Re: [Haskell-cafe] problem reading /proc/interrupts with ByteString

Leandro Lisboa Penz:

I'm having some problems using ByteString.Char8.readFile to read "/proc/interrupts". I reads nothing. I guess maybe that's because the file is sort of special, but I could read it by opening and using ByteString.Char8.hGetContents.

ByteString.Char8.readFile uses hFileSize to determine the buffer size to use:

readFile f = bracket (openFile f ReadMode) hClose (\h -> hFileSize h >>= hGet h . fromIntegral)

Now, if you look at the size of /proc/interrupts, as reported by ls, you should see the problem. By contrast, ByteString.Char8.hGetContents determines the required buffer size by reading to the end of the file.