qemurunner: configurable timeout for run_serial()

Some commands might need to run longer than the default timeout of
five seconds. If that occurred, run_serial() returned with a status
code of zero (sic!) and no other indication of what went wrong.

Now the timeout is configurable (with five still the default) and
an explicit warning ("<<< run_serial(): command timed out after 5 seconds without output >>>")
gets appended at the end of the data returned to the caller.

While at it, the logic for checking for the timeout was updated a bit
because both implementations could overshoot the timeout when entering
select() right before the final deadline.

(From OE-Core rev: accf0362f964cc9d6330b6e52e83d748d890521f)

Signed-off-by: Patrick Ohly <patrick.ohly@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/targetcontrol.py

@@ -206,8 +206,8 @@ class QemuTarget(BaseTarget):
         else:
             raise bb.build.FuncFailed("%s - FAILED to re-start qemu - check the task log and the boot log" % self.pn)
 
-    def run_serial(self, command):
-        return self.runner.run_serial(command)
+    def run_serial(self, command, timeout=5):
+        return self.runner.run_serial(command, timeout=timeout)
 
 
 class SimpleRemoteTarget(BaseTarget):

meta/lib/oeqa/utils/qemurunner.py

@@ -416,7 +416,7 @@ class QemuRunner:
             if "qemu-system" in basecmd and "-serial tcp" in commands[p]:
                 return [int(p),commands[p]]
 
-    def run_serial(self, command, raw=False):
+    def run_serial(self, command, raw=False, timeout=5):
         # We assume target system have echo to get command status
         if not raw:
             command = "%s; echo $?\n" % command
@@ -424,20 +424,23 @@ class QemuRunner:
         data = ''
         status = 0
         self.server_socket.sendall(command.encode('utf-8'))
-        keepreading = True
-        while keepreading:
-            sread, _, _ = select.select([self.server_socket],[],[],5)
+        start = time.time()
+        end = start + timeout
+        while True:
+            now = time.time()
+            if now >= end:
+                data += "<<< run_serial(): command timed out after %d seconds without output >>>\r\n\r\n" % timeout
+                break
+            sread, _, _ = select.select([self.server_socket],[],[], end - now)
             if sread:
                 answer = self.server_socket.recv(1024)
                 if answer:
                     data += answer.decode('utf-8')
                     # Search the prompt to stop
                     if re.search("[a-zA-Z0-9]+@[a-zA-Z0-9\-]+:~#", data):
-                        keepreading = False
+                        break
                 else:
                     raise Exception("No data on serial console socket")
-            else:
-                keepreading = False
 
         if data:
             if raw:

meta/lib/oeqa/utils/qemutinyrunner.py

@@ -107,14 +107,14 @@ class QemuTinyRunner(QemuRunner):
 
         return self.is_alive()
 
-    def run_serial(self, command):
+    def run_serial(self, command, timeout=5):
         self.server_socket.sendall(command+'\n')
         data = ''
         status = 0
         stopread = False
-        endtime = time.time()+5
+        endtime = time.time()+timeout
         while time.time()<endtime and not stopread:
-                sread, _, _ = select.select([self.server_socket],[],[],5)
+                sread, _, _ = select.select([self.server_socket],[],[],1)
                 for sock in sread:
                         answer = sock.recv(1024)
                         if answer:
@@ -124,6 +124,8 @@ class QemuTinyRunner(QemuRunner):
                                 stopread = True
         if not data:
             status = 1
+        if not stopread:
+            data += "<<< run_serial(): command timed out after %d seconds without output >>>\r\n\r\n" % timeout
         return (status, str(data))
 
     def find_child(self,parent_pid):