Python code coverage for Lib/plat-os2emx/_emx_link.py

#	count	content
1	n/a	# _emx_link.py
2	n/a
3	n/a	# Written by Andrew I MacIntyre, December 2002.
4	n/a
5	n/a	"""_emx_link.py is a simplistic emulation of the Unix link(2) library routine
6	n/a	for creating so-called hard links. It is intended to be imported into
7	n/a	the os module in place of the unimplemented (on OS/2) Posix link()
8	n/a	function (os.link()).
9	n/a
10	n/a	We do this on OS/2 by implementing a file copy, with link(2) semantics:-
11	n/a	- the target cannot already exist;
12	n/a	- we hope that the actual file open (if successful) is actually
13	n/a	atomic...
14	n/a
15	n/a	Limitations of this approach/implementation include:-
16	n/a	- no support for correct link counts (EMX stat(target).st_nlink
17	n/a	is always 1);
18	n/a	- thread safety undefined;
19	n/a	- default file permissions (r+w) used, can't be over-ridden;
20	n/a	- implemented in Python so comparatively slow, especially for large
21	n/a	source files;
22	n/a	- need sufficient free disk space to store the copy.
23	n/a
24	n/a	Behaviour:-
25	n/a	- any exception should propagate to the caller;
26	n/a	- want target to be an exact copy of the source, so use binary mode;
27	n/a	- returns None, same as os.link() which is implemented in posixmodule.c;
28	n/a	- target removed in the event of a failure where possible;
29	n/a	- given the motivation to write this emulation came from trying to
30	n/a	support a Unix resource lock implementation, where minimal overhead
31	n/a	during creation of the target is desirable and the files are small,
32	n/a	we read a source block before attempting to create the target so that
33	n/a	we're ready to immediately write some data into it.
34	n/a	"""
35	n/a
36	n/a	import os
37	n/a	import errno
38	n/a
39	n/a	__all__ = ['link']
40	n/a
41	n/a	def link(source, target):
42	n/a	"""link(source, target) -> None
43	n/a
44	n/a	Attempt to hard link the source file to the target file name.
45	n/a	On OS/2, this creates a complete copy of the source file.
46	n/a	"""
47	n/a
48	n/a	s = os.open(source, os.O_RDONLY \| os.O_BINARY)
49	n/a	if os.isatty(s):
50	n/a	raise OSError(errno.EXDEV, 'Cross-device link')
51	n/a	data = os.read(s, 1024)
52	n/a
53	n/a	try:
54	n/a	t = os.open(target, os.O_WRONLY \| os.O_BINARY \| os.O_CREAT \| os.O_EXCL)
55	n/a	except OSError:
56	n/a	os.close(s)
57	n/a	raise
58	n/a
59	n/a	try:
60	n/a	while data:
61	n/a	os.write(t, data)
62	n/a	data = os.read(s, 1024)
63	n/a	except OSError:
64	n/a	os.close(s)
65	n/a	os.close(t)
66	n/a	os.unlink(target)
67	n/a	raise
68	n/a
69	n/a	os.close(s)
70	n/a	os.close(t)
71	n/a
72	n/a	if __name__ == '__main__':
73	n/a	import sys
74	n/a	try:
75	n/a	link(sys.argv[1], sys.argv[2])
76	n/a	except IndexError:
77	n/a	print('Usage: emx_link <source> <target>')
78	n/a	except OSError:
79	n/a	print('emx_link: %s' % str(sys.exc_info()[1]))