fs.lua: fix error message when source file is missing

Fixes #1147.

2 files changed, 18 insertions, 2 deletions

diff --git a/spec/fs_spec.lua b/spec/fs_spec.lua
index 5d8926c4..16295869 100644
--- a/spec/fs_spec.lua
+++ b/spec/fs_spec.lua
@@ -894,7 +894,9 @@ describe("Luarocks fs test #unit", function()
       it("returns false and does nothing if the source file does not exist", function()
          srcfile = get_tmp_path()
          dstfile = get_tmp_path()
-         assert.falsy(fs.copy(srcfile, dstfile, nil))
+         local ok, err = fs.copy(srcfile, dstfile, nil)
+         assert.falsy(ok)
+         assert.not_match("are the same file", err)
          assert.falsy(exists_file(dstfile))
       end)
 
diff --git a/src/luarocks/fs/lua.lua b/src/luarocks/fs/lua.lua
index 6028a925..c5cebd2f 100644
--- a/src/luarocks/fs/lua.lua
+++ b/src/luarocks/fs/lua.lua
@@ -380,6 +380,20 @@ function fs_lua.remove_dir_tree_if_empty(d)
    end
 end
 
+local function are_the_same_file(f1, f2)
+   if f1 == f2 then
+      return true
+   end
+   if cfg.is_platform("unix") then
+      local i1 = lfs.attributes(f1, "ino")
+      local i2 = lfs.attributes(f2, "ino")
+      if i1 ~= nil and i1 == i2 then
+         return true
+      end
+   end
+   return false
+end
+
 --- Copy a file.
 -- @param src string: Pathname of source
 -- @param dest string: Pathname of destination
@@ -395,7 +409,7 @@ function fs_lua.copy(src, dest, perms)
    if destmode == "directory" then
       dest = dir.path(dest, dir.base_name(src))
    end
-   if src == dest or (cfg.is_platform("unix") and lfs.attributes(src, "ino") == lfs.attributes(dest, "ino")) then
+   if are_the_same_file(src, dest) then
       return nil, "The source and destination are the same files"
    end
    local src_h, err = io.open(src, "rb")