server: Extract most logic into the new socket abstraction

- Move event loop code into event/socket
- Reimplement server.c on top of the new SocketWatcher class
- Adapt msgpack_rpc/channel.c

5 files changed, 242 insertions, 189 deletions

diff --git a/src/nvim/event/socket.c b/src/nvim/event/socket.c
new file mode 100644
index 0000000000..bdc632abf0
--- /dev/null
+++ b/src/nvim/event/socket.c
@@ -0,0 +1,157 @@
+#include <assert.h>
+#include <stdint.h>
+
+#include <uv.h>
+
+#include "nvim/event/loop.h"
+#include "nvim/event/socket.h"
+#include "nvim/event/rstream.h"
+#include "nvim/event/wstream.h"
+#include "nvim/os/os.h"
+#include "nvim/ascii.h"
+#include "nvim/vim.h"
+#include "nvim/strings.h"
+#include "nvim/path.h"
+#include "nvim/memory.h"
+
+#ifdef INCLUDE_GENERATED_DECLARATIONS
+# include "event/socket.c.generated.h"
+#endif
+
+#define NVIM_DEFAULT_TCP_PORT 7450
+
+void socket_watcher_init(Loop *loop, SocketWatcher *watcher,
+    const char *endpoint, void *data)
+  FUNC_ATTR_NONNULL_ARG(1) FUNC_ATTR_NONNULL_ARG(2) FUNC_ATTR_NONNULL_ARG(3)
+{
+  // Trim to `ADDRESS_MAX_SIZE`
+  if (xstrlcpy(watcher->addr, endpoint, sizeof(watcher->addr))
+      >= sizeof(watcher->addr)) {
+    // TODO(aktau): since this is not what the user wanted, perhaps we
+    // should return an error here
+    WLOG("Address was too long, truncated to %s", watcher->addr);
+  }
+
+  bool tcp = true;
+  char ip[16], *ip_end = xstrchrnul(watcher->addr, ':');
+
+  // (ip_end - addr) is always > 0, so convert to size_t
+  size_t addr_len = (size_t)(ip_end - watcher->addr);
+
+  if (addr_len > sizeof(ip) - 1) {
+    // Maximum length of an IPv4 address buffer is 15 (eg: 255.255.255.255)
+    addr_len = sizeof(ip) - 1;
+  }
+
+  // Extract the address part
+  xstrlcpy(ip, watcher->addr, addr_len + 1);
+  int port = NVIM_DEFAULT_TCP_PORT;
+
+  if (*ip_end == ':') {
+    // Extract the port
+    long lport = strtol(ip_end + 1, NULL, 10); // NOLINT
+    if (lport <= 0 || lport > 0xffff) {
+      // Invalid port, treat as named pipe or unix socket
+      tcp = false;
+    } else {
+      port = (int) lport;
+    }
+  }
+
+  if (tcp) {
+    // Try to parse ip address
+    if (uv_ip4_addr(ip, port, &watcher->uv.tcp.addr)) {
+      // Invalid address, treat as named pipe or unix socket
+      tcp = false;
+    }
+  }
+
+  if (tcp) {
+    uv_tcp_init(&loop->uv, &watcher->uv.tcp.handle);
+    watcher->stream = (uv_stream_t *)&watcher->uv.tcp.handle;
+  } else {
+    uv_pipe_init(&loop->uv, &watcher->uv.pipe.handle, 0);
+    watcher->stream = (uv_stream_t *)&watcher->uv.pipe.handle;
+  }
+
+  watcher->stream->data = watcher;
+  watcher->cb = NULL;
+  watcher->close_cb = NULL;
+}
+
+int socket_watcher_start(SocketWatcher *watcher, int backlog, socket_cb cb)
+  FUNC_ATTR_NONNULL_ALL
+{
+  watcher->cb = cb;
+  int result;
+
+  if (watcher->stream->type == UV_TCP) {
+    result = uv_tcp_bind(&watcher->uv.tcp.handle,
+                         (const struct sockaddr *)&watcher->uv.tcp.addr, 0);
+  } else {
+    result = uv_pipe_bind(&watcher->uv.pipe.handle, watcher->addr);
+  }
+
+  if (result == 0) {
+    result = uv_listen(watcher->stream, backlog, connection_cb);
+  }
+
