[pdftex] Manual: \pdffiledump and \pdfmdfivesum

[Bruno Le Floch]

Hello,

`\pdffiledump{foo.txt}` gives an empty result.  Using the keyword
`length` is necessary, for instance `\pdffiledump length 10{foo.txt}`.
I think it would be better if the pdfTeX manual (obtained by `texdoc
pdftex` on a TeXLive installation) would explain that the length
keyword is necessary.

Also, `\pdfmdfivesum{...}` is not explained, only `\pdfmdfivesum
file{...}`.  It would be good to state explicitly the difference, as
it is quite easy to miss the need for the keyword `file`.

Regards,

Bruno
PS: Putting Joseph in Cc as we had a related discussion recently.