Ability to modify content in a stream

[cgilling]

I'm in the middle of trying to transition some code that I have written in C/C++ over to go and one of the pieces that I have is something that will go into the file and turn off macros in .doc files so as to make them safer to process in ms word. In order to do this, I merely go into the doc file and flip the length of the micro section to be 0 so that word no longer picks up the macros.

To enable this in go I would need the ability to be able to modify streams. I'm wondering if you would be open to the idea of having File object allow overwriting (not appending as that sounds much more complicated).

[richardlehane]

Hi cgilling
I've just had a quick go at adding the io.Seeker and io.Writer interfaces to File objects.
This should allow you to seek within a File and change bytes.
Make sure your underlying source is an io.WriterAt and has write permissions if a file.

Current implementation is quick and nasty and the test function (https://github.com/richardlehane/mscfb/blob/master/mscfb_test.go#L146) isn't at all comprehensive. So please consider this experimental feature for now.

Will be interested to hear how you get on with it.

cheers
Richard

[richardlehane]

some tests now failing, this needs a bit more work, shouldn't take long

[richardlehane]

basic tests, now passing. Added ReadAt() and WriteAt() methods too. See doco at https://godoc.org/github.com/richardlehane/mscfb for usage. Think this is ready to go now.

[cgilling]

sweet thanks, I'll give it a spin soon

[cgilling]

Just a quick update, works great, I was able to implement what I wanted and sent 100,000 random documents through it (of various filetypes include non mscfb filetypes) and no crashing.

Thanks again for the quick turnaround on the request

[richardlehane]

Glad to hear, thx for the request