Adding code related to Sandbox Detector article

VIII. Sandbox/custom/sandbox_detector.c

@@ -0,0 +1,51 @@
+// clang -o sandbox_detector sandbox_detector.c
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/sysctl.h>
+
+// Prototype for the sandbox_check function
+int sandbox_check(pid_t pid, int *operation, int flags);
+
+// Function to check if a process exists
+int pid_exists(pid_t pid) {
+    int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PID, pid};
+    struct kinfo_proc info;
+    size_t info_size = sizeof(info);
+
+    if (sysctl(mib, 4, &info, &info_size, NULL, 0) < 0) {
+        return 0; // PID does not exist
+    }
+
+    return (info_size > 0) ? 1 : 0; // Check if info_size is non-zero
+}
+
+void usage() {
+    fprintf(stderr, "Usage: %s <pid>\n", getprogname());
+    fprintf(stderr, "Checks if the process with the specified PID is sandboxed.\n");
+    fprintf(stderr, "\n");
+    exit(1);
+}
+
+int main(int argc, char **argv) {
+    if (argc != 2){
+        usage();
+    }
+
+    pid_t pid = atoi(argv[1]);
+
+    // Check if the PID exists
+    if (pid_exists(pid) == 0) {
+        fprintf(stderr, "%d: No such process\n", pid);
+        exit(2);
+    }
+
+    // Check if the process is sandboxed
+    int rc = sandbox_check(pid, 0, 0);
+    if (rc == 0) {
+        printf("Process %d is not sandboxed.\n", pid);
+    }else{
+        printf("Process %d is sandboxed.\n", pid);
+    }
+
+    return 0;
+}