From b404880177a4eb9419a65fdf2536e42df36d524d Mon Sep 17 00:00:00 2001
From: _ov4 <ov4@ov4.org>
Date: Mon, 31 Aug 2026 07:29:46 +0000
Subject: eval

---
 src/eval.cc | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100644 src/eval.cc

(limited to 'src/eval.cc')

diff --git a/src/eval.cc b/src/eval.cc
new file mode 100644
index 0000000..369e032
--- /dev/null
+++ b/src/eval.cc
@@ -0,0 +1,81 @@
+#include "eval.h"
+
+namespace ov4
+{
+
+using namespace std;
+
+/* 
+ * eval - Evaluate the command line that the user has just typed in
+ * 
+ * If the user has requested a built-in command (quit, jobs, bg or fg)
+ * then execute it immediately. Otherwise, fork a child process and
+ * run the job in the context of the child. If the job is running in
+ * the foreground, wait for it to terminate and then return.  Note:
+ * each child process must have a unique process group ID so that our
+ * background children don't receive SIGINT (SIGTSTP) from the kernel
+ * when we type ctrl-c (ctrl-z) at the keyboard.  
+*/
+void eval(char *cmdline) 
+{
+    char arg[MAXARGS][MAXLINE];
+    char *argv[MAXARGS];
+    for (int i = 0 ; i < MAXARGS; i++)
+    {
+        argv[i] = &arg[i][0];
+    }
+    int ground = parseline(cmdline, argv);
+
+    if (argv[0] == nullptr) return;
+    
+    if (builtin_cmd(argv[0])) 
+    {   
+        LOG << "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;
+    }
+
+    sigset_t prev;
+    block_all(&prev);
+
+    pid_t pid = fork();
+    if (pid == 0) // child
+    {
+        sigprocmask(SIG_SETMASK, &prev, nullptr);
+        setpgid(0, 0);
+        
+        execve(argv[0], argv, environ);
+
+        atomic_print(cmdline, true);
+        atomic_print(": Command not found\n");
+        exit(-1); // if no command is found
+    }
+
+    // parent
+
+    if (!ground)  // foreground
+    {   
+        addjob(jobs, pid, FG, cmdline); 
+        sigset_t prev_with_sigchld_blocked = prev;
+        sigaddset(&prev_with_sigchld_blocked, SIGCHLD);
+        sigprocmask(SIG_SETMASK, &prev_with_sigchld_blocked, NULL);
+        waitfg(pid);
+        sigprocmask(SIG_SETMASK, &prev, NULL);
+    }
+    else // background
+    {
+        addjob(jobs, pid, BG, cmdline);
+        sigprocmask(SIG_SETMASK, &prev, NULL);
+        cout << "[" << pid2jid(pid) << "] (" << pid << ") " << cmdline;
+    }
+
+
+
+    return;
+}
+
+}
-- 
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