support max_size attribute

actix-multipart-derive/Cargo.toml

@@ -10,6 +10,7 @@ proc-macro = true
 [dependencies]
 quote = "1"
 syn = { version = "1", features = ["extra-traits"] }
+proc-macro2 = "1"
 
 # [dev-dependencies]
 actix-multipart = "0.3.0-beta.1"

actix-multipart-derive/src/lib.rs

@@ -2,6 +2,7 @@ use proc_macro::TokenStream;
 use quote::quote;
 use syn::{
     parse_macro_input, Data, DataStruct, DeriveInput, Field, Fields, FieldsNamed, Ident,
+    Meta, MetaList, MetaNameValue, NestedMeta, Path,
 };
 
 #[proc_macro_derive(MultipartForm, attributes(multipart))]
@@ -29,12 +30,45 @@ pub fn derive(input: TokenStream) -> TokenStream {
     });
 
     let field_max_sizes = fields.iter().map(|f| {
-        let Field { ident, .. } = f;
+        let Field { ident, attrs, .. } = f;
 
-        // TODO: parse field attributes find
-        // #[multipart(max_size = n)]
+        for attr in attrs {
+            // TODO: use something like https://github.com/TedDriggs/darling ??
 
-        quote! { stringify!(#ident) => Some(8096) }
+            if let Ok(m) = attr.parse_meta() {
+                if let Meta::List(MetaList { path, nested, .. }) = m {
+                    if path.get_ident().unwrap()
+                        != &Ident::new("multipart", proc_macro2::Span::call_site())
+                    {
+                        continue;
+                    }
+
+                    // it's our meta list, marked by multipart
+
+                    if let Some(NestedMeta::Meta(Meta::NameValue(MetaNameValue {
+                        path: Path { segments, .. },
+                        lit,
+                        ..
+                    }))) = nested.first()
+                    {
+                        for seg in segments {
+                            // if there's a max_size attr in the list, extract the lit
+                            if &seg.ident
+                                == &Ident::new(
+                                    "max_size",
+                                    proc_macro2::Span::call_site(),
+                                )
+                            {
+                                // TODO: ensure literal is numeric
+                                return quote! { stringify!(#ident) => Some(#lit) };
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        quote! { stringify!(#ident) => None }
     });
 
     let build_fields = fields.iter().map(|f| {

actix-multipart-derive/src/main.rs

@@ -6,7 +6,7 @@ use bytes::BytesMut;
 struct Form {
     name: String,
 
-    #[multipart(max_size = 8096)]
+    #[multipart(max_size = 1024)]
     file: BytesMut,
 }
 

actix-multipart/src/byte_builder.rs

@@ -0,0 +1,18 @@
+use bytes::{BufMut, Bytes, BytesMut};
+
+pub trait BuildFromBytes {
+    fn append(&mut self, next: Bytes);
+}
+
+impl BuildFromBytes for String {
+    fn append(&mut self, chunk: Bytes) {
+        let chunk_str = std::str::from_utf8(&chunk).expect("string field is not utf-8");
+        self.push_str(chunk_str);
+    }
+}
+
+impl BuildFromBytes for BytesMut {
+    fn append(&mut self, chunk: Bytes) {
+        self.put(&chunk[..]);
+    }
+}

actix-multipart/src/lib.rs

@@ -1,27 +1,10 @@
 #![allow(clippy::borrow_interior_mutable_const)]
 
+mod byte_builder;
 mod error;
 mod extractor;
 mod server;
 
+pub use self::byte_builder::BuildFromBytes;
 pub use self::error::MultipartError;
 pub use self::server::{Field, Multipart};
-
-use bytes::{BufMut, Bytes, BytesMut};
-
-pub trait BuildFromBytes {
-    fn append(&mut self, next: Bytes);
-}
-
-impl BuildFromBytes for String {
-    fn append(&mut self, chunk: Bytes) {
-        let chunk_str = std::str::from_utf8(&chunk).expect("string field is not utf-8");
-        self.push_str(chunk_str);
-    }
-}
-
-impl BuildFromBytes for BytesMut {
-    fn append(&mut self, chunk: Bytes) {
-        self.put(&chunk[..]);
-    }
-}