utils: gen-version: Use posix compliant date

The version string of libcamera is presently appended with a date/time
argument in the case of a dirty tree to show further detail of when it
was built. This string is generated with the iso-8601 parameter to
'date' and produces a date string in the form:
"2024-06-17T22:15:30+01:00"

Strict posix shells or implementations of 'date' which may be optimised
for size such as the one provided by busybox or Alpine Linux may not
support the '--iso-8601' flag.

To support builds on those platforms, use a direct POSIX-compliant
date-format string instead matching as closely as possible to the
iso-8601 definition.

An exact match is not possible with those restrictions so 'date
%Y-%m-%dT%H:%M:%S%Z' is used which produces 2024-06-17T22:15:30BST.

The use of the human readable timezone identifier provides a friendlier
output for the string than a timezone offset at the expense of being
less sortable in the exceptionally low risk and unlikely event of two
custom builds being compared at the same time of different timezones.

Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Zach DeCook <zachdecook@librem.one>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/utils/gen-version.sh b/utils/gen-version.sh
index e1f7ca7b..1b818e9e 100755
--- a/utils/gen-version.sh
+++ b/utils/gen-version.sh
@@ -42,7 +42,7 @@ if [ -z "$build_dir" ] || (echo "$build_dir" | grep -q "$src_dir")
 then
 	git update-index --refresh > /dev/null 2>&1
 fi
-git diff-index --quiet HEAD || version="$version-dirty ($(date --iso-8601=seconds))"
+git diff-index --quiet HEAD || version="$version-dirty ($(date +%Y-%m-%dT%H:%M:%S%Z))"
 
 # If a project version is provided, use it to replace the version number.
 if [ -n "$project_version" ]