make dc_str_from_clist safe and return a string instead of c-string -- this allows to remove some unsafe and now unneccessary cleanup code

src/dc_receive_imf.rs

@@ -1,7 +1,7 @@
 use std::ptr;
 
 use itertools::join;
-use libc::{free, strcmp};
+use libc::strcmp;
 use mmime::clist::*;
 use mmime::mailimf::types::*;
 use mmime::mailmime::content::*;
@@ -319,13 +319,8 @@ unsafe fn add_parts(
     let mut chat_id_blocked = Blocked::Not;
     let mut sort_timestamp = 0;
     let mut rcvd_timestamp = 0;
-    let mut mime_in_reply_to = std::ptr::null_mut();
-    let mut mime_references = std::ptr::null_mut();
-
-    let cleanup = |mime_in_reply_to: *mut libc::c_char, mime_references: *mut libc::c_char| {
-        free(mime_in_reply_to.cast());
-        free(mime_references.cast());
-    };
+    let mut mime_in_reply_to = String::new();
+    let mut mime_references = String::new();
 
     // collect the rest information, CC: is added to the to-list, BCC: is ignored
     // (we should not add BCC to groups as this would split groups. We could add them as "known contacts",
@@ -359,7 +354,6 @@ unsafe fn add_parts(
             message::update_server_uid(context, &rfc724_mid, server_folder.as_ref(), server_uid);
         }
 
-        cleanup(mime_in_reply_to, mime_references);
         bail!("Message already in DB");
     }
 
@@ -588,20 +582,14 @@ unsafe fn add_parts(
     if let Some(field) = mime_parser.lookup_field_typ("In-Reply-To", MAILIMF_FIELD_IN_REPLY_TO) {
         let fld_in_reply_to = (*field).fld_data.fld_in_reply_to;
         if !fld_in_reply_to.is_null() {
-            mime_in_reply_to = dc_str_from_clist(
-                (*(*field).fld_data.fld_in_reply_to).mid_list,
-                b" \x00" as *const u8 as *const libc::c_char,
-            )
+            mime_in_reply_to = dc_str_from_clist((*(*field).fld_data.fld_in_reply_to).mid_list, " ")
         }
     }
 
     if let Some(field) = mime_parser.lookup_field_typ("References", MAILIMF_FIELD_REFERENCES) {
         let fld_references = (*field).fld_data.fld_references;
         if !fld_references.is_null() {
-            mime_references = dc_str_from_clist(
-                (*(*field).fld_data.fld_references).mid_list,
-                b" \x00" as *const u8 as *const libc::c_char,
-            )
+            mime_references = dc_str_from_clist((*(*field).fld_data.fld_references).mid_list, " ")
         }
     }
 
@@ -687,8 +675,8 @@ unsafe fn add_parts(
                         } else {
                             None
                         },
-                        to_string_lossy(mime_in_reply_to),
-                        to_string_lossy(mime_references),
+                        mime_in_reply_to,
+                        mime_references,
                     ])?;
 
                     txt_raw = None;
@@ -698,11 +686,7 @@ unsafe fn add_parts(
                 }
                 Ok(())
             },
-        )
-        .map_err(|err| {
-            cleanup(mime_in_reply_to, mime_references);
-            err
-        })?;
+        )?;
 
     info!(
         context,
@@ -722,8 +706,6 @@ unsafe fn add_parts(
         }
     }
 
-    cleanup(mime_in_reply_to, mime_references);
-
     Ok(())
 }
 

src/dc_tools.rs

@@ -74,36 +74,18 @@ pub(crate) fn dc_truncate(buf: &str, approx_chars: usize, do_unwrap: bool) -> Co
     }
 }
 
-pub(crate) unsafe fn dc_str_from_clist(
-    list: *const clist,
-    delimiter: *const libc::c_char,
-) -> *mut libc::c_char {
+pub(crate) fn dc_str_from_clist(list: *const clist, delimiter: &str) -> String {
     let mut res = String::new();
 
     if !list.is_null() {
-        let mut cur: *mut clistiter = (*list).first;
-        while !cur.is_null() {
-            let rfc724_mid = (if !cur.is_null() {
-                (*cur).data
-            } else {
-                ptr::null_mut()
-            }) as *const libc::c_char;
-
-            if !rfc724_mid.is_null() {
-                if !res.is_empty() && !delimiter.is_null() {
-                    res += as_str(delimiter);
-                }
-                res += as_str(rfc724_mid);
-            }
-            cur = if !cur.is_null() {
-                (*cur).next
-            } else {
-                ptr::null_mut()
+        for rfc724_mid in unsafe { (*list).into_iter() } {
+            if !res.is_empty() {
+                res += delimiter;
             }
+            res += as_str(rfc724_mid as *const libc::c_char);
         }
     }
-
-    res.strdup()
+    res
 }
 
 pub(crate) fn dc_str_to_clist(str: &str, delimiter: &str) -> *mut clist {
@@ -1060,17 +1042,11 @@ mod tests {
         unsafe {
             let list: *mut clist = dc_str_to_clist("foo bar test", " ");
             assert_eq!((*list).count, 3);
-            let str: *mut libc::c_char =
-                dc_str_from_clist(list, b" \x00" as *const u8 as *const libc::c_char);
-
-            assert_eq!(
-                CStr::from_ptr(str as *const libc::c_char).to_str().unwrap(),
-                "foo bar test"
-            );
+            let str = dc_str_from_clist(list, " ");
+            assert_eq!(str, "foo bar test");
 
             clist_free_content(list);
             clist_free(list);
-            free(str as *mut libc::c_void);
         }
     }