+  assert(result <= 0);  // libuv should have returned -errno or zero.
+  if (result < 0) {
+    if (result == -EACCES) {
+      // Libuv converts ENOENT to EACCES for Windows compatibility, but if
+      // the parent directory does not exist, ENOENT would be more accurate.
+      *path_tail((char_u *)watcher->addr) = NUL;
+      if (!os_file_exists((char_u *)watcher->addr)) {
+        result = -ENOENT;
+      }
+    }
+    return result;
+  }
+
+  return 0;
+}
+
+int socket_watcher_accept(SocketWatcher *watcher, Stream *stream, void *data)
+{
+  uv_stream_t *client;
+
+  if (watcher->stream->type == UV_TCP) {
+    client = (uv_stream_t *)&stream->uv.tcp;
+    uv_tcp_init(watcher->uv.tcp.handle.loop, (uv_tcp_t *)client);
+  } else {
+    client = (uv_stream_t *)&stream->uv.pipe;
+    uv_pipe_init(watcher->uv.pipe.handle.loop, (uv_pipe_t *)client, 0);
+  }
+
+  int result = uv_accept(watcher->stream, client);
+
+  if (result) {
+    uv_close((uv_handle_t *)client, NULL);
+    return result;
+  }
+
+  stream_init(NULL, stream, -1, client, data);
+  return 0;
+}
+
+void socket_watcher_close(SocketWatcher *watcher, socket_close_cb cb)
+  FUNC_ATTR_NONNULL_ARG(1)
+{
+  watcher->close_cb = cb;
+  uv_close((uv_handle_t *)watcher->stream, close_cb);
+}
+
+static void connection_cb(uv_stream_t *handle, int status)
+{
+  SocketWatcher *watcher = handle->data;
+  watcher->cb(watcher, status, watcher->data);
+}
+
+static void close_cb(uv_handle_t *handle)
+{
+  SocketWatcher *watcher = handle->data;
+  if (watcher->close_cb) {
+    watcher->close_cb(watcher, watcher->data);
+  }
+}
diff --git a/src/nvim/event/socket.h b/src/nvim/event/socket.h
new file mode 100644
index 0000000000..17fd39f33b
--- /dev/null
+++ b/src/nvim/event/socket.h
@@ -0,0 +1,38 @@
+#ifndef NVIM_EVENT_SOCKET_H
+#define NVIM_EVENT_SOCKET_H
+
+#include <uv.h>
+
+#include "nvim/event/loop.h"
+#include "nvim/event/rstream.h"
+#include "nvim/event/wstream.h"
+
+#define ADDRESS_MAX_SIZE 256
+
+typedef struct socket_watcher SocketWatcher;
+typedef void (*socket_cb)(SocketWatcher *watcher, int result, void *data);
+typedef void (*socket_close_cb)(SocketWatcher *watcher, void *data);
+
+struct socket_watcher {
+  // Pipe/socket path, or TCP address string
+  char addr[ADDRESS_MAX_SIZE];
+  // TCP server or unix socket (named pipe on Windows)
+  union {
+    struct {
+      uv_tcp_t handle;
+      struct sockaddr_in addr;
+    } tcp;
+    struct {
+      uv_pipe_t handle;
+    } pipe;
+  } uv;
+  uv_stream_t *stream;
+  void *data;
+  socket_cb cb;
+  socket_close_cb close_cb;
+};
+
+#ifdef INCLUDE_GENERATED_DECLARATIONS
+# include "event/socket.h.generated.h"
+#endif
+#endif  // NVIM_EVENT_SOCKET_H
diff --git a/src/nvim/msgpack_rpc/channel.c b/src/nvim/msgpack_rpc/channel.c
index 05badc72d4..577965e5ba 100644
--- a/src/nvim/msgpack_rpc/channel.c
+++ b/src/nvim/msgpack_rpc/channel.c
@@ -12,6 +12,7 @@
 #include "nvim/event/loop.h"
 #include "nvim/event/rstream.h"
 #include "nvim/event/wstream.h"
+#include "nvim/event/socket.h"
 #include "nvim/os/job.h"
 #include "nvim/os/job_defs.h"
 #include "nvim/msgpack_rpc/helpers.h"
@@ -140,17 +141,14 @@ uint64_t channel_from_job(char **argv)
   return channel->id;
 }
 
