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glx: Demand success from CreateContext requests (v2)

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GLXCreate{,New}Context, like most X resource creation requests, does not
emit a reply and therefore is emitted into the X stream asynchronously.
However, unlike most resource creation requests, the GLXContext we
return is a handle to library state instead of an XID. So if context
creation fails for any reason - say, the server doesn't support indirect
contexts - then we will fail in strange places for strange reasons.

We could make every GLX entrypoint robust against half-created contexts,
or we could just verify that context creation worked. Reuse the
__glXIsDirect code to do this, as a cheap way of verifying that the
XID is real.

glXCreateContextAttribsARB solves this by using the _checked version of
the xcb command, so effectively this change makes the classic context
creation paths as robust as CreateContextAttribs.

v2: Better use of Bool, check that error != NULL first (Olivier Fourdan)

Signed-off-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
This commit is contained in:
Adam Jackson 2018-08-07 16:55:37 -04:00
parent f7fae7f64e
commit 16f1023037
1 changed files with 55 additions and 38 deletions
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93
src/glx/glxcmds.c
View file

@ -272,6 +272,44 @@ glx_context_init(struct glx_context *gc,
return True;
}
/**
* Determine if a context uses direct rendering.
*
* \param dpy Display where the context was created.
* \param contextID ID of the context to be tested.
* \param error Out parameter, set to True on error if not NULL
*
* \returns \c True if the context is direct rendering or not.
*/
static Bool
__glXIsDirect(Display * dpy, GLXContextID contextID, Bool *error)
{
CARD8 opcode;
xcb_connection_t *c;
xcb_generic_error_t *err;
xcb_glx_is_direct_reply_t *reply;
Bool is_direct;
opcode = __glXSetupForCommand(dpy);
if (!opcode) {
return False;
}
c = XGetXCBConnection(dpy);
reply = xcb_glx_is_direct_reply(c, xcb_glx_is_direct(c, contextID), &err);
is_direct = (reply != NULL && reply->is_direct) ? True : False;
if (err != NULL) {
if (error)
*error = True;
__glXSendErrorForXcb(dpy, err);
free(err);
}
free(reply);
return is_direct;
}
/**
* Create a new context.
@ -376,6 +414,21 @@ CreateContext(Display *dpy, int generic_id, struct glx_config *config,
gc->share_xid = shareList ? shareList->xid : None;
gc->imported = GL_FALSE;
/* Unlike most X resource creation requests, we're about to return a handle
* with client-side state, not just an XID. To simplify error handling
* elsewhere in libGL, force a round-trip here to ensure the CreateContext
* request above succeeded.
*/
{
Bool error = False;
int isDirect = __glXIsDirect(dpy, gc->xid, &error);
if (error != False || isDirect != gc->isDirect) {
gc->vtable->destroy(gc);
gc = NULL;
}
}
return (GLXContext) gc;
}
@ -612,42 +665,6 @@ glXCopyContext(Display * dpy, GLXContext source_user,
}
/**
* Determine if a context uses direct rendering.
*
* \param dpy Display where the context was created.
* \param contextID ID of the context to be tested.
*
* \returns \c True if the context is direct rendering or not.
*/
static Bool
__glXIsDirect(Display * dpy, GLXContextID contextID)
{
CARD8 opcode;
xcb_connection_t *c;
xcb_generic_error_t *err;
xcb_glx_is_direct_reply_t *reply;
Bool is_direct;
opcode = __glXSetupForCommand(dpy);
if (!opcode) {
return False;
}
c = XGetXCBConnection(dpy);
reply = xcb_glx_is_direct_reply(c, xcb_glx_is_direct(c, contextID), &err);
is_direct = (reply != NULL && reply->is_direct) ? True : False;
if (err != NULL) {
__glXSendErrorForXcb(dpy, err);
free(err);
}
free(reply);
return is_direct;
}
/**
* \todo
* Shouldn't this function \b always return \c False when
@ -668,7 +685,7 @@ glXIsDirect(Display * dpy, GLXContext gc_user)
#ifdef GLX_USE_APPLEGL /* TODO: indirect on darwin */
return False;
#else
return __glXIsDirect(dpy, gc->xid);
return __glXIsDirect(dpy, gc->xid, NULL);
#endif
}
@ -1428,7 +1445,7 @@ glXImportContextEXT(Display *dpy, GLXContextID contextID)
return NULL;
}
if (__glXIsDirect(dpy, contextID))
if (__glXIsDirect(dpy, contextID, NULL))
return NULL;
opcode = __glXSetupForCommand(dpy);