738468 - DebuggerScript_getUrl crashes if script->filename is null

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Jason Orendorff [:jorendorff]]

This definitely happens in the browser. We need a shell function that creates functions with null filenames in order to test it.

Comment 1

[Jason Orendorff [:jorendorff]]

So I can't tell if we're actually supposed to support NULL filenames or not. The JSAPI documentation doesn't really say, but we don't JS_ASSERT(filename), and if we did I think we'd break Gecko.

So we probably should support NULL filenames, but there are no tests and in fact if I make it testable then I immediately get weird behavior:

js> evaluate("throw new Error()", {fileName: null});
js>

The error is never thrown. In fact creating the error object mysteriously fails, because of this code in jsexn.cpp:Exception():

669	            filename = FilenameToString(cx, iter.script()->filename);
670	            if (!filename)
671	                return false;

So basically this is a mess.

Comment 2

[Jason Orendorff [:jorendorff]]

oh for the love of Mike

Comment 3

[Jason Orendorff [:jorendorff]]

OK, we definitely have null-filename scripts running around, because the patch in bug 738480 causes us to segfault when browser/devtools/commandline/test/browser_gcli_break.js tries to examine them.

Better to support this everywhere than to ban it... I guess? Any other JSAPI people care?

Comment 4

[Jason Orendorff [:jorendorff]]

Attachment: v1

This is gross. I'm convinced we should do away with null filenames, but let's stop the crashes first and do the API change in a different bug.

Comment 5

[Jim Blandy :jimb]

Comment on attachment 626690 [details] [diff] [review]
v1

Review of attachment 626690 [details] [diff] [review]:
-----------------------------------------------------------------

Looks great. One semi-nit; only change if you agree it's clearer.

::: js/src/jsexn.cpp
@@ +563,5 @@
>              return false;
>          args[1].setString(filename);
>      } else {
> +        const char *cfilename;
> +        if (!iter.done() && (cfilename = iter.script()->filename)) {

nit: Assignment operators in 'if' conditions aren't very legible. Could we perhaps:

filename = cx->runtime->emptyString;
if (!iter.done()) {
  const char *cfilename = iter.script()->filename;
  if (cfilename) {
    filename = FilenameToString(cx, cfilename);
    if (!filename)
      return false;
  }
}

Comment 6

[Jason Orendorff [:jorendorff]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/29a18a93721d

Comment 7

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/29a18a93721d