resource: Add support for multiple search paths

Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>

1 files changed, 36 insertions, 2 deletions

diff --git a/src/resource.rs b/src/resource.rs
index f34d806..dd30678 100644
--- a/src/resource.rs
+++ b/src/resource.rs
@@ -6,13 +6,47 @@
 //! binary and present on disk.
 
 use std::io::{self, Read};
-use std::path::Path;
+use std::path::{Path, PathBuf};
+use std::sync::Mutex;
+
+use lazy_static::lazy_static;
+
+lazy_static! {
+    static ref SEARCH_PATHS: Mutex<Vec<PathBuf>> = {
+        let ret = Vec::new();
+        Mutex::new(ret)
+    };
+}
+
+/// Put a path at the back of the queue to search in
+pub fn add_search_path<P: AsRef<Path>>(path: P) {
+    SEARCH_PATHS
+        .lock()
+        .expect("Unable to lock SEARCH_PATHS")
+        .push(path.as_ref().into());
+}
 
 /// Open a file for reading, honouring search paths established during
 /// startup, and falling back to potentially embedded file content
 pub fn open<P: AsRef<Path>>(subpath: P) -> io::Result<Box<impl Read>> {
     let subpath = subpath.as_ref();
-    Ok(Box::new(std::fs::File::open(subpath)?))
+    let search_paths = SEARCH_PATHS.lock().expect("Unable to lock SEARCH_PATHS");
+    let search_paths = search_paths.iter().map(|p| p.as_path());
+    let search_paths = std::iter::empty()
+        .chain(Some(Path::new(".")))
+        .chain(search_paths);
+    let mut ret = Err(io::Error::new(
+        io::ErrorKind::NotFound,
+        format!("Unable to find {} in resource paths", subpath.display()),
+    ));
+    for basepath in search_paths {
+        let full_path = basepath.join(subpath);
+        ret = std::fs::File::open(full_path);
+        if ret.is_ok() {
+            break;
+        }
+    }
+    Ok(Box::new(ret?))
 }
 
 /// Read a file, honouring search paths established during startup, and