[WIP] use g_fork_execvp instead of g_fork

common/os_calls.c

@@ -2921,6 +2921,29 @@ g_fork(void)
 #endif
 }
 
+/*****************************************************************************/
+int
+g_fork_execvp(const char *p1, char *args[])
+{
+    int pid;
+
+    pid = g_fork();
+
+    if (pid == 0)
+    {
+        g_execvp(p1, args);
+
+        /* should not get here */
+        LOG(LOG_LEVEL_ERROR,
+            "Failed to execute %s: execvp(3) failed with %s (%d)",
+            p1, g_get_strerror(), g_get_errno());
+
+        exit(1);
+    }
+
+    return pid;
+}
+
 /*****************************************************************************/
 /* does not work in win32 */
 int
@@ -3049,6 +3072,26 @@ g_set_allusercontext(int uid)
     return (rv != 0);  /* Return 0 or 1 */
 }
 #endif
+
+/*****************************************************************************/
+void
+g_get_executable_path(enum xrdp_exe xe, char *buf, int bufsize)
+{
+    switch (xe)
+    {
+        case E_XE_XRDP:
+            g_snprintf(buf, bufsize, XRDP_SBIN_PATH "/xrdp");
+            break;
+        case E_XE_SESMAN:
+            g_snprintf(buf, bufsize, XRDP_SBIN_PATH "/xrdp-sesman");
+            break;
+
+        default:
+            LOG(LOG_LEVEL_WARNING, "g_get_executable_path(): Unsupported exe %d", (int)xe);
+    }
+}
+
+
 /*****************************************************************************/
 /* does not work in win32
    returns pid of process that exits or zero if signal occurred */

common/os_calls.h

@@ -23,6 +23,14 @@
 
 #include "arch.h"
 
+enum xrdp_exe
+{
+    E_XE_XRDP = 0,
+    E_XE_SESMAN = 1,
+
+    /* TODO: add others below */
+};
+
 struct exit_status
 {
     /* set to -1 when the process exited via a signal */
@@ -258,6 +266,7 @@ void     g_signal_terminate(void (*func)(int));
 void     g_signal_pipe(void (*func)(int));
 void     g_signal_usr1(void (*func)(int));
 int      g_fork(void);
+int      g_fork_execvp(const char *p1, char *args[]);
 int      g_setgid(int pid);
 int      g_initgroups(const char *user);
 int      g_getuid(void);
@@ -273,6 +282,7 @@ int      g_setlogin(const char *name);
  */
 int      g_set_allusercontext(int uid);
 #endif
+void     g_get_executable_path(enum xrdp_exe xe, char *buf, int bufsize);
 int      g_waitchild(void);
 int      g_waitpid(int pid);
 struct exit_status g_waitpid_status(int pid);

xrdp/xrdp.c

@@ -213,6 +213,15 @@ xrdp_process_params(int argc, char **argv,
             index++;
             startup_params->xrdp_ini = value;
         }
+        else if (nocase_matches(option, "--child-process", NULL))
+        {
+            startup_params->is_child = 1;
+        }
+        else if (nocase_matches(option, "--child-fd", NULL))
+        {
+            index++;
+            startup_params->child_fd = g_atoi(value);
+        }
         else /* unknown option */
         {
             return index;
@@ -405,7 +414,30 @@ main(int argc, char **argv)
         g_exit(1);
     }
 
+    if (startup_params.is_child)
+    {
+        if (startup_params.child_fd < 3)
+        {
+            g_writeln("requested act as child process, but --child-fd option is not given");
+            g_deinit();
+            g_exit(1);
+        }
+
+        g_set_threadid(tc_get_threadid());
+        g_listen = xrdp_listen_create();
+        g_signal_user_interrupt(xrdp_shutdown); /* SIGINT */
+        g_signal_pipe(xrdp_sig_no_op);          /* SIGPIPE */
+        g_signal_terminate(xrdp_shutdown);      /* SIGTERM */
+        g_signal_child_stop(xrdp_child);        /* SIGCHLD */
+        g_signal_hang_up(xrdp_sig_no_op);       /* SIGHUP */
+
+        g_listen->startup_params = &startup_params;
 
