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List:       kmail-devel
Subject:    Re: [patch] kmail startup lock revisited
From:       David Faure <dfaure () klaralvdalens-datakonsult ! se>
Date:       2007-03-22 15:02:28
Message-ID: 200703221602.31381.dfaure () klaralvdalens-datakonsult ! se
[Download RAW message or body]

On Tuesday 06 February 2007, David Faure wrote:
> On Tuesday 06 February 2007, Ingo Klöcker wrote:
> > On Tuesday 06 February 2007 00:03, David Faure wrote:
> > > Yes, but I'm really annoyed by this constant bogus warning box, when
> > > I know very well that I'm not running kmail on two displays...
> > 
> > I guess checking the name of the process with PID oldPid isn't a 
> > feasible (and portable) alternative?
> 
> It's not portable, but it's definitely feasible on at least linux :-)
> That sounds like a good plan, actually. Rather simple.

Works fine, too.

(It's quite fortunate that neither kmail nor kontact are kdeinit modules,
otherwise the solution would become much more complex.)

-- 
David Faure, faure@kde.org, dfaure@klaralvdalens-datakonsult.se
KDE/KOffice developer, Qt consultancy projects
Klarälvdalens Datakonsult AB, Platform-independent software solutions

["kmstartup.diff" (text/x-diff)]

Index: kmstartup.cpp
===================================================================
--- kmstartup.cpp	(revision 643307)
+++ kmstartup.cpp	(working copy)
@@ -36,10 +36,12 @@
 
 #include <errno.h>
 #include <sys/types.h>
+#include <sys/param.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <qfile.h>
 
 #undef Status // stupid X headers
 
@@ -154,12 +156,34 @@
   bool first_instance = false;
   if ( oldPid == -1 )
       first_instance = true;
-  // check if the lock file is stale by trying to see if
-  // the other pid is currently running.
-  // Not 100% correct but better safe than sorry
   else if (hostName == oldHostName && oldPid != getpid()) {
-      if ( kill(oldPid, 0) == -1 )
-          first_instance = ( errno == ESRCH );
+      // check if the lock file is stale
+#ifdef Q_OS_LINUX
+      if ( ::access("/proc", X_OK ) == 0 ) {
+          // On linux with /proc we can even check that it's really kmail and not something else
+          char path_buffer[MAXPATHLEN + 1];
+          path_buffer[MAXPATHLEN] = 0;
+          const QString procPath = QString("/proc/%1/exe").arg(oldPid);
+          const int length = readlink (procPath.latin1(), path_buffer, MAXPATHLEN);
+          if ( length == -1 ) // not such pid
+              first_instance = true;
+          else {
+              path_buffer[length] = '\0';
+              const QString path = QFile::decodeName(path_buffer);
+              kdDebug() << k_funcinfo << path << endl;
+              const int pos = path.findRev('/');
+              const QString fileName = path.mid(pos+1);
+              kdDebug() << "Found process " << oldPid << " running. It's: " << fileName << endl;
+              first_instance = fileName != "kmail" && fileName != "kontact";
+          }
+      } else
+#endif
+      {
+          // Otherwise we just check if the other pid is currently running.
+          // Not 100% correct but better safe than sorry.
+          if ( kill(oldPid, 0) == -1 )
+              first_instance = ( errno == ESRCH );
+      }
   }
 
   if ( !first_instance ) {


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