nixpkgs/pkgs/build-support/fetchpatch/default.nix

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# This function downloads and normalizes a patch/diff file.
# This is primarily useful for dynamically generated patches,
# such as GitHub's or cgit's, where the non-significant content parts
# often change with updating of git or cgit.
# stripLen acts as the -p parameter when applying a patch.
{ lib, fetchurl, buildPackages }:
let
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# 0.3.4 would change hashes: https://github.com/NixOS/nixpkgs/issues/25154
patchutils = buildPackages.patchutils_0_3_3;
in
{ stripLen ? 0, extraPrefix ? null, excludes ? [], includes ? [], revert ? false, ... }@args:
let
# Make base-64 encoded SRI hash filename-safe using RFC 4648 §5
tmpname = lib.replaceStrings [ "+" "/" "=" ] [ "-" "_" "" ] args.sha256;
in
fetchurl ({
postFetch = ''
tmpfile="$TMPDIR/${tmpname}"
if [ ! -s "$out" ]; then
echo "error: Fetched patch file '$out' is empty!" 1>&2
exit 1
fi
"${patchutils}/bin/lsdiff" "$out" \
| sort -u | sed -e 's/[*?]/\\&/g' \
| xargs -I{} \
"${patchutils}/bin/filterdiff" \
--include={} \
--strip=${toString stripLen} \
${lib.optionalString (extraPrefix != null) ''
--addoldprefix=a/${extraPrefix} \
--addnewprefix=b/${extraPrefix} \
''} \
--clean "$out" > "$tmpfile"
if [ ! -s "$tmpfile" ]; then
echo "error: Normalized patch '$tmpfile' is empty (while the fetched file was not)!" 1>&2
echo "Did you maybe fetch a HTML representation of a patch instead of a raw patch?" 1>&2
echo "Fetched file was:" 1>&2
cat "$out" 1>&2
exit 1
fi
${patchutils}/bin/filterdiff \
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-p1 \
${builtins.toString (builtins.map (x: "-x ${lib.escapeShellArg x}") excludes)} \
${builtins.toString (builtins.map (x: "-i ${lib.escapeShellArg x}") includes)} \
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"$tmpfile" > "$out"
if [ ! -s "$out" ]; then
echo "error: Filtered patch '$out$' is empty (while the original patch file was not)!" 1>&2
echo "Check your includes and excludes." 1>&2
echo "Normalizd patch file was:" 1>&2
cat "$tmpfile" 1>&2
exit 1
fi
'' + lib.optionalString revert ''
${patchutils}/bin/interdiff "$out" /dev/null > "$tmpfile"
mv "$tmpfile" "$out"
'' + (args.postFetch or "");
meta.broken = excludes != [] && includes != [];
} // builtins.removeAttrs args ["stripLen" "extraPrefix" "excludes" "includes" "revert" "postFetch"])