"""Mailcap file handling. See RFC 1524."""

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import os

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import warnings

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import re

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__all__ = ["getcaps","findmatch"]

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_find_unsafe = re.compile(r'[^\xa1-\xff\w@+=:,./-]').search

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class UnsafeMailcapInput(Warning):

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"""Warning raised when refusing unsafe input"""

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# Part 1: top-level interface.

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def getcaps():

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"""Return a dictionary containing the mailcap database.

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The dictionary maps a MIME type (in all lowercase, e.g. 'text/plain')

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to a list of dictionaries corresponding to mailcap entries. The list

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collects all the entries for that MIME type from all available mailcap

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files. Each dictionary contains key-value pairs for that MIME type,

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where the viewing command is stored with the key "view".

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"""

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caps = {}

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for mailcap in listmailcapfiles():

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try:

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fp = open(mailcap, 'r')

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except IOError:

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continue

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with fp:

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morecaps = readmailcapfile(fp)

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for key, value in morecaps.iteritems():

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if not key in caps:

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caps[key] = value

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else:

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caps[key] = caps[key] + value

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return caps

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def listmailcapfiles():

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"""Return a list of all mailcap files found on the system."""

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# XXX Actually, this is Unix-specific

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if 'MAILCAPS' in os.environ:

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str = os.environ['MAILCAPS']

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mailcaps = str.split(':')

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else:

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if 'HOME' in os.environ:

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home = os.environ['HOME']

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else:

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# Don't bother with getpwuid()

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home = '.' # Last resort

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mailcaps = [home + '/.mailcap', '/etc/mailcap',

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'/usr/etc/mailcap', '/usr/local/etc/mailcap']

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return mailcaps

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# Part 2: the parser.

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def readmailcapfile(fp):

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"""Read a mailcap file and return a dictionary keyed by MIME type.

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Each MIME type is mapped to an entry consisting of a list of

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dictionaries; the list will contain more than one such dictionary

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if a given MIME type appears more than once in the mailcap file.

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Each dictionary contains key-value pairs for that MIME type, where

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the viewing command is stored with the key "view".

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"""

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caps = {}

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while 1:

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line = fp.readline()

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if not line: break

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# Ignore comments and blank lines

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if line[0] == '#' or line.strip() == '':

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continue

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nextline = line

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# Join continuation lines

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while nextline[-2:] == '\\\n':

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nextline = fp.readline()

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if not nextline: nextline = '\n'

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line = line[:-2] + nextline

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# Parse the line

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key, fields = parseline(line)

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if not (key and fields):

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continue

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# Normalize the key

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types = key.split('/')

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for j in range(len(types)):

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types[j] = types[j].strip()

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key = '/'.join(types).lower()

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# Update the database

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if key in caps:

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caps[key].append(fields)

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else:

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caps[key] = [fields]

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return caps

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def parseline(line):

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"""Parse one entry in a mailcap file and return a dictionary.

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The viewing command is stored as the value with the key "view",

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and the rest of the fields produce key-value pairs in the dict.

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"""

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fields = []

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i, n = 0, len(line)

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while i < n:

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field, i = parsefield(line, i, n)

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fields.append(field)

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i = i+1 # Skip semicolon

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if len(fields) < 2:

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return None, None

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key, view, rest = fields[0], fields[1], fields[2:]

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fields = {'view': view}

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for field in rest:

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i = field.find('=')

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if i < 0:

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fkey = field

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fvalue = ""

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else:

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fkey = field[:i].strip()

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fvalue = field[i+1:].strip()

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if fkey in fields:

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# Ignore it

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pass

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else:

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fields[fkey] = fvalue

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return key, fields

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def parsefield(line, i, n):

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"""Separate one key-value pair in a mailcap entry."""

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start = i

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while i < n:

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c = line[i]

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if c == ';':

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break

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elif c == '\\':

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i = i+2

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else:

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i = i+1

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return line[start:i].strip(), i

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# Part 3: using the database.

