Avoid overflowing the wake up when handling events in Unix console apps.

[wxWidgets.git] / src / unix / snglinst.cpp

diff --git a/src/unix/snglinst.cpp b/src/unix/snglinst.cpp
index 23fce16f82cabc2f530bfcce4b0fdaf1ac82638b..ef2f83ac9532fe816cfb0cdb9c1fc56a5d0cc35f 100644 (file)
--- a/src/unix/snglinst.cpp
+++ b/src/unix/snglinst.cpp
@@ -1,5 +1,5 @@
 ///////////////////////////////////////////////////////////////////////////////
-// Name:        unix/snglinst.cpp
+// Name:        src/unix/snglinst.cpp
 // Purpose:     implements wxSingleInstanceChecker class for Unix using
 //              lock files with fcntl(2) or flock(2)
 // Author:      Vadim Zeitlin
@@ -7,7 +7,7 @@
 // Created:     09.06.01
 // RCS-ID:      $Id$
 // Copyright:   (c) 2001 Vadim Zeitlin <zeitlin@dptmaths.ens-cachan.fr>
-// License:     wxWindows licence
+// Licence:     wxWindows licence
 ///////////////////////////////////////////////////////////////////////////////
 
 // ============================================================================
@@ -18,10 +18,6 @@
 // headers
 // ----------------------------------------------------------------------------
 
-#ifdef __GNUG__
-    #pragma implementation "snglinst.h"
-#endif
-
 // For compilers that support precompilation, includes "wx.h".
 #include "wx/wxprec.h"
 
@@ -35,10 +31,10 @@
     #include "wx/string.h"
     #include "wx/log.h"
     #include "wx/intl.h"
-    #include "wx/file.h"
+    #include "wx/utils.h"           // wxGetHomeDir()
 #endif //WX_PRECOMP
 
-#include "wx/utils.h"           // wxGetHomeDir()
+#include "wx/file.h"
 
 #include "wx/snglinst.h"
 
@@ -89,9 +85,9 @@ static int wxLockFile(int fd, LockOperation lock)
     fl.l_type = lock == LOCK ? F_WRLCK : F_UNLCK;
 
     // lock the entire file
-    fl.l_whence =
     fl.l_start =
-    fl.l_len = 0;
+    fl.l_len =
+    fl.l_whence = 0;
 
     // is this needed?
     fl.l_pid = getpid();
@@ -180,6 +176,17 @@ LockResult wxSingleInstanceCheckerImpl::CreateLockFile()
 
             fsync(m_fdLock);
 
+            // change file's permission so that only this user can access it:
+            if ( chmod(m_nameLock.fn_str(), S_IRUSR | S_IWUSR) != 0 )
+            {
+                wxLogSysError(_("Failed to set permissions on lock file '%s'"),
+                              m_nameLock.c_str());
+
+                Unlock();
+
+                return LOCK_ERROR;
+            }
+
             return LOCK_CREATED;
         }
         else // failure: see what exactly happened
@@ -219,11 +226,31 @@ bool wxSingleInstanceCheckerImpl::Create(const wxString& name)
 
         case LOCK_CREATED:
             // nothing more to do
-            return TRUE;
+            return true;
 
         case LOCK_ERROR:
             // oops...
-            return FALSE;
+            return false;
+    }
+
+    // Check if the file is owned by current user and has 0600 permissions.
+    // If it doesn't, it's a fake file, possibly meant as a DoS attack, and
+    // so we refuse to touch it:
+    wxStructStat stats;
+    if ( wxStat(name, &stats) != 0 )
+    {
+        wxLogSysError(_("Failed to inspect the lock file '%s'"), name.c_str());
+        return false;
+    }
+    if ( stats.st_uid != getuid() )
+    {
+        wxLogError(_("Lock file '%s' has incorrect owner."), name.c_str());
+        return false;
+    }
+    if ( stats.st_mode != (S_IFREG | S_IRUSR | S_IWUSR) )
+    {
+        wxLogError(_("Lock file '%s' has incorrect permissions."), name.c_str());
+        return false;
     }
 
     // try to open the file for reading and get the PID of the process
@@ -242,11 +269,11 @@ bool wxSingleInstanceCheckerImpl::Create(const wxString& name)
         // rarely in practice that we don't care
         wxLogError(_("Failed to access lock file."));
 
-        return FALSE;
+        return false;
     }
 
     char buf[256];
-    off_t count = file.Read(buf, WXSIZEOF(buf));
+    ssize_t count = file.Read(buf, WXSIZEOF(buf));
     if ( count == wxInvalidOffset )
     {
         wxLogError(_("Failed to read PID from lock file."));
@@ -262,7 +289,7 @@ bool wxSingleInstanceCheckerImpl::Create(const wxString& name)
                     wxLogError(_("Failed to remove stale lock file '%s'."),
                                name.c_str());
 
-                    // return TRUE in this case for now...
+                    // return true in this case for now...
                 }
                 else
                 {
@@ -281,7 +308,7 @@ bool wxSingleInstanceCheckerImpl::Create(const wxString& name)
         }
     }
 
-    // return TRUE if we could get the PID of the process owning the lock file
+    // return true if we could get the PID of the process owning the lock file
     // (whether it is still running or not), FALSE otherwise as it is
     // unexpected
     return m_pidLocker != 0;
@@ -321,10 +348,10 @@ bool wxSingleInstanceChecker::Create(const wxString& name,
                                      const wxString& path)
 {
     wxASSERT_MSG( !m_impl,
-                  _T("calling wxSingleInstanceChecker::Create() twice?") );
+                  wxT("calling wxSingleInstanceChecker::Create() twice?") );
 
     // must have the file name to create a lock file
-    wxASSERT_MSG( !name.empty(), _T("lock file name can't be empty") );
+    wxASSERT_MSG( !name.empty(), wxT("lock file name can't be empty") );
 
     m_impl = new wxSingleInstanceCheckerImpl;
 
@@ -334,9 +361,9 @@ bool wxSingleInstanceChecker::Create(const wxString& name,
         fullname = wxGetHomeDir();
     }
 
-    if ( fullname.Last() != _T('/') )
+    if ( fullname.Last() != wxT('/') )
     {
-        fullname += _T('/');
+        fullname += wxT('/');
     }
 
     fullname << name;
@@ -344,13 +371,23 @@ bool wxSingleInstanceChecker::Create(const wxString& name,
     return m_impl->Create(fullname);
 }
 
-bool wxSingleInstanceChecker::IsAnotherRunning() const
+bool wxSingleInstanceChecker::DoIsAnotherRunning() const
 {
-    wxCHECK_MSG( m_impl, FALSE, _T("must call Create() first") );
+    wxCHECK_MSG( m_impl, false, wxT("must call Create() first") );
+
+    const pid_t lockerPid = m_impl->GetLockerPID();
+
+    if ( !lockerPid )
+    {
+        // we failed to open the lock file, return false as we're definitely
+        // not sure that another our process is running and so it's better not
+        // to prevent this one from starting up
+        return false;
+    }
 
     // if another instance is running, it must own the lock file - otherwise
     // we have it and the locker PID is ours one
-    return m_impl->GetLockerPID() != getpid();
+    return lockerPid != getpid();
 }
 
 wxSingleInstanceChecker::~wxSingleInstanceChecker()
@@ -359,4 +396,3 @@ wxSingleInstanceChecker::~wxSingleInstanceChecker()
 }
 
 #endif // wxUSE_SNGLINST_CHECKER
-