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diff --git a/src/background.c b/src/background.c
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+++ b/src/background.c
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+/* {{{ Copyright */
+
+/* Background support.
+
+ Copyright (C) 1996-2023
+ Free Software Foundation, Inc.
+
+ Written by:
+ Miguel de Icaza, 1996
+
+ This file is part of the Midnight Commander.
+
+ The Midnight Commander is free software: you can redistribute it
+ and/or modify it under the terms of the GNU General Public License as
+ published by the Free Software Foundation, either version 3 of the License,
+ or (at your option) any later version.
+
+ The Midnight Commander is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* }}} */
+
+/** \file background.c
+ * \brief Source: Background support
+ */
+
+#include <config.h>
+
+#include <stdlib.h>
+#include <errno.h>
+#include <signal.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/wait.h> /* waitpid() */
+
+#include "lib/global.h"
+
+#include "lib/unixcompat.h"
+#include "lib/tty/key.h" /* add_select_channel(), delete_select_channel() */
+#include "lib/widget.h" /* message() */
+#include "lib/event-types.h"
+
+#include "filemanager/fileopctx.h" /* file_op_context_t */
+
+#include "background.h"
+
+/*** global variables ****************************************************************************/
+
+#define MAXCALLARGS 4 /* Number of arguments supported */
+
+/*** file scope macro definitions ****************************************************************/
+
+/*** file scope type declarations ****************************************************************/
+
+enum ReturnType
+{
+ Return_String,
+ Return_Integer
+};
+
+/*** forward declarations (file scope functions) *************************************************/
+
+static int background_attention (int fd, void *closure);
+
+/*** file scope variables ************************************************************************/
+
+/* File descriptor for talking to our parent */
+static int parent_fd;
+
+/* File descriptor for messages from our parent */
+static int from_parent_fd;
+
+TaskList *task_list = NULL;
+
+/* --------------------------------------------------------------------------------------------- */
+/*** file scope functions ************************************************************************/
+/* --------------------------------------------------------------------------------------------- */
+
+static void
+register_task_running (file_op_context_t * ctx, pid_t pid, int fd, int to_child, char *info)
+{
+ TaskList *new;
+
+ new = g_new (TaskList, 1);
+ new->pid = pid;
+ new->info = info;
+ new->state = Task_Running;
+ new->next = task_list;
+ new->fd = fd;
+ new->to_child_fd = to_child;
+ task_list = new;
+
+ add_select_channel (fd, background_attention, ctx);
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static int
+destroy_task (pid_t pid)
+{
+ TaskList *p = task_list;
+ TaskList *prev = NULL;
+
+ while (p != NULL)
+ {
+ if (p->pid == pid)
+ {
+ int fd = p->fd;
+
+ if (prev != NULL)
+ prev->next = p->next;
+ else
+ task_list = p->next;
+ g_free (p->info);
+ g_free (p);
+ return fd;
+ }
+ prev = p;
+ p = p->next;
+ }
+
+ /* pid not found */
+ return (-1);
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/* {{{ Parent handlers */
+
+/* Parent/child protocol
+ *
+ * the child (the background) process send the following:
+ * void *routine -- routine to be invoked in the parent
+ * int nargc -- number of arguments
+ * int type -- Return argument type.
+ *
+ * If the routine is zero, then it is a way to tell the parent
+ * that the process is dying.
+ *
+ * nargc arguments in the following format:
+ * int size of the coming block
+ * size bytes with the block
+ *
+ * Now, the parent loads all those and then invokes
+ * the routine with pointers to the information passed
+ * (we just support pointers).
+ *
+ * If the return type is integer:
+ *
+ * the parent then writes an int to the child with
+ * the return value from the routine and the values
+ * of any global variable that is modified in the parent
+ * currently: do_append and recursive_result.
+ *
+ * If the return type is a string:
+ *
+ * the parent writes the resulting string length
+ * if the result string was NULL or the empty string,
+ * then the length is zero.
+ * The parent then writes the string length and frees
+ * the result string.