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def findmatch(caps, MIMEtype, key='view', filename="/dev/null", plist=[]):

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"""Find a match for a mailcap entry.

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Return a tuple containing the command line, and the mailcap entry

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used; (None, None) if no match is found. This may invoke the

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'test' command of several matching entries before deciding which

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entry to use.

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"""

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if _find_unsafe(filename):

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msg = "Refusing to use mailcap with filename %r. Use a safe temporary filename." % (filename,)

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warnings.warn(msg, UnsafeMailcapInput)

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return None, None

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entries = lookup(caps, MIMEtype, key)

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# XXX This code should somehow check for the needsterminal flag.

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for e in entries:

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if 'test' in e:

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test = subst(e['test'], filename, plist)

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if test is None:

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continue

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if test and os.system(test) != 0:

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continue

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command = subst(e[key], MIMEtype, filename, plist)

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if command is not None:

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return command, e

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return None, None

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def lookup(caps, MIMEtype, key=None):

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entries = []

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if MIMEtype in caps:

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entries = entries + caps[MIMEtype]

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MIMEtypes = MIMEtype.split('/')

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MIMEtype = MIMEtypes[0] + '/*'

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if MIMEtype in caps:

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entries = entries + caps[MIMEtype]

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if key is not None:

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entries = filter(lambda e, key=key: key in e, entries)

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return entries

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def subst(field, MIMEtype, filename, plist=[]):

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# XXX Actually, this is Unix-specific

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res = ''

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i, n = 0, len(field)

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while i < n:

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c = field[i]; i = i+1

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if c != '%':

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if c == '\\':

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c = field[i:i+1]; i = i+1

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res = res + c

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else:

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c = field[i]; i = i+1

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if c == '%':

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res = res + c

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elif c == 's':

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res = res + filename

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elif c == 't':

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if _find_unsafe(MIMEtype):

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msg = "Refusing to substitute MIME type %r into a shell command." % (MIMEtype,)

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warnings.warn(msg, UnsafeMailcapInput)

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return None

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res = res + MIMEtype

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elif c == '{':

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start = i

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while i < n and field[i] != '}':

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i = i+1

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name = field[start:i]

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i = i+1

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param = findparam(name, plist)

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if _find_unsafe(param):

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msg = "Refusing to substitute parameter %r (%s) into a shell command" % (param, name)

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warnings.warn(msg, UnsafeMailcapInput)

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return None

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res = res + param

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# XXX To do:

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# %n == number of parts if type is multipart/*

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# %F == list of alternating type and filename for parts

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else:

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res = res + '%' + c

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return res

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def findparam(name, plist):

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name = name.lower() + '='

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n = len(name)

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for p in plist:

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if p[:n].lower() == name:

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return p[n:]

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return ''

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# Part 4: test program.

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def test():

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import sys

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caps = getcaps()

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if not sys.argv[1:]:

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show(caps)

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return

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for i in range(1, len(sys.argv), 2):

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args = sys.argv[i:i+2]

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if len(args) < 2:

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print "usage: mailcap [MIMEtype file] ..."

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return

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MIMEtype = args[0]

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file = args[1]

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command, e = findmatch(caps, MIMEtype, 'view', file)

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if not command:

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print "No viewer found for", type

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else:

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print "Executing:", command

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sts = os.system(command)

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if sts:

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print "Exit status:", sts

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def show(caps):

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print "Mailcap files:"

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for fn in listmailcapfiles(): print "\t" + fn

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print

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if not caps: caps = getcaps()

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print "Mailcap entries:"

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print

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ckeys = caps.keys()

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ckeys.sort()

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for type in ckeys:

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print type

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entries = caps[type]

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for e in entries:

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keys = e.keys()

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keys.sort()

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for k in keys:

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print " %-15s" % k, e[k]

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print

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if __name__ == '__main__':

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test()

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