startPipeServer broken since 1.5.3.1

[PromyLOPh]

I’ve been debugging an issue I’m having with rmarkdown/shiny and came to the conclusion this must be a bug in httpuv. Originally I tried to run:

$ R -q --no-save -e 'rmarkdown::run(file = NULL, dir = ".", shiny_args=list(port=structure("test.sock", mask=0), quiet=FALSE, launch.browser=FALSE))'

But I can reproduce the issue with the example code from the README as well, replacing startServer with startPipeServer:

library(httpuv)

s <- startPipeServer(name="test.sock", mask=NULL,
  app = list(
    call = function(req) {
      body <- paste0("Time: ", Sys.time(), "<br>Path requested: ", req$PATH_INFO)
      list(
        status = 200L,
        headers = list('Content-Type' = 'text/html'),
        body = body
      )
    }
  )
)

This is the output with 1.5.3.1:

$ R -q -f server.R
> library(httpuv)
>
> s <- startPipeServer(name="test.sock", mask=NULL,
+   app = list(
+     call = function(req) {
+       body <- paste0("Time: ", Sys.time(), "<br>Path requested: ", req$PATH_INFO)
+       list(
+         status = 200L,
+         headers = list('Content-Type' = 'text/html'),
+         body = body
+       )
+     }
+   )
+ )
createPipeServer: invalid argument
Error in .subset2(public_bind_env, "initialize")(...) :
  Failed to create server
Calls: startPipeServer -> <Anonymous> -> <Anonymous>
In addition: Warning message:
In normalizePath(name) : path[1]="test.sock": No such file or directory
Execution halted

(notice the error “invalid argument”)
This works with 1.5.2, so I’m assuming this is a regression introduced by the upgrade from libuv 1.27 to 1.37.

[wch]

It looks like the error is coming from here:
https://github.com/libuv/libuv/blob/v1.x/src/unix/pipe.c#L98-L99

That was introduced by:
libuv/libuv#2559