[X2Go-Commits] [nx-libs] 283/429: Compext.c: fix comparisons of 16bit sequence numbers

[git-admin at x2go.org]

This is an automated email from the git hooks/post-receive script.

x2go pushed a commit to branch 3.6.x
in repository nx-libs.

commit 1b4ebce2ce8ef29c01bd124ed56c9d6a14c9a82d
Author: Ulrich Sibiller <uli42 at gmx.de>
Date:   Wed Mar 17 22:17:55 2021 +0100

    Compext.c: fix comparisons of 16bit sequence numbers
    
    rep->generic.sequenceNumber is of type CARD16
    state->sequence is of type unsigned long
    
    Converting state->sequence to an int as it has been done since the
    first version of nxcomp I know of (1.3.0-18 from 2003) is wrong here
    because for numbers > INT_MAX this will result in a negative number,
    which, after applying the 16bit modulo, will not match
    rep->generic.sequenceNumber.
    
    Example with numbers:
    
    CARD16 c = 24565
    unsigned long u = 3179110389
    
    c % 65536 = 24565
    u % 65536 = 24565
    
    (int)(u) = -1115856907
    (int)(u) % 65536 = -40971
    
    -40971 will not match 24565
    
    To fix this we need to ensure the number stays positive. We use CARD16
    for this to match the type in the request which is a 16bit number. On
    my system CARD16 is unsigned short which is guaranteed to contain _at
    least_ the 0-65,535 range. As there is no upper limit of the range we
    cannot drop the modulo because we need this value to be 16bit and not
    more.
    
    Thanks to Norm Green for providing log after log until we could
    finally identify the reason for him seeing "Xlib: unexpected async
    reply (sequence 0x94b01439)!" when pasting stopped working.
---
 nx-X11/programs/Xserver/hw/nxagent/compext/Compext.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/nx-X11/programs/Xserver/hw/nxagent/compext/Compext.c b/nx-X11/programs/Xserver/hw/nxagent/compext/Compext.c
index 4a8dacaf4..7a6cb9e30 100644
--- a/nx-X11/programs/Xserver/hw/nxagent/compext/Compext.c
+++ b/nx-X11/programs/Xserver/hw/nxagent/compext/Compext.c
@@ -3435,7 +3435,7 @@ static Bool _NXCollectImageHandler(Display *dpy, xReply *rep, char *buf,
   state = (_NXCollectImageState *) data;
 
   if ((rep -> generic.sequenceNumber % 65536) !=
-          ((int)(state -> sequence) % 65536))
+          ((CARD16)(state -> sequence) % 65536))
   {
     #ifdef TEST
     fprintf(stderr, "******_NXCollectImageHandler: Unmatched sequence [%d] for opcode [%d] "
@@ -3819,7 +3819,7 @@ static Bool _NXCollectPropertyHandler(Display *dpy, xReply *rep, char *buf,
   state = (_NXCollectPropertyState *) data;
 
   if ((rep -> generic.sequenceNumber % 65536) !=
-          ((int)(state -> sequence) % 65536))
+          ((CARD16)(state -> sequence) % 65536))
   {
     #ifdef TEST
     fprintf(stderr, "******_NXCollectPropertyHandler: Unmatched sequence [%d] for opcode [%d] "
@@ -4173,7 +4173,7 @@ static Bool _NXCollectGrabPointerHandler(Display *dpy, xReply *rep, char *buf,
   state = (_NXCollectGrabPointerState *) data;
 
   if ((rep -> generic.sequenceNumber % 65536) !=
-          ((int)(state -> sequence) % 65536))
+          ((CARD16)(state -> sequence) % 65536))
   {
     #ifdef TEST
     fprintf(stderr, "******_NXCollectGrabPointerHandler: Unmatched sequence [%d] for opcode [%d] "
@@ -4447,7 +4447,7 @@ static Bool _NXCollectInputFocusHandler(Display *dpy, xReply *rep, char *buf,
   state = (_NXCollectInputFocusState *) data;
 
   if ((rep -> generic.sequenceNumber % 65536) !=
-          ((int)(state -> sequence) % 65536))
+          ((CARD16)(state -> sequence) % 65536))
   {
     #ifdef TEST
     fprintf(stderr, "******_NXCollectInputFocusHandler: Unmatched sequence [%d] for opcode [%d] "

--
Alioth's /home/x2go-admin/maintenancescripts/git/hooks/post-receive-email on /srv/git/code.x2go.org/nx-libs.git