Changed return type of C interface

.idea/markdown.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="MarkdownSettings">
+    <option name="areInjectionsEnabled" value="false" />
+  </component>
+</project>

Cargo.toml

@@ -1,8 +1,8 @@
 [package]
 name = "libcaesium"
-version = "0.7.0"
+version = "0.8.0"
 authors = ["Matteo Paonessa <matteo.paonessa@gmail.com>"]
-edition = "2018"
+edition = "2021"
 categories = ["multimedia::images"]
 keywords = [
     "compression",
@@ -24,17 +24,17 @@ license = "Apache-2.0"
 [dependencies]
 mozjpeg-sys = "1.0.1"
 oxipng = "5.0.1"
-libc = "0.2.76"
+libc = "0.2.119"
 gifsicle = "1.92.5"
 webp = "0.2.1"
-infer = "0.6.0"
+infer = "0.7.0"
 image = { version = "0.24", default-features = false, features = ["jpeg", "png", "webp", "gif"] }
 img-parts = "0.2.3"
 bytes = "1.1.0"
 
 [dev-dependencies]
 dssim = "3.2.0"
-kamadak-exif = "0.5.0"
+kamadak-exif = "0.5.4"
 
 [lib]
 name = "caesium"

README.md

@@ -17,7 +17,7 @@ pub fn compress(
 - `output_path` - output file path (full filename)
 - `parameters` - options struct, containing compression parameters (see below)
 