-/// Creates an API channel from a libuv stream representing a tcp or
-/// pipe/socket client connection
+/// Creates an API channel from a tcp/pipe socket connection
 ///
-/// @param stream The established connection
-void channel_from_stream(uv_stream_t *uvstream)
+/// @param watcher The SocketWatcher ready to accept the connection
+void channel_from_connection(SocketWatcher *watcher)
 {
   Channel *channel = register_channel(kChannelTypeSocket);
-  stream_init(NULL, &channel->data.stream, -1, uvstream, channel);
-  // write stream
+  socket_watcher_accept(watcher, &channel->data.stream, channel);
   wstream_init(&channel->data.stream, 0);
-  // read stream
   rstream_init(&channel->data.stream, CHANNEL_BUFFER_SIZE);
   rstream_start(&channel->data.stream, parse_msgpack);
 }
diff --git a/src/nvim/msgpack_rpc/channel.h b/src/nvim/msgpack_rpc/channel.h
index df742fe368..104547a7b8 100644
--- a/src/nvim/msgpack_rpc/channel.h
+++ b/src/nvim/msgpack_rpc/channel.h
@@ -5,6 +5,7 @@
 #include <uv.h>
 
 #include "nvim/api/private/defs.h"
+#include "nvim/event/socket.h"
 #include "nvim/vim.h"
 
 #define METHOD_MAXLEN 512
diff --git a/src/nvim/msgpack_rpc/server.c b/src/nvim/msgpack_rpc/server.c
index 1a78b3498f..8dffea35ca 100644
--- a/src/nvim/msgpack_rpc/server.c
+++ b/src/nvim/msgpack_rpc/server.c
@@ -3,11 +3,10 @@
 #include <string.h>
 #include <stdint.h>
 
-#include <uv.h>
-
 #include "nvim/msgpack_rpc/channel.h"
 #include "nvim/msgpack_rpc/server.h"
 #include "nvim/os/os.h"
+#include "nvim/event/socket.h"
 #include "nvim/ascii.h"
 #include "nvim/eval.h"
 #include "nvim/garray.h"
@@ -19,35 +18,9 @@
 #include "nvim/strings.h"
 
 #define MAX_CONNECTIONS 32
-#define ADDRESS_MAX_SIZE 256
-#define NVIM_DEFAULT_TCP_PORT 7450
 #define LISTEN_ADDRESS_ENV_VAR "NVIM_LISTEN_ADDRESS"
 
-typedef enum {
-  kServerTypeTcp,
-  kServerTypePipe
-} ServerType;
-
-typedef struct {
-  // Pipe/socket path, or TCP address string
-  char addr[ADDRESS_MAX_SIZE];
-
-  // Type of the union below
-  ServerType type;
-
-  // TCP server or unix socket (named pipe on Windows)
-  union {
-    struct {
-      uv_tcp_t handle;
-      struct sockaddr_in addr;
-    } tcp;
-    struct {
-      uv_pipe_t handle;
-    } pipe;
-  } socket;
-} Server;
-
-static garray_T servers = GA_EMPTY_INIT_VALUE;
+static garray_T watchers = GA_EMPTY_INIT_VALUE;
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "msgpack_rpc/server.c.generated.h"
@@ -56,7 +29,7 @@ static garray_T servers = GA_EMPTY_INIT_VALUE;
 /// Initializes the module
 bool server_init(void)
 {
-  ga_init(&servers, sizeof(Server *), 1);
+  ga_init(&watchers, sizeof(SocketWatcher *), 1);
 
   bool must_free = false;
   const char *listen_address = os_getenv(LISTEN_ADDRESS_ENV_VAR);
@@ -72,18 +45,10 @@ bool server_init(void)
   return ok;
 }
 
