core/pkgs/build-support/setup-hooks/separate-debug-info.sh
2024-05-13 11:34:52 -04:00

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export NIX_SET_BUILD_ID=1
export NIX_LDFLAGS+=" --compress-debug-sections=zlib"
export NIX_CFLAGS_COMPILE+=" -ggdb -Wa,--compress-debug-sections"
export NIX_RUSTFLAGS+=" -g"
fixupOutputHooks+=(_separateDebugInfo)
_separateDebugInfo() {
[ -e "$prefix" ] || return 0
local dst="${debug:-$out}"
if [ "$prefix" = "$dst" ]; then return 0; fi
# in case there is nothing to strip, don't fail the build
mkdir -p "$dst"
dst="$dst/lib/debug/.build-id"
# Find executables and dynamic libraries.
local i
while IFS= read -r -d $'\0' i; do
if ! isELF "$i"; then continue; fi
[ -z "${READELF:-}" ] && echo "_separateDebugInfo: '\$READELF' variable is empty, skipping." 1>&2 && break
[ -z "${OBJCOPY:-}" ] && echo "_separateDebugInfo: '\$OBJCOPY' variable is empty, skipping." 1>&2 && break
# Extract the Build ID. FIXME: there's probably a cleaner way.
local id="$($READELF -n "$i" | sed 's/.*Build ID: \([0-9a-f]*\).*/\1/; t; d')"
if [ "${#id}" != 40 ]; then
echo "could not find build ID of $i, skipping" >&2
continue
fi
# Extract the debug info.
echo "separating debug info from $i (build ID $id)"
mkdir -p "$dst/${id:0:2}"
# This may fail, e.g. if the binary is for a different
# architecture than we're building for. (This happens with
# firmware blobs in QEMU.)
(
if [ -f "$dst/${id:0:2}/${id:2}.debug" ]
then
echo "separate-debug-info: warning: multiple files with build id $id found, overwriting"
fi
$OBJCOPY --only-keep-debug "$i" "$dst/${id:0:2}/${id:2}.debug"
# Also a create a symlink <original-name>.debug.
ln -sfn ".build-id/${id:0:2}/${id:2}.debug" "$dst/../$(basename "$i")"
) || rmdir -p "$dst/${id:0:2}"
done < <(find "$prefix" -type f -print0 | sort -z)
}