cargo-nfpm 0.1.3

//! Stripping of Cargo generated binaries.

use std::process::Command;

use anyhow::Context;
use camino::{Utf8Path, Utf8PathBuf};

use crate::cargo::get_host_triple;

#[derive(Debug, Default, Clone, Copy, PartialEq, clap::ValueEnum)]
pub enum StripAction {
    /// Don't do anything. Default.
    #[default]
    Skip,
    /// Keep only line-tables debug information. This is the minimum requirement for stacktraces.
    KeepLineTables,
    /// Strip off all debug information. Information is lost if not preserved otherwise.
    Strip,
    /// Debug information is saved in a separate .debug file.
    Split,
}

pub fn strip_if_required<P>(
    binary_path: P,
    target_triple: &str,
    action: StripAction,
) -> anyhow::Result<()>
where
    P: AsRef<Utf8Path>,
{
    match action {
        StripAction::Skip => Ok(()),
        StripAction::KeepLineTables => todo!(),
        StripAction::Strip => {
            let status = objcopy(target_triple)?
                .arg("--strip-debug")
                .arg("--strip-unneeded")
                .arg(binary_path.as_ref().as_str())
                .status()
                .context("calling llvm-objcopy")?;
            if !status.success() {
                return Err(anyhow::anyhow!("llvm-objcopy exited with non-zero"));
            }

            Ok(())
        }

        StripAction::Split => {
            let debug_sym_path = binary_path.as_ref().with_extension("debug");

            let status = objcopy(target_triple)?
                .arg("--only-keep-debug")
                .arg("--compress-debug-sections=zlib")
                .arg(binary_path.as_ref().as_str())
                .arg(debug_sym_path.as_str())
                .status()
                .context("calling llvm-objcopy")?;
            if !status.success() {
                return Err(anyhow::anyhow!("llvm-objcopy exited with non-zero"));
            }

            let symbol_name = debug_sym_path.file_name().context("missing filename")?;
            // We will need to `chdir` to the `target` directory because the `.gnu_debuglink` will
            // otherwise not use the relative path.
            let status = objcopy(target_triple)?
                .current_dir(
                    debug_sym_path
                        .parent()
                        .context("symbol path not pointing to file")?,
                )
                .arg("--strip-debug")
                .arg("--strip-unneeded")
                .arg("--remove-section=.gnu_debuglink")
                .arg(format!("--add-gnu-debuglink={symbol_name}"))
                .arg(binary_path.as_ref().as_str())
                .status()
                .context("calling llvm-objcopy")?;
            if !status.success() {
                return Err(anyhow::anyhow!("llvm-objcopy exited with non-zero"));
            }

            Ok(())
        }
    }
}

fn objcopy(target_triple: &str) -> anyhow::Result<Command> {
    fn get_llvm_tools_path(target_triple: &str) -> anyhow::Result<Utf8PathBuf> {
        let out = Command::new("rustc")
            .args(["--print", "sysroot"])
            .output()
            .context("finding rustc sysroot")?;
        if !out.status.success() {
            return Err(anyhow::anyhow!("failed to find rustc sysroot"));
        }

        let outstr = String::from_utf8(out.stdout).context("invalid utf8")?;
        let sysroot = Utf8PathBuf::from(outstr.trim());
        let path = sysroot.join("lib/rustlib").join(target_triple).join("bin");
        Ok(path)
    }

    let bin_path = get_llvm_tools_path(target_triple)?;
    if bin_path.is_dir() {
        return Ok(Command::new(bin_path.join("llvm-objcopy")));
    }

    let host_triple = get_host_triple()?;
    let bin_path = get_llvm_tools_path(&host_triple)?;
    if bin_path.is_dir() {
        return Ok(Command::new(bin_path.join("llvm-objcopy")));
    }

    Err(anyhow::anyhow!(
        "couldn't find llvm-objcopy. is the rustup component `llvm-tools` installed?"
    ))
}