polish up installer

install.lua

@@ -64,34 +64,39 @@ local function main()
     end
   end
 
-  log.info(#toDownload .. " files to download")
-  for k, v in ipairs(toDownload) do
-    if not fs.exists("/tmp") then
-      fs.makeDir("/tmp")
+  if #toDownload > 0 then
+    log.info(#toDownload .. " files to download")
+    for k, v in ipairs(toDownload) do
+      if not fs.exists("/tmp") then
+        fs.makeDir("/tmp")
+      end
+      log.info("Downloading '" .. v.dest .. "'")
+      local filerequest = http.get(repoRoot .. v.src)
+      local tempfile = fs.open("/tmp/" .. v.hash .. ".lua", "w")
+      tempfile.write(filerequest.readAll())
+      filerequest.close()
+      tempfile.close()
+      -- Check the validity of the hash, this acts both as a checksum
+      -- and a way to raise an error if the index is incorrect
+      tempfile = fs.open("/tmp/" .. v.hash .. ".lua", "r")
+      local filehash = hash.sha256(tempfile.readAll() .. "\n") -- newline is weird hack because of awkward hashes
+      tempfile.close()
+      if filehash ~= v.hash then
+        log.error("File " .. v.dest .. " (from " .. v.src .. ") has a mismatched hash.")
+        log.error("Installation aborted. Remember to clean /tmp manually.")
+        return
+      end
     end
-    log.info("Downloading '" .. v.dest .. "'")
-    local filerequest = http.get(repoRoot .. v.src)
-    local tempfile = fs.open("/tmp/" .. v.hash .. ".lua", "w")
-    tempfile.write(filerequest.readAll())
-    filerequest.close()
-    tempfile.close()
-    -- Check the validity of the hash, this acts both as a checksum
-    -- and a way to raise an error if the index is incorrect
-    tempfile = fs.open("/tmp/" .. v.hash .. ".lua", "r")
-    local filehash = hash.sha256(tempfile.readAll() .. "\n") -- newline is weird hack because of awkward hashes
-    tempfile.close()
-    if filehash ~= v.hash then
-      log.error("File " .. v.dest .. " (from " .. v.src .. ") has a mismatched hash.")
-      log.error("Installation aborted.")
-      return
+
+    log.info("Installing")
+    for k, v in ipairs(toDownload) do
+      fs.delete(v.dest)
+      fs.move("/tmp/" .. v.hash .. ".lua", v.dest)
     end
+  else
+    log.info("Nothing to do")
   end
-
-  log.info("Installing")
-  for k, v in ipairs(toDownload) do
-    fs.move("/tmp/" .. v.hash .. ".lua", v.dest)
-  end
-
+  
   log.info("Installation complete!")
 end