[PATCH] Fix logic in exec_file_locate_attach

[Gary Benson <gbenson@redhat.com>]

Hi all,

This commit fixes an error in exec_file_locate_attach where
the main executable could be loaded from outside the sysroot
if a nonempty, non-"target:" sysroot was set but the discovered
executable filename did not exist in that sysroot and did exist
on the main filesystem.

Before:
  gdb -q \
    -ex "set sysroot /whatever" \
    -ex "target remote | gdbserver - /bin/ls"
  ...
  Reading symbols from /bin/ls...(no debugging symbols found)...done.

After:
  gdb -q \
    -ex "set sysroot /whatever" \
    -ex "target remote | gdbserver - /bin/ls"
  ...
  /bin/ls: in sysroot "/whatever": No such file or directory.

Built and regtested on RHEL 6.6 x86_64.

Ok to commit?

Cheers,
Gary

--
gdb/ChangeLog:

	* exec.c (exec_file_locate_attach): Throw error if
	exec_file_find fails to locate the main executable.

gdb/testsuite/ChangeLog:

	* gdb.base/attach-bad-sysroot.exp: New file.
	* gdb.base/attach-bad-sysroot.c: Likewise.
---
 gdb/ChangeLog                                 |    5 +++
 gdb/exec.c                                    |   13 +++++++--
 gdb/testsuite/ChangeLog                       |    5 +++
 gdb/testsuite/gdb.base/attach-bad-sysroot.c   |   25 +++++++++++++++++
 gdb/testsuite/gdb.base/attach-bad-sysroot.exp |   36 +++++++++++++++++++++++++
 5 files changed, 81 insertions(+), 3 deletions(-)
 create mode 100644 gdb/testsuite/gdb.base/attach-bad-sysroot.c
 create mode 100644 gdb/testsuite/gdb.base/attach-bad-sysroot.exp

diff --git a/gdb/exec.c b/gdb/exec.c
index 0b8c077..8f19871 100644
--- a/gdb/exec.c
+++ b/gdb/exec.c
@@ -156,9 +156,16 @@ exec_file_locate_attach (int pid, int from_tty)
   /* If gdb_sysroot is not empty and the discovered filename
      is absolute then prefix the filename with gdb_sysroot.  */
   if (*gdb_sysroot != '\0' && IS_ABSOLUTE_PATH (exec_file))
-    full_exec_path = exec_file_find (exec_file, NULL);
-
-  if (full_exec_path == NULL)
+    {
+      full_exec_path = exec_file_find (exec_file, NULL);
+      if (full_exec_path == NULL)
+	{
+	  error (_("%s: in sysroot \"%s\":"
+		   " No such file or directory."),
+		 exec_file, gdb_sysroot);
+	}
+    }
+  else
     {
       /* It's possible we don't have a full path, but rather just a
 	 filename.  Some targets, such as HP-UX, don't provide the
diff --git a/gdb/testsuite/gdb.base/attach-bad-sysroot.c b/gdb/testsuite/gdb.base/attach-bad-sysroot.c
new file mode 100644
index 0000000..e1c1e70
--- /dev/null
+++ b/gdb/testsuite/gdb.base/attach-bad-sysroot.c
@@ -0,0 +1,25 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2011-2016 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <unistd.h>
+
+int
+main (void)
+{
+  sleep (600);
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.base/attach-bad-sysroot.exp b/gdb/testsuite/gdb.base/attach-bad-sysroot.exp
new file mode 100644
index 0000000..014da65
--- /dev/null
+++ b/gdb/testsuite/gdb.base/attach-bad-sysroot.exp
@@ -0,0 +1,36 @@
+# Copyright (C) 2011-2016 Free Software Foundation, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+if {![can_spawn_for_attach]} {
+    return 0
+}
+
+standard_testfile .c
+if { [build_executable ${testfile}.exp $binfile "${testfile}.c"] == -1 } {
+    untested ${testfile}.exp
+    return -1
+}
+
+set test_spawn_id [spawn_wait_for_attach $binfile]
+set testpid [spawn_id_get_pid $test_spawn_id]
+
+set outdir [make_gdb_parallel_path outputs $subdir $testfile]
+set sysroot ${outdir}/does-not-exist
+
+gdb_start
+gdb_test_no_output "set sysroot $sysroot"
+gdb_test "attach $testpid" "Attaching to process $testpid\r\n.*: No such file or directory\\."
+
+kill_wait_spawned_process $test_spawn_id
-- 
1.7.1