nih-plug/xtask/src/symbols.rs

use anyhow::{bail, Context, Result};
use std::fs;
use std::path::Path;

/// Check whether a binary exports the specified symbol. Used to detect the plugin formats supported
/// by a plugin library. Returns an error if the binary cuuld not be read. This function will also
/// parse non-native binaries.
pub fn exported<P: AsRef<Path>>(binary: P, symbol: &str) -> Result<bool> {
    // Parsing the raw binary instead of relying on nm-like tools makes cross compiling a bit easier
    let bytes = fs::read(&binary)
        .with_context(|| format!("Could not read '{}'", binary.as_ref().display()))?;
    match goblin::Object::parse(&bytes)? {
        goblin::Object::Elf(obj) => Ok(obj.dynsyms.iter().any(|sym| {
            !sym.is_import()
                && sym.is_function()
                && obj.dynstrtab.get_at(sym.st_name) == Some(symbol)
        })),
        goblin::Object::Mach(obj) => {
            let obj = match obj {
                goblin::mach::Mach::Fat(arches) => arches
                    .get(0)
                    .context("Fat Mach-O binary without any binaries")?,
                goblin::mach::Mach::Binary(obj) => obj,
            };

            // XXX: Why are all exported symbols on macOS prefixed with an underscore?
            let symbol = format!("_{}", symbol);

            Ok(obj.exports()?.into_iter().any(|sym| sym.name == symbol))
        }
        goblin::Object::PE(obj) => Ok(obj.exports.iter().any(|sym| sym.name == Some(symbol))),
        obj => bail!("Unsupported object type: {:?}", obj),
    }
}