handle errors without crash

src/lib.rs

@@ -1,47 +1,69 @@
 use syntect::parsing::SyntaxSet;
-use syntect::highlighting::{ThemeSet, Style};
+use syntect::highlighting::{ThemeSet};
 use syntect::html::highlighted_html_for_string;
 
+use std::ptr;
+use std::str::Utf8Error;
 use std::ffi::{CStr, CString};
 use std::os::raw::c_char;
 
-static mut ps : Option<SyntaxSet> = None;
+static mut PS : Option<SyntaxSet> = None;
 // Load these once at the start of your program
-static mut ts : Option<ThemeSet> = None;
+static mut TS : Option<ThemeSet> = None;
+
+
+unsafe fn setup_to_html(langext: *const c_char, theme: *const c_char, code: *const c_char
+                 ) -> Option<CString> {
+
+    let ext = CStr::from_ptr(langext).to_str().ok()?;
+    let thm = CStr::from_ptr(theme).to_str().ok()?;
+    let cod = CStr::from_ptr(code).to_str().ok()?;
+
+    match (CString::new(to_html(ext, thm, cod)?)) {
+        Ok(h) => Some(h),
+        Err(r) => None
+    }
+
+}
 
 
 #[no_mangle]
 pub extern fn syntect_to_html(langext: *const c_char, theme: *const c_char, code: *const c_char) -> *const c_char {
     unsafe {
-        let ext = CStr::from_ptr(langext).to_str().expect("fail");
-        let thm = CStr::from_ptr(theme).to_str().expect("fail");
-        let cod = CStr::from_ptr(code).to_str().expect("fail");
+        match (setup_to_html(langext, theme, code)) {
+            Some(h) => h.into_raw(),
+            None => ptr::null()
+        }
+    }
+}
 
-        let html = to_html(ext, thm, cod);
-        let highlighted = CString::new(html).expect("Makecstr");
 
-        highlighted.into_raw()
+#[no_mangle]
+pub extern fn syntect_release_str(s: *mut c_char) {
+    unsafe {
+    let _ss = CString::from_raw(s);
     }
 }
 
+
 #[no_mangle]
 pub extern fn syntect_init() {
     unsafe {
-    ps = Some(SyntaxSet::load_defaults_newlines());
-    ts = Some(ThemeSet::load_defaults());
+    PS = Some(SyntaxSet::load_defaults_newlines());
+    TS = Some(ThemeSet::load_defaults());
     }
 }
 
+unsafe fn to_html(langext: &str, theme: &str, code: &str) -> Option<String> {
 
-unsafe fn to_html(langext: &str, theme: &str, code: &str) -> String {
-
-    if let Some(pps) = &ps {
-        let syntax = pps.find_syntax_by_extension("rs").unwrap();
-        if let Some(tts) = &ts {
-            return highlighted_html_for_string(code, &pps, syntax, &tts.themes[theme]);
+    if let Some(pps) = &PS {
+        let syntax = pps.find_syntax_by_token(langext)?;
+        if let Some(tts) = &TS {
+            return Some(highlighted_html_for_string(code, &pps, syntax, &tts.themes[theme]));
         }
     } 
 
-    return String::from("");
+    None
+
 }