-The output folder where the file is compressed **must** exist.
+NOTE: The output folder where the file is compressed **must** exist.
 ### Compression options
 Libcaesium supports a few compression parameters for each file it supports.
 They are defined into a top level struct containing each supported file parameters, as follows:
@@ -57,7 +57,7 @@ pub struct Parameters {
 ```
 - `oxipng`: oxipng options. Should be left as default unless you want to do something advanced. Refer to [oxipng](https://github.com/shssoichiro/oxipng) for documentation.
 - `level`: level of optimization, from 1 to 7. Increasing the level will result in a smaller file, at the cost of computation time. If the optimization flag is `true`, the level is set to `6`. Default: `3`.
-- `force_zopfli`: if `optimization` is `true` and this option is also `true`, will use zopfli algorithm for compression, resulting in a smaller image but it may take minutes to finish the process. Default `false`.
+- `force_zopfli`: if `optimization` is `true` and this option is also `true`, will use zopfli algorithm for compression, resulting in a smaller image, but it may take minutes to finish the process. Default `false`.
 
 #### gif
 GIF support is experimental, has many know issues and does not support optimization. Expect bugs (especially on Windows).
@@ -69,7 +69,7 @@ pub struct Parameters {
 - `quality`: in a range from 0 to 100, the quality of the resulting image. If the optimization flag is `true`, the level is set to `100`. Default: `80`.
 
 #### webp
-WebP compression is tricky. The format is already well optimized and using the `optimize` flag will probably result in a bigger image.
+WebP's compression is tricky. The format is already well optimized and using the `optimize` flag will probably result in a bigger image.
 ```Rust
 pub struct Parameters {
     pub quality: u32,
@@ -84,14 +84,23 @@ pub extern fn c_compress(
     input_path: *const c_char,
     output_path: *const c_char,
     params: CCSParameters
-) -> bool
+) -> CCSResult
 ```
 #### Parameters
 - `input_path` - input file path (full filename)
 - `output_path` - output file path (full filename)
 - `parameters` - options struct, containing compression parameters (see below)
 #### Return
-`true` if all goes well, `false` otherwise.
+A `CCSResult` struct
+```Rust
+#[repr(C)]
+pub struct CCSResult {
+    pub success: bool,
+    pub error_message: *const c_char,
+}
+```
+If `success` is `true` the compression process ended successfully and `error_message` will be empty.  
+On failure, the `error_message` will be filled with a string containing a brief explanation of the error.
 
 ### Compression options
 The C options struct is slightly different from the Rust one:
@@ -131,4 +140,4 @@ Libcaesium also supports optimization, by setting the _quality_ to 0. This perfo
 but with a smaller size (10-12% usually).  
 PNG is lossless, so libcaesium will always perform optimization rather than compression.
 GIF optimization is possible, but currently not supported.
-WebP optimization is also possible, but it will probably result in a bigger output file as it's well suited to losslessly convert from PNG or JPEG.s
+WebP's optimization is also possible, but it will probably result in a bigger output file as it's well suited to losslessly convert from PNG or JPEG.s

src/jpeg.rs

@@ -16,6 +16,7 @@ pub fn compress(input_path: String, output_path: String, parameters: CSParameter
 {
     let mut in_file = fs::read(input_path)?;
 
+
     if parameters.width > 0 || parameters.height > 0 {
         if parameters.keep_metadata {
             let metadata = extract_metadata(in_file.clone());
@@ -27,12 +28,11 @@ pub fn compress(input_path: String, output_path: String, parameters: CSParameter
     }
 
     unsafe {
-        let compression_buffer: (*mut u8, u64);
-        if parameters.optimize {
-            compression_buffer = lossless(in_file, parameters)?;
+        let compression_buffer: (*mut u8, u64) = if parameters.optimize {
+            lossless(in_file, parameters)?
         } else {
-            compression_buffer = lossy(in_file, parameters)?;
-        }
+            lossy(in_file, parameters)?
+        };
         let mut output_file_buffer = File::create(output_path)?;
         output_file_buffer.write_all(std::slice::from_raw_parts(compression_buffer.0, compression_buffer.1 as usize))?;
     }

src/lib.rs

@@ -7,7 +7,7 @@ mod resize;
 
 use std::error::Error;
 use crate::utils::get_filetype;
-use std::ffi::CStr;
+use std::ffi::{CStr, CString};
 use std::os::raw::c_char;
 
 #[repr(C)]
@@ -23,6 +23,12 @@ pub struct CCSParameters {
     pub height: u32,
 }
 
+#[repr(C)]
+pub struct CCSResult {
+    pub success: bool,
+    pub error_message: *const c_char,
+}
+
 pub struct CSParameters {
     pub jpeg: jpeg::Parameters,
     pub png: png::Parameters,
@@ -68,8 +74,9 @@ pub fn initialize_parameters() -> CSParameters
 
 #[no_mangle]
 #[allow(clippy::missing_safety_doc)]
-pub unsafe extern fn c_compress(input_path: *const c_char, output_path: *const c_char, params: CCSParameters) -> bool {
+pub unsafe extern fn c_compress(input_path: *const c_char, output_path: *const c_char, params: CCSParameters) -> CCSResult {
     let mut parameters = initialize_parameters();
+
     parameters.jpeg.quality = params.jpeg_quality;
     parameters.png.level = params.png_level;
     parameters.optimize = params.optimize;
@@ -80,10 +87,29 @@ pub unsafe extern fn c_compress(input_path: *const c_char, output_path: *const c
     parameters.width = params.width;
     parameters.height = params.height;
 
-    let x = compress(CStr::from_ptr(input_path).to_str().unwrap().to_string(),
+    let mut error_message = CString::new("").unwrap();
+
+    match compress(CStr::from_ptr(input_path).to_str().unwrap().to_string(),
                    CStr::from_ptr(output_path).to_str().unwrap().to_string(),
-                     parameters).is_ok();
-    x
+                   parameters) {
+        Ok(_) => {
+            let em_pointer = error_message.as_ptr();
+            std::mem::forget(error_message);
+            CCSResult {
+                success: true,
+                error_message: em_pointer
+            }
+        }
+        Err(e) => {
+            error_message = CString::new(e.to_string()).unwrap();
+            let em_pointer = error_message.as_ptr();
+            std::mem::forget(error_message);
+            CCSResult {
+                success: false,
+                error_message: em_pointer
+            }
+        }
+    }
 }
 
 pub fn compress(input_path: String, output_path: String, parameters: CSParameters) -> Result<(), Box<dyn Error>> {
@@ -92,43 +118,21 @@ pub fn compress(input_path: String, output_path: String, parameters: CSParameter
 
     match file_type {
         utils::SupportedFileTypes::Jpeg => {
-            return match jpeg::compress(input_path, output_path, parameters) {
-                Ok(_) => Ok(()),
-                Err(e) => {
-                    eprintln!("JPEG compression error: {}", e.to_string());
-                    Err(e.into())
-                }
-            };
+            jpeg::compress(input_path, output_path, parameters)?;
         }
         utils::SupportedFileTypes::Png => {
-            return match png::compress(input_path, output_path, parameters) {
-                Ok(_) => Ok(()),
-                Err(e) => {
-                    eprintln!("PNG compression error: {}", e.to_string());
-                    Err(e.into())
-                }
-            };
+            png::compress(input_path, output_path, parameters)?;
         }
         utils::SupportedFileTypes::Gif => {
-            return match gif::compress(input_path, output_path, parameters) {
-                Ok(_) => Ok(()),
-                Err(e) => {
-                    eprintln!("GIF compression error: {}", e.to_string());
-                    Err(e.into())
-                }
-            };
+            gif::compress(input_path, output_path, parameters)?;
         }
         utils::SupportedFileTypes::WebP => {
-            return match webp::compress(input_path, output_path, parameters) {
-                Ok(_) => Ok(()),
-                Err(e) => {
-                    eprintln!("WebP compression error: {}", e.to_string());
-                    Err(e.into())
-                }
-            };
+            webp::compress(input_path, output_path, parameters)?;
         }
         _ => return Err("Unknown file type".into())
     }
+
+    Ok(())
 }
 
 fn validate_parameters(parameters: &CSParameters) -> Result<(), Box<dyn Error>> {

tests/integration.rs

@@ -1,5 +1,3 @@
-use caesium;
-
 #[test]
 fn unknown_file_type() {
     let output = "tests/samples/output/should_not_be_there";

tests/webp.rs

@@ -1,4 +1,3 @@
-use caesium;
 use std::sync::Once;
 use std::fs;