Add hardlinking support

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Changelog
 
 ## Unreleased
+- Add `create_link` function for hard-linking
 
 ## v2.2.1 - 25 March 2025
 - Remove use of deprecated field in JavaScript ffi

src/simplifile.gleam

@@ -432,6 +432,21 @@ pub fn create_symlink(
   from symlink: String,
 ) -> Result(Nil, FileError)
 
+/// Create a "hard link" called symlink pointing to target.
+/// This does not have the same relative pathing footgun as 
+/// `create_symlink`.
+/// 
+/// ## Example
+/// ```gleam
+/// create_link("../target", "./link")
+/// ```
+@external(erlang, "simplifile_erl", "create_link")
+@external(javascript, "./simplifile_js.mjs", "createLink")
+pub fn create_link(
+  to target: String,
+  from link: String,
+) -> Result(Nil, FileError)
+
 /// Lists the contents of a directory.
 /// The list contains directory and file names, and is not recursive.
 ///

src/simplifile_erl.erl

@@ -12,6 +12,7 @@
     create_directory/1,
     create_dir_all/1,
     delete_file/1,
+    create_link/2,
     create_symlink/2,
     delete/1,
     delete_directory/1,
@@ -115,6 +116,10 @@ create_directory(Dir) ->
 create_symlink(Existing, New) ->
     posix_result(file:make_symlink(Existing, New)).
 
+%% Create a "hard link" New to the file or directory Existing.
+create_link(Existing, New) ->
+    posix_result(file:make_link(Existing, New)).
+
 %% List the contents of a directory
 read_directory(Dir) ->
     case file:list_dir(Dir) of

src/simplifile_js.mjs

@@ -110,6 +110,17 @@ export function createSymlink(target, path) {
   return gleamResult(() => fs.symlinkSync(target, path));
 }
 
+/**
+ * Create the "hard link" called path pointing to the target
+ *
+ * @param {string} target
+ * @param {sting} path
+ * returns {ok | GError}
+ */
+export function createLink(target, path) {
+  return gleamResult(() => fs.linkSync(target, path));
+}
+
 /**
  * Create a directory at the given filepath
  *

test/simplifile_test.gleam

@@ -11,11 +11,11 @@ import simplifile.{
   Eopnotsupp, Eoverflow, Eperm, Epipe, Erange, Erofs, Espipe, Esrch, Estale,
   Etxtbsy, Exdev, Execute, File, FilePermissions, NotUtf8, Read, Unknown, Write,
   append, append_bits, copy, copy_directory, copy_file, create_directory,
-  create_directory_all, create_file, create_symlink, delete, delete_all,
-  file_info, file_info_permissions, file_info_permissions_octal, file_info_type,
-  file_permissions_to_octal, get_files, is_directory, is_file, is_symlink,
-  link_info, read, read_bits, read_directory, rename, set_permissions,
-  set_permissions_octal, write, write_bits,
+  create_directory_all, create_file, create_link, create_symlink, delete,
+  delete_all, file_info, file_info_permissions, file_info_permissions_octal,
+  file_info_type, file_permissions_to_octal, get_files, is_directory, is_file,
+  is_symlink, link_info, read, read_bits, read_directory, rename,
+  set_permissions, set_permissions_octal, write, write_bits,
 }
 
 pub fn main() {
@@ -98,6 +98,27 @@ pub fn make_symlink_test() {
   let assert Ok(_) = delete("./tmp/" <> the_target)
 }
 
+pub fn make_link_test() {
+  let the_target = "target_of_created_link"
+  let the_link = "./tmp/created_link"
+
+  // File does not exist yet
+  let assert Error(_) = create_link(the_target, the_link)
+
+  let assert Ok(_) =
+    "some txt"
+    |> write(to: the_target)
+
+  let assert Ok(_) = create_link(the_target, the_link)
+  // Link already exists
+  let assert Error(_) = create_link(the_target, the_link)
+
+  let assert Ok("some txt") = read(the_link)
+
+  let assert Ok(_) = delete(the_target)
+  let assert Ok(_) = delete(the_link)
+}
+
 pub fn read_directory_test() {
   // Test setup
   let test_dir = "./tmp/test_dir"