Daemon plain file and plain text format support

[nikolayKeniston]

Added format command to daemon, which allows formatting either the specified files, or the specified code if the file list is "-" (similar to CLI), starting from a newline and ending with an ASCII EOT character (04); can be used as (echo "format -"; echo <CODE>; echo -ne '\04\n') | nc localhost <PORT>, or replace "echo <CODE>" with "cat" for standard input. Tests included.

[CLAassistant]

All committers have signed the CLA.

[staktrace]

Generally looks good. Have a question though

[staktrace]

Is this needed? Can we not just the end of stream as the break condition? I think it's possible for legitimate kotlin code files using a multiline string to have this character alone on a line, and then this would fail to format them correctly.

[nikolayKeniston]

I tried this initially and I was able to achieve the expected result only by programmatically closing the output part of the stream. However, such simple tools as nc, as far as I understand, do not provide such an opportunity, and I wanted to keep the ability to use commands entirely from the terminal. Maybe there is a solution to this problem, but I did not find it.

[staktrace]

It seems to work for me. What I did:

• comment out this one line (line 148, where you check for \u0004
• build the shadowjar (../gradlew shadowJar)
• start the daemon (java -jar build/libs/kotlin-format-1.0.4-SNAPSHOT-all.jar --daemon)
• in a separate terminal, get the port number from cat ../.kotlinformatter/kf.lock
• run (echo "format -"; echo "fun main() { println() }") | nc localhost 64957
• as expected I get the output:

0
fun main() {
  println()
}

This matches my understanding that when the input pipe to nc is closed, nc will close the stream, and that will manifest as a reader.readLine() returning null in the daemon.

Do you not get the same behaviour?

[staktrace]

I also get the expected behavior if I cat a file into it:

$ (echo "format -"; cat foo.kt) | nc localhost 65065
0
fun main() {
  println()
}

[nikolayKeniston]

I changed the loop to:

while (true) {
  val line = reader.readLine()
  println(line)
  if (line == null) break;
  // if (line.trim() == "\u0004") break
  inputLines.add(line)
}

Then I do (echo "format -"; echo "fun main() { println() }") | nc localhost 45753. This results in the message fun main() { println() } in the console, and nothing happens until I close nc forcibly with ctrl+c. After closing, I see null (for line) and an exception:

Error handling client connection: Broken pipe
java.net.SocketException: Broken pipe
        at java.base/sun.nio.ch.SocketDispatcher.write0(Native Method)
        at java.base/sun.nio.ch.SocketDispatcher.write(SocketDispatcher.java:62)
        at java.base/sun.nio.ch.NioSocketImpl.tryWrite(NioSocketImpl.java:394)
        at java.base/sun.nio.ch.NioSocketImpl.implWrite(NioSocketImpl.java:410)
        at java.base/sun.nio.ch.NioSocketImpl.write(NioSocketImpl.java:440)
        at java.base/sun.nio.ch.NioSocketImpl$2.write(NioSocketImpl.java:819)
        at java.base/java.net.Socket$SocketOutputStream.implWrite(Socket.java:1231)
        at java.base/java.net.Socket$SocketOutputStream.write(Socket.java:1218)
        at java.base/java.io.OutputStream.write(OutputStream.java:124)
        at xyz.block.kotlinformatter.Daemon.write(Daemon.kt:275)
        at xyz.block.kotlinformatter.Daemon.start(Daemon.kt:162)
        at xyz.block.kotlinformatter.Cli.run(Cli.kt:42)
        at com.github.ajalt.clikt.core.CoreCliktCommandKt.parse(CoreCliktCommand.kt:107)
        at com.github.ajalt.clikt.core.CoreCliktCommandKt.main(CoreCliktCommand.kt:78)
        at com.github.ajalt.clikt.core.CoreCliktCommandKt.main(CoreCliktCommand.kt:90)
        at xyz.block.kotlinformatter.CliKt.main(Cli.kt:117)

It seems that nc closes both read and write streams when you press ctrl+c, and does nothing before this. I'm not sure why this behavior might be happening. Maybe there's some difference in the environments?

[staktrace]

weird. what shell/OS are you using? and what version of nc?

[nikolayKeniston]

bash, arch linux, netcat (The GNU Netcat) 0.7.1

[staktrace]

I was able to reproduce your issue using an arch linux docker image. I also reproduced it on an ubuntu docker image. Some searching online led me to https://stackoverflow.com/questions/53634911/why-does-sending-d-with-netcat-not-trigger-an-eof-when-reading-from-a-unix-sock

I was able to confirm that when using openbsd-netcat on arch linux or Ubuntu with the -N flag it works as intended. On ubuntu with netcat-traditional you have to use -q 1. On arch linux with gnu netcat I couldn't get it working since the -c option closes the connection right away instead of waiting for the response. I did however manage to get it working with socat instead of nc:

$ (echo "format -"; echo "fun main() { print() }") | socat STDIO TCP4:localhost:34169
0
fun main() {
  print()
}

Given the inconsistency of different netcat versions, perhaps you can get by with using socat instead?