From: Junio C Hamano <gitster@pobox.com>
Date: Mon, 30 Jan 2017 17:03:11 GMT
Subject: Re: [PATCH v2] help: improve is_executable() on Windows
Message-ID: <xmqqmve8wkds.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <4b93fe44ff9020ed80e4fd93a24a6ffa647e7678.1485780050.git.johannes.schindelin@gmx.de>

Johannes Schindelin <johannes.schindelin@gmx.de> writes:

> From: Heiko Voigt <hvoigt@hvoigt.net>
>
> On Windows, executables need to have the file extension `.exe`, or they
> are not executables. Hence, to support scripts, Git for Windows also
> looks for a she-bang line by opening the file in question, and executing
> it via the specified script interpreter.
>
> To figure out whether files in the `PATH` are executable, `git help` has
> code that imitates this behavior. With one exception: it *always* opens
> the files and looks for a she-bang line *or* an `MZ` tell-tale
> (nevermind that files with the magic `MZ` but without file extension
> `.exe` would still not be executable).
>
> Opening this many files leads to performance problems that are even more
> serious when a virus scanner is running. Therefore, let's change the
> code to look for the file extension `.exe` early, and avoid opening the
> file altogether if we already know that it is executable.

Much more readable than the initial round.  Will queue; thanks.