Fix the faulty exit code 139 issue in Ubuntu systems

I think it might be an oddity in eglibc, but the status return from waitpid()
is buggered sometimes for signalled children.  Rather than showing up as signal
11 for a segfault, it shows up as an exit value of 139.  This is the most
common offender, but signal 6 (exit value 134) shows up sometimes as well.

The workaround limits the valid exit values of the child to being 0-127.  An
exit value above that is assumed to be a buggered up signal return and is
byteswapped.

As this is most prevalent with mythcommflag, the workaround is only active
for mythcommflag (for now).  If other MythSystem calls need this added, we
can add it later.

mythtv/libs/libmythbase/mythsystem.cpp

@@ -300,6 +300,8 @@ void MythSystem::ProcessFlags(uint flags)
         m_settings["AutoCleanup"] = true;
     if( flags & kMSAnonLog )
         m_settings["AnonLog"] = true;
+    if( flags & kMSLowExitVal )
+        m_settings["OnlyLowExitVal"] = true;
 }
 
 QByteArray  MythSystem::Read(int size)

mythtv/libs/libmythbase/mythsystem.h

@@ -22,6 +22,7 @@ typedef enum MythSystemMask {
     kMSAbortOnJump        = 0x00001000, //< abort this process on a jumppoint
     kMSSetPGID            = 0x00002000, //< set the process group id
     kMSAutoCleanup        = 0x00004000, //< automatically delete if backgrounded
+    kMSLowExitVal         = 0x00008000, //< allow exit values 0-127 only
 } MythSystemFlag;
 
 #ifdef __cplusplus
@@ -73,8 +74,9 @@ class MBASE_PUBLIC MythSystem : public QObject
 
         void JumpAbort(void);
 
-        bool isBackground()  { return GetSetting("RunInBackground"); };
-        bool doAutoCleanup() { return GetSetting("AutoCleanup"); };
+        bool isBackground()   { return GetSetting("RunInBackground"); };
+        bool doAutoCleanup()  { return GetSetting("AutoCleanup"); };
+        bool onlyLowExitVal() { return GetSetting("OnlyLowExitVal"); };
         void HandlePreRun();
         void HandlePostRun();
 

mythtv/libs/libmythbase/system-unix.cpp

@@ -315,6 +315,22 @@ void MythSystemManager::run(void)
 
             msList.append(ms);
 
+            // Deal with (primarily) Ubuntu which seems to consistently be
+            // screwing up and reporting the signalled case as an exit.  This
+            // workaround will limit the valid exit value to 0 - 127.  As all
+            // of our return values match that (other than the occasional 255)
+            // this shouldn't cause any issues
+            if (ms->m_parent->onlyLowExitVal() && WIFEXITED(status) &&
+                WEXITSTATUS(status) != 255 && WEXITSTATUS(status) & 0x80)
+            {
+                // Just byte swap the status and it seems to be correctly done
+                uint16_t oldstatus = status;
+                status = ((status & 0x00FF) << 8) | ((status & 0xFF00) >> 8);
+                LOG(VB_SYSTEM, LOG_INFO,
+                    QString("Odd return value: swapping from %1 to %2")
+                    .arg(oldstatus) .arg(status));
+            }
+
             // handle normal exit
             if( WIFEXITED(status) )
             {

mythtv/libs/libmythtv/jobqueue.cpp

@@ -2296,7 +2296,7 @@ void JobQueue::DoFlagCommercialsThread(int jobID)
     LOG(VB_JOBQUEUE, LOG_INFO, LOC + QString("Running command: '%1'")
             .arg(command));
 
-    breaksFound = myth_system(command);
+    breaksFound = myth_system(command, kMSLowExitVal);
     int priority = LOG_NOTICE;
     QString comment;