1 files changed, 114 insertions, 0 deletions
diff --git a/compiler/rustc_codegen_ssa/src/back/rpath.rs b/compiler/rustc_codegen_ssa/src/back/rpath.rs
new file mode 100644
index 000000000..0b5656c9a
--- /dev/null
+++ b/compiler/rustc_codegen_ssa/src/back/rpath.rs
@@ -0,0 +1,114 @@
+use pathdiff::diff_paths;
+use rustc_data_structures::fx::FxHashSet;
+use std::env;
+use std::fs;
+use std::path::{Path, PathBuf};
+
+pub struct RPathConfig<'a> {
+    pub libs: &'a [&'a Path],
+    pub out_filename: PathBuf,
+    pub is_like_osx: bool,
+    pub has_rpath: bool,
+    pub linker_is_gnu: bool,
+}
+
+pub fn get_rpath_flags(config: &mut RPathConfig<'_>) -> Vec<String> {
+    // No rpath on windows
+    if !config.has_rpath {
+        return Vec::new();
+    }
+
+    debug!("preparing the RPATH!");
+
+    let rpaths = get_rpaths(config);
+    let mut flags = rpaths_to_flags(&rpaths);
+
+    if config.linker_is_gnu {
+        // Use DT_RUNPATH instead of DT_RPATH if available
+        flags.push("-Wl,--enable-new-dtags".to_owned());
+
+        // Set DF_ORIGIN for substitute $ORIGIN
+        flags.push("-Wl,-z,origin".to_owned());
+    }
+
+    flags
+}
+
+fn rpaths_to_flags(rpaths: &[String]) -> Vec<String> {
+    let mut ret = Vec::with_capacity(rpaths.len()); // the minimum needed capacity
+
+    for rpath in rpaths {
+        if rpath.contains(',') {
+            ret.push("-Wl,-rpath".into());
+            ret.push("-Xlinker".into());
+            ret.push(rpath.clone());
+        } else {
+            ret.push(format!("-Wl,-rpath,{}", &(*rpath)));
+        }
+    }
+
+    ret
+}
+
+fn get_rpaths(config: &mut RPathConfig<'_>) -> Vec<String> {
+    debug!("output: {:?}", config.out_filename.display());
+    debug!("libs:");
+    for libpath in config.libs {
+        debug!("    {:?}", libpath.display());
+    }
+
+    // Use relative paths to the libraries. Binaries can be moved
+    // as long as they maintain the relative relationship to the
+    // crates they depend on.
+    let rpaths = get_rpaths_relative_to_output(config);
+
+    debug!("rpaths:");
+    for rpath in &rpaths {
+        debug!("    {}", rpath);
+    }
+
+    // Remove duplicates
+    minimize_rpaths(&rpaths)
+}
+
+fn get_rpaths_relative_to_output(config: &mut RPathConfig<'_>) -> Vec<String> {
+    config.libs.iter().map(|a| get_rpath_relative_to_output(config, a)).collect()
+}
+
+fn get_rpath_relative_to_output(config: &mut RPathConfig<'_>, lib: &Path) -> String {
+    // Mac doesn't appear to support $ORIGIN
+    let prefix = if config.is_like_osx { "@loader_path" } else { "$ORIGIN" };
+
+    let cwd = env::current_dir().unwrap();
+    let mut lib = fs::canonicalize(&cwd.join(lib)).unwrap_or_else(|_| cwd.join(lib));
+    lib.pop(); // strip filename
+    let mut output = cwd.join(&config.out_filename);
+    output.pop(); // strip filename
+    let output = fs::canonicalize(&output).unwrap_or(output);
+    let relative = path_relative_from(&lib, &output)
+        .unwrap_or_else(|| panic!("couldn't create relative path from {:?} to {:?}", output, lib));
+    // FIXME (#9639): This needs to handle non-utf8 paths
+    format!("{}/{}", prefix, relative.to_str().expect("non-utf8 component in path"))
+}
+
+// This routine is adapted from the *old* Path's `path_relative_from`
+// function, which works differently from the new `relative_from` function.
+// In particular, this handles the case on unix where both paths are
+// absolute but with only the root as the common directory.
+fn path_relative_from(path: &Path, base: &Path) -> Option<PathBuf> {
+    diff_paths(path, base)
+}
+
+fn minimize_rpaths(rpaths: &[String]) -> Vec<String> {
+    let mut set = FxHashSet::default();
+    let mut minimized = Vec::new();
+    for rpath in rpaths {
+        if set.insert(rpath) {
+            minimized.push(rpath.clone());
+        }
+    }
+    minimized
+}
+
+#[cfg(all(unix, test))]
+mod tests;