[PATCH] [gdb/testsuite] Fix gdb.base/gdb-index-err.exp for root user

[Tom de Vries <tdevries@suse.de>]

When running test-case gdb.base/gdb-index-err.exp in a container as root user,
I run into:
...
FAIL: gdb.base/gdb-index-err.exp: flag=: \
  try to write index to a non-writable directory
FAIL: gdb.base/gdb-index-err.exp: flag=-dwarf-5: \
  try to write index to a non-writable directory
...

The test-case creates a directory without write permissions:
...
$ ls -ald private
dr-xr-xr-x 2 root root 4096 Dec 29 06:26 private/
...
but apparently the root user is still able to write in it.

Fix this by making the test unsupported for the root user.

Tested on x86_64-linux.

PR testsuite/31197
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31197
---
 gdb/testsuite/gdb.base/gdb-index-err.exp | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/gdb/testsuite/gdb.base/gdb-index-err.exp b/gdb/testsuite/gdb.base/gdb-index-err.exp
index 31f133efbcd..cefd708f5ab 100644
--- a/gdb/testsuite/gdb.base/gdb-index-err.exp
+++ b/gdb/testsuite/gdb.base/gdb-index-err.exp
@@ -62,9 +62,15 @@ remote_exec host "chmod u-w,g-w ${non_writable_dir}"
 
 # Try to write the index into a non-writable directory.
 foreach_with_prefix flag { "" "-dwarf-5" } {
+    set test "try to write index to a non-writable directory"
+    if { [root_user] } {
+	unsupported $test
+	continue
+    }
+
     gdb_test "save gdb-index ${flag} ${non_writable_dir}" \
 	"Error while writing index for `[string_to_regexp $binfile]': couldn't open `[string_to_regexp $non_writable_dir]/${gdb_test_file_name}.*': Permission denied\\." \
-	"try to write index to a non-writable directory"
+	$test
 }
 
 # Create copies of the executable, we will add an index section to

base-commit: a6d0019eb7fcd634e12b7bcc535d5181c47fc82a
-- 
2.35.3