vmm: Move SerialBuffer to its own crate

We want to be able to reuse the SerialBuffer from the virtio-devices
crate, particularly from the virtio-console implementation. That's why
we move the SerialBuffer definition to its own crate so that it can be
accessed from both vmm and virtio-devices crates, without creating any
cyclic dependency.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

Cargo.lock

@@ -1011,6 +1011,10 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "serial_buffer"
+version = "0.1.0"
+
 [[package]]
 name = "signal-hook"
 version = "0.3.14"
@@ -1344,6 +1348,7 @@ dependencies = [
  "seccompiler",
  "serde",
  "serde_json",
+ "serial_buffer",
  "thiserror",
  "versionize",
  "versionize_derive",
@@ -1459,6 +1464,7 @@ dependencies = [
  "seccompiler",
  "serde",
  "serde_json",
+ "serial_buffer",
  "signal-hook",
  "thiserror",
  "uuid",

Cargo.toml

@@ -79,6 +79,7 @@ members = [
     "performance-metrics",
     "qcow",
     "rate_limiter",
+    "serial_buffer",
     "test_infra",
     "vfio_user",
     "vhdx",

serial_buffer/Cargo.toml

@@ -0,0 +1,5 @@
+[package]
+name = "serial_buffer"
+version = "0.1.0"
+authors = ["The Cloud Hypervisor Authors"]
+edition = "2021"

serial_buffer/src/lib.rs

@@ -16,14 +16,14 @@ const MAX_BUFFER_SIZE: usize = 1 << 20;
 
 // Circular buffer implementation for serial output.
 // Read from head; push to tail
-pub(crate) struct SerialBuffer {
+pub struct SerialBuffer {
     buffer: VecDeque<u8>,
     out: Box<dyn Write + Send>,
     write_out: Arc<AtomicBool>,
 }
 
 impl SerialBuffer {
-    pub(crate) fn new(out: Box<dyn Write + Send>, write_out: Arc<AtomicBool>) -> Self {
+    pub fn new(out: Box<dyn Write + Send>, write_out: Arc<AtomicBool>) -> Self {
         Self {
             buffer: VecDeque::new(),
             out,

vmm/Cargo.toml

@@ -41,6 +41,7 @@ qcow = { path = "../qcow" }
 seccompiler = "0.2.0"
 serde = { version = "1.0.144", features = ["rc", "derive"] }
 serde_json = "1.0.85"
+serial_buffer = { path = "../serial_buffer" }
 signal-hook = "0.3.14"
 thiserror = "1.0.32"
 uuid = "1.1.2"

vmm/src/lib.rs

@@ -70,7 +70,6 @@ pub mod memory_manager;
 pub mod migration;
 mod pci_segment;
 pub mod seccomp_filters;
-mod serial_buffer;
 mod serial_manager;
 mod sigwinch_listener;
 pub mod vm;

vmm/src/serial_manager.rs

@@ -5,12 +5,12 @@
 
 use crate::config::ConsoleOutputMode;
 use crate::device_manager::PtyPair;
-use crate::serial_buffer::SerialBuffer;
 #[cfg(target_arch = "aarch64")]
 use devices::legacy::Pl011;
 #[cfg(target_arch = "x86_64")]
 use devices::legacy::Serial;
 use libc::EFD_NONBLOCK;
+use serial_buffer::SerialBuffer;
 use std::fs::File;
 use std::io::Read;
 use std::os::unix::io::{AsRawFd, FromRawFd};