--- include/proftpd.h

+++ include/proftpd.h

@@ -133,7 +133,7 @@ typedef struct {

   struct config_struc *anon_config;	/* Anonymous FTP configuration */

   char *anon_user;			/* E-mail address sent to us */

-  char *curr_cmd;                       /* Current FTP command */

+  const char *curr_cmd;                 /* Current FTP command */

   int curr_phase;                       /* Current handler phase */

   off_t restart_pos;			/* Restart marked position */

--- src/data.c

+++ src/data.c

@@ -653,7 +653,7 @@ void pr_data_close(int quiet) {

  */

 void pr_data_cleanup(void) {

   /* sanity check */

-  if (session.d) {

+  if (session.d != NULL) {

     pr_inet_lingering_close(session.pool, session.d, timeout_linger);

     session.d = NULL;

   }

@@ -675,7 +675,7 @@ void pr_data_abort(int err, int quiet) {

   int true_abort = XFER_ABORTED;

   nstrm = NULL;

-  if (session.d) {

+  if (session.d != NULL) {

     if (!true_abort)

       pr_inet_lingering_close(session.pool, session.d, timeout_linger);

@@ -856,6 +856,11 @@ void pr_data_abort(int err, int quiet) {

      */

     if (!true_abort)

       pr_response_add_err(respcode, _("Transfer aborted. %s"), msg ? msg : "");

+

+    /* Forcibly clear the data-transfer instigating command pool from the

+     * Response API.

+     */

+    pr_response_set_pool(NULL);

   }

   if (true_abort)

@@ -939,8 +944,8 @@ int pr_data_xfer(char *cl_buf, int cl_si

         pr_response_flush(&resp_err_list);

-        destroy_pool(cmd->pool);

         pr_response_set_pool(resp_pool);

+        destroy_pool(cmd->pool);

       /* We don't want to actually dispatch the NOOP command, since that

        * would overwrite the scoreboard with the NOOP state; admins probably

@@ -965,13 +970,13 @@ int pr_data_xfer(char *cl_buf, int cl_si

         pr_response_flush(&resp_list);

-        destroy_pool(cmd->pool);

         pr_response_set_pool(resp_pool);

+        destroy_pool(cmd->pool);

       } else {

         char *title_buf = NULL;

         int title_len = -1;

-        const char *sce_cmd = NULL, *sce_cmd_arg = NULL;

+        const char *curr_cmd = NULL, *sce_cmd = NULL, *sce_cmd_arg = NULL;

         pr_trace_msg(trace_channel, 5,

           "client sent '%s' command during data transfer, dispatching",

@@ -983,6 +988,7 @@ int pr_data_xfer(char *cl_buf, int cl_si

           pr_proctitle_get(title_buf, title_len + 1); 

         }

+        curr_cmd = session.curr_cmd;

         sce_cmd = pr_scoreboard_entry_get(PR_SCORE_CMD);

         sce_cmd_arg = pr_scoreboard_entry_get(PR_SCORE_CMD_ARG);

@@ -998,6 +1004,7 @@ int pr_data_xfer(char *cl_buf, int cl_si

         }

         destroy_pool(cmd->pool);

+        session.curr_cmd = curr_cmd;

       }

     } else {

--- src/main.c

+++ src/main.c

@@ -940,9 +940,10 @@ static void cmd_loop(server_rec *server,

       pr_timer_reset(PR_TIMER_IDLE, ANY_MODULE);

     }

-    if (cmd) {

+    if (cmd != NULL) {

       pr_cmd_dispatch(cmd);

       destroy_pool(cmd->pool);

+      session.curr_cmd = NULL;

     } else {

       pr_response_send(R_500, _("Invalid command: try being more creative"));

--- src/response.c

+++ src/response.c

@@ -194,6 +194,16 @@ void pr_response_add_err(const char *num

   pr_response_t *resp = NULL, **head = NULL;

   va_list msg;

+  if (fmt == NULL) {

+    return;

+  }

+

+  if (resp_pool == NULL) {

+    pr_trace_msg(trace_channel, 1,

+      "no response pool set, ignoring added %s error response", numeric);

+    return;

+  }

+

   va_start(msg, fmt);

   vsnprintf(resp_buf, sizeof(resp_buf), fmt, msg);

   va_end(msg);

@@ -239,6 +249,16 @@ void pr_response_add(const char *numeric

   pr_response_t *resp = NULL, **head = NULL;

   va_list msg;

+  if (fmt == NULL) {

+    return;

+  }

+

+  if (resp_pool == NULL) {

+    pr_trace_msg(trace_channel, 1,

+      "no response pool set, ignoring added %s response", numeric);

+    return;

+  }

+

   va_start(msg, fmt);

   vsnprintf(resp_buf, sizeof(resp_buf), fmt, msg);

   va_end(msg);