From 16215b98d2df29165f0a2ad5d4083293f080453b Mon Sep 17 00:00:00 2001 From: "Enrico Weigelt, metux IT consult" Date: Mon, 17 Mar 2025 18:26:21 +0100 Subject: [PATCH] dix: add selection filtering hooks Add hooks for filtering and fully rewrite rewrite selection requests and events (what existing XACE hooks cannot do), e.g. for supporting separate selection name spaces. The hook can change individual fields in the parameter struct, so operation continues with these changed values (eg. replace the original selection name atom by a different one). It's also possible to stop operations completely (with given result code) - in that case the hook needs to take care of the remaining work to do (eg. sending events) Signed-off-by: Enrico Weigelt, metux IT consult --- dix/selection.c | 174 ++++++++++++++++++++++++++++++++----------- dix/selection_priv.h | 22 ++++++ xfixes/select.c | 43 +++++++++-- 3 files changed, 189 insertions(+), 50 deletions(-) diff --git a/dix/selection.c b/dix/selection.c index 7425b42c5..92e66ee16 100644 --- a/dix/selection.c +++ b/dix/selection.c @@ -66,6 +66,7 @@ SOFTWARE. Selection *CurrentSelections; CallbackListPtr SelectionCallback; +CallbackListPtr SelectionFilterCallback = NULL; int dixLookupSelection(Selection ** result, Atom selectionName, @@ -171,12 +172,27 @@ ProcSetSelectionOwner(ClientPtr client) if (CompareTimeStamps(time, currentTime) == LATER) return Success; - if (stuff->window != None) { - rc = dixLookupWindow(&pWin, stuff->window, client, DixSetAttrAccess); + /* allow extensions to intercept */ + SelectionFilterParamRec param = { + .client = client, + .selection = stuff->selection, + .owner = stuff->window, + .op = SELECTION_FILTER_SETOWNER, + }; + CallCallbacks(&SelectionFilterCallback, ¶m); + if (param.skip) { + if (param.status != Success) + client->errorValue = stuff->selection; + return param.status; + } + + if (param.owner != None) { + rc = dixLookupWindow(&pWin, param.owner, client, DixSetAttrAccess); if (rc != Success) return rc; } - if (!ValidAtom(stuff->selection)) { + + if (!ValidAtom(param.selection)) { client->errorValue = stuff->selection; return BadAtom; } @@ -184,10 +200,11 @@ ProcSetSelectionOwner(ClientPtr client) /* * First, see if the selection is already set... */ - rc = dixLookupSelection(&pSel, stuff->selection, client, DixSetAttrAccess); - - if (rc != Success) + rc = dixLookupSelection(&pSel, param.selection, client, DixSetAttrAccess); + if (rc != Success) { + client->errorValue = stuff->selection; return rc; + } /* If the timestamp in client's request is in the past relative to the time stamp indicating the last time the owner of the @@ -196,17 +213,27 @@ ProcSetSelectionOwner(ClientPtr client) if (CompareTimeStamps(time, pSel->lastTimeChanged) == EARLIER) return Success; if (pSel->client && (!pWin || (pSel->client != client))) { - xEvent event = { - .u.selectionClear.time = time.milliseconds, - .u.selectionClear.window = pSel->window, - .u.selectionClear.atom = pSel->selection + SelectionFilterParamRec eventParam = { + .client = client, + .recvClient = pSel->client, + .owner = pSel->window, + .selection = stuff->selection, + .op = SELECTION_FILTER_EV_CLEAR, }; - event.u.u.type = SelectionClear; - WriteEventsToClient(pSel->client, 1, &event); + CallCallbacks(&SelectionFilterCallback, &eventParam); + if (!param.skip) { + xEvent event = { + .u.selectionClear.time = time.milliseconds, + .u.selectionClear.window = eventParam.owner, + .u.selectionClear.atom = eventParam.selection, + }; + event.u.u.type = SelectionClear; + WriteEventsToClient(eventParam.recvClient, 1, &event); + } } pSel->lastTimeChanged = time; - pSel->window = stuff->window; + pSel->window = param.owner; pSel->pWin = pWin; pSel->client = (pWin ? client : NullClient); @@ -217,15 +244,25 @@ ProcSetSelectionOwner(ClientPtr client) int ProcGetSelectionOwner(ClientPtr client) { - int rc; Selection *pSel; REQUEST(xResourceReq); REQUEST_SIZE_MATCH(xResourceReq); - if (!ValidAtom(stuff->id)) { - client->errorValue = stuff->id; - return BadAtom; + /* allow extensions to intercept */ + SelectionFilterParamRec param = { + .client = client, + .selection = stuff->id, + .op = SELECTION_FILTER_GETOWNER, + }; + CallCallbacks(&SelectionFilterCallback, ¶m); + if (param.skip) { + goto out; + } + + if (!ValidAtom(param.selection)) { + param.status = BadAtom; + goto