procutil: make stream detection in make_line_buffered more correct and strict
In make_line_buffered(), we don’t want to wrap the stream if we know that lines
get flushed to the underlying raw stream already.
Previously, the heuristic was too optimistic. It assumed that any stream which
is not an instance of io.BufferedIOBase doesn’t need wrapping. However, there
are buffered streams that aren’t instances of io.BufferedIOBase, like
Mercurial’s own winstdout.
The new logic is different in two ways:
First, only for the check, if unwraps any combination of WriteAllWrapper and
winstdout.
Second, it skips wrapping the stream only if it is an instance of io.RawIOBase
(or already wrapped). If it is an instance of io.BufferedIOBase, it gets
wrapped. In any other case, the function raises an exception. This ensures
that, if an unknown stream is passed or we add another wrapper in the future,
we don’t wrap the stream if it’s already line buffered or not wrap the stream
if it’s not line buffered. In fact, this was already helpful during development
of this change. Without it, I possibly would have forgot that WriteAllWrapper
needs to be ignored for the check, leading to unnecessary wrapping if stdout is
unbuffered.
The alternative would have been to always wrap unknown streams. However, I
don’t think that anyone would benefit from being less strict. We can expect
streams from the standard library to be subclassing either io.RawIOBase or
io.BufferedIOBase, so running Mercurial in the standard way should not regress
by this change. Py2exe might replace sys.stdout and sys.stderr, but that
currently breaks Mercurial anyway and also these streams don’t claim to be
interactive, so this function is not called for them.
Tests of the file helper tool
$ f -h
?sage: f [options] [filenames] (glob)
?ptions: (glob)
-h, --help show this help message and exit
-t, --type show file type (file or directory)
-m, --mode show file mode
-l, --links show number of links
-s, --size show size of file
-n NEWER, --newer=NEWER
check if file is newer (or same)
-r, --recurse recurse into directories
-S, --sha1 show sha1 hash of the content
--sha256 show sha256 hash of the content
-M, --md5 show md5 hash of the content
-D, --dump dump file content
-H, --hexdump hexdump file content
-B BYTES, --bytes=BYTES
number of characters to dump
-L LINES, --lines=LINES
number of lines to dump
-q, --quiet no default output
$ mkdir dir
$ cd dir
$ f --size
size=0
$ echo hello | f --md5 --size
size=6, md5=b1946ac92492d2347c6235b4d2611184
$ f foo
foo: file not found
$ echo foo > foo
$ f foo
foo:
$ f --sha1 foo
foo: sha1=f1d2d2f924e986ac86fdf7b36c94bcdf32beec15
$ f --sha256 foo
foo: sha256=b5bb9d8014a0f9b1d61e21e796d78dccdf1352f23cd32812f4850b878ae4944c
#if symlink
$ f foo --mode
foo: mode=644
#endif
#if no-windows
$ "$PYTHON" $TESTDIR/seq.py 10 > bar
#else
Convert CRLF -> LF for consistency
$ "$PYTHON" $TESTDIR/seq.py 10 | sed "s/$//" > bar
#endif
#if unix-permissions symlink
$ chmod +x bar
$ f bar --newer foo --mode --type --size --dump --links --bytes 7
bar: file, size=21, mode=755, links=1, newer than foo
>>>
1
2
3
4
<<< no trailing newline
#endif
#if unix-permissions
$ ln bar baz
$ f bar -n baz -l --hexdump -t --sha1 --lines=9 -B 20
bar: file, links=2, newer than baz, sha1=612ca68d0305c821750a
0000: 31 0a 32 0a 33 0a 34 0a 35 0a 36 0a 37 0a 38 0a |1.2.3.4.5.6.7.8.|
0010: 39 0a |9.|
$ rm baz
#endif
#if unix-permissions symlink
$ ln -s yadda l
$ f . --recurse -MStmsB4
.: directory with 3 files, mode=755
./bar: file, size=21, mode=755, md5=3b03, sha1=612c
./foo: file, size=4, mode=644, md5=d3b0, sha1=f1d2
./l: link, size=5, md5=2faa, sha1=af93
#endif
$ f --quiet bar -DL 3
1
2
3
$ cd ..
Yadda is a symlink
$ f -qr dir -HB 17
dir: directory with 3 files (symlink !)
dir: directory with 2 files (no-symlink !)
dir/bar:
0000: 31 0a 32 0a 33 0a 34 0a 35 0a 36 0a 37 0a 38 0a |1.2.3.4.5.6.7.8.|
0010: 39 |9|
dir/foo:
0000: 66 6f 6f 0a |foo.|
dir/l: (symlink !)
0000: 79 61 64 64 61 |yadda| (symlink !)