+ */
+/*
+ * Receive requests from background process and invoke the
+ * specified routine
+ */
+
+static int
+reading_failed (int i, char **data)
+{
+ while (i >= 0)
+ g_free (data[i--]);
+ message (D_ERROR, _("Background protocol error"), "%s", _("Reading failed"));
+ return 0;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static int
+background_attention (int fd, void *closure)
+{
+ file_op_context_t *ctx;
+ int have_ctx;
+ union
+ {
+ int (*have_ctx0) (int);
+ int (*have_ctx1) (int, char *);
+ int (*have_ctx2) (int, char *, char *);
+ int (*have_ctx3) (int, char *, char *, char *);
+ int (*have_ctx4) (int, char *, char *, char *, char *);
+
+ int (*non_have_ctx0) (file_op_context_t *, int);
+ int (*non_have_ctx1) (file_op_context_t *, int, char *);
+ int (*non_have_ctx2) (file_op_context_t *, int, char *, char *);
+ int (*non_have_ctx3) (file_op_context_t *, int, char *, char *, char *);
+ int (*non_have_ctx4) (file_op_context_t *, int, char *, char *, char *, char *);
+
+ char *(*ret_str0) (void);
+ char *(*ret_str1) (char *);
+ char *(*ret_str2) (char *, char *);
+ char *(*ret_str3) (char *, char *, char *);
+ char *(*ret_str4) (char *, char *, char *, char *);
+
+ void *pointer;
+ } routine;
+ /* void *routine; */
+ int argc, i, status;
+ char *data[MAXCALLARGS];
+ ssize_t bytes, ret;
+ TaskList *p;
+ int to_child_fd = -1;
+ enum ReturnType type;
+ const char *background_process_error = _("Background process error");
+
+ ctx = closure;
+
+ bytes = read (fd, &routine.pointer, sizeof (routine));
+ if (bytes == -1 || (size_t) bytes < (sizeof (routine)))
+ {
+ unregister_task_running (ctx->pid, fd);
+
+ if (waitpid (ctx->pid, &status, WNOHANG) == 0)
+ {
+ /* the process is still running, but it misbehaves - kill it */
+ kill (ctx->pid, SIGTERM);
+ message (D_ERROR, background_process_error, "%s", _("Unknown error in child"));
+ return 0;
+ }
+
+ /* 0 means happy end */
+ if (WIFEXITED (status) && (WEXITSTATUS (status) == 0))
+ return 0;
+
+ message (D_ERROR, background_process_error, "%s", _("Child died unexpectedly"));
+
+ return 0;
+ }
+
+ if (read (fd, &argc, sizeof (argc)) != sizeof (argc) ||
+ read (fd, &type, sizeof (type)) != sizeof (type) ||
+ read (fd, &have_ctx, sizeof (have_ctx)) != sizeof (have_ctx))
+ return reading_failed (-1, data);
+
+ if (argc > MAXCALLARGS)
+ message (D_ERROR, _("Background protocol error"), "%s",
+ _("Background process sent us a request for more arguments\n"
+ "than we can handle."));
+
+ if (have_ctx != 0 && read (fd, ctx, sizeof (*ctx)) != sizeof (*ctx))
+ return reading_failed (-1, data);
+
+ for (i = 0; i < argc; i++)
+ {
+ int size;
+
+ if (read (fd, &size, sizeof (size)) != sizeof (size))
+ return reading_failed (i - 1, data);
+
+ data[i] = g_malloc (size + 1);
+
+ if (read (fd, data[i], size) != size)
+ return reading_failed (i, data);
+
+ data[i][size] = '\0'; /* NULL terminate the blocks (they could be strings) */
+ }
+
+ /* Find child task info by descriptor */
+ /* Find before call, because process can destroy self after */
+ for (p = task_list; p != NULL; p = p->next)
+ if (p->fd == fd)
+ break;
+
+ if (p != NULL)
+ to_child_fd = p->to_child_fd;
+
+ if (to_child_fd == -1)
+ message (D_ERROR, background_process_error, "%s", _("Unknown error in child"));
+ else if (type == Return_Integer)
+ {
+ /* Handle the call */
+
+ int result = 0;
+
+ if (have_ctx == 0)
+ switch (argc)
+ {
+ case 0:
+ result = routine.have_ctx0 (Background);
+ break;
+ case 1:
+ result = routine.have_ctx1 (Background, data[0]);
+ break;
+ case 2:
+ result = routine.have_ctx2 (Background, data[0], data[1]);
+ break;
+ case 3:
+ result = routine.have_ctx3 (Background, data[0], data[1], data[2]);
+ break;
+ case 4:
