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# Pretty printer for errno.
# Copyright (C) 2016-2017 Free Software Foundation, Inc.
# This file is part of the GNU C Library.
#
# The GNU C Library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# The GNU C Library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with the GNU C Library; if not, see
# <http://www.gnu.org/licenses/>.
"""This file contains the gdb pretty printers for the following types:
* __error_t (the type of 'errno')
* error_t (cast any 'int' to 'error_t' to print it like an errno value)
You can check which printers are registered and enabled by issuing the
'info pretty-printer' gdb command. Printers should trigger automatically when
trying to print a variable of one of the types mentioned above.
"""
import gdb
import gdb.printing
import errno_constants
def make_errno_reverse_mapping():
"""Construct a reverse mapping from errno values to symbolic names.
The result is a dictionary indexed by integers, not a list,
because errno values are not necessarily contiguous.
"""
# Certain errno symbols are allowed to have the same numeric value.
# If they do, one of them (whichever one is in POSIX, or if both or
# neither are, the shortest) is selected as the preferred name.
# This map goes from non-preferred name(s) to preferred name.
permitted_collisions = {
"EDEADLOCK": "EDEADLK",
"EOPNOTSUPP": "ENOTSUP",
"EWOULDBLOCK": "EAGAIN",
}
errno_names = { 0: "Success" }
for name in dir(errno_constants):
if name[0] == 'E':
number = getattr(errno_constants, name)
other = errno_names.get(number)
if other is None:
errno_names[number] = name
else:
p1 = permitted_collisions.get(name)
p2 = permitted_collisions.get(other)
if p1 is not None and p1 == other:
pass # the value in errno_names is already what we want
elif p2 is not None and p2 == name:
errno_names[number] = name
else:
raise RuntimeError(
"errno value collision: {} = {}, {}"
.format(number, name, errno_names[number]))
return errno_names
errno_names = make_errno_reverse_mapping()
class ErrnoPrinter(object):
"""Pretty printer for errno values."""
def __init__(self, val):
self._val = int(val)
def to_string(self):
"""gdb API function.
This is called from gdb when we try to print an error_t.
"""
if self._val in errno_names:
return "{:d} ({})".format(self._val, errno_names[self._val])
else:
return "{:d}".format(self._val)
def register(objfile):
"""Register pretty printers for the current objfile."""
printer = gdb.printing.RegexpCollectionPrettyPrinter("glibc-errno")
printer.add_printer('error_t', r'^(?:__)?error_t', ErrnoPrinter)
if objfile == None:
objfile = gdb
gdb.printing.register_pretty_printer(objfile, printer)
register(gdb.current_objfile())
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