[New-bugs-announce] [issue29659] Expose the `length` arg from shutil.copyfileobj for public use

[tyler]

New submission from tyler:

It would be handy to be able to pass the `length` default argument defined by `shutil.copyfileobj()` to other public functions througout the module. When copying very large files (1GB +), increasing the memory buffer can divide the copy time in half and currently the only way to accomplish this is by overriding the needed function(s) which call `shutil.copyfileobj()`.

I propose a simple non-invasive change where the following functions will also expose the `length` kwarg and pass it downwards to `copyfileobj`:
- copyfile
- copy
- copy2

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messages: 288616
nosy: goodboy
priority: normal
severity: normal
status: open
title: Expose the `length` arg from shutil.copyfileobj for public use
versions: Python 3.7

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue29659>
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