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# Copyright (c) 2010, 2011, 2012 Nicira Networks
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at:
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import os
import os.path
import sys
PROGRAM_NAME = os.path.basename(sys.argv[0])
EOF = -1
def abs_file_name(dir_, file_name):
"""If 'file_name' starts with '/', returns a copy of 'file_name'.
Otherwise, returns an absolute path to 'file_name' considering it relative
to 'dir_', which itself must be absolute. 'dir_' may be None or the empty
string, in which case the current working directory is used.
Returns None if 'dir_' is None and getcwd() fails.
This differs from os.path.abspath() in that it will never change the
meaning of a file name."""
if file_name.startswith('/'):
return file_name
else:
if dir_ is None or dir_ == "":
try:
dir_ = os.getcwd()
except OSError:
return None
if dir_.endswith('/'):
return dir_ + file_name
else:
return "%s/%s" % (dir_, file_name)
def ovs_retval_to_string(retval):
"""Many OVS functions return an int which is one of:
- 0: no error yet
- >0: errno value
- EOF: end of file (not necessarily an error; depends on the function
called)
Returns the appropriate human-readable string."""
if not retval:
return ""
if retval > 0:
return os.strerror(retval)
if retval == EOF:
return "End of file"
return "***unknown return value: %s***" % retval
def ovs_error(err_no, message, vlog=None):
"""Prints 'message' on stderr and emits an ERROR level log message to
'vlog' if supplied. If 'err_no' is nonzero, then it is formatted with
ovs_retval_to_string() and appended to the message inside parentheses.
'message' should not end with a new-line, because this function will add
one itself."""
err_msg = "%s: %s" % (PROGRAM_NAME, message)
if err_no:
err_msg += " (%s)" % ovs_retval_to_string(err_no)
sys.stderr.write("%s\n" % err_msg)
if vlog:
vlog.err(err_msg)
def ovs_fatal(*args, **kwargs):
"""Prints 'message' on stderr and emits an ERROR level log message to
'vlog' if supplied. If 'err_no' is nonzero, then it is formatted with
ovs_retval_to_string() and appended to the message inside parentheses.
Then, terminates with exit code 1 (indicating a failure).
'message' should not end with a new-line, because this function will add
one itself."""
ovs_error(*args, **kwargs)
sys.exit(1)
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