out; } xGetSelectionOwnerReply rep = { @@ -234,13 +271,13 @@ ProcGetSelectionOwner(ClientPtr client) .length = 0, }; - rc = dixLookupSelection(&pSel, stuff->id, client, DixGetAttrAccess); - if (rc == Success) + param.status = dixLookupSelection(&pSel, param.selection, param.client, DixGetAttrAccess); + if (param.status == Success) rep.owner = pSel->window; - else if (rc == BadMatch) + else if (param.status == BadMatch) rep.owner = None; else - return rc; + goto out; if (client->swapped) { swaps(&rep.sequenceNumber); @@ -249,6 +286,11 @@ ProcGetSelectionOwner(ClientPtr client) WriteToClient(client, sizeof(rep), &rep); return Success; + +out: + if (param.status != Success) + client->errorValue = stuff->id; + return param.status; } int @@ -263,12 +305,29 @@ ProcConvertSelection(ClientPtr client) REQUEST(xConvertSelectionReq); REQUEST_SIZE_MATCH(xConvertSelectionReq); - rc = dixLookupWindow(&pWin, stuff->requestor, client, DixSetAttrAccess); + /* allow extensions to intercept */ + SelectionFilterParamRec param = { + .client = client, + .selection = stuff->selection, + .op = SELECTION_FILTER_CONVERT, + .requestor = stuff->requestor, + .property = stuff->property, + .target = stuff->target, + .time = stuff->time, + }; + CallCallbacks(&SelectionFilterCallback, ¶m); + if (param.skip) { + if (param.status != Success) + client->errorValue = stuff->selection; + return param.status; + } + + rc = dixLookupWindow(&pWin, param.requestor, client, DixSetAttrAccess); if (rc != Success) return rc; - paramsOkay = ValidAtom(stuff->selection) && ValidAtom(stuff->target); - paramsOkay &= (stuff->property == None) || ValidAtom(stuff->property); + paramsOkay = ValidAtom(param.selection) && ValidAtom(param.target); + paramsOkay &= (param.property == None) || ValidAtom(param.property); if (!paramsOkay) { client->errorValue = stuff->property; return BadAtom; @@ -277,32 +336,63 @@ ProcConvertSelection(ClientPtr client) if (stuff->time == CurrentTime) UpdateCurrentTime(); - rc = dixLookupSelection(&pSel, stuff->selection, client, DixReadAccess); + rc = dixLookupSelection(&pSel, param.selection, client, DixReadAccess); memset(&event, 0, sizeof(xEvent)); if (rc != Success && rc != BadMatch) return rc; - else if (rc == Success && pSel->window != None) { - event.u.u.type = SelectionRequest; - event.u.selectionRequest.owner = pSel->window; - event.u.selectionRequest.time = stuff->time; - event.u.selectionRequest.requestor = stuff->requestor; - event.u.selectionRequest.selection = stuff->selection; - event.u.selectionRequest.target = stuff->target; - event.u.selectionRequest.property = stuff->property; - if (pSel->client && pSel->client != serverClient && - !pSel->client->clientGone) { - WriteEventsToClient(pSel->client, 1, &event); - return Success; + + /* If the specified selection has an owner, the X server sends + SelectionRequest event to that owner */ + if (rc == Success && pSel->window != None && pSel->client && + pSel->client != serverClient && !pSel->client->clientGone) + { + SelectionFilterParamRec evParam = { + .client = client, + .selection = stuff->selection, + .op = SELECTION_FILTER_EV_REQUEST, + .owner = pSel->window, + .requestor = stuff->requestor, + .property = stuff->property, + .target = stuff->target, + .time = stuff->time, + .recvClient = pSel->client, + }; + + CallCallbacks(&SelectionFilterCallback, &evParam); + if (evParam.skip) { + if (evParam.status != Success) + client->errorValue = stuff->selection; + return evParam.status; } + + event.u.u.type = SelectionRequest; + event.u.selectionRequest.owner = evParam.owner; + event.u.selectionRequest.time = evParam.time; + event.u.selectionRequest.requestor = evParam.requestor; + event.u.selectionRequest.selection = evParam.selection; + event.u.selectionRequest.target = evParam.target; + event.u.selectionRequest.property = evParam.property; + WriteEventsToClient(evParam.recvClient, 1, &event); + return Success; + } + + /* If no owner for the specified selection exists, the X server generates + a SelectionNotify event to the requestor with property None. */ + param.property = None; + CallCallbacks(&SelectionFilterCallback, ¶m); + if (param.skip) { + if (param.status != Success) + client->errorValue = stuff->selection; + return param.status; } event.u.u.type = SelectionNotify; - event.u.selectionNotify.time = stuff->time; - event.u.selectionNotify.requestor = stuff->requestor; - event.u.selectionNotify.selection = stuff->selection; - event.u.selectionNotify.target = stuff->target; - event.u.selectionNotify.property = None; + event.u.selectionNotify.time = param.time; + event.u.selectionNotify.requestor = param.requestor; + event.u.selectionNotify.selection = param.selection; + event.u.selectionNotify.target = param.target; + event.u.selectionNotify.property = param.property; WriteEventsToClient(client, 1, &event); return Success; } diff --git a/dix/selection_priv.h b/dix/selection_priv.h index 3eea9413e..24492d9ca 100644 --- a/dix/selection_priv.h +++ b/dix/selection_priv.h @@ -34,10 +34,32 @@ typedef struct { SelectionCallbackKind kind; } SelectionInfoRec; +#define SELECTION_FILTER_GETOWNER 1 +#define SELECTION_FILTER_SETOWNER 2 +#define SELECTION_FILTER_CONVERT 3 +#define SELECTION_FILTER_LISTEN 4 +#define SELECTION_FILTER_EV_REQUEST 5 +#define SELECTION_FILTER_EV_CLEAR 6 +#define SELECTION_FILTER_NOTIFY 7 + +typedef struct { + int op; + Bool skip; + int status; + Atom selection; + ClientPtr client; // initiating client + ClientPtr recvClient; // client receiving event + Time time; // request time stamp + Window requestor; + Window owner; + Atom property; + Atom target; +} SelectionFilterParamRec, *SelectionFilterParamPtr; extern Selection *CurrentSelections; extern CallbackListPtr SelectionCallback; +extern CallbackListPtr SelectionFilterCallback; int dixLookupSelection(Selection **result, Atom name, diff --git a/xfixes/select.c b/xfixes/select.c index 58fa514f3..e199934af 100644 --- a/xfixes/select.c +++ b/xfixes/select.c @@ -23,6 +23,7 @@ #include #include "dix/dix_priv.h" +#include "dix/selection_priv.h" #include "xfixesint.h" #include "xace.h" @@ -78,13 +79,25 @@ XFixesSelectionCallback(CallbackListPtr *callbacks, void *data, void *args) UpdateCurrentTimeIf(); for (e = selectionEvents; e; e = e->next) { if (e->selection == selection && (e->eventMask & eventMask)) { + + /* allow extensions to intercept */ + SelectionFilterParamRec param = { + .client = e->pClient, + .selection = selection->selection, + .owner = (subtype == XFixesSetSelectionOwnerNotify) ? + selection->window : 0, + .op = SELECTION_FILTER_NOTIFY, + }; + CallCallbacks(&SelectionFilterCallback, ¶m); + if (param.skip) + continue; + xXFixesSelectionNotifyEvent ev = { .type = XFixesEventBase + XFixesSelectionNotify, .subtype = subtype, .window = e->pWindow->drawable.id, - .owner = (subtype == XFixesSetSelectionOwnerNotify) ? - selection->window : 0, - .selection = e->selection->selection, + .owner = param.owner, + .selection = param.selection, .timestamp = currentTime.milliseconds, .selectionTimestamp = selection->lastTimeChanged.milliseconds }; @@ -122,8 +135,22 @@ ProcXFixesSelectSelectionInput(ClientPtr client) REQUEST(xXFixesSelectSelectionInputReq); REQUEST_SIZE_MATCH(xXFixesSelectSelectionInputReq); + /* allow extensions to intercept */ + SelectionFilterParamRec param = { + .client = client, + .selection = stuff->selection, + .owner = stuff->window, + .op = SELECTION_FILTER_LISTEN, + }; + CallCallbacks(&SelectionFilterCallback, ¶m); + if (param.skip) { + if (param.status != Success) + client->errorValue = param.selection; + return param.status; + } + WindowPtr pWindow; - int rc = dixLookupWindow(&pWindow, stuff->window, client, DixGetAttrAccess); + int rc = dixLookupWindow(&pWindow, param.owner, param.client, DixGetAttrAccess); if (rc != Success) return rc; if (stuff->eventMask & ~SelectionAllEvents) { @@ -135,13 +162,13 @@ ProcXFixesSelectSelectionInput(ClientPtr client) SelectionEventPtr *prev, e; Selection *selection; - rc = dixLookupSelection(&selection, stuff->selection, client, DixGetAttrAccess); + rc = dixLookupSelection(&selection, param.selection, param.client, DixGetAttrAccess); if (rc != Success) return rc; for (prev = &selectionEvents; (e = *prev); prev = &e->next) { if (e->selection == selection && - e->pClient == client && e->pWindow == pWindow) { + e->pClient == param.client && e->pWindow == pWindow) { break; } } @@ -158,9 +185,9 @@ ProcXFixesSelectSelectionInput(ClientPtr client) e->next = 0; e->selection = selection; - e->pClient = client; + e->pClient = param.client; e->pWindow = pWindow; - e->clientResource = FakeClientID(client->index); + e->clientResource = FakeClientID(param.client->index); /* * Add a resource hanging from the window to