armybox 0.3.0

//! i2cset - write to I2C device
//!
//! Write a value to an I2C device register.

use crate::io;
use crate::sys;
use super::get_arg;

// I2C ioctl
const I2C_SLAVE: crate::io::IoctlReq = 0x0703u32 as crate::io::IoctlReq;

/// i2cset - write to I2C device
///
/// # Synopsis
/// ```text
/// i2cset [-y] BUS ADDRESS REGISTER VALUE
/// ```
///
/// # Description
/// Write a byte to an I2C device register.
///
/// # Options
/// - `-y`: Disable interactive mode
///
/// # Exit Status
/// - 0: Success
/// - 1: Error
pub fn i2cset(argc: i32, argv: *const *const u8) -> i32 {
    if argc < 5 {
        io::write_str(2, b"i2cset: usage: i2cset [-y] BUS ADDRESS REGISTER VALUE\n");
        return 1;
    }

    let mut bus: i32 = -1;
    let mut addr: i32 = -1;
    let mut reg: i32 = -1;
    let mut value: i32 = -1;
    let mut arg_idx = 1;

    while arg_idx < argc {
        if let Some(arg) = unsafe { get_arg(argv, arg_idx) } {
            if arg == b"-y" {
                // Skip
            } else if bus < 0 {
                bus = sys::parse_i64(arg).unwrap_or(-1) as i32;
            } else if addr < 0 {
                addr = parse_hex_or_dec(arg) as i32;
            } else if reg < 0 {
                reg = parse_hex_or_dec(arg) as i32;
            } else if value < 0 {
                value = parse_hex_or_dec(arg) as i32;
            }
        }
        arg_idx += 1;
    }

    if bus < 0 || addr < 0 || reg < 0 || value < 0 {
        io::write_str(2, b"i2cset: missing arguments\n");
        return 1;
    }

    // Open I2C device
    let mut path = [0u8; 32];
    let prefix = b"/dev/i2c-";
    path[..prefix.len()].copy_from_slice(prefix);
    let mut num_buf = [0u8; 12];
    let num_str = sys::format_i64(bus as i64, &mut num_buf);
    path[prefix.len()..prefix.len() + num_str.len()].copy_from_slice(num_str);

    let fd = io::open(&path, libc::O_RDWR, 0);
    if fd < 0 {
        sys::perror(&path);
        return 1;
    }

    if unsafe { libc::ioctl(fd, I2C_SLAVE, addr) } < 0 {
        sys::perror(b"I2C_SLAVE");
        io::close(fd);
        return 1;
    }

    // Write register and value
    let buf = [reg as u8, value as u8];
    if unsafe { libc::write(fd, buf.as_ptr() as *const libc::c_void, 2) } != 2 {
        sys::perror(b"write");
        io::close(fd);
        return 1;
    }

    io::close(fd);
    0
}

fn parse_hex_or_dec(s: &[u8]) -> u64 {
    if s.len() > 2 && s[0] == b'0' && (s[1] == b'x' || s[1] == b'X') {
        let mut result: u64 = 0;
        for &c in &s[2..] {
            let digit = match c {
                b'0'..=b'9' => c - b'0',
                b'a'..=b'f' => c - b'a' + 10,
                b'A'..=b'F' => c - b'A' + 10,
                _ => return 0,
            };
            result = result * 16 + digit as u64;
        }
        result
    } else {
        sys::parse_u64(s).unwrap_or(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_i2cset_no_args() {
        let armybox = get_armybox_path();
        if !armybox.exists() { return; }

        let output = Command::new(&armybox)
            .args(["i2cset"])
            .output()
            .unwrap();

        assert_eq!(output.status.code(), Some(1));
        let stderr = std::string::String::from_utf8_lossy(&output.stderr);
        assert!(stderr.contains("usage"));
    }

    #[test]
    fn test_i2cset_nonexistent_bus() {
        let armybox = get_armybox_path();
        if !armybox.exists() { return; }

        let output = Command::new(&armybox)
            .args(["i2cset", "-y", "99", "0x50", "0x00", "0xff"])
            .output()
            .unwrap();

        assert_eq!(output.status.code(), Some(1));
    }
}