lib/vfscore: Accept negative timestamps

[andreittr]

Description of changes

Previously vfs code would reject timestamps that are more than 1 second before the epoch as invalid. This is wrong; unix time is defined as a signed offset and as such can and must support dates before the epoch. This change relaxes the overly-strict validity check, allowing the full range of valid file timestamps to be used.

Prerequisite checklist

• Read the contribution guidelines regarding submitting new changes to the project;
• Tested your changes against relevant architectures and platforms;
• Ran the checkpatch.uk on your commit series before opening this PR;
• Updated relevant documentation.

Base target

• Architecture(s): N/A
• Platform(s): N/A
• Application(s): N/A

Additional configuration

Test with:

struct utimbuf t = {-1, -1};
int r = utime("file", &t);
if (r) perror("Bug in utime");

[StefanJum]

@andreittr the changes make sense, but shouldn't they be made in is_timeval_valid too (since that is the function that is eventually called by the utime syscall)?

[andreittr]

@andreittr the changes make sense, but shouldn't they be made in is_timeval_valid too (since that is the function that is eventually called by the utime syscall)?

Good catch, thanks! Updated with fix.

[unikraft-bot]

✅ Checkpatch passed

Beep boop! I ran Unikraft's checkpatch.pl support script on your pull request and it all looks good!

SHA	commit	checkpatch
9f11dc8	lib/vfscore: Accept negative timestamps	✅

[StefanJum]

All good, thank you.
Reviewed-by: Stefan Jumarea stefanjumarea02@gmail.com

[razvand]

Approved-by: Razvan Deaconescu razvand@unikraft.io