install: allow the combination of --compare and --preserve-timestamps

* NEWS: Mention the improvement.
* src/install.c (enum copy_status): New type to let the caller know if
the copy was performed or skipped.
(copy_file): Return the new type instead of bool. Reduce variable scope.
(install_file_in_file): Only strip the file if the copy was
performed. Update the timestamps if the copy was skipped.
(main): Don't error when --compare and --preserve-timestamps are
combined.
* tests/install/install-C.sh: Add some test cases.

diff --git a/NEWS b/NEWS
index 5302c1ccd951aa543853402625b77c136dac147c..3639e1ba39fc3684769ed0760a54d80f647683b8 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -37,6 +37,9 @@ GNU coreutils NEWS                                    -*- outline -*-
   'groups' and 'id' will now exit sooner after a write error,
   which is significant when listing information for many users.
 
+  'install' now allows the combination of the --compare and
+  --preserve-timestamps options.
+
   'nl' now supports multi-byte --section-delimiter characters.
 
   'shuf -i' now operates up to two times faster on systems with unlocked stdio

diff --git a/src/install.c b/src/install.c
index 58ecfbc31c8e0ce78388eced29d954facd1f38d3..bccfe606fa7e8b388cad95b986918cb6e8105ee4 100644 (file)
--- a/src/install.c
+++ b/src/install.c
@@ -406,17 +406,18 @@ process_dir (char *dir, struct savewd *wd, void *options)
   return ret;
 }
 
+enum copy_status { COPY_FAILED, COPY_OK, COPY_SKIPPED };
+
 /* Copy file FROM onto file TO aka TO_DIRFD+TO_RELNAME, creating TO if
-   necessary.  Return true if successful.  */
+   necessary.  Return COPY_OK if successful or COPY_SKIPPED if the copy
+   was skipped.  */
 
-static bool
+static enum copy_status
 copy_file (char const *from, char const *to,
            int to_dirfd, char const *to_relname, const struct cp_options *x)
 {
-  bool copy_into_self;
-
   if (copy_only_if_needed && !need_copy (from, to, to_dirfd, to_relname, x))
-    return true;
+    return COPY_SKIPPED;
 
   /* Allow installing from non-regular files like /dev/null.
      Charles Karney reported that some Sun version of install allows that
@@ -424,7 +425,9 @@ copy_file (char const *from, char const *to,
      However, since !x->recursive, the call to "copy" will fail if FROM
      is a directory.  */
 
-  return copy (from, to, to_dirfd, to_relname, 0, x, &copy_into_self, NULL);
+  bool copy_into_self;
+  return (copy (from, to, to_dirfd, to_relname, 0, x, &copy_into_self, NULL)
+          ? COPY_OK : COPY_FAILED);
 }
 
 /* Set the attributes of file or directory NAME aka DIRFD+RELNAME.
@@ -721,16 +724,17 @@ install_file_in_file (char const *from, char const *to,
       error (0, errno, _("cannot stat %s"), quoteaf (from));
       return false;
     }
-  if (! copy_file (from, to, to_dirfd, to_relname, x))
+  enum copy_status copy_status = copy_file (from, to, to_dirfd, to_relname, x);
+  if (copy_status == COPY_FAILED)
     return false;
-  if (strip_files)
-    if (! strip (to))
-      {
-        if (unlinkat (to_dirfd, to_relname, 0) != 0)  /* Cleanup.  */
-          error (EXIT_FAILURE, errno, _("cannot unlink %s"), quoteaf (to));
-        return false;
-      }
-  if (x->preserve_timestamps && (strip_files || ! S_ISREG (from_sb.st_mode))
+  if (copy_status == COPY_OK && strip_files && ! strip (to))
+    {
+      if (unlinkat (to_dirfd, to_relname, 0) != 0)  /* Cleanup.  */
+        error (EXIT_FAILURE, errno, _("cannot unlink %s"), quoteaf (to));
+      return false;
+    }
+  if (x->preserve_timestamps && (copy_status == COPY_SKIPPED || strip_files
+                                 || ! S_ISREG (from_sb.st_mode))
       && ! change_timestamps (&from_sb, to, to_dirfd, to_relname))
     return false;
   return change_attributes (to, to_dirfd, to_relname);
@@ -1051,13 +1055,6 @@ main (int argc, char **argv)
     error (0, 0, _("WARNING: ignoring --strip-program option as -s option was "
                    "not specified"));
 
-  if (copy_only_if_needed && x.preserve_timestamps)
-    {
-      error (0, 0, _("options --compare (-C) and --preserve-timestamps are "
-                     "mutually exclusive"));
-      usage (EXIT_FAILURE);
-    }
-
   if (copy_only_if_needed && strip_files)
     {
       error (0, 0, _("options --compare (-C) and --strip are mutually "

diff --git a/tests/install/install-C.sh b/tests/install/install-C.sh
index 7f188c06e53cc1030573d3d391b452c6a2286882..447247c8f50214193e0741a61c8a2660135b5ede 100755 (executable)
--- a/tests/install/install-C.sh
+++ b/tests/install/install-C.sh
@@ -115,8 +115,32 @@ compare out out_installed_second || fail=1
 ginstall -Cv -m$mode2 a b > out || fail=1
 compare out out_empty || fail=1
 
-# options -C and --preserve-timestamps are mutually exclusive
-returns_ 1 ginstall -C --preserve-timestamps a b || fail=1
+# Check -C without --preserve-timestamps with files having the same contents.
+echo a > a || framework_failure_
+echo a > b || framework_failure_
+touch -d 2026-01-01 a || framework_failure_
+test b -nt a || framework_failure_  # Handle systems with bad time.
+ginstall -C a b || fail=1
+test b -nt a || fail=1
+
+# Likewise, but with --preserve-timestamps.
+ginstall -C --preserve-timestamps a b || fail=1
+case $(stat --format=%y b) in
+  2026-01-01*) ;;
+  *) fail=1 ;;
+esac
+
+# Check -C without --preserve-timestamps with files having differing contents.
+echo b > b || framework_failure_
+ginstall -C a b || fail=1
+test b -nt a || fail=1
+
+# Check -C with --preserve-timestamps with files having differing contents.
+ginstall -C --preserve-timestamps a b || fail=1
+case $(stat --format=%y b) in
+  2026-01-01*) ;;
+  *) fail=1 ;;
+esac
 
 # options -C and --strip are mutually exclusive
 returns_ 1 ginstall -C --strip --strip-program=echo a b || fail=1