1 files changed, 72 insertions, 0 deletions
diff --git a/cli/fs_util.rs b/cli/fs_util.rs
index fe0ef8857..578a2ec37 100644
--- a/cli/fs_util.rs
+++ b/cli/fs_util.rs
@@ -5,6 +5,7 @@ use deno_core::error::{uri_error, AnyError};
 pub use deno_core::normalize_path;
 use deno_core::ModuleSpecifier;
 use deno_runtime::deno_crypto::rand;
+use std::borrow::Cow;
 use std::env::current_dir;
 use std::fs::OpenOptions;
 use std::io::{Error, Write};
@@ -362,6 +363,44 @@ pub fn specifier_parent(specifier: &ModuleSpecifier) -> ModuleSpecifier {
   specifier
 }
 
+/// `from.make_relative(to)` but with fixes.
+pub fn relative_specifier(
+  from: &ModuleSpecifier,
+  to: &ModuleSpecifier,
+) -> Option<String> {
+  let is_dir = to.path().ends_with('/');
+
+  if is_dir && from == to {
+    return Some("./".to_string());
+  }
+
+  // workaround using parent directory until https://github.com/servo/rust-url/pull/754 is merged
+  let from = if !from.path().ends_with('/') {
+    if let Some(end_slash) = from.path().rfind('/') {
+      let mut new_from = from.clone();
+      new_from.set_path(&from.path()[..end_slash + 1]);
+      Cow::Owned(new_from)
+    } else {
+      Cow::Borrowed(from)
+    }
+  } else {
+    Cow::Borrowed(from)
+  };
+
+  // workaround for url crate not adding a trailing slash for a directory
+  // it seems to be fixed once a version greater than 2.2.2 is released
+  let mut text = from.make_relative(to)?;
+  if is_dir && !text.ends_with('/') && to.query().is_none() {
+    text.push('/');
+  }
+
+  Some(if text.starts_with("../") || text.starts_with("./") {
+    text
+  } else {
+    format!("./{}", text)
+  })
+}
+
 /// This function checks if input path has trailing slash or not. If input path
 /// has trailing slash it will return true else it will return false.
 pub fn path_has_trailing_slash(path: &Path) -> bool {
@@ -749,6 +788,39 @@ mod tests {
   }
 
   #[test]
+  fn test_relative_specifier() {
+    run_test("file:///from", "file:///to", Some("./to"));
+    run_test("file:///from", "file:///from/other", Some("./from/other"));
+    run_test("file:///from", "file:///from/other/", Some("./from/other/"));
+    run_test("file:///from", "file:///other/from", Some("./other/from"));
+    run_test("file:///from/", "file:///other/from", Some("../other/from"));
+    run_test("file:///from", "file:///other/from/", Some("./other/from/"));
+    run_test(
+      "file:///from",
+      "file:///to/other.txt",
+      Some("./to/other.txt"),
+    );
+    run_test(
+      "file:///from/test",
+      "file:///to/other.txt",
+      Some("../to/other.txt"),
+    );
+    run_test(
+      "file:///from/other.txt",
+      "file:///to/other.txt",
+      Some("../to/other.txt"),
+    );
+
+    fn run_test(from: &str, to: &str, expected: Option<&str>) {
+      let result = relative_specifier(
+        &ModuleSpecifier::parse(from).unwrap(),
+        &ModuleSpecifier::parse(to).unwrap(),
+      );
+      assert_eq!(result.as_deref(), expected);
+    }
+  }
+
+  #[test]
   fn test_path_has_trailing_slash() {
     #[cfg(not(windows))]
     {