From c97a162e8c60aa20a1de02cd828db8f35bd53085 Mon Sep 17 00:00:00 2001
From: _ov4 <ov4@ov4.org>
Date: Wed, 12 Aug 2026 14:06:28 +0000
Subject: bg/fg

---
 tsh.cc | 35 +++++++++++++++++++++++++++++++++++
 util.h |  5 +++--
 2 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/tsh.cc b/tsh.cc
index f6027ae..985c083 100644
--- a/tsh.cc
+++ b/tsh.cc
@@ -96,6 +96,8 @@ handler_t *Signal(int signum, handler_t *handler);
 // built-in commands
 void builtin_command_quit();
 
+inline int block_all(sigset_t *prev);
+
 vector<string> builtin_cmd_list = {"quit", "fg", "bg", "jobs"};
 
 /*
@@ -194,6 +196,9 @@ void eval(char *cmdline)
         cout << "built-in" << endl;
         if (strcmp(argv[0], "quit") == 0) builtin_command_quit();
         else if (strcmp(argv[0], "jobs") == 0) listjobs(jobs);
+        else if (strcmp(argv[0], "fg") == 0) do_bgfg(argv);
+        else if (strcmp(argv[0], "bg") == 0) do_bgfg(argv);
+        else cerr << "built-in but not supported" << endl;
         return;
     }
 
@@ -327,6 +332,29 @@ int builtin_cmd(char *c_str)
  */
 void do_bgfg(char **argv) 
 {
+    if (strcmp(argv[0], "fg") == 0)
+    {
+        LOG << "fg" << endl;
+        int jid = atoi(argv[1]);
+        sigset_t prev;
+        block_all(&prev);
+        job_t *j = getjobjid(jobs, jid);
+        j->state = FG;
+        kill(-(j->pid), SIGCONT);
+        sigprocmask(SIG_SETMASK, &prev, NULL);
+        waitfg(j->pid);
+    } else if (strcmp(argv[0], "bg") == 0)
+    {
+        LOG << "bg" << endl;
+        int jid = atoi(argv[1]);
+        sigset_t prev;
+        block_all(&prev);
+        job_t *j = getjobjid(jobs, jid);
+        j->state = BG;
+        kill(-(j->pid), SIGCONT);
+        sigprocmask(SIG_SETMASK, &prev, NULL);
+    } else 
+        cerr << "not fg/bg" << endl;
     return;
 }
 
@@ -655,3 +683,10 @@ bool job_suspend(struct job_t *jobs, pid_t pid) {
     }
     return false;
 }
+
+inline int block_all(sigset_t *prev)
+{
+    sigset_t set;
+    sigfillset(&set);
+    return sigprocmask(SIG_SETMASK, &set, prev);
+}
diff --git a/util.h b/util.h
index 9d939f9..072f65e 100644
--- a/util.h
+++ b/util.h
@@ -22,8 +22,9 @@ void atomic_print(int x);
 void reverse(char str[], int length);
 char* itoa(int num, char* str, int base);
 
-constexpr bool GLOBAL_DEBUG = false;
-bool DEBUG = false; // verbose mode
+constexpr bool GLOBAL_DEBUG = true;
+bool DEBUG = true; // verbose mode, can be enabled on demand using something like -v
+struct LogVoidify { void operator&(std::ostream&) const {} };
 
 const int DECIMAL = 10;
 const int LENGTH = 20;
-- 
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