[X2Go-Commits] [nx-libs] 300/429: Compext.c: fix comparisons of 16bit sequence numbers

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

commit 2739d0868f849a186f7b06cb0032ee0d2c599532
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.
---
 .../programs/Xserver/hw/nxagent/compext/Compext.c  | 24 +++++++++++-----------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/nx-X11/programs/Xserver/hw/nxagent/compext/Compext.c b/nx-X11/programs/Xserver/hw/nxagent/compext/Compext.c
index 7e5a9799d..dcb91348b 100644
--- a/nx-X11/programs/Xserver/hw/nxagent/compext/Compext.c
+++ b/nx-X11/programs/Xserver/hw/nxagent/compext/Compext.c
@@ -3451,10 +3451,10 @@ static Bool _NXCollectImageHandler(Display *dpy, xReply *rep, char *buf,
   state = (_NXCollectImageState *) data;
 
   #ifdef DEBUG_IMAGE
-  fprintf(stderr, "******%s: sequence: received [%ld] expected [%ld]  16bit received [%d] expected [%d]\n",
+  fprintf(stderr, "******%s: sequence: received [%hu] expected [%lu]  16bit received [%hu] expected [%hu]\n",
           __func__,
-          (long) rep -> generic.sequenceNumber, (long)state -> sequence,
-          rep -> generic.sequenceNumber % 65536, (int)(state -> sequence) % 65536);
+          rep -> generic.sequenceNumber, state -> sequence,
+          rep -> generic.sequenceNumber % 65536, (CARD16)(state -> sequence) % 65536);
   #endif
 
   if ((rep -> generic.sequenceNumber % 65536) !=
@@ -3846,10 +3846,10 @@ static Bool _NXCollectPropertyHandler(Display *dpy, xReply *rep, char *buf,
   state = (_NXCollectPropertyState *) data;
 
   #ifdef DEBUG_PROPERTY
-  fprintf(stderr, "******%s: sequence: received [%ld] expected [%ld]  16bit received [%d] expected [%d]\n",
+  fprintf(stderr, "******%s: sequence: received [%hu] expected [%lu]  16bit received [%hu] expected [%hu]\n",
           __func__,
-          (long) rep -> generic.sequenceNumber, (long)state -> sequence,
-          rep -> generic.sequenceNumber % 65536, (int)(state -> sequence) % 65536);
+          rep -> generic.sequenceNumber, state -> sequence,
+          rep -> generic.sequenceNumber % 65536, (CARD16)(state -> sequence) % 65536);
   #endif
 
   if ((rep -> generic.sequenceNumber % 65536) !=
@@ -4219,10 +4219,10 @@ static Bool _NXCollectGrabPointerHandler(Display *dpy, xReply *rep, char *buf,
   state = (_NXCollectGrabPointerState *) data;
 
   #ifdef DEBUG_POINTER
-  fprintf(stderr, "******%s: sequence: received [%ld] expected [%ld]  16bit received [%d] expected [%d]\n",
+  fprintf(stderr, "******%s: sequence: received [%hu] expected [%lu]  16bit received [%hu] expected [%hu]\n",
           __func__,
-          (long) rep -> generic.sequenceNumber, (long)state -> sequence,
-          rep -> generic.sequenceNumber % 65536, (int)(state -> sequence) % 65536);
+          rep -> generic.sequenceNumber, state -> sequence,
+          rep -> generic.sequenceNumber % 65536, (CARD16)(state -> sequence) % 65536);
   #endif
 
   if ((rep -> generic.sequenceNumber % 65536) !=
@@ -4511,10 +4511,10 @@ static Bool _NXCollectInputFocusHandler(Display *dpy, xReply *rep, char *buf,
   state = (_NXCollectInputFocusState *) data;
 
   #ifdef DEBUG_INPUT
-  fprintf(stderr, "******%s: sequence: received [%ld] expected [%ld]  16bit received [%d] expected [%d]\n",
+  fprintf(stderr, "******%s: sequence: received [%hu] expected [%lu]  16bit received [%hu] expected [%hu]\n",
           __func__,
-          (long) rep -> generic.sequenceNumber, (long)state -> sequence,
-          rep -> generic.sequenceNumber % 65536, (int)(state -> sequence) % 65536);
+          rep -> generic.sequenceNumber, state -> sequence,
+          rep -> generic.sequenceNumber % 65536, (CARD16)(state -> sequence) % 65536);
   #endif
 
   if ((rep -> generic.sequenceNumber % 65536) !=

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