examples: Add exec

Related: #22

examples/exec.rs

@@ -0,0 +1,56 @@
+// Copyright (c) 2024 Xu Shaohua <[email protected]>. All rights reserved.
+// Use of this source is governed by Apache-2.0 License that can be found
+// in the LICENSE file.
+
+fn call_ls() {
+    println!("[ls] pid: {}", unsafe { nc::getpid() });
+    let args = ["ls", "-l", "-a"];
+    let env = ["DISPLAY=wayland"];
+    let ret = unsafe { nc::execve("/bin/ls", &args, &env) };
+    assert!(ret.is_ok());
+}
+
+fn call_date() {
+    println!("[date] pid: {}", unsafe { nc::getpid() });
+    let args = ["date", "+%Y:%m:%d %H:%M:%S"];
+    let env = [];
+    let ret = unsafe { nc::execve("/bin/date", &args, &env) };
+    assert!(ret.is_ok());
+}
+
+fn main() {
+    let pid = unsafe { nc::fork() };
+    match pid {
+        Err(errno) => eprintln!("Failed to call fork(), err: {errno}"),
+        Ok(0) => {
+            // Child process
+            call_ls();
+        }
+        Ok(child_pid) => {
+            // Parent process
+            println!("[main] child pid is: {child_pid}");
+        }
+    }
+
+    let pid = unsafe { nc::fork() };
+    match pid {
+        Err(errno) => eprintln!("Failed to call fork(), err: {errno}"),
+        Ok(0) => {
+            // Child process
+            call_date();
+        }
+        Ok(child_pid) => {
+            // Parent process
+            println!("[main] child pid is: {child_pid}");
+        }
+    }
+
+    // Wait for a while.
+    let ts = nc::timespec_t {
+        tv_sec: 2,
+        tv_nsec: 0,
+    };
+    unsafe {
+        let _ret = nc::nanosleep(&ts, None);
+    }
+}