Deprecated filepath.HasPrefix

[ankitm123]

While trying to solve the issue #290, I took a look at the dep source code. I see multiple instances of filepath.HasPrefix. The function is deprecated, so should we not remove/replace it from the source code? Take a look at this link:
https://golang.org/pkg/path/filepath/#HasPrefix

Ankit

[sdboyer]

@adg could you speak to this one?

[adg]

@sdboyer I don't remember this being deprecated, but I can see why it is. The places where we use it were once a simple strings.HasPrefix (which is all filepath.HasPrefix does).

We should probably replace such occurrences with our own function that uses filepath.Abs to canonicalize the paths before comparing them.

[sdboyer]

It's just strings.HasPrefix() on unix flavors, but there's more to it on windows. But it's that windows impl that seems - I guess? - to be more incorrect.

Either way, yeah, we should write our own implementation.

[ankitm123]

@adg, @sdboyer, I can work on it this weekend, if it is ok.

[adg]

I'd be very happy if you did! Thank you.

…

On 9 March 2017 at 15:08, ankitm123 ***@***.***> wrote: @adg <https://github.com/adg>, @sdboyer <https://github.com/sdboyer>, I can work on it this weekend, if it is ok. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#296 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AIDildDSds8wTdzxLUfzydN11cPVLJsfks5rj3s-gaJpZM4MVkXI> .

[zacps]

@ankitm123 Are you still working on this? I might take a look at it if you don't have time.

[ankitm123]

@zacps, I should have it done within 2 days.

[mattn]

any update on this?

[zacps]

I'll do it tomorrow unless @ankitm123 has a pull in.

[ankitm123]

@sdboyer, @zacps Sorry for the delay, I am in the process of joining a new job and relocating!
Please take a look at this piece of code, I will polish it a bit over the weekend, and if it fixes the issue, then I will submit a PR.
https://play.golang.org/p/EoAliG0rNG

I will use the os.pathseparator in the hasSuffix function, to make it cross platform.

[sdboyer]

Honestly, I'm not sure if that works or not, because I don't know what "not respecting path boundaries" means in those comments on the windows filepath.HasPrefix() implementation.

[zacps]

Should we expand special paths/environment variables/UNC paths? I think it makes sense for this:
~/path
to be the same as:
/home/USERNAME/path
and:
C:\Users\username\Documents
to be the same as:
\\HOSTNAME\Users\USERNAME\Documents
Do the current path/filepath tools handle this?

---

You also shouldn't use strings.compare() just use ==.

[ankitm123]

@sdboyer, I think what they mean by path boundaries is just path separator (/ in linux and \ in windows)
For instance:
filepath.HasPrefix("/home/user4/some-file","/home/user") returns true, where it should return false, because the real prefix that should get matched is /home/user4, and not /home/user. But I will investigate it a bit further.
The issues with HasPrefix are outlined here. I got this link from this discussion.

@zacps, Thanks for the suggestion. Using strings.Compare is not the ideal way to compare. I will change it to ==. Also, I think we can check is the filepath has ~ (say ~/file), and then use the os.environ function to replace it with /home/. I will include the changes, and we can see how it works. Thanks!
Update: Also, filepath.HasPrefix is just strings.HasPrefix, so it does not handle ~ and HOSTNAME