The mkemmc.sh script calculates file sizes via `wc -c'. `wc' normally works by reading the entire file, resulting in O(n) performance.
Unix file systems obviously know a file's size and POSIX `ls' reports this information unambiguously, so replacing `wc' with `ls' ensures O(1) performance. The files in question tend to be large making this change worthwhile. Signed-off-by: Konrad Schwarz <[email protected]> --- scripts/mkemmc.sh | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/scripts/mkemmc.sh b/scripts/mkemmc.sh index 45dc3f08fa..d2c4e84b16 100755 --- a/scripts/mkemmc.sh +++ b/scripts/mkemmc.sh @@ -37,13 +37,19 @@ usage() { exit "$1" } +file_size() { + ls_line=$(ls -Hdog "$1") || return + printf %s\\n "$ls_line" | cut -d\ -f3 + unset ls_line +} + process_size() { name=$1 image_file=$2 alignment=$3 image_arg=$4 if [ "${image_arg#*:}" = "$image_arg" ]; then - if ! size=$(wc -c < "$image_file" 2>/dev/null); then + if ! size=$(file_size "$image_file"); then echo "Missing $name image '$image_file'." >&2 exit 1 fi @@ -105,7 +111,7 @@ check_truncation() { if [ "$image_file" = "/dev/zero" ]; then return fi - if ! actual_size=$(wc -c < "$image_file" 2>/dev/null); then + if ! actual_size=$(file_size "$image_file"); then echo "Missing image '$image_file'." >&2 exit 1 fi -- 2.39.5