-/// Retrieve the file handle from a server.
-static uv_handle_t *server_handle(Server *server)
-{
-  return server->type == kServerTypeTcp
-    ? (uv_handle_t *)&server->socket.tcp.handle
-    : (uv_handle_t *) &server->socket.pipe.handle;
-}
-
 /// Teardown a single server
-static void server_close_cb(Server **server)
+static void close_socket_watcher(SocketWatcher **watcher)
 {
-  uv_close(server_handle(*server), free_server);
+  socket_watcher_close(*watcher, free_server);
 }
 
 /// Set v:servername to the first server in the server list, or unset it if no
@@ -91,7 +56,7 @@ static void server_close_cb(Server **server)
 static void set_vservername(garray_T *srvs)
 {
   char *default_server = (srvs->ga_len > 0)
-    ? ((Server **)srvs->ga_data)[0]->addr
+    ? ((SocketWatcher **)srvs->ga_data)[0]->addr
     : NULL;
   set_vim_var_string(VV_SEND_SERVER, (char_u *)default_server, -1);
 }
@@ -99,7 +64,7 @@ static void set_vservername(garray_T *srvs)
 /// Teardown the server module
 void server_teardown(void)
 {
-  GA_DEEP_CLEAR(&servers, Server *, server_close_cb);
+  GA_DEEP_CLEAR(&watchers, SocketWatcher *, close_socket_watcher);
 }
 
 /// Starts listening for API calls on the TCP address or pipe path `endpoint`.
@@ -116,120 +81,38 @@ void server_teardown(void)
 int server_start(const char *endpoint)
   FUNC_ATTR_NONNULL_ALL
 {
-  char addr[ADDRESS_MAX_SIZE];
-
-  // Trim to `ADDRESS_MAX_SIZE`
-  if (xstrlcpy(addr, endpoint, sizeof(addr)) >= sizeof(addr)) {
-    // TODO(aktau): since this is not what the user wanted, perhaps we
-    // should return an error here
-    WLOG("Address was too long, truncated to %s", addr);
-  }
-
-  // Check if the server already exists
-  for (int i = 0; i < servers.ga_len; i++) {
-    if (strcmp(addr, ((Server **)servers.ga_data)[i]->addr) == 0) {
-      ELOG("Already listening on %s", addr);
+  SocketWatcher *watcher = xmalloc(sizeof(SocketWatcher));
+  socket_watcher_init(&loop, watcher, endpoint, NULL);
+
+  // Check if a watcher for the endpoint already exists
+  for (int i = 0; i < watchers.ga_len; i++) {
+    if (!strcmp(watcher->addr, ((SocketWatcher **)watchers.ga_data)[i]->addr)) {
+      ELOG("Already listening on %s", watcher->addr);
+      socket_watcher_close(watcher, free_server);
       return 1;
     }
   }
 