+        xrdp_process_child_entrypoint(g_listen, startup_params.child_fd);
+
+        g_deinit();
+        g_exit(0);
+    }
 
     if (g_file_exist(pid_file)) /* xrdp.pid */
     {

xrdp/xrdp.h

@@ -184,6 +184,8 @@ void
 xrdp_process_delete(struct xrdp_process *self);
 int
 xrdp_process_main_loop(struct xrdp_process *self);
+int
+xrdp_process_child_entrypoint(struct xrdp_listen *owner, int socket_fd);
 
 /* xrdp_listen.c */
 struct xrdp_listen *

xrdp/xrdp_listen.c

@@ -771,41 +771,45 @@ xrdp_listen_process_startup_params(struct xrdp_listen *self)
 static int
 xrdp_listen_fork(struct xrdp_listen *self, struct trans *server_trans)
 {
+    char server_trans_fd_str[32];
+    char executable_path[4096];
+    struct list *child_arguments;
+
     int pid;
     int index;
     struct xrdp_process *process;
     struct trans *ltrans;
 
-    pid = g_fork();
+    g_get_executable_path(E_XE_XRDP, executable_path, 4096);
+    g_snprintf(server_trans_fd_str, 32, "%d", (int) server_trans->sck);
+
+    child_arguments = list_create();
 
-    if (pid == 0)
+    if (child_arguments != NULL)
     {
-        /* child */
-        /* recreate some main globals */
-        xrdp_child_fork();
-        /* recreate the process done wait object, not used in fork mode */
-        /* close, don't delete this */
-        g_close_wait_obj(self->pro_done_event);
-        xrdp_listen_create_pro_done(self);
-        /* delete listener, child need not listen */
-        for (index = 0; index < self->trans_list->count; index++)
+        /* FIXME: pass log_fd to child */
+        child_arguments->auto_free = 1;
+        if (!list_add_strdup_multi(child_arguments,
+                                   "xrdp",
+                                   "--child-process",
+                                   "--child-fd", server_trans_fd_str,
+                                   NULL))
         {
-            ltrans = (struct trans *) list_get_item(self->trans_list, index);
-            trans_delete_from_child(ltrans);
+            list_delete(child_arguments);
+            child_arguments = NULL;
         }
-        list_delete(self->trans_list);
-        self->trans_list = NULL;
-        /* new connect instance */
-        process = xrdp_process_create(self, 0);
-        process->server_trans = server_trans;
-        g_process = process;
-        xrdp_process_run(0);
-        tc_sem_dec(g_process_sem);
-        xrdp_process_delete(process);
-        /* mark this process to exit */
-        g_set_term(1);
+    }
+
+    if (!child_arguments)
+    {
+        LOG(LOG_LEVEL_ERROR, "xrdp_listen_fork(): could not prepare arguments list for child process");
         return 1;
     }
+    else
+    {
+        pid = g_fork_execvp(executable_path, (char **) child_arguments->items);
+        list_delete(child_arguments);
+    }
 
     /* parent */
     trans_delete(server_trans);

xrdp/xrdp_process.c

@@ -312,3 +312,24 @@ xrdp_process_main_loop(struct xrdp_process *self)
     g_set_wait_obj(self->done_event);
     return 0;
 }
+
+/*****************************************************************************/
+int
+xrdp_process_child_entrypoint(struct xrdp_listen *owner, int socket_fd)
+{
+    struct trans *server_trans;
+    struct xrdp_process *process;
+
+    server_trans = trans_create(TRANS_MODE_TCP, 16, 16);
+    server_trans->status = TRANS_STATUS_UP;
+    server_trans->sck = socket_fd;
+
+    process = xrdp_process_create(owner, 0);
+    process->server_trans = server_trans;
+
+    xrdp_process_main_loop(process);
+
+    xrdp_process_delete(process);
+    g_set_term(1);
+    return 0;
+}

xrdp/xrdp_types.h

@@ -684,6 +684,8 @@ struct xrdp_startup_params
     int tcp_nodelay;
     int tcp_keepalive;
     int use_vsock;
+    int is_child;
+    int child_fd;
 };
 
 /*