[TestLldbGdbServer and TestGdbRemoteXXX] Use "ls -l" instead of "readlink"

[sivachandra]

Summary

Old Android devices, for example API 16, do not have the "readlink"
command. To take care of such devices, this commit changes to use "ls -l"
instead of "readlink" to get the lldb-server exe path.

The tests fixed with this change for an Android API 16 arm device are:

TestGdbRemoteAttach
TestGdbRemoteAuxvSupport
TestGdbRemoteExpeditedRegisters
TestGdbRemoteKill
TestGdbRemoteProcessInfo
TestGdbRemoteSegFault
TestGdbRemoteThreadsInStopReply
TestGdbRemote_qThreadStopInfo

Further, all tests in TestLldbGdbServer pass (previously erroring out),
except one which times out.

[ovyalov]

Please see my comments.

test/tools/lldb-server/gdbremote_testcase.py

157

Please consider calling strip() on output string here -so, caller won't need to strip at each call site.

169

You may run "ls -l /proc/.../exe" and then take last item from output array separated by spaces - it should contain deferenced link.

[sivachandra]

Modify according to comments.

[ovyalov]

LGTM

[sivachandra]

Thanks for the prompt review.

test/tools/lldb-server/gdbremote_testcase.py

def get_stub_port_from_named_socket(self, read_timeout_seconds=5):
         stub_port_raw = stub_port_raw[:-1]
         stub_port = int(stub_port_raw)
         self.assertTrue(stub_port > 0)
 
         return stub_port
 
     def init_llgs_test(self, use_named_pipe=True):
         if lldb.remote_platform:
+            def run_shell_cmd(cmd):
+                platform = self.dbg.GetSelectedPlatform()
+                shell_cmd = lldb.SBPlatformShellCommand(cmd)
+                err = platform.Run(shell_cmd)
+                if err.Fail() or shell_cmd.GetStatus():
+                    m = "remote_platform.RunShellCommand('%s') failed:\n" % cmd
+                    m += ">>> return code: %d\n" % shell_cmd.GetStatus()
+                    if err.Fail():
+                        m += ">>> %s\n" % str(err).strip()
+                    m += ">>> %s\n" % (shell_cmd.GetOutput() or
+                                       "Command generated no output.")
+                    raise Exception(m)
+                return shell_cmd.GetOutput().strip()
             # Remote platforms don't support named pipe based port negotiation
             use_named_pipe = False
 
-            platform = self.dbg.GetSelectedPlatform()
-
-            shell_command = lldb.SBPlatformShellCommand("echo $PPID")
-            err = platform.Run(shell_command)
-            if err.Fail():
-                raise Exception("remote_platform.RunShellCommand('echo $PPID') failed: %s" % err)
-            pid = shell_command.GetOutput().strip()
+            pid = run_shell_cmd("echo $PPID")
+            ls_output = run_shell_cmd("ls -l /proc/%s/exe" % pid)
+            exe = ls_output.split()[-1]
 
-            shell_command = lldb.SBPlatformShellCommand("readlink /proc/%s/exe" % pid)
-            err = platform.Run(shell_command)
-            if err.Fail():
-                raise Exception("remote_platform.RunShellCommand('readlink /proc/%d/exe') failed: %s" % (pid, err))
             # If the binary has been deleted, the link name has " (deleted)" appended.
             # Remove if it's there.
-            self.debug_monitor_exe = re.sub(r' \(deleted\)$', '', shell_command.GetOutput().strip())
+            self.debug_monitor_exe = re.sub(r' \(deleted\)$', '', exe)
         else:
             self.debug_monitor_exe = get_lldb_server_exe()
             if not self.debug_monitor_exe:
                 self.skipTest("lldb-server exe not found")
 
         self.debug_monitor_extra_args = ["gdbserver"]
 
         if len(lldbtest_config.channels) > 0:
             self.debug_monitor_extra_args.append("--log-file={}-server.log".format(self.log_basename))
             self.debug_monitor_extra_args.append("--log-channels={}".format(":".join(lldbtest_config.channels)))