cp: improve status message when omitting directories

* src/copy.h (cp_options): Add a new flag for install(1).
* src/copy.c (copy_internal): For cp, also output remediation
advice which also indicates why directories aren't copied by default.
The message is unchanged for install(1).
* src/cp.c (cp_option_init): Init install_mode to false.
* src/mv.c (cp_option_init): Likewise.
* src/install.c (cp_option_init): Init install_mode to true.
* tests/install/basic-1.sh: Add a test case.
* tests/cp/link-deref.sh: Adjust test case.
Fixes http://bugs.gnu.org/24958

5 files changed, 10 insertions, 1 deletions

diff --git a/src/copy.c b/src/copy.c
index 422d50efe..b3acff347 100644
--- a/src/copy.c
+++ b/src/copy.c
@@ -1873,7 +1873,10 @@ copy_internal (char const *src_name, char const *dst_name,
 
   if (S_ISDIR (src_mode) && !x->recursive)
     {
-      error (0, 0, _("omitting directory %s"), quoteaf (src_name));
+      error (0, 0, ! x->install_mode /* cp */
+                   ? _("-r not specified; omitting directory %s")
+                   : _("omitting directory %s"),
+             quoteaf (src_name));
       return false;
     }
 
diff --git a/src/copy.h b/src/copy.h
index fa0c2aeae..a516002c2 100644
--- a/src/copy.h
+++ b/src/copy.h
@@ -137,6 +137,9 @@ struct cp_options
      If that fails, then resort to copying.  */
   bool move_mode;
 
+  /* If true, install(1) is the caller.  */
+  bool install_mode;
+
   /* Whether this process has appropriate privileges to chown a file
      whose owner is not the effective user ID.  */
   bool chown_privileges;
diff --git a/src/cp.c b/src/cp.c
index 926e05be3..1b528c6a2 100644
--- a/src/cp.c
+++ b/src/cp.c
@@ -771,6 +771,7 @@ cp_option_init (struct cp_options *x)
   x->hard_link = false;
   x->interactive = I_UNSPECIFIED;
   x->move_mode = false;
+  x->install_mode = false;
   x->one_file_system = false;
   x->reflink_mode = REFLINK_NEVER;
 
diff --git a/src/install.c b/src/install.c
index 4fa4bb3d3..414d645cc 100644
--- a/src/install.c
+++ b/src/install.c
@@ -271,6 +271,7 @@ cp_option_init (struct cp_options *x)
   x->hard_link = false;
   x->interactive = I_UNSPECIFIED;
   x->move_mode = false;
+  x->install_mode = true;
   x->one_file_system = false;
   x->preserve_ownership = false;
   x->preserve_links = false;
diff --git a/src/mv.c b/src/mv.c
index 6a3d0d277..04d2be3ec 100644
--- a/src/mv.c
+++ b/src/mv.c
@@ -114,6 +114,7 @@ cp_option_init (struct cp_options *x)
   x->hard_link = false;
   x->interactive = I_UNSPECIFIED;
   x->move_mode = true;
+  x->install_mode = false;
   x->one_file_system = false;
   x->preserve_ownership = true;
   x->preserve_links = true;