path: Move is_absolute check to sys::path

[Ayush1325]

I am working on fs support for UEFI 0, which similar to windows has prefix components, but is not quite same as Windows. It also seems that Prefix is tied closely to Windows and cannot really be extended 1.

This PR just tries to remove coupling between Prefix and absolute path checking to allow platforms to provide there own implementation to check if a path is absolute or not.

I am not sure if any platform other than windows currently uses Prefix, so I have kept the path.prefix().is_some() check in most cases.

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[tgross35]

This winds up keeping roughly the same pattern but has it repeated it in a few places, I'm not sure how strong the benefit is here. The UEFI implementation does look more complex though - would it work to leave the existing code but do something like this?

#[cfg(not(target_os = "uefi")]
return sys::path::is_absolute(self);

if cfg!(target_os = "redox") { /* rest of the existing code */ }

[Ayush1325]

This winds up keeping roughly the same pattern but has it repeated it in a few places, I'm not sure how strong the benefit is here. The UEFI implementation does look more complex though - would it work to leave the existing code but do something like this?

#[cfg(not(target_os = "uefi")]
return sys::path::is_absolute(self);

if cfg!(target_os = "redox") { /* rest of the existing code */ }

Well, the UEFI absolute check is pretty simple as well:

cfg!(target_os = "uefi") && (path.as_os_str().as_encoded_bytes().contains(&COLON) || path.as_os_str().as_encoded_bytes().contains(&FORWARD_SLASH))

With that said, I thought it was the policy not to introduce any new platform-specific behaviour outside of sys.

[tgross35]

Well, the UEFI absolute check is pretty simple as well:

Ah thanks, I was looking at the wrong code.

With that said, I thought it was the policy not to introduce any new platform-specific behaviour outside of sys.

I wouldn't think there could be much wrong with adding another branch to the existing config, especially considering that exact if block more or less has to exist in Unix anyway. That being said, this change is fine and may make things cleaner in the future with more targets. One small request then lgtm.

[tgross35]

@bors r+ rollup

[bors]

📌 Commit 1107382 has been approved by tgross35

It is now in the queue for this repository.