use knitr (knit2pdf) to generate a PDF report in a Shiny app

readme.md

To see this app in action, run this in R:

library(shiny)
runGist('https://gist.github.com/yihui/6091942')

input.Rnw

\documentclass{article}

\begin{document}

<<names>>=
input$firstname
input$lastname
@

\end{document}

server.R

library(knitr)

shinyServer(function(input, output) {
  output$report = downloadHandler(
    filename = 'myreport.pdf',
    
    content = function(file) {
      out = knit2pdf('input.Rnw', clean = TRUE)
      file.rename(out, file) # move pdf to file for downloading
    },
    
    contentType = 'application/pdf'
  )
})

ui.R

library(shiny)

shinyUI(basicPage(
  textInput('firstname', 'First name', value = 'Jimmy'),
  textInput('lastname', 'Last name', value = 'John'),
  downloadButton('report')
))

Hi yihui,
This is really a very helpful information. However, I am getting the following warning while executing "app".

Warning in file.rename(out, file) : cannot rename file 'input.pdf' to '/tmp/RtmpAeLXey/file1c6b135b80b9.pdf', reason 'Invalid cross-device link'

No output file is being created after...
Will you please help me how to solve this? Thanks