From 389f7c25dd3ddd8a530eaa61ef7c333fb4e5d6cf Mon Sep 17 00:00:00 2001
From: Gavin Chappell <2798739+g-a-c@users.noreply.github.com>
Date: Sat, 20 Nov 2021 19:30:46 +0000
Subject: [PATCH] refactor downloading of binaries

* If `/tmp` is a `tmpfs` or somehow not the same filesystem, `os.Rename()` will fail so use `io.Copy()` instead
* don't defer cleanup of `to` as this removes the newly-created file if the operation is successful, making `install` and `upgrade` _functionally_ `uninstall`
* defer cleanup of the temporary file since it will still be in place if `os.Rename()` fails

Fixes: #130
---
 internal/bins/bins.go | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/internal/bins/bins.go b/internal/bins/bins.go
index 27c640c..2d90667 100644
--- a/internal/bins/bins.go
+++ b/internal/bins/bins.go
@@ -87,9 +87,23 @@ func downloadAndInstallAsset(body GithubRelease, name string) error {
 			}
 
 			to := path.Join(INSTALL_PATH, name)
-			defer os.Remove(to) // Delete if current, ignore error if file does not exits.
+			defer os.Remove(tmp.Name()) // Cleanup temporary file after thread exits
 			if err := os.Rename(tmp.Name(), to); err != nil {
-				return nil
+				colors.Error.Printf("os.Rename() failed (%v), retrying with io.Copy()\n", err.Error())
+				var src *os.File
+				var dst *os.File
+				if src, err = os.Open(tmp.Name()); err != nil {
+					return err
+				}
+				if dst, err = os.Create(to); err != nil {
+					return err
+				}
+				if _, err := io.Copy(dst, src); err != nil {
+					return err
+				}
+				if err := os.Chmod(to, 0755); err != nil {
+					return err
+				}
 			}
 
 			colors.Success.Printf("Successfully installed '%s' under %s\n", name, INSTALL_PATH)