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- """
- vis.py
- ======
- Ctypes based module to access libbsd's strvis & strunvis functions.
- The `vis` function is the equivalent of strvis.
- The `unvis` function is the equivalent of strunvis.
- All functions accept unicode string as input and return a unicode string.
- Constants:
- ----------
- * to select alternate encoding format
- `VIS_OCTAL`: use octal \ddd format
- `VIS_CSTYLE`: use \[nrft0..] where appropiate
- * to alter set of characters encoded
- (default is to encode all non-graphic except space, tab, and newline).
- `VIS_SP`: also encode space
- `VIS_TAB`: also encode tab
- `VIS_NL`: also encode newline
- `VIS_WHITE`: same as (VIS_SP | VIS_TAB | VIS_NL)
- `VIS_SAFE`: only encode "unsafe" characters
- * other
- `VIS_NOSLASH`: inhibit printing '\'
- `VIS_HTTP1808`: http-style escape % hex hex
- `VIS_HTTPSTYLE`: http-style escape % hex hex
- `VIS_MIMESTYLE`: mime-style escape = HEX HEX
- `VIS_HTTP1866`: http-style &#num; or &string;
- `VIS_NOESCAPE`: don't decode `\'
- `VIS_GLOB`: encode glob(3) magic characters
- :Authors:
- - ju1ius (http://github.com/ju1ius)
- :Version: 1
- :Date: 2014-01-05
- """
- from ctypes import CDLL, c_char_p, c_int
- from ctypes.util import find_library
- __all__ = [
- 'vis', 'unvis',
- 'VIS_OCTAL', 'VIS_CSTYLE',
- 'VIS_SP', 'VIS_TAB', 'VIS_NL', 'VIS_WHITE', 'VIS_SAFE',
- 'VIS_NOSLASH', 'VIS_HTTP1808', 'VIS_HTTPSTYLE', 'VIS_MIMESTYLE',
- 'VIS_HTTP1866', 'VIS_NOESCAPE', 'VIS_GLOB'
- ]
- #############################################################
- # Constants from bsd/vis.h
- #############################################################
- #to select alternate encoding format
- VIS_OCTAL = 0x0001
- VIS_CSTYLE = 0x0002
- # to alter set of characters encoded
- # (default is to encode all non-graphic except space, tab, and newline).
- VIS_SP = 0x0004
- VIS_TAB = 0x0008
- VIS_NL = 0x0010
- VIS_WHITE = VIS_SP | VIS_TAB | VIS_NL
- VIS_SAFE = 0x0020
- # other
- VIS_NOSLASH = 0x0040
- VIS_HTTP1808 = 0x0080
- VIS_HTTPSTYLE = 0x0080
- VIS_MIMESTYLE = 0x0100
- VIS_HTTP1866 = 0x0200
- VIS_NOESCAPE = 0x0400
- VIS_GLOB = 0x1000
- #############################################################
- # Import libbsd/vis functions
- #############################################################
- _libbsd = CDLL(find_library('bsd'))
- _strvis = _libbsd.strvis
- _strvis.argtypes = [c_char_p, c_char_p, c_int]
- _strvis.restype = c_int
- _strunvis = _libbsd.strunvis
- _strvis.argtypes = [c_char_p, c_char_p]
- _strvis.restype = c_int
- def vis(src, flags=VIS_WHITE):
- """
- Encodes the string `src` into libbsd's vis encoding.
- `flags` must be one of the VIS_* constants
- C definition:
- int strvis(char *dst, char *src, int flags);
- """
- src = bytes(src, 'utf-8')
- dst_p = c_char_p(bytes(len(src) * 4))
- src_p = c_char_p(src)
- flags = c_int(flags)
- bytes_written = _strvis(dst_p, src_p, flags)
- if -1 == bytes_written:
- raise RuntimeError('vis failed to encode string "{}"'.format(src))
- return dst_p.value.decode('utf-8')
- def unvis(src):
- """
- Decodes a string encoded by vis.
- C definition:
- int strunvis(char *dst, char *src);
- """
- src = bytes(src, 'utf-8')
- dst_p = c_char_p(bytes(len(src)))
- src_p = c_char_p(src)
- bytes_written = _strunvis(dst_p, src_p)
- if -1 == bytes_written:
- raise RuntimeError('unvis failed to decode string "{}"'.format(src))
- return dst_p.value.decode('utf-8')
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