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"""Conversions to/from quoted-printable transport encoding as per RFC 1521."""

# (Dec 1991 version).

__all__ = ["encode", "decode", "encodestring", "decodestring"]

ESCAPE = b'='

MAXLINESIZE = 76

HEX = b'0123456789ABCDEF'

EMPTYSTRING = b''

try:

from binascii import a2b_qp, b2a_qp

except ImportError:

a2b_qp = None

b2a_qp = None

def needsquoting(c, quotetabs, header):

"""Decide whether a particular byte ordinal needs to be quoted.

The 'quotetabs' flag indicates whether embedded tabs and spaces should be

quoted. Note that line-ending tabs and spaces are always encoded, as per

RFC 1521.

"""

assert isinstance(c, bytes)

if c in b' \t':

return quotetabs

# if header, we have to escape _ because _ is used to escape space

if c == b'_':

return header

return c == ESCAPE or not (b' ' <= c <= b'~')

def quote(c):

"""Quote a single character."""

assert isinstance(c, bytes) and len(c)==1

c = ord(c)

return ESCAPE + bytes((HEX[c//16], HEX[c%16]))

def encode(input, output, quotetabs, header=False):

"""Read 'input', apply quoted-printable encoding, and write to 'output'.

'input' and 'output' are binary file objects. The 'quotetabs' flag

indicates whether embedded tabs and spaces should be quoted. Note that

line-ending tabs and spaces are always encoded, as per RFC 1521.

The 'header' flag indicates whether we are encoding spaces as _ as per RFC

1522."""

if b2a_qp is not None:

data = input.read()

odata = b2a_qp(data, quotetabs=quotetabs, header=header)

output.write(odata)

return

def write(s, output=output, lineEnd=b'\n'):

# RFC 1521 requires that the line ending in a space or tab must have

# that trailing character encoded.

if s and s[-1:] in b' \t':

output.write(s[:-1] + quote(s[-1:]) + lineEnd)

elif s == b'.':

output.write(quote(s) + lineEnd)

else:

output.write(s + lineEnd)

prevline = None

while line := input.readline():

outline = []

# Strip off any readline induced trailing newline

stripped = b''

if line[-1:] == b'\n':

line = line[:-1]

stripped = b'\n'

# Calculate the un-length-limited encoded line

for c in line:

c = bytes((c,))

if needsquoting(c, quotetabs, header):

c = quote(c)

if header and c == b' ':

outline.append(b'_')

else:

outline.append(c)

# First, write out the previous line

if prevline is not None:

write(prevline)

# Now see if we need any soft line breaks because of RFC-imposed

# length limitations. Then do the thisline->prevline dance.

thisline = EMPTYSTRING.join(outline)

while len(thisline) > MAXLINESIZE:

# Don't forget to include the soft line break `=' sign in the

# length calculation!

write(thisline[:MAXLINESIZE-1], lineEnd=b'=\n')

thisline = thisline[MAXLINESIZE-1:]

# Write out the current line

prevline = thisline

# Write out the last line, without a trailing newline

if prevline is not None:

write(prevline, lineEnd=stripped)

def encodestring(s, quotetabs=False, header=False):

if b2a_qp is not None:

return b2a_qp(s, quotetabs=quotetabs, header=header)

from io import BytesIO

infp = BytesIO(s)

outfp = BytesIO()

encode(infp, outfp, quotetabs, header)

return outfp.getvalue()

def decode(input, output, header=False):

"""Read 'input', apply quoted-printable decoding, and write to 'output'.

'input' and 'output' are binary file objects.

If 'header' is true, decode underscore as space (per RFC 1522)."""

if a2b_qp is not None:

data = input.read()

odata = a2b_qp(data, header=header)

output.write(odata)

return

new = b''

while line := input.readline():

i, n = 0, len(line)

if n > 0 and line[n-1:n] == b'\n':

partial = 0; n = n-1

# Strip trailing whitespace

while n > 0 and line[n-1:n] in b" \t\r":

n = n-1

else:

partial = 1

while i < n:

c = line[i:i+1]

if c == b'_' and header:

new = new + b' '; i = i+1

elif c != ESCAPE:

new = new + c; i = i+1

elif i+1 == n and not partial:

partial = 1; break

elif i+1 < n and line[i+1:i+2] == ESCAPE:

new = new + ESCAPE; i = i+2

elif i+2 < n and ishex(line[i+1:i+2]) and ishex(line[i+2:i+3]):

new = new + bytes((unhex(line[i+1:i+3]),)); i = i+3

else: # Bad escape sequence -- leave it in

new = new + c; i = i+1

if not partial:

output.write(new + b'\n')

new = b''

if new:

output.write(new)

def decodestring(s, header=False):

if a2b_qp is not None:

return a2b_qp(s, header=header)

from io import BytesIO

infp = BytesIO(s)

outfp = BytesIO()

decode(infp, outfp, header=header)

return outfp.getvalue()

# Other helper functions

def ishex(c):

"""Return true if the byte ordinal 'c' is a hexadecimal digit in ASCII."""

assert isinstance(c, bytes)

return b'0' <= c <= b'9' or b'a' <= c <= b'f' or b'A' <= c <= b'F'

def unhex(s):

"""Get the integer value of a hexadecimal number."""

bits = 0

for c in s:

c = bytes((c,))

if b'0' <= c <= b'9':

i = ord('0')

elif b'a' <= c <= b'f':

i = ord('a')-10

elif b'A' <= c <= b'F':

i = ord(b'A')-10

else:

assert False, "non-hex digit "+repr(c)

bits = bits*16 + (ord(c) - i)

return bits

def main():

import sys

import getopt

try:

opts, args = getopt.getopt(sys.argv[1:], 'td')

except getopt.error as msg:

sys.stdout = sys.stderr

print(msg)

print("usage: quopri [-t | -d] [file] ...")

print("-t: quote tabs")

print("-d: decode; default encode")

sys.exit(2)

deco = False

tabs = False

for o, a in opts:

if o == '-t': tabs = True

if o == '-d': deco = True

if tabs and deco:

sys.stdout = sys.stderr

print("-t and -d are mutually exclusive")

sys.exit(2)

if not args: args = ['-']

sts = 0

for file in args:

if file == '-':

fp = sys.stdin.buffer

else:

try:

fp = open(file, "rb")

except OSError as msg:

sys.stderr.write("%s: can't open (%s)\n" % (file, msg))

sts = 1

continue

try:

if deco:

decode(fp, sys.stdout.buffer)

else:

encode(fp, sys.stdout.buffer, tabs)

finally:

if file != '-':

fp.close()

if sts:

sys.exit(sts)

if __name__ == '__main__':

main()

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