Change `zarrs{LastError,ArrayGetMetadataString,ArrayGetAttributesStri…

…ng}` to return non-const pointers

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
  - Bump `cbindgen` to 0.27
+ - Change `zarrs{LastError,ArrayGetMetadataString,ArrayGetAttributesString}` to return non-const pointers
 
 ### Fixed
  - Bump MSRV to 1.75 (needed since 0.6.1)

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "zarrs_ffi"
 description = "FFI bindings for the zarrs crate"
-version = "0.8.1"
+version = "0.8.2"
 authors = ["Lachlan Deakin <ljdgit@gmail.com>"]
 edition = "2021"
 rust-version = "1.75"

src/array.rs

@@ -474,7 +474,7 @@ pub unsafe extern "C" fn zarrsArrayGetSubsetSize(
 pub unsafe extern "C" fn zarrsArrayGetMetadataString(
     array: ZarrsArray,
     pretty: bool,
-    pMetadataString: *mut *const c_char,
+    pMetadataString: *mut *mut c_char,
 ) -> ZarrsResult {
     // Validation
     if array.is_null() {
@@ -509,7 +509,7 @@ pub unsafe extern "C" fn zarrsArrayGetMetadataString(
 pub unsafe extern "C" fn zarrsArrayGetAttributesString(
     array: ZarrsArray,
     pretty: bool,
-    pAttributesString: *mut *const c_char,
+    pAttributesString: *mut *mut c_char,
 ) -> ZarrsResult {
     // Validation
     if array.is_null() {

src/lib.rs

@@ -39,8 +39,10 @@ pub enum ZarrsResult {
 static mut LAST_ERROR: Lazy<String> = Lazy::new(|| "".to_string());
 
 /// Get the last error string.
+///
+/// The string must be freed with `zarrsFreeString`.
 #[no_mangle]
-pub extern "C" fn zarrsLastError() -> *const c_char {
+pub extern "C" fn zarrsLastError() -> *mut c_char {
     let c_str = CString::new(unsafe { LAST_ERROR.as_str() }).unwrap();
     c_str.into_raw()
 }

zarrs.h

@@ -104,9 +104,7 @@ extern "C" {
  * # Safety
  * `array` must be a valid `ZarrsArray` handle.
  */
-ZarrsResult zarrsArrayGetAttributesString(ZarrsArray array,
-                                          bool pretty,
-                                          const char **pAttributesString);
+ZarrsResult zarrsArrayGetAttributesString(ZarrsArray array, bool pretty, char **pAttributesString);
 
 /**
  * Return the number of chunks in the chunk grid.
@@ -241,9 +239,7 @@ ZarrsResult zarrsArrayGetInnerChunkShape(ZarrsArray array,
  * # Safety
  * `array` must be a valid `ZarrsArray` handle.
  */
-ZarrsResult zarrsArrayGetMetadataString(ZarrsArray array,
-                                        bool pretty,
-                                        const char **pMetadataString);
+ZarrsResult zarrsArrayGetMetadataString(ZarrsArray array, bool pretty, char **pMetadataString);
 
 /**
  * Returns the shape of the array.
@@ -481,8 +477,10 @@ ZarrsResult zarrsFreeString(char *string);
 
 /**
  * Get the last error string.
+ *
+ * The string must be freed with `zarrsFreeString`.
  */
-const char *zarrsLastError(void);
+char *zarrsLastError(void);
 
 /**
  * Create a handle to an existing array (read/write capability).