Changeset 75724 in vbox for trunk/src/VBox/Additions/common/VBoxGuest/lib

Timestamp:

Nov 25, 2018 7:12:16 PM (6 years ago)

Author:

vboxsync

Message:

VBoxService/VBoxGuestR3LibGuestCtrl.cpp: Fixed mkdir with OS X guests (probably any unix guest). HGCM is a bundle of joy when signals gets into the mix. Sigh.

File:

• trunk/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibGuestCtrl.cpp (modified) (2 diffs)

trunk/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibGuestCtrl.cpp

@@ -37 +37 @@
 #include <VBox/HostServices/GuestControlSvc.h>
 
+#ifndef RT_OS_WINDOWS
+# include <signal.h>
+#endif
+
 #include "VBoxGuestR3LibInternal.h"
 
@@ -99 +103 @@
      *       one for retriving the actual message parameters.  Not this weird
      *       stuff, to put it rather bluntly.
+     *
+     * Note! As a result of this weird design, we are not able to correctly
+     *       retrieve message if we're interrupted by a signal, like SIGCHLD.
+     *       Because IPRT wants to use waitpid(), we're forced to have a handler
+     *       installed for SIGCHLD, so when working with child processes there
+     *       will be signals in the air and we will get VERR_INTERRUPTED returns.
+     *       The way HGCM handles interrupted calls is to silently (?) drop them
+     *       as they complete (see VMMDev), so the server knows little about it
+     *       and just goes on to the next message inline.
+     *
+     *       So, as a "temporary" mesasure, we block SIGCHLD here while waiting,
+     *       because it will otherwise be impossible do simple stuff like 'mkdir'
+     *       on a mac os x guest, and probably most other unix guests.
      */
-    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+#ifdef RT_OS_WINDOWS
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+#else
+    sigset_t SigSet;
+    sigemptyset(&SigSet);
+    sigaddset(&SigSet, SIGCHLD);
+    sigprocmask(SIG_BLOCK, &SigSet, NULL);
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    sigprocmask(SIG_UNBLOCK, &SigSet, NULL);
+#endif
     if (   rc == VERR_TOO_MUCH_DATA
         || RT_SUCCESS(rc))