show curl error message when error occurs

src/cpp/session/modules/SessionRPubs.R

@@ -332,16 +332,20 @@ rpubsUpload <- function(title,
                        "--header", paste("Content-Length:", fileLength, sep=""),
                        extraHeaders,
                        "--header", "Expect:",
-                       "-s",
+                       "--silent",
+                       "--show-error",
                        "-o", shQuote(outputFile),
                        paste("https://rpubs.com", path, sep=""))
 
-      system(command)
+      result <- system(command)
 
-      fileConn <- file(outputFile, "rb")
-      on.exit(close(fileConn))
-
-      readResponse(fileConn)
+      if (result == 0) {
+        fileConn <- file(outputFile, "rb")
+        on.exit(close(fileConn))
+        readResponse(fileConn)
+      } else {
+        stop(paste("Upload failed (curl error", result, "occurred)"))
+      }
    }
 
    # determine the upload function, scheme, and port

src/cpp/session/modules/SessionRPubs.cpp

@@ -11,17 +11,6 @@
  *
  */
 
-// TODO: is there a way to get a better error diagnostic out of a
-//       network failure in calling system(curl) -- we get a file
-//       output error right now, any way for R to capture standard error?
-
-// NOTE: may be able to do this with a combination of passing --show-error
-//       to curl and then capturing the output from R using:
-//          output <- suppressWarnings(system(command, intern = TRUE))
-//       then if the output file doesn't exist we return the output as
-//       an error
-
-// TODO: should we prefer RCurl due to the above error reporting issue?
 // TODO: notification of public publishing w/ "don't show again"
 
 // TODO: progress dialog for preparing to publish (including cancel)