build: update all crates to Rust 2024 edition

Largest change is in the FFI crate.
With 2024 (but not 2021) edition unsafe code
inside unsafe functions should be marked separately
so we can mark exactly the code that is unsafe.
Some CFFI functions even have no unsafe code inside.

Most interesting change is that .strdup()
functions are not marked as unsafe anymore.
They are allocating memory and return raw pointers,
but there is nothing unsafe about it.
Only using the returned raw pointers is unsafe.
This way calls to .strdup() don't have to be marked
with unsafe{} blocks.

deltachat-ffi/src/string.rs

@@ -17,13 +17,15 @@ use std::ptr;
 /// }
 /// ```
 unsafe fn dc_strdup(s: *const libc::c_char) -> *mut libc::c_char {
-    let ret: *mut libc::c_char = if !s.is_null() {
-        libc::strdup(s)
-    } else {
-        libc::calloc(1, 1) as *mut libc::c_char
-    };
-    assert!(!ret.is_null());
-    ret
+    unsafe {
+        let ret: *mut libc::c_char = if !s.is_null() {
+            libc::strdup(s)
+        } else {
+            libc::calloc(1, 1) as *mut libc::c_char
+        };
+        assert!(!ret.is_null());
+        ret
+    }
 }
 
 /// Error type for the [OsStrExt] trait
@@ -164,34 +166,40 @@ pub(crate) trait Strdup {
     /// This function will panic when the original string contains an
     /// interior null byte as this can not be represented in raw C
     /// strings.
-    unsafe fn strdup(&self) -> *mut libc::c_char;
+    fn strdup(&self) -> *mut libc::c_char;
 }
 
 impl Strdup for str {
-    unsafe fn strdup(&self) -> *mut libc::c_char {
-        let tmp = CString::new_lossy(self);
-        dc_strdup(tmp.as_ptr())
+    fn strdup(&self) -> *mut libc::c_char {
+        unsafe {
+            let tmp = CString::new_lossy(self);
+            dc_strdup(tmp.as_ptr())
+        }
     }
 }
 
 impl Strdup for String {
-    unsafe fn strdup(&self) -> *mut libc::c_char {
+    fn strdup(&self) -> *mut libc::c_char {
         let s: &str = self;
         s.strdup()
     }
 }
 
 impl Strdup for std::path::Path {
-    unsafe fn strdup(&self) -> *mut libc::c_char {
-        let tmp = self.to_c_string().unwrap_or_else(|_| CString::default());
-        dc_strdup(tmp.as_ptr())
+    fn strdup(&self) -> *mut libc::c_char {
+        unsafe {
+            let tmp = self.to_c_string().unwrap_or_else(|_| CString::default());
+            dc_strdup(tmp.as_ptr())
+        }
     }
 }
 
 impl Strdup for [u8] {
-    unsafe fn strdup(&self) -> *mut libc::c_char {
-        let tmp = CString::new_lossy(self);
-        dc_strdup(tmp.as_ptr())
+    fn strdup(&self) -> *mut libc::c_char {
+        unsafe {
+            let tmp = CString::new_lossy(self);
+            dc_strdup(tmp.as_ptr())
+        }
     }
 }
 
@@ -209,15 +217,15 @@ pub(crate) trait OptStrdup {
     /// Allocate a new raw C `*char` version of this string, or NULL.
     ///
     /// See [Strdup::strdup] for details.
-    unsafe fn strdup(&self) -> *mut libc::c_char;
+    fn strdup(&self) -> *mut libc::c_char;
 }
 
 impl<T: AsRef<str>> OptStrdup for Option<T> {
-    unsafe fn strdup(&self) -> *mut libc::c_char {
+    fn strdup(&self) -> *mut libc::c_char {
         match self {
             Some(s) => {
                 let tmp = CString::new_lossy(s.as_ref());
-                dc_strdup(tmp.as_ptr())
+                unsafe { dc_strdup(tmp.as_ptr()) }
             }
             None => ptr::null_mut(),
         }
@@ -258,11 +266,9 @@ pub(crate) fn to_opt_string_lossy(s: *const libc::c_char) -> Option<String> {
 pub(crate) fn as_path<'a>(s: *const libc::c_char) -> &'a std::path::Path {
     assert!(!s.is_null(), "cannot be used on null pointers");
     use std::os::unix::ffi::OsStrExt;
-    unsafe {
-        let c_str = std::ffi::CStr::from_ptr(s).to_bytes();
-        let os_str = std::ffi::OsStr::from_bytes(c_str);
-        std::path::Path::new(os_str)
-    }
+    let c_str = unsafe { std::ffi::CStr::from_ptr(s) }.to_bytes();
+    let os_str = std::ffi::OsStr::from_bytes(c_str);
+    std::path::Path::new(os_str)
 }
 
 // as_path() implementation for windows, documented above.