blob: 498fe150ab46baf42428fae2ee02ac75f35689af (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
|
"""
A simple context manager for redirecting streams in Python.
The streams are redirected at the the C runtime level so that the output of C extensions
that use stdio will also be redirected.
null_file : a stream representing the null device (e.g. /dev/null on Unix)
redirect: a context manager for redirecting streams
Author: Baruch Sterin (sterin@berkeley.edu)
"""
import os
import sys
from contextlib import contextmanager
null_file = open( os.devnull, "w" )
@contextmanager
def _dup( f ):
fd = os.dup( f.fileno() )
yield fd
os.close(fd)
@contextmanager
def redirect(dst = null_file, src = sys.stdout):
"""
Redirect the src stream into dst.
Example:
with redirect( open("somefile.txt", sys.stdout ) ):
do some stuff ...
"""
if src.fileno() == dst.fileno():
yield
return
with _dup( src ) as fd_dup_src:
dst.flush()
src.flush()
os.close( src.fileno() )
os.dup2( dst.fileno(), src.fileno() )
yield
src.flush()
os.close( src.fileno() )
os.dup2( fd_dup_src, src.fileno() )
def start_redirect(dst = null_file, src = sys.stdout):
"""
Start redirection of src stream into dst. Return the duplicated file handle of the source.
Example:
fd = start_redirect( open("somefile.txt"), sys.stdout )
... do some stuff ...
end_redirect(sys.stdout, fd)
"""
if src.fileno() == dst.fileno():
return None
fd_dup_src = os.dup( src.fileno() )
dst.flush()
src.flush()
os.close( src.fileno() )
os.dup2( dst.fileno(), src.fileno() )
return fd_dup_src
def end_redirect(src, fd_dup_src):
"""
End redirection of stream src.Redirect the src stream into dst. src is the source stream and fd_dup_src is the value returned by
start_redirect()
"""
if fd_dup_src is None:
return
src.flush()
os.close( src.fileno() )
os.dup2( fd_dup_src, src.fileno() )
os.close(fd_dup_src)
|
