-# Copyright (c) 2010 Nicira Networks
+# Copyright (c) 2010, 2011, 2012 Nicira, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# limitations under the License.
import os
+import os.path
import sys
-_argv0 = sys.argv[0]
-PROGRAM_NAME = _argv0[_argv0.rfind('/') + 1:]
+PROGRAM_NAME = os.path.basename(sys.argv[0])
+EOF = -1
-def abs_file_name(dir, file_name):
+
+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
+ 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 null and getcwd() fails.
+ 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 == "":
+ if dir_ is None or dir_ == "":
try:
- dir = os.getcwd()
+ dir_ = os.getcwd()
except OSError:
return None
- if dir.endswith('/'):
- return dir + file_name
+ if dir_.endswith('/'):
+ return dir_ + file_name
else:
- return "%s/%s" % (dir, file_name)
+ 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)