Re: [PATCH 1/3] getpwuid(mingw): initialize the structure only once

From: Eric Sunshine <sunshine@sunshineco.com>
Date: Oct 15, 2018, 14:25 UTC
Message-ID: <CAPig+cS3Bz3uaxWv23bQEXB7Ok=Q+V07mGc-Fysg-WU3DKKagA@mail.gmail.com>
In-Reply-To: <63373dd91d0be324273ab34ff49d630453954173.1539596822.git.gitgitgadget@gmail.com>

On Mon, Oct 15, 2018 at 5:47 AM Johannes Schindelin via GitGitGadget <gitgitgadget@gmail.com> wrote:

Show 19 quoted lines

> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> ---
> diff --git a/compat/mingw.c b/compat/mingw.c
> @@ -1800,16 +1800,27 @@ int mingw_getpagesize(void)
>  struct passwd *getpwuid(int uid)
>  {
> +       static unsigned initialized;
>         static char user_name[100];
> -       static struct passwd p;
> +       static struct passwd *p;
>
> +       if (initialized)
> +               return p;
> +
> +       len = sizeof(user_name);
> +       if (!GetUserName(user_name, &len)) {
> +               initialized = 1;
>                 return NULL;
> +       }

If GetUserName() fails, that failure is recorded (as "initialized=1" and 'p' is still NULL), so subsequent invocations just return NULL without doing any more work. Makes sense.

Show 8 quoted lines

> +       p = xmalloc(sizeof(*p));
> +       p->pw_name = user_name;
> +       p->pw_gecos = "unknown";
> +       p->pw_dir = NULL;
> +
> +       initialized = 1;
> +       return p;
>  }