-  ServerType server_type = kServerTypeTcp;
-  Server *server = xmalloc(sizeof(Server));
-  char ip[16], *ip_end = strrchr(addr, ':');
-
-  if (!ip_end) {
-    ip_end = strchr(addr, NUL);
-  }
-
-  // (ip_end - addr) is always > 0, so convert to size_t
-  size_t addr_len = (size_t)(ip_end - addr);
-
-  if (addr_len > sizeof(ip) - 1) {
-    // Maximum length of an IPv4 address buffer is 15 (eg: 255.255.255.255)
-    addr_len = sizeof(ip) - 1;
-  }
-
-  // Extract the address part
-  xstrlcpy(ip, addr, addr_len + 1);
-
-  int port = NVIM_DEFAULT_TCP_PORT;
-
-  if (*ip_end == ':') {
-    // Extract the port
-    long lport = strtol(ip_end + 1, NULL, 10); // NOLINT
-    if (lport <= 0 || lport > 0xffff) {
-      // Invalid port, treat as named pipe or unix socket
-      server_type = kServerTypePipe;
-    } else {
-      port = (int) lport;
-    }
-  }
-
-  if (server_type == kServerTypeTcp) {
-    // Try to parse ip address
-    if (uv_ip4_addr(ip, port, &server->socket.tcp.addr)) {
-      // Invalid address, treat as named pipe or unix socket
-      server_type = kServerTypePipe;
-    }
-  }
-
-  int result;
-  uv_stream_t *stream = NULL;
-
-  xstrlcpy(server->addr, addr, sizeof(server->addr));
-
-  if (server_type == kServerTypeTcp) {
-    // Listen on tcp address/port
-    uv_tcp_init(&loop.uv, &server->socket.tcp.handle);
-    result = uv_tcp_bind(&server->socket.tcp.handle,
-                         (const struct sockaddr *)&server->socket.tcp.addr,
-                         0);
-    stream = (uv_stream_t *)&server->socket.tcp.handle;
-  } else {
-    // Listen on named pipe or unix socket
-    uv_pipe_init(&loop.uv, &server->socket.pipe.handle, 0);
-    result = uv_pipe_bind(&server->socket.pipe.handle, server->addr);
-    stream = (uv_stream_t *)&server->socket.pipe.handle;
-  }
-
-  stream->data = server;
-
-  if (result == 0) {
-    result = uv_listen((uv_stream_t *)&server->socket.tcp.handle,
-                       MAX_CONNECTIONS,
-                       connection_cb);
-  }
-
-  assert(result <= 0);  // libuv should have returned -errno or zero.
+  int result = socket_watcher_start(watcher, MAX_CONNECTIONS, connection_cb);
   if (result < 0) {
-    if (result == -EACCES) {
-      // Libuv converts ENOENT to EACCES for Windows compatibility, but if
-      // the parent directory does not exist, ENOENT would be more accurate.
-      *path_tail((char_u *) addr) = NUL;
-      if (!os_file_exists((char_u *) addr)) {
-        result = -ENOENT;
-      }
-    }
-    uv_close((uv_handle_t *)stream, free_server);
     ELOG("Failed to start server: %s", uv_strerror(result));
+    socket_watcher_close(watcher, free_server);
     return result;
   }
 
   // Update $NVIM_LISTEN_ADDRESS, if not set.
   const char *listen_address = os_getenv(LISTEN_ADDRESS_ENV_VAR);
   if (listen_address == NULL) {
-    os_setenv(LISTEN_ADDRESS_ENV_VAR, addr, 1);
+    os_setenv(LISTEN_ADDRESS_ENV_VAR, watcher->addr, 1);
   }
 
-  server->type = server_type;
-
-  // Add the server to the list.
-  ga_grow(&servers, 1);
-  ((Server **)servers.ga_data)[servers.ga_len++] = server;
+  // Add the watcher to the list.
+  ga_grow(&watchers, 1);
+  ((SocketWatcher **)watchers.ga_data)[watchers.ga_len++] = watcher;
 
   // Update v:servername, if not set.
   if (STRLEN(get_vim_var_str(VV_SEND_SERVER)) == 0) {
-    set_vservername(&servers);
+    set_vservername(&watchers);
   }
 
   return 0;
@@ -240,21 +123,21 @@ int server_start(const char *endpoint)
 /// @param endpoint Address of the server.
 void server_stop(char *endpoint)
 {
-  Server *server;
+  SocketWatcher *watcher;
   char addr[ADDRESS_MAX_SIZE];
 
