[PATCH] screen: fix breakage when used inside qemu

[John Spencer]

From: John Spencer <address@hidden>
Date: Tue Sep 24 16:50:49 2013 +0200

Subject: [PATCH] screen: fix breakage when used inside qemu
    
when a rootfs is used in qemu with virtio mount,
new files created get the uid of the qemu user, not the uid of the
user inside qemu. this is usually no problem since you have full
access permissions to everything - however, screen did some uid
comparison checks, which only make sense when the screen sockets
are stored in a public place such as /var/run or /tmp.
in our case, they are stored in $HOME, so any screen there belongs
to us and we do not need to compare uids.

Signed-off-by: John Spencer <address@hidden>

--- screen-4.0.3.org/screen.c   2013-09-24 14:07:50.595849001 +0000
+++ screen-4.0.3/screen.c       2013-09-24 14:36:40.817786893 +0000
@@ -1020,8 +1020,11 @@
   else
 #endif
     {
+#ifdef SOCKDIR /* if SOCKDIR is not defined, the socket is in $HOME.
+                  in that case it does not make sense to compare uids. */
       if ((int)st.st_uid != real_uid)
        Panic(0, "You are not the owner of %s.", SockPath);
+#endif
     }
   if ((st.st_mode & 0777) != 0700)
     Panic(0, "Directory %s must have mode 700.", SockPath);
--- screen-4.2.1/socket.c
+++ screen-4.2.1-patched/socket.c
@@ -230,8 +230,11 @@
 #endif
 
       debug2("st.st_uid = %d, real_uid = %d\n", st.st_uid, real_uid);
+#ifdef SOCKDIR /* if SOCKDIR is not defined, the socket is in $HOME.
+                  in that case it does not make sense to compare uids. */
       if ((int)st.st_uid != real_uid)
        continue;
+#endif
       mode = (int)st.st_mode & 0777;
       debug1("  has mode 0%03o\n", mode);
 #ifdef MULTIUSER 
@@ -450,8 +453,11 @@
       Msg(0, "There is already a screen running on %s.", Filename(SockPath));
       if (stat(SockPath, &st) == -1)
        Panic(errno, "stat");
+#ifdef SOCKDIR /* if SOCKDIR is not defined, the socket is in $HOME.
+                  in that case it does not make sense to compare uids. */
       if ((int)st.st_uid != real_uid)
        Panic(0, "Unfortunately you are not its owner.");
+#endif
       if ((st.st_mode & 0700) == 0600)
        Panic(0, "To resume it, use \"screen -r\"");
       else
@@ -542,8 +548,11 @@
       Msg(0, "There is already a screen running on %s.", Filename(SockPath));
       if (stat(SockPath, &st) == -1)
        Panic(errno, "stat");
+#ifdef SOCKDIR /* if SOCKDIR is not defined, the socket is in $HOME.
+                  in that case it does not make sense to compare uids. */
       if (st.st_uid != real_uid)
        Panic(0, "Unfortunately you are not its owner.");
+#endif
       if ((st.st_mode & 0700) == 0600)
        Panic(0, "To resume it, use \"screen -r\"");
       else