Modification date of /gnu/store files is 1970-01-01

Modification date of /gnu/store files is 1970-01-01

[Martin Michel]

Hi,

I have install Guix on a Virtualbox VM in order to test if Guix could become my future GNU/Linux distribution of choice.  The installation went smoothly and I am learning the differences to Debian, my previous companion for many years, step-by-step.

So far so good, but I could not figure out what is wrong with the file system entries of /gnu/store.  All entries there have a timestamp of UNIX epoch 0.

Can anyone help here?

Directory listing excerpt:

$ ll /gnu/store |head

-r--r--r--   2 root root    3033  1. Jan 1970  0030adf2jgskp31favg7dz4zj2cpfw16-perl-cpan-meta-2.150010-guile-builder
-r--r--r--   2 root root     743  1. Jan 1970  007w6hxpalsvlklfrkb90hrkw1da1vwq-linux-5.8.14.tar.xz.drv
-r--r--r--   2 root root    2714  1. Jan 1970  008293bv06f00ifpn4wz7vmx0547721v-ruby-ae-1.8.2.drv
-r--r--r--   2 root root    2931  1. Jan 1970  009gxaijryq86832dv1j1vadzv4rdy47-ruby-sporkmonger-rack-mount-0.8.3-1.076aa2c-guile-builder
-r--r--r--   2 root root    1125  1. Jan 1970  00cy802583sb82kcpzfd1sz1xwff9hln-config.scm-builder
-r--r--r--   2 root root    2253  1. Jan 1970  00hcbzncmc7syjgswykx1755kypjy62r-xdg-desktop-database.drv
-r--r--r--   2 root root   71005  1. Jan 1970  00ll2n5lfb9wlm2kknc8bpyh8q0wxpdw-shepherd-console-font-tty6.go
-r--r--r--   8 root root     808  1. Jan 1970  00mw48q8s492z4w50mnfpwvmv6rz327x-python-2.7-adjust-tests.patch
-r--r--r--   2 root root    1036  1. Jan 1970  014pbl1jdgg9diiwz32dpxpki4f1a0sh-nghttp2-1.41.0-guile-builder

Details for one example:

$ stat /gnu/store/w8i2dl7j6srvarg3jb5prcp7glm475ag-filezilla-3.50.0.drv 
  File: /gnu/store/w8i2dl7j6srvarg3jb5prcp7glm475ag-filezilla-3.50.0.drv
  Size: 7258            Blocks: 16         IO Block: 4096   regular file
Device: fd00h/64768d    Inode: 3425816     Links: 2
Access: (0444/-r--r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2020-10-21 16:55:28.815206042 +0200
Modify: 1970-01-01 01:00:01.000000000 +0100
Change: 2020-10-18 17:54:21.263040662 +0200
 Birth: 2020-10-18 17:54:21.263040662 +0200

Thanks in advance,
-- Martin

Re: Modification date of /gnu/store files is 1970-01-01

[John Soo]

     Hello and welcome Martin! 

 
The Unix time stamp is set to 0 for one thing to ensure reproducible builds. If two build artifacts suffered in time stamps, they would be considered different.
 

 
Hope you find guix helpful and hackable,
 

 
John
     

Re: Modification date of /gnu/store files is 1970-01-01

[John Soo]

     Oops s/suffered/differed     

Re: Modification date of /gnu/store files is 1970-01-01

[Wiktor Żelazny]

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On Wed, Oct 21, 2020 at 05:53:55PM +0200, Martin Michel wrote:

> All entries there have a timestamp of UNIX epoch 0.

Hello,

To my knowledge, this is intentional, and related to software
reproducibility.

Why do you find it problematic?

WŻ

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Re: Modification date of /gnu/store files is 1970-01-01

[Tobias Geerinckx-Rice]

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Martin,

Martin Michel 写道：
> So far so good, but I could not figure out what is wrong with 
> the file system entries of /gnu/store.  All entries there have a 
> timestamp of UNIX epoch 0.

Well spotted!  This is intentional.  The Guix daemon[0] changes 
all timestamps of all files added to the store to a known value. 
Same for other metadata like ownership and some permission bits.

If it did not, certain software could (and does) behave 
differently between two different machines with otherwise 
identical stores.

Kind regards,

T G-R

[0]: Inherited from Nix and still in C++: 
http://git.savannah.gnu.org/cgit/guix.git/tree/nix/libstore/local-store.hh#n293

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Re: Modification date of /gnu/store files is 1970-01-01

[Martin Michel]

Tobias, John,

thank you for this explanation!  My first thought was… oh, something
broke during my installation.  But I was only spoiled by not resetting
my mind from the usual suspicious package managers.  Next time I will
think more about the nature of using a purely functional system, of
course it makes sense.

Do you think it is worth to spend a sentence about this in the
documentation (I must have skipped this if it is already there)?

And, by the way, thank you for the warm welcome!  I fully believe in
the concept and philosophy, so count me as a new user, ready to stay.

Kind regards,
Martin

Re: Modification date of /gnu/store files is 1970-01-01

[John Soo]

     Good to have you! 

 
A mention and description of purely functional package management ideas I think would be very welcome in the documentation.
 

 
Good luck,
 

 
John