   // Trim to `ADDRESS_MAX_SIZE`
   xstrlcpy(addr, endpoint, sizeof(addr));
 
   int i = 0;  // Index of the server whose address equals addr.
-  for (; i < servers.ga_len; i++) {
-    server = ((Server **)servers.ga_data)[i];
-    if (strcmp(addr, server->addr) == 0) {
+  for (; i < watchers.ga_len; i++) {
+    watcher = ((SocketWatcher **)watchers.ga_data)[i];
+    if (strcmp(addr, watcher->addr) == 0) {
       break;
     }
   }
 
-  if (i >= servers.ga_len) {
+  if (i >= watchers.ga_len) {
     ELOG("Not listening on %s", addr);
     return;
   }
@@ -265,18 +148,18 @@ void server_stop(char *endpoint)
     os_unsetenv(LISTEN_ADDRESS_ENV_VAR);
   }
 
-  uv_close(server_handle(server), free_server);
+  socket_watcher_close(watcher, free_server);
 
   // Remove this server from the list by swapping it with the last item.
-  if (i != servers.ga_len - 1) {
-    ((Server **)servers.ga_data)[i] =
-      ((Server **)servers.ga_data)[servers.ga_len - 1];
+  if (i != watchers.ga_len - 1) {
+    ((SocketWatcher **)watchers.ga_data)[i] =
+      ((SocketWatcher **)watchers.ga_data)[watchers.ga_len - 1];
   }
-  servers.ga_len--;
+  watchers.ga_len--;
 
   // If v:servername is the stopped address, re-initialize it.
   if (STRCMP(addr, get_vim_var_str(VV_SEND_SERVER)) == 0) {
-    set_vservername(&servers);
+    set_vservername(&watchers);
   }
 }
 
@@ -285,52 +168,28 @@ void server_stop(char *endpoint)
 char **server_address_list(size_t *size)
   FUNC_ATTR_NONNULL_ALL
 {
-  if ((*size = (size_t) servers.ga_len) == 0) {
+  if ((*size = (size_t)watchers.ga_len) == 0) {
     return NULL;
   }
 
-  char **addrs = xcalloc((size_t) servers.ga_len, sizeof(const char *));
-  for (int i = 0; i < servers.ga_len; i++) {
-    addrs[i] = xstrdup(((Server **)servers.ga_data)[i]->addr);
+  char **addrs = xcalloc((size_t)watchers.ga_len, sizeof(const char *));
+  for (int i = 0; i < watchers.ga_len; i++) {
+    addrs[i] = xstrdup(((SocketWatcher **)watchers.ga_data)[i]->addr);
   }
   return addrs;
 }
 
-static void connection_cb(uv_stream_t *server, int status)
+static void connection_cb(SocketWatcher *watcher, int result, void *data)
 {
-  int result;
-  uv_stream_t *client;
-  Server *srv = server->data;
-
-  if (status < 0) {
-    abort();
-  }
-
-  if (srv->type == kServerTypeTcp) {
-    client = xmalloc(sizeof(uv_tcp_t));
-    uv_tcp_init(&loop.uv, (uv_tcp_t *)client);
-  } else {
-    client = xmalloc(sizeof(uv_pipe_t));
-    uv_pipe_init(&loop.uv, (uv_pipe_t *)client, 0);
-  }
-
-  result = uv_accept(server, client);
-
   if (result) {
     ELOG("Failed to accept connection: %s", uv_strerror(result));
-    uv_close((uv_handle_t *)client, free_client);
     return;
   }
 
-  channel_from_stream(client);
-}
-
-static void free_client(uv_handle_t *handle)
-{
-  xfree(handle);
+  channel_from_connection(watcher);
 }
 
-static void free_server(uv_handle_t *handle)
+static void free_server(SocketWatcher *watcher, void *data)
 {
-  xfree(handle->data);
+  xfree(watcher);
 }