Started Rust in Action MEAP.

1 files changed, 132 insertions, 0 deletions

diff --git a/meap/meap-code/ch9/ch9-clock2/src/main.rs b/meap/meap-code/ch9/ch9-clock2/src/main.rs
new file mode 100644
index 0000000..9b6968b
--- /dev/null
+++ b/meap/meap-code/ch9/ch9-clock2/src/main.rs
@@ -0,0 +1,132 @@
+extern crate chrono;
+extern crate clap;
+#[cfg(windows)]
+extern crate kernel32;
+#[cfg(not(windows))]
+extern crate libc;
+#[cfg(windows)]
+extern crate winapi;
+
+use chrono::DateTime; // date type
+use chrono::Weekday;
+use chrono::{Datelike, Timelike}; // traits that provides .year(), .month(), .second() ... methods
+use chrono::{FixedOffset, Local, NaiveDateTime, Utc}; // timezone types
+use clap::{App, Arg};
+use std::mem::zeroed;
+use std::thread::sleep;
+struct Clock;
+
+impl Clock {
+    fn get() -> DateTime<Local> {
+        Local::now()
+    }
+
+    #[cfg(windows)]
+    fn set<Tz: TimeZone>(t: DateTime<Tz>) -> () {
+        use chrono::Weekday;
+        use kernel32::SetSystemTime;
+        use winapi::{SYSTEMTIME, WORD};
+
+        let t = t.with_timezone(&Local);
+
+        let mut systime: SYSTEMTIME = unsafe { zeroed() };
+
+        let dow = match t.weekday() {
+            Weekday::Mon => 1,
+            Weekday::Tue => 2,
+            Weekday::Wed => 3,
+            Weekday::Thu => 4,
+            Weekday::Fri => 5,
+            Weekday::Sat => 6,
+            Weekday::Sun => 0,
+        };
+
+        let mut ns = t.nanosecond();
+        let is_leap_second = ns > 1_000_000_000;
+
+        if is_leap_second {
+            ns -= 1_000_000_000;
+        }
+
+        systime.wYear = t.year() as WORD;
+        systime.wMonth = t.month() as WORD;
+        systime.wDayOfWeek = dow as WORD;
+        systime.wDay = t.day() as WORD;
+        systime.wHour = t.hour() as WORD;
+        systime.wMinute = t.minute() as WORD;
+        systime.wSecond = t.second() as WORD;
+        systime.wMilliseconds = (ns / 1_000_000) as WORD;
+
+        let systime_ptr = &systime as *const SYSTEMTIME; // as *mut SYSTEMTIME; // convert to a pointer, then change its mutability
+
+        unsafe {
+            SetSystemTime(systime_ptr); // giving a pointer to a value to something outside of Rust's control is unsafe
+        }
+    }
+
+    #[cfg(not(windows))]
+    fn set<Tz: TimeZone>(t: DateTime<Tz>) -> () {
+        use libc::settimeofday;
+        use libc::{suseconds_t, time_t, timeval, timezone};
+
+        let t = t.with_timezone(&Local); // variable names indicate the data's progression
+        let mut u: timeval = unsafe { zeroed() }; // through the function
+
+        u.tv_sec = t.timestamp() as time_t;
+        u.tv_usec = t.timestamp_subsec_micros() as suseconds_t;
+
+        unsafe {
+            let mock_tz: *const timezone = std::ptr::null();
+            settimeofday(&u as *const timeval, mock_tz);
+        }
+    }
+}
+
+fn main() {
+    let app = App::new("clock")
+        .version("0.1.2")
+        .about("Gets and (aspirationally) sets the time.")
+        .after_help("Note: UNIX timestamps are parsed as whole seconds since 1st January 1970 0:00:00 UTC. For more accuracy, use another format.")
+        .arg(Arg::with_name("action")
+            .takes_value(true)
+            .possible_values(&["get", "set"])
+            .default_value("get"))
+        .arg(Arg::with_name("std")
+            .short("s")
+            .long("use-standard")
+            .takes_value(true)
+            .possible_values(&["rfc2822", "rfc3339", "timestamp"])
+            .default_value("rfc3339"))
+        .arg(Arg::with_name("datetime")
+            .help("When <action> is 'set', apply <datetime>. Otherwise, ignore."));
+
+    let args = app.get_matches();
+
+    let action = args.value_of("std").unwrap(); // default_value() has been supplied,
+    let std = args.value_of("std").unwrap(); // so it's safe to use .unwrap()
+
+    if action == "set" {
+        let t_ = args.value_of("datetime").unwrap();
+
+        let parser = match std {
+            "rfc2822" => DateTime::parse_from_rfc2822,
+            "rfc3339" => DateTime::parse_from_rfc3339,
+            //"rfc3339" => |secs:| NaiveDateTime,
+            _ => unimplemented!(),
+        };
+
+        let err_msg = format!("Unable to parse {} according to {}", t_, std);
+        let t = parser(t_).expect(&err_msg);
+
+        Clock::set(t)
+    }
+
+    let now = Clock::get();
+
+    match std {
+        "timestamp" => println!("{}", now.timestamp()),
+        "rfc2822" => println!("{}", now.to_rfc2822()),
+        "rfc3339" => println!("{}", now.to_rfc3339()),
+        _ => unreachable!(),
+    }
+}