Start work on everywhere prewarm

launcher.c

@@ -5,13 +5,9 @@
  * Distributed under terms of the GPL3 license.
  */
 
-#include <unistd.h>
-#include <stdio.h>
-#include <stdlib.h>
+#include "prewarm-launcher.h"
+
 #include <libgen.h>
-#include <string.h>
-#include <errno.h>
-#include <stdbool.h>
 #ifdef __APPLE__
 #include <mach-o/dyld.h>
 #include <sys/syslimits.h>
@@ -19,9 +15,8 @@
 #else
 #include <limits.h>
 #endif
-#include <Python.h>
 #include <wchar.h>
-#include <stdbool.h>
+#include <Python.h>
 
 #ifndef KITTY_LIB_PATH
 #define KITTY_LIB_PATH "../.."
@@ -275,6 +270,7 @@ read_exe_path(char *exe, size_t buf_sz) {
 
 int main(int argc, char *argv[]) {
     if (argc < 1 || !argv) { fprintf(stderr, "Invalid argc/argv\n"); return 1; }
+    use_prewarmed_process(argc, argv);
     char exe[PATH_MAX+1] = {0};
     char exe_dir_buf[PATH_MAX+1] = {0};
     FREE_AFTER_FUNCTION const char *lc_ctype = NULL;

prewarm-launcher.h

@@ -0,0 +1,57 @@
+/*
+ * Copyright (C) 2022 Kovid Goyal <kovid at kovidgoyal.net>
+ *
+ * Distributed under terms of the GPL3 license.
+ */
+
+#pragma once
+
+// needed for strnlen
+#define _XOPEN_SOURCE 700
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <poll.h>
+#include <string.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+static int
+connect_to_socket_synchronously(const char *addr) {
+    struct sockaddr_un sock_addr = {.sun_family=AF_UNIX};
+    strncpy(sock_addr.sun_path, addr, sizeof(sock_addr.sun_path) - 1);
+    const size_t addrlen = strnlen(sock_addr.sun_path, sizeof(sock_addr.sun_path)) + sizeof(sock_addr.sun_family);
+    if (sock_addr.sun_path[0] == '@') sock_addr.sun_path[0] = 0;
+    int fd = socket(AF_UNIX, SOCK_STREAM, 0);
+    if (connect(fd, (struct sockaddr*)&sock_addr, addrlen) != 0) {
+        if (errno != EINTR) return -1;
+        struct pollfd poll_data = {.fd=fd, .events=POLLOUT};
+        while (poll (&poll_data, 1, -1) == -1) { if (errno != EINTR) return -1; }
+        int socket_error_code = 0;
+        socklen_t sizeof_socket_error_code = sizeof(socket_error_code);
+        if (getsockopt (fd, SOL_SOCKET, SO_ERROR, &socket_error_code, &sizeof_socket_error_code) == -1) return -1;
+        if (socket_error_code != 0) return -1;
+    }
+    return fd;
+}
+
+static bool
+is_prewarmable(int argc, char *argv[]) {
+    if (argc < 2) return false;
+    if (argv[1][0] != '+') return false;
+    if (argv[1][1] != 0) return strcmp(argv[1], "+open") != 0;
+    if (argc < 3) return false;
+    return strcmp(argv[2], "open") != 0;
+}
+
+static void
+use_prewarmed_process(int argc, char *argv[]) {
+    const char *env_addr = getenv("KITTY_PREWARM_SOCKET_ADDRESS");
+    if (!env_addr || !*env_addr || !is_prewarmable(argc, argv)) return;
+    int fd = connect_to_socket_synchronously(env_addr);
+    if (fd < 0) return;
+}

setup.py

@@ -870,7 +870,7 @@ def build_launcher(args: Options, launcher_dir: str = '.', bundle_type: str = 's
            src, '-o', dest] + ldflags + libs + pylib
     key = CompileKey('launcher.c', 'kitty')
     desc = f'Building {emphasis("launcher")} ...'
-    args.compilation_database.add_command(desc, cmd, partial(newer, dest, src), key=key, keyfile=src)
+    args.compilation_database.add_command(desc, cmd, partial(newer, dest, src, "prewarm-launcher.h"), key=key, keyfile=src)
     args.compilation_database.build_all()