Add sesman restart module

Adds a module which can be used when sesman is restarting. This is
initially used to rediscover sessions from a previous run.

sesman/Makefile.am

@@ -32,6 +32,8 @@ xrdp_sesman_SOURCES = \
   sesexec_control.h \
   session_list.c \
   session_list.h \
+  sesman_restart.c \
+  sesman_restart.h \
   sig.c \
   sig.h
 

sesman/sesman.c

@@ -46,6 +46,7 @@
 #include "scp.h"
 #include "scp_process.h"
 #include "sesexec_control.h"
+#include "sesman_restart.h"
 #include "sig.h"
 #include "string_calls.h"
 #include "trans.h"
@@ -940,7 +941,8 @@ main(int argc, char **argv)
     }
 
     if ((error = pre_session_list_init(MAX_PRE_SESSION_ITEMS)) == 0 &&
-            (error = session_list_init()) == 0)
+            (error = session_list_init()) == 0 &&
+            (error = sesman_restart_discover_sessions()) == 0)
     {
         error = sesman_main_loop();
     }

sesman/sesman_restart.c

@@ -0,0 +1,91 @@
+/**
+ * xrdp: A Remote Desktop Protocol server.
+ *
+ * Copyright (C) Matt Burt 2024
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ *
+ * @file sesman_restart.c
+ * @brief Sesman restart definitions
+ * @author Matt Burt
+ *
+ */
+
+#if defined(HAVE_CONFIG_H)
+#include "config_ac.h"
+#endif
+
+#include <stdio.h>
+
+#include "os_calls.h"
+#include "sesman.h"
+#include "sesman_config.h"
+
+#include "sesman_restart.h"
+#include "xrdp_sockets.h"
+
+/******************************************************************************/
+static int
+create_restart_directory(const char *listen_port)
+{
+    int rv = 1;
+    // The restart directory contains Unix Domain sockets, so can't
+    // exceed XRDP_SOCKETS_MAXPATH in length
+    char restart_dir[XRDP_SOCKETS_MAXPATH];
+    // Allow some overhead for the names of the directory entries
+#define MAX_LISTEN_PORT_LEN (XRDP_SOCKETS_MAXPATH - 10)
+
+    if (strlen(listen_port) > MAX_LISTEN_PORT_LEN)
+    {
+        LOG(LOG_LEVEL_ERROR, "Listen port string length must be <= %d",
+            MAX_LISTEN_PORT_LEN);
+    }
+    else
+    {
+        snprintf(restart_dir, sizeof(restart_dir), "%s.r", listen_port);
+        (void)g_mkdir(restart_dir); // Directory may already exist
+        if (!g_directory_exist(restart_dir))
+        {
+            LOG(LOG_LEVEL_ERROR, "Can't create restart directory %s",
+                restart_dir);
+        }
+        else if (g_chown(restart_dir, g_getuid(), g_getuid()) != 0)
+        {
+            LOG(LOG_LEVEL_ERROR, "Can't set ownership of '%s' [%s]",
+                restart_dir, g_get_strerror());
+        }
+        else if ((rv = g_chmod_hex(restart_dir, 0x700)) != 0)
+        {
+            LOG(LOG_LEVEL_ERROR, "%s: Can't set permissions on '%s' [%s]",
+                __func__, restart_dir, g_get_strerror());
+        }
+        else
+        {
+            rv = 0;
+        }
+    }
+
+    return rv;
+#undef MAX_LISTEN_PORT_LEN
+}
+
+/******************************************************************************/
+int
+sesman_restart_discover_sessions(void)
+{
+    // Needs lots of work!
+    return create_restart_directory(g_cfg->listen_port);
+}

sesman/sesman_restart.h

@@ -0,0 +1,40 @@
+/**
+ * xrdp: A Remote Desktop Protocol server.
+ *
+ * Copyright (C) Matt Burt 2024
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ *
+ * @file sesman_restart.h
+ * @brief Sesman restart declarations
+ * @author Matt Burt
+ *
+ */
+
+
+#ifndef SESMAN_RESTART_H
+#define SESMAN_RESTART_H
+
+/**
+ * Discover sessions from a previous sesman run
+ * @return 0 for success
+ *
+ * Errors are logged
+ */
+int
+sesman_restart_discover_sessions(void);
+
+#endif // SESMAN_RESTART_H