From e00a6103ab63d177efeab47b08338426d21f538f Mon Sep 17 00:00:00 2001
From: _ov4 <ov4@ov4.org>
Date: Mon, 31 Aug 2026 07:22:10 +0000
Subject: ground

---
 src/ground.cc | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)
 create mode 100644 src/ground.cc

(limited to 'src/ground.cc')

diff --git a/src/ground.cc b/src/ground.cc
new file mode 100644
index 0000000..2047ebf
--- /dev/null
+++ b/src/ground.cc
@@ -0,0 +1,103 @@
+#include "ground.h"
+
+namespace ov4
+{
+
+using namespace std;
+
+/* 
+ * waitfg - Block until process pid is no longer the foreground process
+ */
+void waitfg(pid_t pid)
+{
+    sigset_t prev_with_sigchld_unblocked;
+    // get current blocked signals
+    sigprocmask(0, nullptr, &prev_with_sigchld_unblocked);
+    sigdelset(&prev_with_sigchld_unblocked, SIGCHLD);
+    LOG << "waiting for pid "<< fgpid(jobs) << endl;
+    while (fgpid(jobs) != 0)
+        sigsuspend(&prev_with_sigchld_unblocked);
+    LOG << "finished fg " << endl;
+    return;
+}
+
+/* 
+ * do_bgfg - Execute the builtin bg and fg commands
+ */
+void do_bgfg(char **argv) 
+{
+    if ((strcmp(argv[0], "fg") == 0) || (strcmp(argv[0], "bg") == 0))
+    {
+        int x;
+        job_t *j = nullptr;
+        sigset_t prev;
+        if (argv[1] == nullptr)
+        {
+            cerr << ((strcmp(argv[0], "fg") == 0) ? "fg" : "bg") << " command requires PID or %jobid argument" << endl;
+            return;
+        }
+        if (argv[1][0] == '%') // jid provided
+        {
+            if (!isnum(&argv[1][1]))
+            {
+                cerr << ((strcmp(argv[0], "fg") == 0) ? "fg" : "bg") << ": argument must be a PID or %jobid" << endl;
+                return;
+            }
+            x = atoi(&argv[1][1]); // eat %
+            j = getjobjid(jobs, x);
+            if (j == nullptr)
+            {
+                cerr << argv[1] << ": No such job" << endl;
+                return;
+            }
+        } else { // pid
+            if (!isnum(&argv[1][0]))
+            {
+                cerr << ((strcmp(argv[0], "fg") == 0) ? "fg" : "bg") << ": argument must be a PID or %jobid" << endl;
+                return;
+            }
+            x = atoi(&argv[1][0]);
+            j = getjobpid(jobs, x);
+            if (j == nullptr)
+            {
+                cerr << "(" << argv[1] << "): No such process" << endl;
+                return;
+            }
+        }
+
+
+        block_all(&prev);
+        if (strcmp(argv[0], "fg") == 0) // fg
+        {
+            LOG << "fg" << endl;
+            j->state = FG;
+            
+            sigset_t prev_with_sigchld_blocked = prev;
+            sigaddset(&prev_with_sigchld_blocked, SIGCHLD);
+            sigprocmask(SIG_SETMASK, &prev_with_sigchld_blocked, NULL);
+            if (kill(-(j->pid), SIGCONT) < 0) 
+            {
+                cerr << "Cannot continue process " << j->pid;
+                sigprocmask(SIG_SETMASK, &prev, NULL);
+                return;
+            }
+
+            waitfg(j->pid);
+
+            sigprocmask(SIG_SETMASK, &prev, NULL);
+        } else // bg
+        {
+            LOG << "bg" << endl;
+            j->state = BG;
+            kill(-(j->pid), SIGCONT);
+            sigprocmask(SIG_SETMASK, &prev, NULL);
+            // cmdline has nerd '\n' at the end
+            // so just flush
+            cout << "[" << j->jid << "] (" << j->pid << ") " << j->cmdline << flush;
+        }
+    }
+    else 
+        cerr << "not fg/bg" << endl;
+}
+
+}
-- 
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