fix: dest folder failsave

functions/rscp.fish

@@ -173,13 +173,16 @@ function rscp --description "Copy SOURCE... to DESTINATION via rsync (local or N
         end
     end
 
-    # Failsafe: if the destination already exists, ask before overwriting.
+    # Failsafe: if the destination already exists *and has content*, ask
+    # before overwriting. An existing but empty directory is not worth
+    # asking about - there is nothing that could be lost.
     set -l dst_disp $dst_raw
     if test "$dst" != "$dst_raw"
         set dst_disp "$dst_raw ($dst)"
     end
     set -l dst_exists 0
     set -l dst_is_dir 0
+    set -l dst_nonempty 0
     if test $dst_remote -eq 1
         set -l qdst (__rscp_shquote $dst_naslocal)
         if ssh $dst_host test -e $qdst
@@ -190,6 +193,15 @@ function rscp --description "Copy SOURCE... to DESTINATION via rsync (local or N
         if test $dst_exists -eq 1
             if ssh $dst_host test -d $qdst
                 set dst_is_dir 1
+                set -l listing (ssh $dst_host ls -A $qdst 2>/dev/null)
+                set -l ls_st $status
+                if test $ls_st -ne 0; or test (count $listing) -gt 0
+                    # Unlistable -> stay safe and treat it as non-empty.
+                    set dst_nonempty 1
+                end
+            else
+                # File (or symlink): overwriting would replace content.
+                set dst_nonempty 1
             end
         end
     else
@@ -199,20 +211,27 @@ function rscp --description "Copy SOURCE... to DESTINATION via rsync (local or N
         if test $dst_exists -eq 1
             if test -d "$dst"
                 set dst_is_dir 1
+                set -l listing (command ls -A -- "$dst" 2>/dev/null)
+                set -l ls_st $status
+                if test $ls_st -ne 0; or test (count $listing) -gt 0
+                    set dst_nonempty 1
+                end
+            else
+                set dst_nonempty 1
             end
         end
     end
-    if test $dst_exists -eq 1
+    if test $dst_nonempty -eq 1
         if test (count $srcs) -gt 1; and test $dst_is_dir -eq 0
             echo "rscp: destination '$dst_disp' exists and is not a directory, but multiple sources were given." >&2
             return 1
         end
         if test $force -eq 0
             if not isatty stdin
-                echo "rscp: destination '$dst_disp' already exists. Re-run interactively or pass -y/--yes to overwrite." >&2
+                echo "rscp: destination '$dst_disp' already exists and is not empty. Re-run interactively or pass -y/--yes to overwrite." >&2
                 return 1
             end
-            if not read -l -P "rscp: destination '$dst_disp' already exists. Overwrite/merge? [y/N] " confirm_raw
+            if not read -l -P "rscp: destination '$dst_disp' already exists and is not empty. Overwrite/merge? [y/N] " confirm_raw
                 echo "rscp: aborted." >&2
                 return 1
             end