update-index

#!/bin/sh -eu
SHIT_PATH=$(dirname "$0")
. $SHIT_PATH/common.sh

write_index_header() (
	nentries="$1"
	printf 'DIRC'
	write_int32 $INDEX_VERSION
	write_int32 $nentries
	# TODO: Extensions would go here if we cared
)

write_index_file() (
	path="$(normalize_path "$1")"
	stat=$(stat -c "%W %Y %d %i %u %g %s" "$path") # XXX: GNUism
	ctime=$(printf "%s" "$stat" | cut -d' ' -f1)
	mtime=$(printf "%s" "$stat" | cut -d' ' -f2)
	dev=$(printf "%s" "$stat" | cut -d' ' -f3)
	inode=$(printf "%s" "$stat" | cut -d' ' -f4)
	uid=$(printf "%s" "$stat" | cut -d' ' -f5)
	gid=$(printf "%s" "$stat" | cut -d' ' -f6)
	size=$(printf "%s" "$stat" | cut -d' ' -f7)

	write_int32 "$ctime"
	write_int32 0 # nanoseconds
	write_int32 "$mtime"
	write_int32 0 # nanoseconds
	write_int32 "$dev"
	write_int32 "$inode"
	# object type & mode
	if [ -x "$path" ]
	then
		write_int32 $((0x8000 | 0755))
	else
		write_int32 $((0x8000 | 0644))
	fi
	write_int32 "$uid"
	write_int32 "$gid"
	write_int32 "$size"
	sha=$("$SHIT_PATH"/hash-object -w "$path")
	write_hex "$sha"
	# XXX: If file name length is >0xFFF this is wrong
	write_int16 "${#path}"
	printf '%s\0' "$path"
	padding=$((${#path} + 1 + 62))
	padding=$((padding % 8))
	padding=$(((8 - padding) % 8))
	while [ $padding -gt 0 ]
	do
		printf '\0'
		padding=$((padding-1))
	done
)

write_index_link() (
	printf '%s' "Symlinks are not implemented\n" >&2
	exit 1
)

do_add=0
do_remove=0
force_remove=0

while [ $# -ne 0 ]
do
	case "$1" in
		--add)
			do_add=1
			;;
		--remove)
			do_remove=1
			;;
		--force-remove)
			do_remove=1
			force_remove=1
			;;
		*)
			break
			;;
	esac
	shift
done

# TODO: Update existing index

cleanup_old_index() {
	if [ $? -eq 0 ]
	then
		rm "$GIT_DIR"/index.old
	else
		# Restore old index on error
		mv "$GIT_DIR"/index.old "$GIT_DIR"/index
	fi
}

if [ -f "$GIT_DIR"/index ]
then
	mv "$GIT_DIR"/index "$GIT_DIR"/index.old
	trap cleanup_old_index EXIT
fi

write_index_header "$#" >>"$GIT_DIR"/index

for path in "$@"
do
	printf "%s\n" "$path"
done | gitsort | while read -r path
do
	if [ -f "$path" ]
	then
		write_index_file "$path" >>"$GIT_DIR"/index
	elif [ -L "$path" ]
	then
		write_index_link "$path" >>"$GIT_DIR"/index
	else
		printf "Invalid path for indexing: %s\n" "$path" >&2
		exit 1
	fi
done

sha=$(sha1sum "$GIT_DIR"/index | cut -d' ' -f1)
write_hex "$sha" >>"$GIT_DIR"/index