+ result = routine.have_ctx4 (Background, data[0], data[1], data[2], data[3]);
+ break;
+ default:
+ break;
+ }
+ else
+ switch (argc)
+ {
+ case 0:
+ result = routine.non_have_ctx0 (ctx, Background);
+ break;
+ case 1:
+ result = routine.non_have_ctx1 (ctx, Background, data[0]);
+ break;
+ case 2:
+ result = routine.non_have_ctx2 (ctx, Background, data[0], data[1]);
+ break;
+ case 3:
+ result = routine.non_have_ctx3 (ctx, Background, data[0], data[1], data[2]);
+ break;
+ case 4:
+ result =
+ routine.non_have_ctx4 (ctx, Background, data[0], data[1], data[2], data[3]);
+ break;
+ default:
+ break;
+ }
+
+ /* Send the result code and the value for shared variables */
+ ret = write (to_child_fd, &result, sizeof (result));
+ if (have_ctx != 0 && to_child_fd != -1)
+ ret = write (to_child_fd, ctx, sizeof (*ctx));
+ }
+ else if (type == Return_String)
+ {
+ int len;
+ char *resstr = NULL;
+
+ /* FIXME: string routines should also use the Foreground/Background
+ * parameter. Currently, this is not used here
+ */
+ switch (argc)
+ {
+ case 0:
+ resstr = routine.ret_str0 ();
+ break;
+ case 1:
+ resstr = routine.ret_str1 (data[0]);
+ break;
+ case 2:
+ resstr = routine.ret_str2 (data[0], data[1]);
+ break;
+ case 3:
+ resstr = routine.ret_str3 (data[0], data[1], data[2]);
+ break;
+ case 4:
+ resstr = routine.ret_str4 (data[0], data[1], data[2], data[3]);
+ break;
+ default:
+ g_assert_not_reached ();
+ }
+
+ if (resstr != NULL)
+ {
+ len = strlen (resstr);
+ ret = write (to_child_fd, &len, sizeof (len));
+ if (len != 0)
+ ret = write (to_child_fd, resstr, len);
+ g_free (resstr);
+ }
+ else
+ {
+ len = 0;
+ ret = write (to_child_fd, &len, sizeof (len));
+ }
+ }
+
+ for (i = 0; i < argc; i++)
+ g_free (data[i]);
+
+ repaint_screen ();
+
+ (void) ret;
+
+ return 0;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/* }}} */
+
+/* {{{ client RPC routines */
+
+/* Sends the header for a call to a routine in the parent process. If the file
+ * operation context is not NULL, then it requests that the first parameter of
+ * the call be a file operation context.
+ */
+
+static void
+parent_call_header (void *routine, int argc, enum ReturnType type, file_op_context_t * ctx)
+{
+ int have_ctx;
+ ssize_t ret;
+
+ have_ctx = ctx != NULL ? 1 : 0;
+
+ ret = write (parent_fd, &routine, sizeof (routine));
+ ret = write (parent_fd, &argc, sizeof (argc));
+ ret = write (parent_fd, &type, sizeof (type));
+ ret = write (parent_fd, &have_ctx, sizeof (have_ctx));
+ if (have_ctx != 0)
+ ret = write (parent_fd, ctx, sizeof (*ctx));
+
+ (void) ret;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static int
+parent_va_call (void *routine, gpointer data, int argc, va_list ap)
+{
+ int i;
+ ssize_t ret;
+ file_op_context_t *ctx = (file_op_context_t *) data;
+
+ parent_call_header (routine, argc, Return_Integer, ctx);
+ for (i = 0; i < argc; i++)
+ {
+ int len;
+ void *value;
+
+ len = va_arg (ap, int);
+ value = va_arg (ap, void *);
+ ret = write (parent_fd, &len, sizeof (len));
+ ret = write (parent_fd, value, len);
+ }
+
+ ret = read (from_parent_fd, &i, sizeof (i));
+ if (ctx != NULL)
+ ret = read (from_parent_fd, ctx, sizeof (*ctx));
+
+ (void) ret;
+
+ return i;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static char *
+parent_va_call_string (void *routine, int argc, va_list ap)
+{
+ char *str;
+ int i;
+
+ parent_call_header (routine, argc, Return_String, NULL);
+ for (i = 0; i < argc; i++)
+ {
+ int len;
+ void *value;
+
+ len = va_arg (ap, int);
+ value = va_arg (ap, void *);
+ if (write (parent_fd, &len, sizeof (len)) != sizeof (len) ||
+ write (parent_fd, value, len) != len)
+ return NULL;
+ }
+
+ if (read (from_parent_fd, &i, sizeof (i)) != sizeof (i) || i == 0)
+ return NULL;
+
+ str = g_malloc (i + 1);
