<div dir="auto">I thought generating tokens for an expression needed a lock since it uses the lexer but that the parser did not. I could be wrong though.</div><div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sat, Feb 19, 2022 at 10:21 AM Steve Lime <<a href="mailto:sdlime@gmail.com">sdlime@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="auto">I don’t remember offhand and will have to check. That said if there is a attribute level token in a layer level expression than that would explain your research. Is there really no way to get info on the expression(s) in question?</div><div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sat, Feb 19, 2022 at 9:22 AM Tamas Szekeres <<a href="mailto:szekerest@gmail.com" target="_blank">szekerest@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">I'm not too familiar in the current parser/lexer implementation, but is msTokenizeExpression and yyparse supposed to be protected by the same parser lock in <span style="color:rgb(0,0,0)">msEvalContext</span>? Or if
msTokenizeExpression doesn't leave any global variables behind, should yyparse be protected by it's own?<div><br></div><div>Thanks,</div><div><br></div><div>Tamas</div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">Steve Lime <<a href="mailto:sdlime@gmail.com" target="_blank">sdlime@gmail.com</a>> ezt írta (időpont: 2022. febr. 19., Szo, 16:02):<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto">Requires and labelrequires aren’t operating at the feature level, rather the layer level so they definitely don’t support attribute binding. We’d need to whip up a test case to figure out a method to trap this. The workaround is to fix the expression. I mean, obviously we don’t want to crash but it’s never going to work if written as you suspect.</div><div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sat, Feb 19, 2022 at 7:55 AM Tamas Szekeres <<a href="mailto:szekerest@gmail.com" target="_blank">szekerest@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">Hi Devs,<div><br></div><div>I got a crash log which shows that the access violation is happening in the following location:</div><div><br></div><div><pre style="white-space:pre-wrap"><i><font color="#ff0000">mapserver!yylex+0x1b5 [e:\builds-t1\src\mapserver-intramaps\vc15x64\mapparser.y @ 858]
mapserver!yyparse+0x247 [e:\home\even\mapserver\mapserver\mapparser.c @ 1461]
mapserver!msEvalContext+0x178 [e:\builds-t1\src\mapserver-intramaps\maputil.c @ 442]
mapserver!msDrawVectorLayer+0xb0 [e:\builds-t1\src\mapserver-intramaps\mapdraw.c @ 918]
mapserver!msDrawLayer+0x3a3 [e:\builds-t1\src\mapserver-intramaps\mapdraw.c @ 813]
mapserver!msDrawMap+0x415 [e:\builds-t1\src\mapserver-intramaps\mapdraw.c @ 403]
mapscript!CSharp_mapObj_draw+0xd</font></i></pre>By looking into the corresponding code, the problem has happened in the following location in yylex():<pre style="white-space:pre-wrap"><i><font color="#ff0000"> case MS_TOKEN_BINDING_INTEGER:<br> token = NUMBER;<br> ----> (*lvalp).dblval = atof(p->shape->values[p->expr->curtoken->tokenval.bindval.index]);<br> break;</font></i><font color="#000000"><br></font></pre>In maputil.c the call stack location is here (msEvalContext):<pre style="white-space:pre-wrap"><i><font color="#ff0000">msTokenizeExpression(&e, NULL, NULL);<br><br> p.shape = NULL;<br> p.expr = &e;<br> p.expr->curtoken = p.expr->tokens; /* reset */<br> p.type = MS_PARSE_TYPE_BOOLEAN;<br><br>-----> status = yyparse(&p);<br><br> msFreeExpression(&e);</font></i><font color="#000000"><br></font></pre>And in mapdraw.c<pre style="white-space:pre-wrap"><i><font color="#ff0000"> /* TODO TBT: draw as raster layer in vector renderers */<br><br>-----> annotate = msEvalContext(map, layer, layer->labelrequires);<br> if(map->scaledenom > 0) {<br> if((layer->labelmaxscaledenom != -1) && (map->scaledenom >= layer->labelmaxscaledenom)) annotate = MS_FALSE;<br> if((layer->labelminscaledenom != -1) && (map->scaledenom < layer->labelminscaledenom)) annotate = MS_FALSE;<br> }</font></i><font color="#000000"><br></font></pre>I'm not sure if the LABELREQUIRES option supports attribute binding (probably not) and in that case the p->expr->curtoken->tokenval.bindval.index would probably have undefined value. I don't have any information about the corresponding LABELREQUIRES expression , but if I assume it doesn't contain attribute binding, then this crash might probably happen due to a missing parser lock around <i style="color:rgb(0,0,0);white-space:pre-wrap">yyparse(&p). </i>What do you think about the problem and how could we work around this?</div><div><br></div><div>Thanks,</div><div><br></div><div>Tamas<br><pre style="color:rgb(0,0,0);white-space:pre-wrap"><br></pre></div></div>
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