[Scons-dev] Contribution to SCons development.

[Gary Oberbrunner]

On Sat, Dec 6, 2014 at 9:37 AM, Shreedhar Manek <shreedharmanek at gmail.com>
wrote:

> 256 is octal 0400, so it looks like it's only getting the S_IRUSR part.
>>> And that's because I steered you wrong; these are bitmasks, so you have to
>>> use bitwise OR:  S_IRUSR | S_IRGRP | S_IROTH
>>>
>>
> This was it. Thanks!
>
> Should I replace *all *integers with their counterpart string? Or only
> select ones?
>

Well, first, don't forget your real goal is to allow SCons users to
actually use a *string* to set the mode bits.  These constants you're using
are in the 'stat' module (so 'import stat' will fix your bug below), but
they are still numeric absolute constants.

I think the original issue (
http://scons.tigris.org/issues/show_bug.cgi?id=2494) asks for allowing
users to use actual strings like the chmod command-line utility, which
allows relative modes like "ug+rw,o-rwx" as well as numeric absolute modes
like "777" (that's still a string, note). (see the chmod man page, for
instance http://linux.die.net/man/1/chmod.)  SCons users could already just
do 'import stat' and use the named constants, but those are absolute; the
desired chmod modes are *relative *to the current state.  The main task for
this issue is, I think, to parse those relative modes (relative to the
file's current state) and compute the desired final mode.

If you can write a function parse_mode_string(mode_string,
original_mode_bits), that's 90% of the work.  (Actually I'm surprised there
isn't one already written out there somewhere.)

-- Gary


> Replacing the first 0777 with S_IRWXU | S_IRWXG | S_IRWXO in
>
> test.write('SConstruct', """
> Execute(Chmod('f1', 0666))
> Execute(Chmod(('f1-File'), 0666))
> Execute(Chmod('d2', S_IRWXU | S_IRWXG | S_IRWXO))
> Execute(Chmod(Dir('d2-Dir'), 0777))
> def cat(env, source, target):
>     target = str(target[0])
>     f = open(target, "wb")
>     for src in source:
>         f.write(open(str(src), "rb").read())
>     f.close()
> Cat = Action(cat)
> env = Environment()
> env.Command('bar.out', 'bar.in', [Cat,
>                                   Chmod("f3", 0666),
>                                   Chmod("d4", 0777)])
> env = Environment(FILE = 'f5')
> env.Command('f6.out', 'f6.in', [Chmod('$FILE', 0666), Cat])
> env.Command('f7.out', 'f7.in', [Cat,
>                                 Chmod('Chmod-$SOURCE', 0666),
>                                 Chmod('${TARGET}-Chmod', 0666)])
>
> # Make sure Chmod works with a list of arguments
> env = Environment(FILE = 'f9')
> env.Command('f8.out', 'f8.in', [Chmod(['$FILE', File('f10')], 0666), Cat])
> Execute(Chmod(['d11', Dir('d12')], 0777))
> """)
>
> gives the following error,
>
> STDERR
> =========================================================================
> NameError: name 'S_IRWXU' is not defined:
>   File "/tmp/testcmd.23013.se_zJm/SConstruct", line 4:
>     Execute(Chmod('d2', S_IRWXU | S_IRWXG | S_IRWXO))
>
> FAILED test of /home/shrox/scons/src/script/scons.py
> at line 598 of /home/shrox/scons/QMTest/TestCommon.py (_complete)
> from line 701 of /home/shrox/scons/QMTest/TestCommon.py (run)
> from line 390 of /home/shrox/scons/QMTest/TestSCons.py (run)
> from line 123 of test/Chmod.py
>
>
>
> --
> Shreedhar Manek
>
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> Scons-dev at scons.org
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>
>


-- 
Gary
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