+ if (read (from_parent_fd, str, i) != i)
+ {
+ g_free (str);
+ return NULL;
+ }
+ str[i] = '\0';
+ return str;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/*** public functions ****************************************************************************/
+/* --------------------------------------------------------------------------------------------- */
+
+void
+unregister_task_running (pid_t pid, int fd)
+{
+ destroy_task (pid);
+ delete_select_channel (fd);
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+void
+unregister_task_with_pid (pid_t pid)
+{
+ int fd;
+
+ fd = destroy_task (pid);
+ if (fd != -1)
+ delete_select_channel (fd);
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Try to make the Midnight Commander a background job
+ *
+ * Returns:
+ * 1 for parent
+ * 0 for child
+ * -1 on failure
+ */
+int
+do_background (file_op_context_t * ctx, char *info)
+{
+ int comm[2]; /* control connection stream */
+ int back_comm[2]; /* back connection */
+ pid_t pid;
+
+ if (pipe (comm) == -1)
+ return (-1);
+
+ if (pipe (back_comm) == -1)
+ {
+ (void) close (comm[0]);
+ (void) close (comm[1]);
+
+ return (-1);
+ }
+
+ pid = fork ();
+ if (pid == -1)
+ {
+ int saved_errno = errno;
+
+ (void) close (comm[0]);
+ (void) close (comm[1]);
+ (void) close (back_comm[0]);
+ (void) close (back_comm[1]);
+ errno = saved_errno;
+
+ return (-1);
+ }
+
+ if (pid == 0)
+ {
+ int nullfd;
+
+ parent_fd = comm[1];
+ from_parent_fd = back_comm[0];
+
+ mc_global.we_are_background = TRUE;
+ top_dlg = NULL;
+
+ /* Make stdin/stdout/stderr point somewhere */
+ close (STDIN_FILENO);
+ close (STDOUT_FILENO);
+ close (STDERR_FILENO);
+
+ nullfd = open ("/dev/null", O_RDWR);
+ if (nullfd != -1)
+ {
+ while (dup2 (nullfd, STDIN_FILENO) == -1 && errno == EINTR)
+ ;
+ while (dup2 (nullfd, STDOUT_FILENO) == -1 && errno == EINTR)
+ ;
+ while (dup2 (nullfd, STDERR_FILENO) == -1 && errno == EINTR)
+ ;
+ close (nullfd);
+ }
+
+ return 0;
+ }
+ else
+ {
+ ctx->pid = pid;
+ register_task_running (ctx, pid, comm[0], back_comm[1], info);
+ return 1;
+ }
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+int
+parent_call (void *routine, file_op_context_t * ctx, int argc, ...)
+{
+ int ret;
+ va_list ap;
+
+ va_start (ap, argc);
+ ret = parent_va_call (routine, (gpointer) ctx, argc, ap);
+ va_end (ap);
+
+ return ret;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+char *
+parent_call_string (void *routine, int argc, ...)
+{
+ va_list ap;
+ char *str;
+
+ va_start (ap, argc);
+ str = parent_va_call_string (routine, argc, ap);
+ va_end (ap);
+
+ return str;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+/* event callback */
+gboolean
+background_parent_call (const gchar * event_group_name, const gchar * event_name,
+ gpointer init_data, gpointer data)
+{
+ ev_background_parent_call_t *event_data = (ev_background_parent_call_t *) data;
+
+ (void) event_group_name;
+ (void) event_name;
+ (void) init_data;
+
+ event_data->ret.i =
+ parent_va_call (event_data->routine, event_data->ctx, event_data->argc, event_data->ap);
+
+ return TRUE;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+/* event callback */
+gboolean
+background_parent_call_string (const gchar * event_group_name, const gchar * event_name,
+ gpointer init_data, gpointer data)
+{
+ ev_background_parent_call_t *event_data = (ev_background_parent_call_t *) data;
+
+ (void) event_group_name;
+ (void) event_name;
+ (void) init_data;
+
+ event_data->ret.s =
+ parent_va_call_string (event_data->routine, event_data->argc, event_data->ap);
+
+ return TRUE;
+}
+
+/* --------------------------------------------------------------------------------------------- */
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