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randr: skip payload assembly in rrGetScreenResources() no data to send 

If there's no data to send, the whole reply payload can be skipped entirely.
This can also ease the whole code flow, and we don't need to rely on the
individual copy loops never trying to dereference a NULL pointer.
(what the analyzer can't proof). Also scoping several some variables that
are only used when there actually is data to send.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
This commit is contained in:
Enrico Weigelt, metux IT consult 2025-05-13 16:16:18 +02:00
parent df85b516c4
commit d93d9af35a
1 changed files with 14 additions and 18 deletions
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32
randr/rrscreen.c
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@ -488,10 +488,6 @@ rrGetScreenResources(ClientPtr client, Bool query)
CARD8 *extra = NULL;
unsigned long extraLen = 0;
int i, rc, has_primary = 0;
RRCrtc *crtcs;
RROutput *outputs;
xRRModeInfo *modeinfos;
CARD8 *names;
REQUEST_SIZE_MATCH(xRRGetScreenResourcesReq);
rc = dixLookupWindow(&pWin, stuff->window, client, DixGetAttrAccess);
@ -543,20 +539,19 @@ rrGetScreenResources(ClientPtr client, Bool query)
bytes_to_int32(rep.nbytesNames));
extraLen = rep.length << 2;
if (extraLen) {
extra = calloc(1, extraLen);
if (!extra) {
free(modes);
return BadAlloc;
}
}
else
extra = NULL;
if (!extraLen)
goto finish;
crtcs = (RRCrtc *) extra;
outputs = (RROutput *) (crtcs + pScrPriv->numCrtcs);
modeinfos = (xRRModeInfo *) (outputs + pScrPriv->numOutputs);
names = (CARD8 *) (modeinfos + num_modes);
extra = calloc(1, extraLen);
if (!extra) {
free(modes);
return BadAlloc;
}
RRCrtc *crtcs = (RRCrtc *) extra;
RROutput *outputs = (RROutput *) (crtcs + pScrPriv->numCrtcs);
xRRModeInfo *modeinfos = (xRRModeInfo *) (outputs + pScrPriv->numOutputs);
CARD8* names = (CARD8 *) (modeinfos + num_modes);
if (pScrPriv->primaryOutput && pScrPriv->primaryOutput->crtc) {
has_primary = 1;
@ -604,8 +599,9 @@ rrGetScreenResources(ClientPtr client, Bool query)
memcpy(names, mode->name, mode->mode.nameLength);
names += mode->mode.nameLength;
}
free(modes);
assert(bytes_to_int32((char *) names - (char *) extra) == rep.length);
finish:
free(modes);
}
if (client->swapped) {