ppm: raise an error if fopen failed

[deltheil]

Apart from this minor PR, note that I faced this problem while re-installing and running tests (that failed / seg. faulted because of missing assets). LuaRocks install logs indicated that:

-- Installing: /path/to/torch/install/lib/luarocks/rocks/image/1.1.alpha-0/lua/image/assets/lena.jpg
[...]
Warning: /path/to/torch/install/share/lua/5.1/image/assets/lena.jpg is not tracked by this installation of LuaRocks. Moving it to /path/to/torch/install/share/lua/5.1/image/assets/lena.jpg~~~

First time ever I encountered this. Plus: it sounds like there is a race or something because it is not reproducible.

So the question is: is it the right way to do to install asset files on behalf of LuaRocks like here? (apparently not)

I thought about using copy_directories:

build = {
   type = "command",
   -- ...
   copy_directories = { "assets" }
}

But then the assets are in a non standard location - see this discussion on this topic: luarocks/luarocks#168

What do you guys think would be the right solution?

[soumith]

we install assets via cmake INSTALL, into the lua directory itself. any issues with that?

[soumith]

for example, we install the .md files already this way (for in-line help)

[deltheil]

This is what is done for torch/image too:

INSTALL(DIRECTORY "assets" DESTINATION "${Torch_INSTALL_LUA_PATH_SUBDIR}/image")

The thing is from time to time LuaRocks complains about files not tracked by this installation of LuaRocks (see above install logs) - and move them with a ~~ suffix.

It's definitely a problem as tests might fail then.

[soumith]

:O luarocks, what are you doing....

[deltheil]

This is why I planned to fix this by using copy_directories - but then things get more complicated with paths even though using something like https://github.com/hishamhm/datafile might help.

[soumith]

i wonder if we can trick luarocks to tracking the file.
datafile seems a bit over the top for the problem at hand, where paths.thisfile works 100% of the time.

[deltheil]

@soumith OK so this is a side-effect. At first I had our custom fork installed (see #133 (comment)) which is named image 1.1.buffer-0. When I (re)install stock torch/image then this problem occurs: assets/lena.png is not tracked by this installation of LuaRocks ...

So in normal conditions it should never appear. Sorry for the noise around that - but I thought it was worth sharing!

[soumith]

oh i see. either ways, good to know.