Merge pull request #42 from rustcoreutils/date

add util: date

Author: jgarzik

Cargo.lock

@@ -62,7 +62,7 @@ https://github.com/jgarzik/posixutils
  - [ ] ctags (Development)
  - [ ] cut
  - [ ] cxref (Development)
- - [ ] date
+ - [x] date
  - [x] dd
  - [ ] delta (SCCS)
  - [x] df

README.md

@@ -11,11 +11,16 @@ plib = { path = "../plib" }
 clap = { version = "4", features = ["derive"] }
 gettext-rs = { version = "0.7", features = ["gettext-system"] }
 chrono = "0.4"
+libc = "0.2"
 
 [[bin]]
 name = "cal"
 path = "src/cal.rs"
 
+[[bin]]
+name = "date"
+path = "src/date.rs"
+
 [[bin]]
 name = "sleep"
 path = "src/sleep.rs"

datetime/Cargo.toml

@@ -0,0 +1,163 @@
+//
+// Copyright (c) 2024 Jeff Garzik
+//
+// This file is part of the posixutils-rs project covered under
+// the MIT License.  For the full license text, please see the LICENSE
+// file in the root directory of this project.
+// SPDX-License-Identifier: MIT
+//
+// TODO:
+// - add tests (how?)
+// - double-check that Rust stftime() is POSIX compliant
+//
+
+extern crate clap;
+extern crate plib;
+
+use chrono::{DateTime, Datelike, Local, LocalResult, TimeZone, Utc};
+use clap::Parser;
+use gettextrs::{bind_textdomain_codeset, textdomain};
+use plib::PROJECT_NAME;
+
+const DEF_TIMESTR: &str = "%a %b %e %H:%M:%S %Z %Y";
+
+/// date - write the date and time
+#[derive(Parser, Debug)]
+#[command(author, version, about, long_about)]
+struct Args {
+    /// Perform operations as if the TZ env var was set to the string "UTC0"
+    #[arg(short, long)]
+    utc: bool,
+
+    /// If prefixed with '+', Display the current time in the given FORMAT,
+    /// as in strftime(3).  Otherwise, set the current time to the given
+    /// string.
+    timestr: Option<String>,
+}
+
+fn show_time_local(formatstr: &str) -> String {
+    let now = chrono::Local::now();
+    now.format(formatstr).to_string()
+}
+
+fn show_time_utc(formatstr: &str) -> String {
+    let now = chrono::Utc::now();
+    now.format(formatstr).to_string()
+}
+
+fn show_time(utc: bool, formatstr: &str) {
+    let timestr = {
+        if utc {
+            show_time_utc(formatstr)
+        } else {
+            show_time_local(formatstr)
+        }
+    };
+
+    println!("{}", timestr);
+}
+
+fn set_time(utc: bool, timestr: &str) -> Result<(), &'static str> {
+    for ch in timestr.chars() {
+        if !ch.is_ascii_digit() {
+            return Err("date: invalid date");
+        }
+    }
+
+    let cur_year = {
+        if utc {
+            let now = chrono::Utc::now();
+            now.year()
+        } else {
+            let now = chrono::Local::now();
+            now.year()
+        }
+    };
+
+    let (year, month, day, hour, minute) = match timestr.len() {
+        8 => {
+            let month = timestr[0..2].parse::<u32>().unwrap();
+            let day = timestr[2..4].parse::<u32>().unwrap();
+            let hour = timestr[4..6].parse::<u32>().unwrap();
+            let minute = timestr[6..8].parse::<u32>().unwrap();
+            (cur_year, month, day, hour, minute)
+        }
+        10 => {
+            let month = timestr[0..2].parse::<u32>().unwrap();
+            let day = timestr[2..4].parse::<u32>().unwrap();
+            let hour = timestr[4..6].parse::<u32>().unwrap();
+            let minute = timestr[6..8].parse::<u32>().unwrap();
+            let year = timestr[8..10].parse::<i32>().unwrap();
+            if year < 70 {
+                (year + 2000, month, day, hour, minute)
+            } else {
+                (year + 1900, month, day, hour, minute)
+            }
+        }
+        12 => {
+            let month = timestr[0..2].parse::<u32>().unwrap();
+            let day = timestr[2..4].parse::<u32>().unwrap();
+            let hour = timestr[4..6].parse::<u32>().unwrap();
+            let minute = timestr[6..8].parse::<u32>().unwrap();
+            let year = timestr[8..12].parse::<i32>().unwrap();
+            (year, month, day, hour, minute)
+        }
+        _ => {
+            return Err("date: invalid date");
+        }
+    };
+
+    // calculate system time
+    let new_time = {
+        if utc {
+            match chrono::Utc.with_ymd_and_hms(year, month, day, hour, minute, 0) {
+                LocalResult::<DateTime<Utc>>::Single(t) => t.timestamp(),
+                _ => {
+                    return Err("date: invalid date");
+                }
+            }
+        } else {
+            match chrono::Local.with_ymd_and_hms(year, month, day, hour, minute, 0) {
+                LocalResult::<DateTime<Local>>::Single(t) => t.timestamp(),
+                _ => {
+                    return Err("date: invalid date");
+                }
+            }
+        }
+    };
+
+    let new_time = libc::timespec {
+        tv_sec: new_time,
+        tv_nsec: 0,
+    };
+
+    // set system time
+    unsafe {
+        if libc::clock_settime(libc::CLOCK_REALTIME, &new_time) != 0 {
+            return Err("date: failed to set time");
+        }
+    }
+
+    Ok(())
+}
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    // parse command line arguments
+    let args = Args::parse();
+
+    textdomain(PROJECT_NAME)?;
+    bind_textdomain_codeset(PROJECT_NAME, "UTF-8")?;
+
+    match &args.timestr {
+        None => show_time(args.utc, DEF_TIMESTR),
+        Some(timestr) => {
+            if timestr.starts_with("+") {
+                show_time(args.utc, &timestr[1..]);
+            } else {
+                set_time(args.utc, &timestr)?;
+            }
+        }
+    }
+
+    Ok(())
+}