Call setsid() for hook/notification commands

We do not want hook or notification commands to interact with the
terminal in any way. Create a new session for them.

Addresses GitHub issue #326.

Signed-off-by: Lukas Fleischer <lfleischer@calcurse.org>

src/calcurse.h

@@ -1250,8 +1250,8 @@ int parse_date_increment(const char *, unsigned *, time_t);
 int parse_datetime(const char *, time_t *, time_t);
 void file_close(FILE *, const char *);
 void psleep(unsigned);
-int fork_exec(int *, int *, int *, const char *, const char *const *);
+int fork_exec(int *, int *, int *, int, const char *, const char *const *);
-int shell_exec(int *, int *, int *, const char *, const char *const *);
+int shell_exec(int *, int *, int *, int, const char *, const char *const *);
 int child_wait(int *, int *, int *, int);
 void press_any_key(void);
 void print_apoint(const char *, time_t, struct apoint *);

src/hooks.c

@@ -51,7 +51,7 @@ int run_hook(const char *name)
 	arg[0] = hook_path;
 	arg[1] = NULL;
 
-	if ((pid = shell_exec(&pin, &pout, &perr, *arg, arg))) {
+	if ((pid = shell_exec(&pin, &pout, &perr, 1, *arg, arg))) {
 		ret = child_wait(&pin, &pout, &perr, pid);
 		if (ret > 0 && WIFEXITED(ret)) {
 			asprintf(&mesg, "%s hook: exit status %d",

src/notify.c

@@ -221,7 +221,7 @@ unsigned notify_launch_cmd(void)
 
 	notify_app.state |= APOINT_NOTIFIED;
 
-	if ((pid = shell_exec(&pin, &pout, &perr, *arg, arg))) {
+	if ((pid = shell_exec(&pin, &pout, &perr, 1, *arg, arg))) {
 		close(pin);
 		close(pout);
 		close(perr);

src/ui-day.c

@@ -1067,7 +1067,7 @@ void ui_day_item_pipe(void)
 		return;
 
 	wins_prepare_external();
-	if ((pid = shell_exec(NULL, &pout, NULL, *arg, arg))) {
+	if ((pid = shell_exec(NULL, &pout, NULL, 0, *arg, arg))) {
 		fpout = fdopen(pout, "w");
 
 		switch (p->type) {

src/ui-todo.c

@@ -158,7 +158,7 @@ void ui_todo_pipe(void)
 		return;
 
 	wins_prepare_external();
-	if ((pid = shell_exec(NULL, &pout, NULL, *arg, arg))) {
+	if ((pid = shell_exec(NULL, &pout, NULL, 0, *arg, arg))) {
 		fpout = fdopen(pout, "w");
 		todo_write(item, fpout);
 		fclose(fpout);

src/utils.c

@@ -1319,9 +1319,11 @@ void psleep(unsigned secs)
  *
  * If pfdin/pfdout/pfderr point to a valid address, a pipe is created and the
  * appropriate file descriptors are written to pfdin/pfdout/pfderr.
+ *
+ * If new_session is non-zero, setsid() is called after forking.
  */
-int fork_exec(int *pfdin, int *pfdout, int *pfderr, const char *path,
+int fork_exec(int *pfdin, int *pfdout, int *pfderr, int new_session,
-	      const char *const *arg)
+              const char *path, const char *const *arg)
 {
 	int pin[2], pout[2], perr[2];
 	int pid;
@@ -1355,6 +1357,11 @@ int fork_exec(int *pfdin, int *pfdout, int *pfderr, const char *path,
 			close(pin[1]);
 		}
 
+		if (new_session) {
+			if ((setsid() < 0))
+				_exit(127);
+		}
+
 		execvp(path, (char *const *)arg);
 		_exit(127);
 	} else {
@@ -1393,8 +1400,8 @@ int fork_exec(int *pfdin, int *pfdout, int *pfderr, const char *path,
 
 /* Execute an external program in a shell. */
 int
-shell_exec(int *pfdin, int *pfdout, int *pfderr, const char *path,
+shell_exec(int *pfdin, int *pfdout, int *pfderr, int new_session,
-	   const char *const *arg)
+           const char *path, const char *const *arg)
 {
 	int argc, i;
 	const char **narg;
@@ -1423,7 +1430,7 @@ shell_exec(int *pfdin, int *pfdout, int *pfderr, const char *path,
 		narg[3] = NULL;
 	}
 
-	ret = fork_exec(pfdin, pfdout, pfderr, *narg, narg);
+	ret = fork_exec(pfdin, pfdout, pfderr, new_session, *narg, narg);
 
 	if (arg0)
 		mem_free(arg0);

src/wins.c

@@ -624,7 +624,7 @@ void wins_launch_external(const char *arg[])
 	int pid;
 
 	wins_prepare_external();
-	if ((pid = shell_exec(NULL, NULL, NULL, *arg, arg)))
+	if ((pid = shell_exec(NULL, NULL, NULL, 0, *arg, arg)))
 		child_wait(NULL, NULL, NULL, pid);
 	wins_unprepare_external();
 }