actix-multipart: Feature: Add typed multipart form extractor (#2883)

Co-authored-by: Rob Ede <robjtede@icloud.com>

actix-multipart/src/form/tempfile.rs

@@ -0,0 +1,206 @@
+//! Writes a field to a temporary file on disk.
+
+use std::{
+    io,
+    path::{Path, PathBuf},
+    sync::Arc,
+};
+
+use actix_web::{http::StatusCode, web, Error, HttpRequest, ResponseError};
+use derive_more::{Display, Error};
+use futures_core::future::LocalBoxFuture;
+use futures_util::TryStreamExt as _;
+use mime::Mime;
+use tempfile_dep::NamedTempFile;
+use tokio::io::AsyncWriteExt;
+
+use super::FieldErrorHandler;
+use crate::{
+    form::{FieldReader, Limits},
+    Field, MultipartError,
+};
+
+/// Write the field to a temporary file on disk.
+#[derive(Debug)]
+pub struct TempFile {
+    /// The temporary file on disk.
+    pub file: NamedTempFile,
+
+    /// The value of the `content-type` header.
+    pub content_type: Option<Mime>,
+
+    /// The `filename` value in the `content-disposition` header.
+    pub file_name: Option<String>,
+
+    /// The size in bytes of the file.
+    pub size: usize,
+}
+
+impl<'t> FieldReader<'t> for TempFile {
+    type Future = LocalBoxFuture<'t, Result<Self, MultipartError>>;
+
+    fn read_field(
+        req: &'t HttpRequest,
+        mut field: Field,
+        limits: &'t mut Limits,
+    ) -> Self::Future {
+        Box::pin(async move {
+            let config = TempFileConfig::from_req(req);
+            let field_name = field.name().to_owned();
+            let mut size = 0;
+
+            let file = config.create_tempfile().map_err(|err| {
+                config.map_error(req, &field_name, TempFileError::FileIo(err))
+            })?;
+
+            let mut file_async = tokio::fs::File::from_std(file.reopen().map_err(|err| {
+                config.map_error(req, &field_name, TempFileError::FileIo(err))
+            })?);
+
+            while let Some(chunk) = field.try_next().await? {
+                limits.try_consume_limits(chunk.len(), false)?;
+                size += chunk.len();
+                file_async.write_all(chunk.as_ref()).await.map_err(|err| {
+                    config.map_error(req, &field_name, TempFileError::FileIo(err))
+                })?;
+            }
+
+            file_async.flush().await.map_err(|err| {
+                config.map_error(req, &field_name, TempFileError::FileIo(err))
+            })?;
+
+            Ok(TempFile {
+                file,
+                content_type: field.content_type().map(ToOwned::to_owned),
+                file_name: field
+                    .content_disposition()
+                    .get_filename()
+                    .map(str::to_owned),
+                size,
+            })
+        })
+    }
+}
+
+#[derive(Debug, Display, Error)]
+#[non_exhaustive]
+pub enum TempFileError {
+    /// File I/O Error
+    #[display(fmt = "File I/O error: {}", _0)]
+    FileIo(std::io::Error),
+}
+
+impl ResponseError for TempFileError {
+    fn status_code(&self) -> StatusCode {
+        StatusCode::INTERNAL_SERVER_ERROR
+    }
+}
+
+/// Configuration for the [`TempFile`] field reader.
+#[derive(Clone)]
+pub struct TempFileConfig {
+    err_handler: FieldErrorHandler<TempFileError>,
+    directory: Option<PathBuf>,
+}
+
+impl TempFileConfig {
+    fn create_tempfile(&self) -> io::Result<NamedTempFile> {
+        if let Some(ref dir) = self.directory {
+            NamedTempFile::new_in(dir)
+        } else {
+            NamedTempFile::new()
+        }
+    }
+}
+
+impl TempFileConfig {
+    /// Sets custom error handler.
+    pub fn error_handler<F>(mut self, f: F) -> Self
+    where
+        F: Fn(TempFileError, &HttpRequest) -> Error + Send + Sync + 'static,
+    {
+        self.err_handler = Some(Arc::new(f));
+        self
+    }
+
+    /// Extracts payload config from app data. Check both `T` and `Data<T>`, in that order, and fall
+    /// back to the default payload config.
+    fn from_req(req: &HttpRequest) -> &Self {
+        req.app_data::<Self>()
+            .or_else(|| req.app_data::<web::Data<Self>>().map(|d| d.as_ref()))
+            .unwrap_or(&DEFAULT_CONFIG)
+    }
+
+    fn map_error(
+        &self,
+        req: &HttpRequest,
+        field_name: &str,
+        err: TempFileError,
+    ) -> MultipartError {
+        let source = if let Some(ref err_handler) = self.err_handler {
+            (err_handler)(err, req)
+        } else {
+            err.into()
+        };
+
+        MultipartError::Field {
+            field_name: field_name.to_owned(),
+            source,
+        }
+    }
+
+    /// Sets the directory that temp files will be created in.
+    ///
+    /// The default temporary file location is platform dependent.
+    pub fn directory(mut self, dir: impl AsRef<Path>) -> Self {
+        self.directory = Some(dir.as_ref().to_owned());
+        self
+    }
+}
+
+const DEFAULT_CONFIG: TempFileConfig = TempFileConfig {
+    err_handler: None,
+    directory: None,
+};
+
+impl Default for TempFileConfig {
+    fn default() -> Self {
+        DEFAULT_CONFIG
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::io::{Cursor, Read};
+
+    use actix_multipart_rfc7578::client::multipart;
+    use actix_web::{http::StatusCode, web, App, HttpResponse, Responder};
+
+    use crate::form::{tempfile::TempFile, tests::send_form, MultipartForm};
+
+    #[derive(MultipartForm)]
+    struct FileForm {
+        file: TempFile,
+    }
+
+    async fn test_file_route(form: MultipartForm<FileForm>) -> impl Responder {
+        let mut form = form.into_inner();
+        let mut contents = String::new();
+        form.file.file.read_to_string(&mut contents).unwrap();
+        assert_eq!(contents, "Hello, world!");
+        assert_eq!(form.file.file_name.unwrap(), "testfile.txt");
+        assert_eq!(form.file.content_type.unwrap(), mime::TEXT_PLAIN);
+        HttpResponse::Ok().finish()
+    }
+
+    #[actix_rt::test]
+    async fn test_file_upload() {
+        let srv = actix_test::start(|| App::new().route("/", web::post().to(test_file_route)));
+
+        let mut form = multipart::Form::default();
+        let bytes = Cursor::new("Hello, world!");
+        form.add_reader_file_with_mime("file", bytes, "testfile.txt", mime::TEXT_PLAIN);
+        let response = send_form(&srv, form, "/").await;
+        assert_eq!(response.status(), StatusCode::OK);
+    }
+}