From d51cf543bb74755ed5dd17ed02859912ec557ef4 Mon Sep 17 00:00:00 2001
From: Maximilian Hils <git@maximilianhils.com>
Date: Tue, 5 Jul 2016 15:11:32 -0700
Subject: remove clean_bin, clarify unicode handling

---
 netlib/strutils.py | 80 +++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 52 insertions(+), 28 deletions(-)

(limited to 'netlib/strutils.py')

diff --git a/netlib/strutils.py b/netlib/strutils.py
index 414b2e57..4beb6ffd 100644
--- a/netlib/strutils.py
+++ b/netlib/strutils.py
@@ -1,4 +1,4 @@
-import unicodedata
+import re
 import codecs
 
 import six
@@ -28,51 +28,71 @@ def native(s, *encoding_opts):
     return s
 
 
-def clean_bin(s, keep_spacing=True):
-    # type: (Union[bytes, six.text_type], bool) -> six.text_type
+# Translate control characters to "safe" characters. This implementation initially
+# replaced them with the matching control pictures (http://unicode.org/charts/PDF/U2400.pdf),
+# but that turned out to render badly with monospace fonts. We are back to "." therefore.
+_control_char_trans = {
+    x: ord(".")  # x + 0x2400 for unicode control group pictures
+    for x in range(32)
+}
+_control_char_trans[127] = ord(".")  # 0x2421
+_control_char_trans_newline = _control_char_trans.copy()
+for x in ("\r", "\n", "\t"):
+    del _control_char_trans_newline[ord(x)]
+
+
+if six.PY2:
+    pass
+else:
+    _control_char_trans = str.maketrans(_control_char_trans)
+    _control_char_trans_newline = str.maketrans(_control_char_trans_newline)
+
+
+def escape_control_characters(text, keep_spacing=True):
     """
-        Cleans binary data to make it safe to display.
+    Replace all unicode C1 control characters from the given text with their respective control pictures.
+    For example, a null byte is replaced with the unicode character "\u2400".
 
-        Args:
-            keep_spacing: If False, tabs and newlines will also be replaced.
+    Args:
+        keep_spacing: If True, tabs and newlines will not be replaced.
     """
-    if isinstance(s, six.text_type):
-        if keep_spacing:
-            keep = u" \n\r\t"
-        else:
-            keep = u" "
+    # type: (six.text_type) -> six.text_type
+    if not isinstance(text, six.text_type):
+        raise ValueError("text type must be unicode but is {}".format(type(text).__name__))
+
+    trans = _control_char_trans_newline if keep_spacing else _control_char_trans
+    if six.PY2:
         return u"".join(
-            ch if (unicodedata.category(ch)[0] not in "CZ" or ch in keep) else u"."
-            for ch in s
-        )
-    else:
-        if keep_spacing:
-            keep = (9, 10, 13)  # \t, \n, \r,
-        else:
-            keep = ()
-        return "".join(
-            chr(ch) if (31 < ch < 127 or ch in keep) else "."
-            for ch in six.iterbytes(s)
+            six.unichr(trans.get(ord(ch), ord(ch)))
+            for ch in text
         )
+    return text.translate(trans)
 
 
-def bytes_to_escaped_str(data):
+def bytes_to_escaped_str(data, keep_spacing=False):
     """
     Take bytes and return a safe string that can be displayed to the user.
 
     Single quotes are always escaped, double quotes are never escaped:
         "'" + bytes_to_escaped_str(...) + "'"
     gives a valid Python string.
+
+    Args:
+        keep_spacing: If True, tabs and newlines will not be escaped.
     """
-    # TODO: We may want to support multi-byte characters without escaping them.
-    # One way to do would be calling .decode("utf8", "backslashreplace") first
-    # and then escaping UTF8 control chars (see clean_bin).
 
     if not isinstance(data, bytes):
         raise ValueError("data must be bytes, but is {}".format(data.__class__.__name__))
     # We always insert a double-quote here so that we get a single-quoted string back
     # https://stackoverflow.com/questions/29019340/why-does-python-use-different-quotes-for-representing-strings-depending-on-their
-    return repr(b'"' + data).lstrip("b")[2:-1]
+    ret = repr(b'"' + data).lstrip("b")[2:-1]
+    if keep_spacing:
+        ret = re.sub(
+            r"(?<!\\)(\\\\)*\\([nrt])",
+            lambda m: (m.group(1) or "") + dict(n="\n", r="\r", t="\t")[m.group(2)],
+            ret
+        )
+    return ret
 
 
 def escaped_str_to_bytes(data):
@@ -136,4 +156,8 @@ def hexdump(s):
         part = s[i:i + 16]
         x = " ".join("{:0=2x}".format(i) for i in six.iterbytes(part))
         x = x.ljust(47)  # 16*2 + 15
-        yield (offset, x, clean_bin(part, False))
+        part_repr = escape_control_characters(
+            part.decode("ascii", "replace").replace(u"\ufffd", u"."),
+            False
+        )
+        yield (offset, x, part_repr)
-- 
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