shadow: Avoid nss warning/error with musl

The libnss configuration file is only installed when glibc is used. The
inexistence of it on a musl-based rootfs, will make shadow complain
about it:

Failed opening /etc/nsswitch.conf

This is because shadow will try to use nsswich when dealing with
subordinate IDs and the message is just a warning as the tool will still
generate them correctly in subuid/subgid files.

We drop this log message for class native to avoid an error when rootfs
logs are checked ('Failed' will match the regex bitbake is using to
check for rootfs generation errors).

(From OE-Core rev: 3000840a271534fa907ce0684b81a6d278e64a44)

Signed-off-by: Andrei Gherzan <andrei.gherzan@huawei.com>
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-extended/shadow/files/0001-Drop-nsswitch.conf-message-when-not-in-place-eg.-musl.patch

@@ -0,0 +1,27 @@
+From 11290e897a49adddee215833944a518443d9b0d6 Mon Sep 17 00:00:00 2001
+From: Andrei Gherzan <andrei.gherzan@huawei.com>
+Date: Wed, 24 Aug 2022 00:54:47 +0200
+Subject: [PATCH] Drop nsswitch.conf message when not in place - eg. musl
+
+Upstream-Status: Inappropriate [issue reported at https://github.com/shadow-maint/shadow/issues/557]
+Signed-off-by: Andrei Gherzan <andrei.gherzan@huawei.com>
+---
+ lib/nss.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/lib/nss.c b/lib/nss.c
+index 06fa48e..44245da 100644
+--- a/lib/nss.c
++++ b/lib/nss.c
+@@ -59,7 +59,7 @@ void nss_init(const char *nsswitch_path) {
+ 	//   subid:	files
+ 	nssfp = fopen(nsswitch_path, "r");
+ 	if (!nssfp) {
+-		fprintf(shadow_logfd, "Failed opening %s: %m\n", nsswitch_path);
++		//fprintf(shadow_logfd, "Failed opening %s: %m\n", nsswitch_path);
+ 		atomic_store(&nss_init_completed, true);
+ 		return;
+ 	}
+-- 
+2.25.1
+

meta/recipes-extended/shadow/shadow.inc

@@ -25,12 +25,14 @@ SRC_URI:append:class-target = " \
 SRC_URI:append:class-native = " \
            file://0001-Disable-use-of-syslog-for-sysroot.patch \
            file://commonio.c-fix-unexpected-open-failure-in-chroot-env.patch \
+           file://0001-Drop-nsswitch.conf-message-when-not-in-place-eg.-musl.patch \
            "
 SRC_URI:append:class-nativesdk = " \
            file://0001-Disable-use-of-syslog-for-sysroot.patch \
            "
 SRC_URI[sha256sum] = "9fdb73b5d2b44e8ba9fcee1b4493ac75dd5040bda35b9ac8b06570cd192e7ee3"
 
+
 # Additional Policy files for PAM
 PAM_SRC_URI = "file://pam.d/chfn \
                file://pam.d/chpasswd \