"""Mailcap file handling. See RFC 1524."""
import os
import warnings
import re
__all__ = ["getcaps","findmatch"]
def lineno_sort_key(entry):
# Sort in ascending order, with unspecified entries at the end
if 'lineno' in entry:
return 0, entry['lineno']
else:
return 1, 0
_find_unsafe = re.compile(r'[^\xa1-\U0010FFFF\w@+=:,./-]').search
class UnsafeMailcapInput(Warning):
"""Warning raised when refusing unsafe input"""
# 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 = {}
lineno = 0
for mailcap in listmailcapfiles():
try:
fp = open(mailcap, 'r')
except OSError:
continue
with fp:
morecaps, lineno = _readmailcapfile(fp, lineno)
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."""
warnings.warn('readmailcapfile is deprecated, use getcaps instead',
DeprecationWarning, 2)
caps, _ = _readmailcapfile(fp, None)
return caps
def _readmailcapfile(fp, lineno):
"""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
if lineno is not None:
fields['lineno'] = lineno
lineno += 1
# 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, lineno
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.
"""
if _find_unsafe(filename):
msg = "Refusing to use mailcap with filename %r. Use a safe temporary filename." % (filename,)
warnings.warn(msg, UnsafeMailcapInput)
return None, None
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 is None:
continue
if test and os.system(test) != 0:
continue
command = subst(e[key], MIMEtype, filename, plist)
if command is not None:
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]
entries = sorted(entries, key=lineno_sort_key)
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':
if _find_unsafe(MIMEtype):
msg = "Refusing to substitute MIME type %r into a shell command." % (MIMEtype,)
warnings.warn(msg, UnsafeMailcapInput)
return None
res = res + MIMEtype
elif c == '{':
start = i
while i < n and field[i] != '}':
i = i+1
name = field[start:i]
i = i+1
param = findparam(name, plist)
if _find_unsafe(param):
msg = "Refusing to substitute parameter %r (%s) into a shell command" % (param, name)
warnings.warn(msg, UnsafeMailcapInput)
return None
res = res + param
# 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()