From patchwork Tue Jul 19 21:44:42 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Willy Tarreau X-Patchwork-Id: 12923110 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 49B97C43334 for ; Tue, 19 Jul 2022 21:45:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240126AbiGSVpW (ORCPT ); Tue, 19 Jul 2022 17:45:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51184 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240133AbiGSVpU (ORCPT ); Tue, 19 Jul 2022 17:45:20 -0400 Received: from 1wt.eu (wtarreau.pck.nerim.net [62.212.114.60]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id EAA65B7E2; Tue, 19 Jul 2022 14:45:16 -0700 (PDT) Received: (from willy@localhost) by pcw.home.local (8.15.2/8.15.2/Submit) id 26JLj5qH002591; Tue, 19 Jul 2022 23:45:05 +0200 From: Willy Tarreau To: "Paul E . McKenney" Cc: Pranith Kumar , Alviro Iskandar Setiawan , Ammar Faizi , David Laight , Mark Brown , Linus Torvalds , Shuah Khan , linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Willy Tarreau Subject: [PATCH 10/17] selftests/nolibc: recreate and populate /dev and /proc if missing Date: Tue, 19 Jul 2022 23:44:42 +0200 Message-Id: <20220719214449.2520-12-w@1wt.eu> X-Mailer: git-send-email 2.17.5 In-Reply-To: <20220719214449.2520-1-w@1wt.eu> References: <20220719214449.2520-1-w@1wt.eu> Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Most of the time the program will be run alone in an initramfs. There is no value in requiring the user to populate /dev and /proc for such tests, we can do it ourselves, and it participates to the tests at the same time. What's done here is that when called as init (getpid()==1) we check if /dev exists or create it, if /dev/console and /dev/null exists, otherwise we try to mount a devtmpfs there, and if it fails we fall back to mknod. The console is reopened if stdout was closed. Finally /proc is created and mounted if /proc/self cannot be found. This is sufficient for most tests. Signed-off-by: Willy Tarreau --- tools/testing/selftests/nolibc/nolibc-test.c | 56 ++++++++++++++++++++ 1 file changed, 56 insertions(+) diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c index 45793b6f2244..0bbfe0b3b648 100644 --- a/tools/testing/selftests/nolibc/nolibc-test.c +++ b/tools/testing/selftests/nolibc/nolibc-test.c @@ -530,6 +530,54 @@ int run_stdlib(int min, int max) return ret; } +/* prepare what needs to be prepared for pid 1 (stdio, /dev, /proc, etc) */ +int prepare(void) +{ + struct stat stat_buf; + + /* It's possible that /dev doesn't even exist or was not mounted, so + * we'll try to create it, mount it, or create minimal entries into it. + * We want at least /dev/null and /dev/console. + */ + if (stat("/dev/.", &stat_buf) == 0 || mkdir("/dev", 0755) == 0) { + if (stat("/dev/console", &stat_buf) != 0 || + stat("/dev/null", &stat_buf) != 0) { + /* try devtmpfs first, otherwise fall back to manual creation */ + if (mount("/dev", "/dev", "devtmpfs", 0, 0) != 0) { + mknod("/dev/console", 0600 | S_IFCHR, makedev(5, 1)); + mknod("/dev/null", 0666 | S_IFCHR, makedev(1, 3)); + } + } + } + + /* If no /dev/console was found before calling init, stdio is closed so + * we need to reopen it from /dev/console. If it failed above, it will + * still fail here and we cannot emit a message anyway. + */ + if (close(dup(1)) == -1) { + int fd = open("/dev/console", O_RDWR); + + if (fd >= 0) { + if (fd != 0) + dup2(fd, 0); + if (fd != 1) + dup2(fd, 1); + if (fd != 2) + dup2(fd, 2); + if (fd > 2) + close(fd); + puts("\nSuccessfully reopened /dev/console."); + } + } + + /* try to mount /proc if not mounted. Silently fail otherwise */ + if (stat("/proc/.", &stat_buf) == 0 || mkdir("/proc", 0755) == 0) { + if (stat("/proc/self", &stat_buf) != 0) + mount("/proc", "/proc", "proc", 0, 0); + } + + return 0; +} /* This is the definition of known test names, with their functions */ static struct test test_names[] = { @@ -550,6 +598,14 @@ int main(int argc, char **argv, char **envp) environ = envp; + /* when called as init, it's possible that no console was opened, for + * example if no /dev file system was provided. We'll check that fd#1 + * was opened, and if not we'll attempt to create and open /dev/console + * and /dev/null that we'll use for later tests. + */ + if (getpid() == 1) + prepare(); + /* the definition of a series of tests comes from either argv[1] or the * "NOLIBC_TEST" environment variable. It's made of a comma-delimited * series of test names and optional ranges: