254 lines
7.3 KiB
Python
254 lines
7.3 KiB
Python
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"""Mailcap file handling. See RFC 1524."""
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import os
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__all__ = ["getcaps","findmatch"]
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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 OSError:
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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.items():
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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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# This is mostly a Unix thing, but we use the OS path separator anyway
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if 'MAILCAPS' in os.environ:
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pathstr = os.environ['MAILCAPS']
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mailcaps = pathstr.split(os.pathsep)
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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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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 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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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 = [e for e in entries if key in e]
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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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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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res = res + findparam(name, plist)
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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 = sorted(caps)
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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 = sorted(e)
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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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