[Issue 19484] New: Fix it so that DirEntry on POSIX only calls lstat once

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19484

          Issue ID: 19484
           Summary: Fix it so that DirEntry on POSIX only calls lstat once
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: phobos
          Assignee: nobody at puremagic.com
          Reporter: issues.dlang at jmdavisProg.com

On POSIX, DirEntry's constructor calls exists to verify that the file exists
and then throws if it doesn't - which makes perfect sense until you look at
what exists does. exists calls lstat, which is fine in and of itself, but
calling exists means that that information is thrown away, whereas DirEntry
then later calls lstat again when certain functions are called. It has the
_didLStat member to keep track of whether it's called lstat yet, so it avoids
calling it multiple times when the properties on it are used which require it,
but it would be more efficient to just call lstat directly in the constructor
and always save the result. If lstat fails, the exception can be thrown like it
is now, but by checking the result of lstat directly rather than using exists,
we remove the need for _didLStat, and we make it so that lstat is always called
exactly once instead of being called once if the information from lstat isn't
needed later or twice if it is.

--