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nixpkgs/pkgs/build-support/setup-hooks/compress-man-pages.sh
Arnout Engelen 777cb35eb8
compress-man-pages: symlink compressed manpages deterministically
For example graphviz has chained symlinked manpages: dot2gxl.1 is
a symlink to gv2gxl.1 which is a symlink to gxl2gv.1

The second loop replaces each non-compressed symlink to a compressed
symlink. The target is determined with 'readlink -f', which follows
links recursively until the first name that is not a link (so either
the 'target name' or the first 'dangling' symlink).

This means that if the loop converted dot2gxl.1 before converting
gv2gxl.1 it would add a symlink `dot2gxl.1.gz->gxl2gv.1.gz`. When
it converted gv2gxl.1 first, it would then add a
`dot2gxl.1.gz->gv2gxl.1.gz` symlink.

Both are 'correct', but it's weird the result depends on the order
in which 'find' returns the files. This PR makes the behaviour
deterministic.

fixes #104708
2020-12-04 09:24:37 +01:00

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fixupOutputHooks+=('if [ -z "${dontGzipMan-}" ]; then compressManPages "$prefix"; fi')
compressManPages() {
local dir="$1"
if [ -L "$dir"/share ] || [ -L "$dir"/share/man ] || [ ! -d "$dir/share/man" ]
then return
fi
echo "gzipping man pages under $dir/share/man/"
# Compress all uncompressed manpages. Don't follow symlinks, etc.
find "$dir"/share/man/ -type f -a '!' -regex '.*\.\(bz2\|gz\)$' -print0 \
| while IFS= read -r -d $'\0' f
do
if gzip -c -n "$f" > "$f".gz; then
rm "$f"
else
rm "$f".gz
fi
done
# Point symlinks to compressed manpages.
find "$dir"/share/man/ -type l -a '!' -regex '.*\.\(bz2\|gz\)$' -print0 \
| sort -z \
| while IFS= read -r -d $'\0' f
do
local target
target="$(readlink -f "$f")"
if [ -f "$target".gz ]; then
ln -sf "$target".gz "$f".gz && rm "$f"
fi
done
}