In the nix file, I can see fetchpatch used to fetch “most” of the patches, but I’d like to get this information from the patch derivation itself (or is it in the package requiring the patch? can’t find either in those)
fetchpatch is just a wrapper around fetchurl that does some normalization in the postFetch phase. To get the URL of the original files you can make use of this:
However, you still need to replicate the normalization done in postFetch which also depends on arguments passed to fetchpatch! This makes what you have in mind very difficult. Because the output hash pins the normalized patch, just downloading the original file and importing it to the store won’t help you here.
I started to write some boiler plate to my perl script downloading the tarballs, to run postFetch on the file, so far I still get a different hash value but this could be possible… I forked the find-tarballs.nix file into a find-patches.nix that only return files with a postFetch step.
I’m currently a bit puzzled about the hash difference because it seems I’m running the exact same postFetch
Here is the code for curious
if ($val->{postFetch}) {
my $TMPFILE = `mktemp /tmp/patch.XXXXXXXXXXXXXXX`;
chomp($TMPFILE);
open(OUT, ">","/tmp/download_patch.sh");
print OUT "#!/usr/bin/env nix-shell\n";
print OUT "#! nix-shell -i bash -p patchutils\n";
print OUT "curl -L -o $TMPFILE $url\n";
print OUT "out=\"$TMPFILE\"\n";
print OUT "$val->{postFetch}\n";
`sed 's,.*/lsdiff.*,lsdiff \\\\,g ; s,.*/filterdiff.*,filterdiff \\\\,g' -i /tmp/script.sh`;
`chmod +x /tmp/download_patch.sh`;
`/tmp/download_patch.sh "$url" "$TMPFILE"`;
my $return = `nix-instantiate --eval -E 'builtins.fetchurl { url = "file://$TMPFILE" ; sha256 = "$val->{hash}"; }'`;
print $return;
} else {
my $return = `nix-instantiate --eval -E 'builtins.fetchurl { url = $url ; sha256 = "$val->{hash}"; }'`;
}
