ignore exec.ErrDot when starting caddy in background

[WeidiDeng]

Fix 6508.

[mholt]

But isn't this a security risk? The reason this error is returned is because this may be unexpected. (Sigh, I don't understand why Windows does this. Of course putting binaries in an explicit PATH is a security benefit.)

[WeidiDeng]

os.Arg[0] is the program name, which may or may not be a relative path. In case it's a relative path, it still points to the path where the executable is. The security risk is only when the executable it points to may not be what we wanted. That has to do with executable resolution in PWD.

The only way this path resolve to an executable that' not wanted is very complex and depends too much on timing. Caddy has to start and the original executable get unlinked and a new executable named caddy has to be created before the original caddy gets to the place where it spawns a new caddy process. This is very unlikely to happen in the real world.

I think caddy start is a convenient way to run a caddy. Denying user usage simply because it's not put in the PATH directory is against simple to use philosophy.

[mholt]

Ah, that's a good point, it's always the 0th CLI arg, which I guess makes it more trustworthy.