The "ctime" field from stat is not time of file creation.

[zookoatleastauthoritycom]

rust/src/libstd/io/fs.rs

Line 332 in 108b8b6

fn from_rtio(s: rtio::FileStat) -> FileStat {

seems to be reading the 4th field of stat result and storing it as "created", but if that 4th field is coming from stat_ctime then this is a bug, because stat_ctime is not the time of file creation, but is instead the most recent time that either the content or the metadata of the file changed: https://en.wikipedia.org/wiki/Stat_%28Unix%29#ctime

[alexcrichton]

Indeed! Looks like we need to switch to birthtime where necessary

[pdovy]

I took a look at this as it seemed like possibly an easy first issue. On Windows, st_ctime is indeed the file creation time - so on that platform the current implementation is correct. On Unix platforms it is wrong as mentioned, but the birthtime field mentioned by @alexcrichton doesn't seem to exist outside of BSD - it's not a standard part of POSIX.

Do we have any ability to have platform-dependent code in src/libnative/io/file_unix.rs?

It seems like the right approach may be to have an additional field on FileStat to hold the status change timestamp, which would be zero on Windows and hold the st_ctime value on Unix, and (possibly excepting BSD) the existing created field would be zero on Unix since it's unavailable.

[omasanori]

FYI:
Ruby's birthtime discussion (in Japanese; let me know if you need a summary in English)
Commits adding File#birthtime and File.birthtime to Ruby ruby/ruby@6b4f921 ruby/ruby@bfa4f32

[thestinger]

OS X and *BSD do have the ability to get creation time via stat. It's also possible on Linux for some file systems too.

[salemtalha]

@thestinger just experimented on ext4 and neither crtime nor btime are returned by the stat systemcall. maybe there's some other syscall that will expose that variable. investigating..

[omasanori]

On Linux, you can get creation time via debugfs if you are root. AFAIK (and, according to the Ruby's discussion linked from my previous comment,) there is no way to get it on Linux via any system call for now.

[salemtalha]

i took a preliminary stab at it in #17272, could someone let me know if I'm on the right track?

[alexcrichton]

This was handled in the new std::fs