Add support for CURLFORM_STREAM

Closes #158

Author: alexcrichton

src/easy/form.rs

@@ -2,9 +2,12 @@ use std::ffi::CString;
 use std::fmt;
 use std::path::Path;
 
+use libc::c_void;
+
 use FormError;
 use curl_sys;
-use easy::{list, List};
+use easy::list;
+use easy::{List, ReadError};
 
 /// Multipart/formdata for an HTTP POST request.
 ///
@@ -16,6 +19,7 @@ pub struct Form {
     headers: Vec<List>,
     buffers: Vec<Vec<u8>>,
     strings: Vec<CString>,
+    streams: Option<Box<StreamNode>>,
 }
 
 /// One part in a multipart upload, added to a `Form`.
@@ -26,10 +30,19 @@ pub struct Part<'form, 'data> {
     error: Option<FormError>,
 }
 
+struct StreamNode {
+    stream: Box<FnMut(&mut [u8]) -> Result<usize, ReadError>>,
+    _next: Option<Box<StreamNode>>,
+}
+
 pub fn raw(form: &Form) -> *mut curl_sys::curl_httppost {
     form.head
 }
 
+pub unsafe fn read(raw: *mut c_void, into: &mut [u8]) -> Result<usize, ReadError> {
+    ((*(raw as *mut StreamNode)).stream)(into)
+}
+
 impl Form {
     /// Creates a new blank form ready for the addition of new data.
     pub fn new() -> Form {
@@ -39,6 +52,7 @@ impl Form {
             headers: Vec::new(),
             buffers: Vec::new(),
             strings: Vec::new(),
+            streams: None,
         }
     }
 
@@ -254,6 +268,48 @@ impl<'form, 'data> Part<'form, 'data> {
         self
     }
 
+    /// Tells libcurl to use the callback provided to get data.
+    ///
+    /// If you want the part to look like a file upload one, set the `filename`
+    /// parameter as well. Note that when using `stream` the `len` option must
+    /// also be set with the total expected length of the part unless the
+    /// formpost is sent chunked encoded in which case it can be `None`.
+    ///
+    /// The callback provided must live for the `'static` lifetime and must
+    /// adhere to the `Send` bound.
+    pub fn stream<F>(&mut self,
+                     len: Option<usize>,
+                     f: F) -> &mut Self
+        where F: FnMut(&mut [u8]) -> Result<usize, ReadError> + 'static + Send,
+    {
+        self._stream(len, Box::new(f));
+        self
+    }
+
+    fn _stream(&mut self,
+               len: Option<usize>,
+               stream: Box<FnMut(&mut [u8]) -> Result<usize, ReadError> + Send>)
+    {
+        let mut node = Box::new(StreamNode {
+            stream: stream,
+            _next: self.form.streams.take(),
+        });
+        let pos = self.array.len() - 1;
+        let ptr = &mut *node as *mut StreamNode as usize;
+        assert!(ptr & 1 == 0);
+        self.array.insert(pos, curl_sys::curl_forms {
+            option: curl_sys::CURLFORM_STREAM,
+            value: (ptr | 1) as *mut _,
+        });
+        if let Some(len) = len {
+            self.array.insert(pos + 1, curl_sys::curl_forms {
+                option: curl_sys::CURLFORM_CONTENTSLENGTH,
+                value: len as *mut _,
+            });
+        }
+        self.form.streams = Some(node);
+    }
+
     /// Attempts to add this part to the `Form` that it was created from.
     ///
     /// If any error happens while adding, that error is returned, otherwise

src/easy/handler.rs

@@ -613,6 +613,7 @@ impl<H: Handler> Easy2<H> {
         let cb: curl_sys::curl_read_callback = read_cb::<H>;
         self.setopt_ptr(curl_sys::CURLOPT_READFUNCTION, cb as *const _)
             .expect("failed to set read callback");
+        assert!((ptr as usize) & 1 == 0);
         self.setopt_ptr(curl_sys::CURLOPT_READDATA, ptr)
             .expect("failed to set read callback");
 
@@ -2783,7 +2784,18 @@ extern fn read_cb<H: Handler>(ptr: *mut c_char,
     panic::catch(|| unsafe {
         let input = slice::from_raw_parts_mut(ptr as *mut u8,
                                               size * nmemb);
-        match (*(data as *mut Inner<H>)).handler.read(input) {
+
+        // We use a bit of a "tricky encoding" here to handle CURLFORM_STREAM
+        // callbacks. If the lower bit of the data pointer is 1 it's a stream
+        // callback so we delegate to the `form` module, otherwise we handle
+        // that here as part of `Handler`.
+        let ret = if data as usize & 1 == 0 {
+            (*(data as *mut Inner<H>)).handler.read(input)
+        } else {
+            let data = data as usize & !1;
+            form::read(data as *mut c_void, input)
+        };
+        match ret {
             Ok(s) => s,
             Err(ReadError::Pause) => {
                 curl_sys::CURL_READFUNC_PAUSE

tests/post.rs

@@ -1,5 +1,6 @@
 extern crate curl;
 
+use std::io::Read;
 use std::str;
 use std::time::Duration;
 
@@ -106,3 +107,44 @@ hello\n\
     t!(handle.httppost(form));
     t!(handle.perform());
 }
+
+#[test]
+fn stream() {
+    let s = Server::new();
+    s.receive("\
+POST / HTTP/1.1\r\n\
+Host: 127.0.0.1:$PORT\r\n\
+Accept: */*\r\n\
+Content-Length: 238\r\n\
+Expect: 100-continue\r\n\
+Content-Type: multipart/form-data; boundary=--[..]\r\n\
+\r\n\
+--[..]\r\n\
+Content-Disposition: form-data; name=\"foo\"\r\n\
+\r\n\
+1234\r\n\
+--[..]\r\n\
+Content-Disposition: form-data; name=\"bar\"\r\n\
+\r\n\
+5678\r\n\
+--[..]\r\n\
+");
+    s.send("HTTP/1.1 200 OK\r\n\r\n");
+
+    let mut handle = handle();
+    let mut form = Form::new();
+
+    let mut contents = "1234".as_bytes();
+    t!(form.part("foo").stream(Some(contents.len()), move |buf| {
+        Ok(contents.read(buf).unwrap())
+    }).add());
+
+    let mut contents = "5678".as_bytes();
+    t!(form.part("bar").stream(Some(contents.len()), move |buf| {
+        Ok(contents.read(buf).unwrap())
+    }).add());
+
+    t!(handle.url(&s.url("/")));
+    t!(handle.httppost(form));
+    t!(handle.perform());
+}