armybox 0.3.0

A memory-safe #[no_std] BusyBox/Toybox clone in Rust - 299 Unix utilities in ~500KB
Documentation 
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//! free - display amount of free and used memory
//!
//! Display the total amount of free and used physical and swap memory.

use crate::io;

/// free - display amount of free and used memory
///
/// # Synopsis
/// ```text
/// free
/// ```
///
/// # Description
/// Display information about free and used memory on the system.
///
/// # Exit Status
/// - 0: Success
/// - >0: An error occurred
pub fn free(_argc: i32, _argv: *const *const u8) -> i32 {
    let fd = io::open(b"/proc/meminfo", libc::O_RDONLY, 0);
    if fd >= 0 {
        let mut buf = [0u8; 2048];
        let n = io::read(fd, &mut buf);
        io::close(fd);
        if n > 0 { io::write_all(1, &buf[..n as usize]); }
    }
    0
}

#[cfg(test)]
mod tests {
    extern crate std;
    use std::process::Command;
    use std::path::PathBuf;

    fn get_armybox_path() -> PathBuf {
        if let Ok(path) = std::env::var("ARMYBOX_PATH") {
            return PathBuf::from(path);
        }
        let manifest_dir = std::env::var("CARGO_MANIFEST_DIR")
            .map(PathBuf::from)
            .unwrap_or_else(|_| std::env::current_dir().unwrap());
        let release = manifest_dir.join("target/release/armybox");
        if release.exists() { return release; }
        manifest_dir.join("target/debug/armybox")
    }

    #[test]
    fn test_free_runs() {
        let armybox = get_armybox_path();
        if !armybox.exists() { return; }

        let output = Command::new(&armybox)
            .args(["free"])
            .output()
            .unwrap();

        assert_eq!(output.status.code(), Some(0));
    }

    #[test]
    fn test_free_contains_memtotal() {
        let armybox = get_armybox_path();
        if !armybox.exists() { return; }

        let output = Command::new(&armybox)
            .args(["free"])
            .output()
            .unwrap();

        let stdout = std::string::String::from_utf8_lossy(&output.stdout);
        // /proc/meminfo should contain MemTotal
        assert!(stdout.contains("MemTotal"));
    }

    #[test]
    fn test_free_contains_memfree() {
        let armybox = get_armybox_path();
        if !armybox.exists() { return; }

        let output = Command::new(&armybox)
            .args(["free"])
            .output()
            .unwrap();

        let stdout = std::string::String::from_utf8_lossy(&output.stdout);
        assert!(stdout.contains("MemFree"));
    }
}