From 24c5c05308abaffe59f84a403b0d7c27c772700b Mon Sep 17 00:00:00 2001
From: Omar Brikaa <brikaaomar@gmail.com>
Date: Fri, 4 Oct 2024 19:30:57 +0300
Subject: [PATCH 1/3] Give friendlier messages when cgroup v2 is not enabled

---
 api/src/docker-entrypoint.sh | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/api/src/docker-entrypoint.sh b/api/src/docker-entrypoint.sh
index 7cf37e3..2a4e49c 100755
--- a/api/src/docker-entrypoint.sh
+++ b/api/src/docker-entrypoint.sh
@@ -1,5 +1,21 @@
 #!/bin/bash
 
+CGROUP_FS="/sys/fs/cgroup"
+if [ ! -e "$CGROUP_FS" ]; then
+  echo "Cannot find $CGROUP_FS. Please make sure your system is using cgroup v2"
+  exit 1
+fi
+
+if [ -e "$CGROUP_FS/unified" ]; then
+  echo "Combined cgroup v1+v2 mode is not supported. Please make sure your system is using pure cgroup v2"
+  exit 1
+fi
+
+if [ ! -e "$CGROUP_FS/cgroup.subtree_control" ]; then
+  echo "Cgroup v2 not found. Please make sure cgroup v2 is enabled on your system"
+  exit 1
+fi
+
 cd /sys/fs/cgroup && \
 mkdir isolate/ && \
 echo 1 > isolate/cgroup.procs && \

From 512b63d2b50902cb4a79ad85dfa1e726ec0f4041 Mon Sep 17 00:00:00 2001
From: Omar Brikaa <brikaaomar@gmail.com>
Date: Fri, 4 Oct 2024 19:53:33 +0300
Subject: [PATCH 2/3] Document interactive execution

---
 readme.md | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/readme.md b/readme.md
index f1172d3..9034264 100644
--- a/readme.md
+++ b/readme.md
@@ -320,6 +320,40 @@ Content-Type: application/json
 }
 ```
 
+#### Interactive execution endpoint (not available through the public API)
+
+To interact with running processes in real time, you can establish a WebSocket connection at `/api/v2/connect`. This allows you to both receive output and send input to active processes.
+
+Each message is structured as a JSON object with a `type` key, which indicates the action to perform. Below is a list of message types, their directions, and descriptions:
+
+-   **init** (client -> server): Initializes a job with the same parameters as the `/execute` endpoint, except that stdin is discarded.
+-   **runtime** (server -> client): Provides details on the runtime environment, including the version and language.
+-   **stage** (server -> client): Indicates the current execution stage, either "compile" or "run."
+-   **data** (server <-> client): Exchanges data between the client and server, such as stdin, stdout, or stderr streams.
+-   **signal** (client -> server): Sends a signal (e.g., for termination) to the running process, whether it's in the "compile" or "run" stage.
+-   **exit** (server -> client): Signals the end of a stage, along with the exit code or signal.
+-   **error** (server -> client): Reports an error, typically right before the WebSocket is closed.
+
+An example of this endpoint in use is depicted below (**<** = client to server, **>** = server to client)
+
+1. Client establishes WebSocket connection to `/api/v2/connect`
+2. **<** `{"type":"init", "language":"bash", "version":"*", "files":[{"content": "cat"}]}`
+3. **>** `{"type":"runtime","language": "bash", "version": "5.1.0"}`
+4. **>** `{"type":"stage", "stage":"run"}`
+5. **<** `{"type":"data", "stream":"stdin", "data":"Hello World!"}`
+6. **>** `{"type":"data", "stream":"stdout", "data":"Hello World!"}`
+7. _time passes_
+8. **>** `{"type":"exit", "stage":"run", "code":null, "signal": "SIGKILL"}`
+
+Errors may return status codes as follows:
+
+-   **4000: Already Initialized**: Sent when a second `init` command is issued.
+-   **4001: Initialization Timeout**: No `init` command was sent within 1 second of connection.
+-   **4002: Notified Error**: A fatal error occurred, and an `error` packet was transmitted.
+-   **4003: Not yet Initialized**: A non-`init` command was sent without a job context.
+-   **4004: Can only write to stdin**: The client attempted to write to a stream other than stdin.
+-   **4005: Invalid Signal**: An invalid signal was sent in a `signal` packet.
+
 <br>
 
 # Supported Languages

From 4e361dcf924b4594f038511ff69752ee1a3f49a9 Mon Sep 17 00:00:00 2001
From: Omar Brikaa <brikaaomar@gmail.com>
Date: Fri, 11 Oct 2024 21:42:58 +0300
Subject: [PATCH 3/3] Add note to ensure the repository is cloned with LF line
 endings

---
 readme.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/readme.md b/readme.md
index 9034264..7724fdb 100644
--- a/readme.md
+++ b/readme.md
@@ -114,6 +114,10 @@ POST https://emkc.org/api/v2/piston/execute
 git clone https://github.com/engineer-man/piston
 ```
 
+> [!NOTE]
+>
+> Ensure the repository is cloned with LF line endings
+
 ### Installation
 
 ```sh