Fix sprite name generation so symlinks work

This addresses an issue creating valid sprite names for symlinks, as
detailed in issue #81. Symlinked files were being canonicalised, which
caused a problem if the target was outside the base path. This change
replaces the canonicalisation step with `std::path::absolute()`, which
doesn't resolve symlinks and so they remain within the base path.

The change has two side-effects:

- It allows sprite names to be generated for non-existent files (a good
  thing, since there's no need for names to be linked to the
  filesystem)
- It modifies the `spreet::sprite_name()` function to return a
  `PathError` instead of an `IoError` when the `abs_path` argument is
  not an ancestor of the `path` argument.

Use of `std::path::absolute()` means the minimum supported Rust version
(MSRV) is now 1.74.

CHANGELOG.md

@@ -2,14 +2,17 @@
 
 ## Development version
 
+- Fix issue creating valid sprite names for symlinks (see [#81](https://github.com/flother/spreet/issues/81)). This has two side effects:
+  1. sprite names can now be generated for files that don't exist
+  2. `spreet::sprite_name()` now returns a `PathError` instead of an `IoError` when the `abs_path` argument is not an ancestor of the `path` argument.
 - Update [clap](https://crates.io/crates/clap) dependency to v4.5
 - Update [multimap](https://crates.io/crates/multimap) dependency to v0.10
 - Update [oxipng](https://crates.io/crates/multimap) dependency to v9.1
 - Update [resvg](https://crates.io/crates/resvg) dependency to v0.43
 - Update [assert_fs](https://crates.io/crates/assert_fs) dev dependency to v1.1
 - Update [softprops/action-gh-release](https://github.com/softprops/action-gh-release) to v2
 
-The minimum supported version of Rust is now 1.74.0 (released November 2023).
+The minimum supported version of Rust is now 1.79.0 (released June 2024).
 
 ## v0.11.0 (2023-12-05)
 

Cargo.toml

@@ -2,7 +2,7 @@
 name = "spreet"
 version = "0.12.0-dev"
 edition = "2021"
-rust-version = "1.74"
+rust-version = "1.79"
 description = "Create a spritesheet from a set of SVG images"
 readme = "README.md"
 repository = "https://github.com/flother/spreet"

src/sprite/mod.rs

@@ -533,15 +533,15 @@ impl Spritesheet {
 ///
 /// This function will return an error if:
 ///
-/// - `path` does not exist
-/// - `abs_path` does not exist
-/// - `abs_path` is not a ancestor of `path`
+/// - `abs_path` is not an ancestor of `path`
+/// - `path` is empty
+/// - getting the current directory fails
 pub fn sprite_name<P1: AsRef<Path>, P2: AsRef<Path>>(
     path: P1,
     base_path: P2,
 ) -> SpreetResult<String> {
-    let abs_path = path.as_ref().canonicalize()?;
-    let abs_base_path = base_path.as_ref().canonicalize()?;
+    let abs_path = std::path::absolute(path.as_ref())?;
+    let abs_base_path = std::path::absolute(base_path)?;
     let Ok(rel_path) = abs_path.strip_prefix(abs_base_path) else {
         return Err(SpreetError::PathError(path.as_ref().to_path_buf()));
     };

tests/sprite.rs

@@ -41,10 +41,10 @@ fn sprite_name_works_with_deeply_nested_files() {
 }
 
 #[test]
-fn sprite_name_returns_error_for_non_existent_path() {
-    assert_matches!(
-        sprite_name(Path::new("./does_not_exist.svg"), Path::new("./")),
-        Err(SpreetError::IoError(_))
+fn sprite_name_returns_ok_for_non_existent_path() {
+    assert_eq!(
+        sprite_name(Path::new("./does_not_exist.svg"), Path::new("./")).unwrap(),
+        "does_not_exist"
     );
 }
 
@@ -63,7 +63,7 @@ fn sprite_name_returns_error_for_non_existent_base_path() {
             Path::new("./tests/fixtures/svgs/bicycle.svg"),
             Path::new("./tests/fixtures/foo"),
         ),
-        Err(SpreetError::IoError(_))
+        Err(SpreetError::PathError(_))
     );
 }