handling.  See RFC 1524."""

import os

__all__ = ["getcaps","findmatch"]

# Part 1: top-level interface.

def getcaps():
    """Return a dictionary containing the mailcap database.

    The dictionary maps a MIME type (in all lowercase, e.g. 'text/plain')
    to a list of dictionaries corresponding to mailcap entries.  The list
    collects all the entries for that MIME type from all available mailcap
    files.  Each dictionary contains key-value pairs for that MIME type,
    where the viewing command is stored with the key "view".

    """
    caps = {}
    for mailcap in listmailcapfiles():
        try:
            fp = open(mailcap, 'r')
        except IOError:
            continue
        with fp:
            morecaps = readmailcapfile(fp)
        for key, value in morecaps.items():
            if not key in caps:
                caps[key] = value
            else:
                caps[key] = caps[key] + value
    return caps

def listmailcapfiles():
    """Return a list of all mailcap files found on the system."""
    # This is mostly a Unix thing, but we use the OS path separator anyway
    if 'MAILCAPS' in os.environ:
        pathstr = os.environ['MAILCAPS']
        mailcaps = pathstr.split(os.pathsep)
    else:
        if 'HOME' in os.environ:
            home = os.environ['HOME']
        else:
            # Don't bother with getpwuid()
            home = '.' # Last resort
        mailcaps = [home + '/.mailcap', '/etc/mailcap',
                '/usr/etc/mailcap', '/usr/local/etc/mailcap']
    return mailcaps


# Part 2: the parser.

def readmailcapfile(fp):
    """Read a mailcap file and return a dictionary keyed by MIME type.

    Each MIME type is mapped to an entry consisting of a list of
    dictionaries; the list will contain more than one such dictionary
    if a given MIME type appears more than once in the mailcap file.
    Each dictionary contains key-value pairs for that MIME type, where
    the viewing command is stored with the key "view".
    """
    caps = {}
    while 1:
        line = fp.readline()
        if not line: break
        # Ignore comments and blank lines
        if line[0] == '#' or line.strip() == '':
            continue
        nextline = line
        # Join continuation lines
        while nextline[-2:] == '\\\n':
            nextline = fp.readline()
            if not nextline: nextline = '\n'
            line = line[:-2] + nextline
        # Parse the line
        key, fields = parseline(line)
        if not (key and fields):
            continue
        # Normalize the key
        types = key.split('/')
        for j in range(len(types)):
            types[j] = types[j].strip()
        key = '/'.join(types).lower()
        # Update the database
        if key in caps:
            caps[key].append(fields)
        else:
            caps[key] = [fields]
    return caps

def parseline(line):
    """Parse one entry in a mailcap file and return a dictionary.

    The viewing command is stored as the value with the key "view",
    and the rest of the fields produce key-value pairs in the dict.
    """
    fields = []
    i, n = 0, len(line)
    while i < n:
        field, i = parsefield(line, i, n)
        fields.append(field)
        i = i+1 # Skip semicolon
    if len(fields) < 2:
        return None, None
    key, view, rest = fields[0], fields[1], fields[2:]
    fields = {'view': view}
    for field in rest:
        i = field.find('=')
        if i < 0:
            fkey = field
            fvalue = ""
        else:
            fkey = field[:i].strip()
            fvalue = field[i+1:].strip()
        if fkey in fields:
            # Ignore it
            pass
        else:
            fields[fkey] = fvalue
    return key, fields

def parsefield(line, i, n):
    """Separate one key-value pair in a mailcap entry."""
    start = i
    while i < n:
        c = line[i]
        if c == ';':
            break
        elif c == '\\':
            i = i+2
        else:
            i = i+1
    return line[start:i].strip(), i


# Part 3: using the database.

def findmatch(caps, MIMEtype, key='view', filename="/dev/null", plist=[]):
    """Find a match for a mailcap entry.

    Return a tuple containing the command line, and the mailcap entry
    used; (None, None) if no match is found.  This may invoke the
    'test' command of several matching entries before deciding which
    entry to use.

    """
    entries = lookup(caps, MIMEtype, key)
    # XXX This code should somehow check for the needsterminal flag.
    for e in entries:
        if 'test' in e:
            test = subst(e['test'], filename, plist)
            if test and os.system(test) != 0:
                continue
        command = subst(e[key], MIMEtype, filename, plist)
        return command, e
    return None, None

def lookup(caps, MIMEtype, key=None):
    entries = []
    if MIMEtype in caps:
        entries = entries + caps[MIMEtype]
    MIMEtypes = MIMEtype.split('/')
    MIMEtype = MIMEtypes[0] + '/*'
    if MIMEtype in caps:
        entries = entries + caps[MIMEtype]
    if key is not None:
        entries = [e for e in entries if key in e]
    return entries

def subst(field, MIMEtype, filename, plist=[]):
    # XXX Actually, this is Unix-specific
    res = ''
    i, n = 0, len(field)
    while i < n:
        c = field[i]; i = i+1
        if c != '%':
            if c == '\\':
                c = field[i:i+1]; i = i+1
            res = res + c
        else:
            c = field[i]; i = i+1
            if c == '%':
                res = res + c
            elif c == 's':
                res = res + filename
            elif c == 't':
                res = res + MIMEtype
            elif c == '{':
                start = i
                while i < n and field[i] != '}':
                    i = i+1
                name = field[start:i]
                i = i+1
                res = res + findparam(name, plist)
            # XXX To do:
            # %n == number of parts if type is multipart/*
            # %F == list of alternating type and filename for parts
            else:
                res = res + '%' + c
    return res

def findparam(name, plist):
    name = name.lower() + '='
    n = len(name)
    for p in plist:
        if p[:n].lower() == name:
            return p[n:]
    return ''


# Part 4: test program.

def test():
    import sys
    caps = getcaps()
    if not sys.argv[1:]:
        show(caps)
        return
    for i in range(1, len(sys.argv), 2):
        args = sys.argv[i:i+2]
        if len(args) < 2:
            print("usage: mailcap [MIMEtype file] ...")
            return
        MIMEtype = args[0]
        file = args[1]
        command, e = findmatch(caps, MIMEtype, 'view', file)
        if not command:
            print("No viewer found for", type)
        else:
            print("Executing:", command)
            sts = os.system(command)
            if sts:
                print("Exit status:", sts)

def show(caps):
    print("Mailcap files:")
    for fn in listmailcapfiles(): print("\t" + fn)
    print()
    if not caps: caps = getcaps()
    print("Mailcap entries:")
    print()
    ckeys = sorted(caps)
    for type in ckeys:
        print(type)
        entries = caps[type]
        for e in entries:
            keys = sorted(e)
            for k in keys:
                print("  %-15s" % k, e[k])
            print()

if __name__ == '__main__':
    test()