[Dev-luatex] file permissions

[Hans Hagen]

On 5-2-2011 9:11, Reinhard Kotucha wrote:

> In order to test whether a file is readable I currently open this file
> in a protected call.  This is also possible for directories when I run
> lfs.dir() inside pcall().  It's not very elegant, and I still have
> no idea how to test whether a file is writable.  I could try to open
> the file in append mode, but I fear that if the file is writable, this
> test would change the time stamps.  Not very elegant either.

I use something

function file.is_writable(name)
     local d = string.match(name,"^(.+)[/\\].-$") or "."
     local a = lfs.attributes(name) or lfs.attributes(d)
     return a and string/sub(a.permissions,2,2) == "w"
end

function file.is_readable(name)
     local a = lfs.attributes(name)
     return a and string.sub(a.permissions,1,1) == "r"
end

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