[WIP] File deduplication

Cargo.toml

@@ -110,6 +110,7 @@ toml = "0.8"
 url = "2"
 uuid = { version = "1", features = ["serde", "v4"] }
 webpki-roots = "0.26.7"
+blake3 = "1.5.5"
 
 [dev-dependencies]
 anyhow = { workspace = true, features = ["backtrace"] } # Enable `backtrace` feature in tests.

deltachat-ffi/deltachat.h

@@ -4726,6 +4726,25 @@ void            dc_msg_set_override_sender_name(dc_msg_t* msg, const char* name)
 void            dc_msg_set_file               (dc_msg_t* msg, const char* file, const char* filemime);
 
 
+/**
+ * Sets the file associated with a message.
+ *
+ * If `name` is non-null, it is used as the file name
+ * and the actual current name of the file is ignored.
+ *
+ * In order to deduplicate files that contain the same data,
+ * the file will be renamed to a hash of the file data.
+ * The file must not be modified after this function was called.
+ *
+ * @memberof dc_msg_t
+ * @param msg The message object.
+ * @param file The file to attach.
+ * @param name The original filename of the attachment.
+ * @param filemime The MIME type of the file. NULL if you don't know or don't care.
+ */
+void            dc_msg_set_file_and_deduplicate(dc_msg_t* msg, const char* file, const char* name, const char* filemime);
+
+
 /**
  * Set the dimensions associated with message object.
  * Typically this is the width and the height of an image or video associated using dc_msg_set_file().

deltachat-ffi/src/lib.rs

@@ -3813,6 +3813,33 @@ pub unsafe extern "C" fn dc_msg_set_file(
     )
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn dc_msg_set_file_and_deduplicate(
+    msg: *mut dc_msg_t,
+    file: *const libc::c_char,
+    name: *const libc::c_char,
+    filemime: *const libc::c_char,
+) {
+    if msg.is_null() || file.is_null() {
+        eprintln!("ignoring careless call to dc_msg_set_file()");
+        return;
+    }
+    let ffi_msg = &mut *msg;
+    let ctx = &*ffi_msg.context;
+
+    ffi_msg
+        .message
+        .set_file_and_deduplicate(
+            ctx,
+            &as_path(file),
+            to_opt_string_lossy(name).as_deref(),
+            to_opt_string_lossy(filemime).as_deref(),
+        )
+        .context("failed to set file")
+        .log_err(&*ffi_msg.context)
+        .ok();
+}
+
 #[no_mangle]
 pub unsafe extern "C" fn dc_msg_set_dimension(
     msg: *mut dc_msg_t,