From 6d9469d916bb80aa76c82097e60b725de1661d5c Mon Sep 17 00:00:00 2001
From: _ov4 <ov4@ov4.org>
Date: Tue, 1 Sep 2026 10:41:39 +0000
Subject: real foreground/background

---
 include/eval.h    | 21 +--------------------
 include/ground.h  |  3 +++
 include/handler.h | 11 +++++++----
 src/eval.cc       | 29 +++++++++++++++++++++++++++--
 src/ground.cc     |  8 ++++++++
 src/handler.cc    | 26 +++++++++++++++++++-------
 src/init.cc       |  3 +++
 7 files changed, 68 insertions(+), 33 deletions(-)

diff --git a/include/eval.h b/include/eval.h
index 919d03f..5e8a1c7 100644
--- a/include/eval.h
+++ b/include/eval.h
@@ -1,25 +1,6 @@
 #pragma once
 
-#include <stdio.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <string.h>
-#include <ctype.h>
-#include <signal.h>
-#include <sys/types.h>
-#include <sys/wait.h>
-#include <errno.h>
-#include <iostream>
-#include <vector>
-#include <string>
-
-#include "global.h"
-#include "util/io.h"
-#include "command/builtin.h"
-#include "job.h"
-#include "ground.h"
-#include "parse.h"
-#include "path.h"
+#include "all.h"
 
 namespace ov4
 {
diff --git a/include/ground.h b/include/ground.h
index d57f085..a1985eb 100644
--- a/include/ground.h
+++ b/include/ground.h
@@ -13,6 +13,9 @@
 namespace ov4
 {
 
+extern pid_t shell_pgid;
+extern int tty_fd;
+
 void waitfg(pid_t pid);
 void do_bgfg(char **argv);
     
diff --git a/include/handler.h b/include/handler.h
index 225fc93..100c548 100644
--- a/include/handler.h
+++ b/include/handler.h
@@ -1,7 +1,5 @@
 #pragma once
 
-#include "global.h"
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -12,20 +10,25 @@
 #include <sys/wait.h>
 #include <errno.h>
 
-#include "util/io.h"
-#include "job.h"
+#include "all.h"
 
 namespace ov4
 {
 
 typedef void handler_t(int);
 
+extern sigset_t 
+    block_sig_TTOU,
+    block_job,
+    block_io;
+
 void signal_init();
 handler_t *Signal(int signum, handler_t *handler);
 void sigchld_handler(int sig);
 void sigint_handler(int sig);
 void sigtstp_handler(int sig);
 void sigquit_handler(int sig);
+
 int block_all(sigset_t *prev);
 int block_handler(sigset_t *prev);
 
diff --git a/src/eval.cc b/src/eval.cc
index 8785dd6..09d1196 100644
--- a/src/eval.cc
+++ b/src/eval.cc
@@ -1,5 +1,18 @@
 #include "eval.h"
 
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <ctype.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <errno.h>
+#include <iostream>
+#include <vector>
+#include <string>
+
 using namespace std;
 
 namespace ov4
@@ -29,17 +42,29 @@ void eval(char *cmdline)
     if (argv[0] == nullptr) return;
     if (exe_bultin_command(argv)) return;
     
+    // block_io signals can stop shell
+    // when child is at foreground, parent shell is at background
+    sigprocmask(SIG_BLOCK, &block_io, nullptr);
 
     sigset_t prev;
     block_all(&prev);
 
-    pid_t pid = fork();
     string cmd = find_cmd(argv[0]);
     const char* cmd_c = cmd.c_str();
+
+    shell_pgid = getpgid(0);
+    pid_t pid = fork();
+    
     if (pid == 0) // child
     {
-        sigprocmask(SIG_SETMASK, &prev, nullptr);
         setpgid(0, 0);
+        if (!ground) // foreground
+            tcsetpgrp(tty_fd, getpgrp());
+
+        // program inside execve may use SIGTTIN/SIGTTOU so just restore in child
+        sigprocmask(SIG_UNBLOCK, &block_io, nullptr);
+
+        sigprocmask(SIG_SETMASK, &prev, nullptr);
         
         execve(cmd_c, argv, environ);
 
diff --git a/src/ground.cc b/src/ground.cc
index 54a333f..265a22d 100644
--- a/src/ground.cc
+++ b/src/ground.cc
@@ -5,6 +5,9 @@ using namespace std;
 namespace ov4
 {
 
+pid_t shell_pgid;
+int tty_fd;
+
 /* 
  * waitfg - Block until process pid is no longer the foreground process
  */
@@ -17,6 +20,11 @@ void waitfg(pid_t pid)
     LOG << "waiting for pid "<< fgpid(jobs) << endl;
     while (fgpid(jobs) != 0)
         sigsuspend(&prev_with_sigchld_unblocked);
+
+    // set shell to foreground again
+    tcsetpgrp(tty_fd, shell_pgid);
+    sigprocmask(SIG_BLOCK, &block_io, nullptr);
+
     LOG << "finished fg " << endl;
     return;
 }
diff --git a/src/handler.cc b/src/handler.cc
index b6399c2..4fa3e2f 100644
--- a/src/handler.cc
+++ b/src/handler.cc
@@ -4,17 +4,29 @@ namespace ov4
 {
 
 extern char **environ;
-sigset_t BLOCK_HANDLER;
+
+sigset_t 
+    block_sig_TTOU,
+    block_job,
+    block_io;
 
 void signal_init()
 {
     /* Install the signal handlers */
     
-    sigemptyset(&BLOCK_HANDLER);
-    sigaddset(&BLOCK_HANDLER, SIGINT);
-    sigaddset(&BLOCK_HANDLER, SIGTSTP);
-    sigaddset(&BLOCK_HANDLER, SIGCHLD);
-    
+    sigemptyset(&block_job);
+    sigemptyset(&block_sig_TTOU);
+    sigemptyset(&block_io);
+
+    sigaddset(&block_job, SIGINT);
+    sigaddset(&block_job, SIGTSTP);
+    sigaddset(&block_job, SIGCHLD);
+
+    sigaddset(&block_sig_TTOU, SIGTTOU);
+
+    sigaddset(&block_io, SIGTTOU);
+    sigaddset(&block_io, SIGTTIN);
+
     Signal(SIGINT,  sigint_handler);   /* ctrl-c */
     Signal(SIGTSTP, sigtstp_handler);  /* ctrl-z */
     Signal(SIGCHLD, sigchld_handler);  /* Terminated or stopped child */
@@ -161,7 +173,7 @@ int block_all(sigset_t *prev)
 
 int block_handler(sigset_t *prev)
 {
-    return sigprocmask(SIG_BLOCK, &BLOCK_HANDLER, prev);
+    return sigprocmask(SIG_BLOCK, &block_job, prev);
 }
 
 void sigquit_handler(int sig) 
diff --git a/src/init.cc b/src/init.cc
index 5f6e325..a38aec4 100644
--- a/src/init.cc
+++ b/src/init.cc
@@ -1,5 +1,7 @@
 #include "init.h"
 
+#include <fcntl.h>
+
 using namespace std;
 
 namespace ov4
@@ -15,6 +17,7 @@ Published under GNU AFFERO GENERAL PUBLIC LICENSE (AGPL) Version 3." << endl;
 
     signal_init();
 
+    tty_fd = open("/dev/tty", O_RDWR);
 
 }
 
-- 
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