Re: regression: "96b9e0e3 config: treat user and xdg config permission problems as errors" busted git-daemon

> So here's what I came up with. I tried to make the exception as tight as
> possible by checking that $HOME was actually the problem, as that is the
> common problem (you switch users, but HOME is pointing to the old user).
> ...
> diff --git a/daemon.c b/daemon.c
> index 131b049..6c56cc0 100644
> --- a/daemon.c
> +++ b/daemon.c
> @@ -1091,7 +1091,7 @@ static void drop_privileges(struct credentials *cred)
>  	if (cred && (initgroups(cred->pass->pw_name, cred->gid) ||
>  	    setgid (cred->gid) || setuid(cred->pass->pw_uid)))
>  		die("cannot drop privileges");
> -	setenv("GIT_CONFIG_INACCESSIBLE_HOME_OK", "1", 0);
> +	setenv(GIT_INACCESSIBLE_HOME_OK_ENVIRONMENT, "1", 0);
>  }

>  
>  static struct credentials *prepare_credentials(const char *user_name,
> diff --git a/wrapper.c b/wrapper.c
> index bac59d2..644f867 100644
> --- a/wrapper.c
> +++ b/wrapper.c
> @@ -416,11 +416,52 @@ int access_or_die(const char *path, int mode)
>  	return ret;
>  }
>  
> +/*
> + * Returns true iff the path is under $HOME, that directory is inaccessible,
> + * and the user has told us through the environment that an inaccessible HOME
> + * is OK. The results are cached so that repeated calls will not make multiple
> + * syscalls.
> + */
> +static int inaccessible_home_ok(const char *path)
> +{
> +	static int gentle = -1;
> +	static int home_inaccessible = -1;
> +	const char *home;
> +
> +	if (gentle < 0)
> +		gentle = git_env_bool(GIT_INACCESSIBLE_HOME_OK_ENVIRONMENT, 0);
> +	if (!gentle)
> +		return 0;
> +
> +	home = getenv("HOME");
> +	if (!home)
> +		return 0;
> +	/*
> +	 * We do not bother with normalizing PATHs to avoid symlinks
> +	 * here, since the point is to catch paths that are
> +	 * constructed as "$HOME/...".
> +	 */
> +	if (prefixcmp(path, home) && path[strlen(home)] == '/')
> +		return 0;
> +
> +	if (home_inaccessible < 0)
> +		home_inaccessible = access(home, R_OK|X_OK) < 0 && errno == EACCES;
> +	return home_inaccessible;
> +}
> +
>  int access_or_die(const char *path, int mode)
>  {
>  	int ret = access(path, mode);
> -	if (ret && errno != ENOENT && errno != ENOTDIR)
> +	if (ret && errno != ENOENT && errno != ENOTDIR) {
> +		/*
> +		 * We do not have to worry about clobbering errno
> +		 * in inaccessible_home_ok, because we get either EACCES
> +		 * again, or we die.
> +		 */
> +		if (errno == EACCES && inaccessible_home_ok(path))
> +			return ret;