[PATCH, master + 11][gdb/cli] Don't assert on empty string for core-file

[Tom de Vries via Gdb-patches <gdb-patches@sourceware.org>]

Hi,

With current gdb we run into:
...
$ gdb -batch '' ''
: No such file or directory.
pathstuff.cc:132: internal-error: \
  gdb::unique_xmalloc_ptr<char> gdb_abspath(const char*): \
  Assertion `path != NULL && path[0] != '\0'' failed.
...

Fix this by skipping the call to gdb_abspath in core_target_open in the
empty-string case, such that we have instead:
...
$ gdb -batch '' ''
: No such file or directory.
: No such file or directory.
$
...

Tested on x86_64-linux.

Any comments?

Thanks,
- Tom

[gdb/cli] Don't assert on empty string for core-file

gdb/ChangeLog:

2021-08-30  Tom de Vries  <tdevries@suse.de>

	PR cli/28290
	* gdb/corelow.c (core_target_open): Skip call to gdb_abspath in the
	empty-string case.

gdb/testsuite/ChangeLog:

2021-08-30  Tom de Vries  <tdevries@suse.de>

	PR cli/28290
	* gdb.base/batch-exit-status.exp: Add gdb '' and gdb '' '' tests.

---
 gdb/corelow.c                                | 3 ++-
 gdb/testsuite/gdb.base/batch-exit-status.exp | 4 ++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/gdb/corelow.c b/gdb/corelow.c
index eb785a08633..711e86c4cd4 100644
--- a/gdb/corelow.c
+++ b/gdb/corelow.c
@@ -428,7 +428,8 @@ core_target_open (const char *arg, int from_tty)
     }
 
   gdb::unique_xmalloc_ptr<char> filename (tilde_expand (arg));
-  if (!IS_ABSOLUTE_PATH (filename.get ()))
+  if (strlen (filename.get ()) != 0
+      && !IS_ABSOLUTE_PATH (filename.get ()))
     filename = gdb_abspath (filename.get ());
 
   flags = O_BINARY | O_LARGEFILE;
diff --git a/gdb/testsuite/gdb.base/batch-exit-status.exp b/gdb/testsuite/gdb.base/batch-exit-status.exp
index 085dfc6ad56..9a080196bd6 100644
--- a/gdb/testsuite/gdb.base/batch-exit-status.exp
+++ b/gdb/testsuite/gdb.base/batch-exit-status.exp
@@ -76,3 +76,7 @@ test_exit_status 1 "-batch -x $good_commands -x $bad_commands" \
     "-batch -x good-commands -x bad-commands"
 test_exit_status 1 "-batch -x $good_commands -ex \"set not-a-thing 4\"" \
     "-batch -x good-commands -ex \"set not-a-thing 4\""
+
+set no_such_re ": No such file or directory\\."
+test_exit_status 1 "-batch \"\"" $no_such_re
+test_exit_status 1 "-batch \"\" \"\"" [multi_line $no_such_re $no_such_re]