cpython/Lib/mailcap.py

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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.
def getcaps():
"""Return a dictionary containing the mailcap database.
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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".
"""
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caps = {}
for mailcap in listmailcapfiles():
try:
fp = open(mailcap, 'r')
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except OSError:
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
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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)
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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']
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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".
"""
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caps = {}
while 1:
line = fp.readline()
if not line: break
# Ignore comments and blank lines
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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
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types = key.split('/')
for j in range(len(types)):
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types[j] = types[j].strip()
key = '/'.join(types).lower()
# Update the database
if key in caps:
caps[key].append(fields)
else:
caps[key] = [fields]
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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.
"""
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fields = []
i, n = 0, len(line)
while i < n:
field, i = parsefield(line, i, n)
fields.append(field)
i = i+1 # Skip semicolon
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if len(fields) < 2:
return None, None
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key, view, rest = fields[0], fields[1], fields[2:]
fields = {'view': view}
for field in rest:
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i = field.find('=')
if i < 0:
fkey = field
fvalue = ""
else:
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fkey = field[:i].strip()
fvalue = field[i+1:].strip()
if fkey in fields:
# Ignore it
pass
else:
fields[fkey] = fvalue
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return key, fields
def parsefield(line, i, n):
"""Separate one key-value pair in a mailcap entry."""
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start = i
while i < n:
c = line[i]
if c == ';':
break
elif c == '\\':
i = i+2
else:
i = i+1
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return line[start:i].strip(), i
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# Part 3: using the database.
def findmatch(caps, MIMEtype, key='view', filename="/dev/null", plist=[]):
"""Find a match for a mailcap entry.
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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)
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# XXX This code should somehow check for the needsterminal flag.
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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
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return None, None
def lookup(caps, MIMEtype, key=None):
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entries = []
if MIMEtype in caps:
entries = entries + caps[MIMEtype]
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MIMEtypes = MIMEtype.split('/')
MIMEtype = MIMEtypes[0] + '/*'
if MIMEtype in caps:
entries = entries + caps[MIMEtype]
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if key is not None:
entries = [e for e in entries if key in e]
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return entries
def subst(field, MIMEtype, filename, plist=[]):
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# 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
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return res
def findparam(name, plist):
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name = name.lower() + '='
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n = len(name)
for p in plist:
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if p[:n].lower() == name:
return p[n:]
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return ''
# Part 4: test program.
def test():
import sys
caps = getcaps()
if not sys.argv[1:]:
show(caps)
return
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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)
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def show(caps):
print("Mailcap files:")
for fn in listmailcapfiles(): print("\t" + fn)
print()
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if not caps: caps = getcaps()
print("Mailcap entries:")
print()
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ckeys = sorted(caps)
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for type in ckeys:
print(type)
entries = caps[type]
for e in entries:
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keys = sorted(e)
for k in keys:
print(" %-15s" % k, e[k])
print()
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if __name__ == '__main__':
test()