[glibc] resolv: Run tst-getaddrinfo-eai-again in a network namespace

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=1b2f868fb4958fd59875695c1828d9804b116dc2

commit 1b2f868fb4958fd59875695c1828d9804b116dc2
Author: Florian Weimer <[email protected]>
Date:   Tue Apr 7 10:49:13 2026 +0200

    resolv: Run tst-getaddrinfo-eai-again in a network namespace
    
    This ensures that the test does not accidentally use a name server
    running on 127.0.0.1.
    
    Tested-by:  Frédéric Bérat <[email protected]>
    Reviewed-by: Frédéric Bérat <[email protected]>

Diff:
---
 resolv/tst-getaddrinfo-eai-again.c                                    | 4 ++++
 .../tst-getaddrinfo-eai-again.root/tst-getaddrinfo-eai-again.script   | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/resolv/tst-getaddrinfo-eai-again.c b/resolv/tst-getaddrinfo-eai-again.c
index f035d694e8..43505818b6 100644
--- a/resolv/tst-getaddrinfo-eai-again.c
+++ b/resolv/tst-getaddrinfo-eai-again.c
@@ -20,6 +20,7 @@
 
 #include <netdb.h>
 #include <support/check.h>
+#include <support/namespace.h>
 
 /* Query getaddrinfo with various address families and verify that
    it returns EAI_AGAIN when DNS resolution fails.  */
@@ -49,6 +50,9 @@ query_host (const char *host_name)
 static int
 do_test (void)
 {
+  /* Hide any name server that might be running on 127.0.0.1.  */
+  support_enter_network_namespace ();
+
   query_host ("site.example");
   return 0;
 }
diff --git a/resolv/tst-getaddrinfo-eai-again.root/tst-getaddrinfo-eai-again.script b/resolv/tst-getaddrinfo-eai-again.root/tst-getaddrinfo-eai-again.script
new file mode 100644
index 0000000000..383f92b5b0
--- /dev/null
+++ b/resolv/tst-getaddrinfo-eai-again.root/tst-getaddrinfo-eai-again.script
@@ -0,0 +1,2 @@
+# Enable entering a network namespace.
+su