Move the functions launching clients to main.c

They belong in the compositor rather than libweston since they
set signals handlers, and a library should not do that behind its
user's back. Besides, they were using functions in main.c already
so they were not usable by other compositors.

Signed-off-by: Giulio Camuffo <giuliocamuffo@gmail.com>
Reviewed-by: Quentin Glidic <sardemff7+git@sardemff7.net>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
diff --git a/src/main.c b/src/main.c
index 39a13cf..2251101 100644
--- a/src/main.c
+++ b/src/main.c
@@ -37,6 +37,7 @@
 #include <sys/utsname.h>
 #include <sys/stat.h>
 #include <sys/wait.h>
+#include <sys/socket.h>
 
 #ifdef HAVE_LIBUNWIND
 #define UNW_LOCAL_ONLY
@@ -48,6 +49,7 @@
 #include "../shared/helpers.h"
 #include "git-version.h"
 #include "version.h"
+#include "weston.h"
 
 #include "compositor-drm.h"
 #include "compositor-headless.h"
@@ -168,12 +170,156 @@
 
 #endif
 
+static void
+child_client_exec(int sockfd, const char *path)
+{
+	int clientfd;
+	char s[32];
+	sigset_t allsigs;
+
+	/* do not give our signal mask to the new process */
+	sigfillset(&allsigs);
+	sigprocmask(SIG_UNBLOCK, &allsigs, NULL);
+
+	/* Launch clients as the user. Do not lauch clients with wrong euid.*/
+	if (seteuid(getuid()) == -1) {
+		weston_log("compositor: failed seteuid\n");
+		return;
+	}
+
+	/* SOCK_CLOEXEC closes both ends, so we dup the fd to get a
+	 * non-CLOEXEC fd to pass through exec. */
+	clientfd = dup(sockfd);
+	if (clientfd == -1) {
+		weston_log("compositor: dup failed: %m\n");
+		return;
+	}
+
+	snprintf(s, sizeof s, "%d", clientfd);
+	setenv("WAYLAND_SOCKET", s, 1);
+
+	if (execl(path, path, NULL) < 0)
+		weston_log("compositor: executing '%s' failed: %m\n",
+			path);
+}
+
+WL_EXPORT struct wl_client *
+weston_client_launch(struct weston_compositor *compositor,
+		     struct weston_process *proc,
+		     const char *path,
+		     weston_process_cleanup_func_t cleanup)
+{
+	int sv[2];
+	pid_t pid;
+	struct wl_client *client;
+
+	weston_log("launching '%s'\n", path);
+
+	if (os_socketpair_cloexec(AF_UNIX, SOCK_STREAM, 0, sv) < 0) {
+		weston_log("weston_client_launch: "
+			"socketpair failed while launching '%s': %m\n",
+			path);
+		return NULL;
+	}
+
+	pid = fork();
+	if (pid == -1) {
+		close(sv[0]);
+		close(sv[1]);
+		weston_log("weston_client_launch: "
+			"fork failed while launching '%s': %m\n", path);
+		return NULL;
+	}
+
+	if (pid == 0) {
+		child_client_exec(sv[1], path);
+		_exit(-1);
+	}
+
+	close(sv[1]);
+
+	client = wl_client_create(compositor->wl_display, sv[0]);
+	if (!client) {
+		close(sv[0]);
+		weston_log("weston_client_launch: "
+			"wl_client_create failed while launching '%s'.\n",
+			path);
+		return NULL;
+	}
+
+	proc->pid = pid;
+	proc->cleanup = cleanup;
+	weston_watch_process(proc);
+
+	return client;
+}
+
 WL_EXPORT void
 weston_watch_process(struct weston_process *process)
 {
 	wl_list_insert(&child_process_list, &process->link);
 }
 
+struct process_info {
+	struct weston_process proc;
+	char *path;
+};
+
+static void
+process_handle_sigchld(struct weston_process *process, int status)
+{
+	struct process_info *pinfo =
+		container_of(process, struct process_info, proc);
+
+	/*
+	 * There are no guarantees whether this runs before or after
+	 * the wl_client destructor.
+	 */
+
+	if (WIFEXITED(status)) {
+		weston_log("%s exited with status %d\n", pinfo->path,
+			   WEXITSTATUS(status));
+	} else if (WIFSIGNALED(status)) {
+		weston_log("%s died on signal %d\n", pinfo->path,
+			   WTERMSIG(status));
+	} else {
+		weston_log("%s disappeared\n", pinfo->path);
+	}
+
+	free(pinfo->path);
+	free(pinfo);
+}
+
+WL_EXPORT struct wl_client *
+weston_client_start(struct weston_compositor *compositor, const char *path)
+{
+	struct process_info *pinfo;
+	struct wl_client *client;
+
+	pinfo = zalloc(sizeof *pinfo);
+	if (!pinfo)
+		return NULL;
+
+	pinfo->path = strdup(path);
+	if (!pinfo->path)
+		goto out_free;
+
+	client = weston_client_launch(compositor, &pinfo->proc, path,
+				      process_handle_sigchld);
+	if (!client)
+		goto out_str;
+
+	return client;
+
+out_str:
+	free(pinfo->path);
+
+out_free:
+	free(pinfo);
+
+	return NULL;
+}
+
 static void
 log_uname(void)
 {