Windows crash after DAG generation

[Quiark]

In short, it crashes because it tries to load the wrong path:

I0429 11:39:21.558773    5604 ethash.go:136] ... still generating DAG (825.0001873) ...
I0429 11:39:22.967854    5604 ethash.go:138] ... DAG generation completed ...
panic: open /tmp/dag: The system cannot find the path specified.

Details:
Downloaded the build Geth-Win64-20150428110804-0.9.12-60--a6a49cc.7z (a previous build had the same problem), then did

admin.newAccount()
admin.miner.start()

got expected result

I0429 11:25:34.912492    5604 ethash.go:94] Making cache for epoch: 6 (198524) (582b06447f087674bcc0a32a19961e77dafb9e17955792f79ec8936e3d9742fc)
true←[0m

> I0429 11:25:36.557586    5604 ethash.go:99] Took: 1.6440941s
> I0429 11:25:36.557586    5604 ethash.go:198] Retrieving DAG
> I0429 11:25:36.557586    5604 ethash.go:203] No DAG found. Generating new DAG in '/tmp/dag' (this takes a while)...
> I0429 11:25:39.978781    5604 chain_manager.go:605] imported 1 block(s) 0 queued in 13.0007ms. #198525 [aaa5e26b / aaa5e26b]
> I0429 11:25:41.558872    5604 ethash.go:136] ... still generating DAG (5.000286) ...
> I0429 11:25:46.559158    5604 ethash.go:136] ... still generating DAG (10.000572) ...
> I0429 11:25:51.559444    5604 ethash.go:136] ... still generating DAG (15.000858) ...
> I0429 11:25:51.959467    5604 chain_manager.go:605] imported 1 block(s) 0 queued in 7.0004ms. #198526 [667e7798 / 667e7798]
> I0429 11:25:56.558730    5604 ethash.go:136] ... still generating DAG (20.0001439) ...
> 
> ```
> ```

but then after finished it crashed with the message above. See http://pastebin.com/50Sq2QVP for full log

[Quiark]

EDIT: disregard, I didn't know I had to include a parameter

It seems like a general path problem, after starting again it can't find my previous account

> admin.unlock()
Please enter a passphrase now.
Passphrase:
Unlock account failed 'read C:\Users\Roman/AppData/Roaming/Ethereum/keys: The handle is invalid.'
false←[0m

[tgerring]

We should replace all instances of filesystem-related "/" or "" with http://golang.org/pkg/os/#PathSeparator or use http://golang.org/pkg/path/#Join

[obscuren]

PR #828 merged. Could you test again @Quiark ?

[Quiark]

I downloaded this build https://build.ethdev.com/builds/Windows%20Go%20develop%20branch/Geth-Win64-20150429085552-0.9.12-60--32373e3.7z

No change. geth is still trying to open /tmp/dag which is not going to work on Windows. I found in \ethereum\ethash\ethash.go in writeDagToDisk hardcoded /tmp/dag path.

EDIT: deleted comment about unlocking keys, I didn't understand how it works.

[maran]

This is pretty weird. I made a PR to fix this in ethereum/ethash#13 but @LefterisJP closed it because it was already fixed. Perhaps he could comment?

[fjl]

                                                                                  It is fixed In the ethash rewrite, which hasn't been merged yet.

[LefterisJP]

what he said.
Sorry for taking so long to merge. There are many issues that have come up in the meantime. Merging that PR on master may still not mean that it's gonna be immediately used by go-ethereum so maybe you could take a patch of maran's prorposed change and add it in go-ethereum temporarily so that users don't have this problem?

[drocta]

This seems (to me) to work now, with the build linked in the readme.