git-utimes: add --newer flag and don't touch files in the working tree and index

Commands.md

@@ -1520,12 +1520,14 @@ $ git browse-ci upstream
 
 ## git utimes
 
-Change files modification time to their last commit date.
+Change files modification time to their last commit date.  Does not touch files that are in the working tree or index.
+
+The `-n` or `--newer` flag preserves the original modification time of files that were committed from the local repo, by only touching files that are newer than their last commit date.
 
 ```bash
 git-extras$ ls -l bin | head
 total 308
--rwxr-xr-x 1 vt vt   489 Nov  8 13:56 git-alias
+-rwxr-xr-x 1 vt vt   489 Jul 28  2015 git-alias
 -rwxr-xr-x 1 vt vt  1043 Nov  8 13:56 git-archive-file
 -rwxr-xr-x 1 vt vt   970 Nov  8 13:56 git-authors
 -rwxr-xr-x 1 vt vt   267 Nov  8 13:56 git-back
@@ -1534,8 +1536,7 @@ total 308
 -rwxr-xr-x 1 vt vt  6282 Nov  8 13:56 git-bulk
 -rwxr-xr-x 1 vt vt 18561 Nov  8 13:56 git-changelog
 -rwxr-xr-x 1 vt vt   215 Nov  8 13:56 git-clear
-git-extras$ git utimes
-+ touch -d 2015-08-09T19:27:49+08:00 bin/git-alias
+git-extras$ git utimes --newer
 + touch -d 2020-05-22T10:40:29+08:00 bin/git-archive-file
 + touch -d 2017-05-05T16:02:09+08:00 bin/git-authors
 + touch -d 2020-02-23T11:41:54+08:00 bin/git-back
@@ -1547,7 +1548,7 @@ git-extras$ git utimes
 [...]
 git-extras$ ls -l bin | head
 total 308
--rwxr-xr-x 1 vt vt   489 Aug  9  2015 git-alias
+-rwxr-xr-x 1 vt vt   489 Jul 28  2015 git-alias
 -rwxr-xr-x 1 vt vt  1043 May 22 05:40 git-archive-file
 -rwxr-xr-x 1 vt vt   970 May  5  2017 git-authors
 -rwxr-xr-x 1 vt vt   267 Feb 23  2020 git-back
@@ -1558,6 +1559,8 @@ total 308
 -rwxr-xr-x 1 vt vt   215 Nov 19  2016 git-clear
 ```
 
+Note above, `git-alias` was not touched because of the `--newer` flag.
+
 ## git abort
 
 Abort current rebase, merge or cherry-pick, without the need to find exact command in history.

bin/git-utimes

@@ -2,20 +2,28 @@
 #
 # Change files modification time to their last commit date
 #
-if [ "$1" = --touch ]; then
+if [ "$1" = "--touch" ]; then
   # Internal use option only just to parallelize things.
-  shift
+  newer_flag=""
+  [ "$2" = "--newer" ] || [ "$2" = "-n" ] && newer_flag="true"
+  shift 2
+  bsd=$(date -j > /dev/null 2>&1 && echo 'true')
+  if [ -n "$bsd" ]; then
+    stat_flags="-f %m"
+    date_flags="-r"
+  else
+    stat_flags="-c %Y"
+    date_flags="-d@"
+  fi
   for f; do
-    iso_t=$(git --no-pager log --no-renames --pretty=format:%cI -1 @ -- "$f" 2>/dev/null)
-    if [ -n "$iso_t" ]; then
-      bsd=$(date -j > /dev/null 2>&1 && echo 'true')
-      if [ "$bsd" == "true" ]; then
-        t=$(date -j -f %Y-%m-%dT%H:%M:%S "$iso_t" +%Y%m%d%H%M.%S)
-      else
-        t=$(date -d"$iso_t" +%Y%m%d%H%M.%S)
+    git_s=$(git --no-pager log --no-renames --pretty=format:%ct -1 @ -- "$f" 2>/dev/null)
+    mod_s=$(stat $stat_flags "$f" 2>/dev/null)
+    if [ -n "$git_s" ] && [ -n "$mod_s" ] && [ $mod_s -ne $git_s ]; then
+      if [ $mod_s -gt $git_s ] || [ ! -n "$newer_flag" ]; then
+        t=$(date $date_flags$git_s '+%Y%m%d%H%M.%S')
+        echo "+ touch -h -t $t $f" >&2
+        touch -h -t "$t" "$f"
       fi
-      echo "+ touch -t $t $f" >&2
-      touch -t "$t" "$f"
     fi
   done
 else
@@ -25,6 +33,12 @@ else
   # because all args will go into single worker.
   NPROC=$(nproc 2>/dev/null || sysctl -n hw.ncpu 2>/dev/null || getconf _NPROCESSORS_ONLN 2>/dev/null)
   # shellcheck disable=SC2086
-  git ls-tree -z -r -t --name-only @ \
-  | xargs -0 -P${NPROC:-1} -n${NPROC:-1} $opt_r git utimes --touch
+  # don't touch files that have been modified in the worktree or index
+  #   bsd doesn't have `-z` option for `comm` and `cut`, so use `tr` as work around
+  prefix="$(git rev-parse --show-prefix) "
+  comm -23 <(git ls-tree -z -r --name-only --full-name @ | tr '\0' '\n') \
+           <(git status -z --porcelain | tr '\0' '\n' | cut -c 4- | sort) \
+  | cut -c ${#prefix}- \
+  | tr '\n' '\0' \
+  | xargs -0 -P${NPROC:-1} -n 24 $opt_r git utimes --touch "$1"
 fi

man/git-utimes.md

@@ -3,23 +3,31 @@ git-utimes(1) -- Change files modification time to their last commit date
 
 ## SYNOPSIS
 
-`git-utimes`
+`git-utimes` [-n, --newer]
 
 ## DESCRIPTION
 
-  Change files modification time to their last commit date.
+  Change files modification time to their last commit date.  Does not touch files that are in the working tree or index.
 
 ## OPTIONS
 
-  No options needed.
+  -n, --newer
+
+  Preserves the original modification time of files that were committed from the local repo, by only touching files that are newer than their last commit date.
 
 ## EXAMPLES
 
-  git utimes
+  * Update all files' modification time to their last commit date, except those in working tree or index:
+
+    $ git utimes
+
+  * As above, but preserve original modification time of files that were committed from local repo:
+
+    $ git utimes -n
 
 ## AUTHOR
 
-Written by Vitaly Chikunov &lt;<[email protected]>&gt;, inspired by Stackexchange comments.
+Written by Vitaly Chikunov &lt;<[email protected]>&gt;, inspired by Stackexchange comments.  Updated by Bill Wood to add --newer flag and ignore files in the working tree or index.
 
 ## REPORTING BUGS