Add ptrace::syscall in BSD

src/sys/ptrace/bsd.rs

@@ -75,6 +75,21 @@ pub fn traceme() -> Result<()> {
     unsafe { ptrace_other(Request::PT_TRACE_ME, Pid::from_raw(0), ptr::null_mut(), 0).map(drop) }
 }
 
+/// Ask for next syscall, as with `ptrace(PT_SYSCALL, ...)`
+///
+/// Arranges for the tracee to be stopped at the next entry to or exit from a system call,
+/// optionally delivering a signal specified by `sig`.
+pub fn syscall<T: Into<Option<Signal>>>(pid: Pid, sig: T) -> Result<()> {
+    let data = match sig.into() {
+        Some(s) => s as c_int,
+        None => 0,
+    };
+    unsafe {
+        // Ignore the useless return value
+        ptrace_other(Request::PT_SYSCALL, pid, 1 as AddressType, data).map(drop)
+    }
+}
+
 /// Attach to a running process, as with `ptrace(PT_ATTACH, ...)`
 ///
 /// Attaches to the process specified in pid, making it a tracee of the calling process.