diff --git a/API-C.md b/API-C.md
index fad90ea..8b99870 100644
--- a/API-C.md
+++ b/API-C.md
@@ -48,6 +48,8 @@ C Library for creating WebAssembly modules for use with NGINX Unit.
   * [luw_mem_writep](#luw_mem_writep)
   * [luw_mem_writep_data](#luw_mem_writep_data)
   * [luw_req_buf_append](#luw_req_buf_append)
+  * [luw_req_buf_copy](#luw_req_buf_copy)
+  * [luw_mem_splice_file](#luw_mem_splice_file)
   * [luw_mem_fill_buf_from_req](#luw_mem_fill_buf_from_req)
   * [luw_mem_reset](#luw_mem_reset)
   * [luw_http_set_response_status](#luw_http_set_response_status)
@@ -207,10 +209,10 @@ struct luw_req {
         u32 server_name_off;
         u32 server_name_len;
 
-        u32 content_off;
-        u32 content_len;
+        u64 content_len;
+        u64 total_content_sent;
         u32 content_sent;
-        u32 total_content_sent;
+        u32 content_off;
 
         u32 request_size;
 
@@ -218,6 +220,8 @@ struct luw_req {
 
         u32 tls;
 
+        char __pad[4];
+
         struct luw_hdr_field fields[];
 };
 ```
@@ -701,11 +705,12 @@ This function returns a pointer to the start of the request body.
 ### luw_get_http_content_len
 
 ```C
-size_t luw_get_http_content_len(const luw_ctx_t *ctx);
+u64 luw_get_http_content_len(const luw_ctx_t *ctx);
 ```
 
 This function returns the size of the overall content. I.e Content-Length.
 
+Prior to version 0.3.0 it returned a size_t
 
 ### luw_get_http_content_sent
 
@@ -720,14 +725,14 @@ split over several calls to luw_request_handler().
 ### luw_get_http_total_content_sent
 
 ```C
-size_t luw_get_http_total_content_sent(const luw_ctx_t *ctx);
+u64 luw_get_http_total_content_sent(const luw_ctx_t *ctx);
 ```
 
 This function returns the total length of the content that was sent to the
 WebAssembly module so far. Remember, a single HTTP request may be split over
 several calls to luw_request_handler().
 
-_Version: 0.2.0_
+_Version: 0.2.0_ Prior to 0.3.0 it returned a size_t
 
 ### luw_http_is_tls
 
@@ -867,6 +872,93 @@ int luw_request_handler(u8 *addr)
 }
 ```
 
+### luw_req_buf_copy
+
+```C
+void luw_req_buf_copy(luw_ctx_t *ctx, const u8 *src);
+```
+
+This function is analogous to [luw_req_buf_append](#luw_req_buf_append) but
+rather than appending the request data contained in _src_ to the previously
+setup *request_buffer* with luw_set_req_buf(), it simply overwrites what's
+currently there.
+
+This function could be used to handle large requests/uploads that you want to
+save out to disk or some such and can't buffer it all in memory.
+
+Example
+
+```C
+int luw_request_handler(u8 *addr)
+{
+        const u8 *buf;
+        ssize_t bytes_wrote;
+
+        if (total_bytes_wrote == 0) {
+                luw_init_ctx(&ctx, addr, 0);
+                luw_set_req_buf(&ctx, &request_buf, LUW_SRB_NONE);
+
+                fd = open("/var/tmp/large-file.dat", O_CREAT|O_TRUNC|O_WRONLY,
+                          0666);
+        } else {
+                luw_req_buf_copy(&ctx, addr);
+        }
+
+        buf = luw_get_http_content(&ctx);
+        bytes_wrote = write(fd, buf, luw_get_http_content_sent(&ctx));
+        if (bytes_wrote == -1)
+                return -1;
+
+        total_bytes_wrote += bytes_wrote;
+        if (total_bytes_wrote == luw_get_http_content_len(&ctx))
+                luw_http_response_end();
+
+        return 0;
+}
+```
+
+_Version: 0.3.0_
+
+### luw_mem_splice_file
+
+```C
+ssize_t luw_mem_splice_file(const u8 *src, int fd);
+```
+
+This function write(2)'s the request data directly from the shared memory
+(_src_) to the file represented by the given file-descriptor (_fd_).
+
+This can be used as an alternative to [luw_req_buf_copy](#luw_req_buf_copy)
+and avoids an extra copying of the request data.
+
+Example
+
+```C
+int luw_request_handler(u8 *addr) {
+        ssize_t bytes_wrote;
+
+        if (total_bytes_wrote == 0) {
+                luw_init_ctx(&ctx, addr, 0);
+                luw_set_req_buf(&ctx, &request_buf, LUW_SRB_NONE);
+
+                fd = open("/var/tmp/large-file.dat", O_CREAT|O_TRUNC|O_WRONLY,
+                          0666);
+        }
+
+        bytes_wrote = luw_mem_splice_file(addr, fd);
+        if (bytes_wrote == -1)
+                return -1;
+
+        total_bytes_wrote += bytes_wrote;
+        if (total_bytes_wrote == luw_get_http_content_len(&ctx))
+                luw_http_response_end();
+
+        return 0;
+}
+```
+
+_Version: 0.3.0_
+
 ### luw_mem_fill_buf_from_req
 
 ```C
diff --git a/API-Rust.md b/API-Rust.md
index 14e0f16..66e65d5 100644
--- a/API-Rust.md
+++ b/API-Rust.md
@@ -76,6 +76,8 @@ and there isn't a real need to create wrappers specifically for them.
   * [uwr_get_response_data_size](#uwr_get_response_data_size)
   * [uwr_mem_write_buf](#uwr_mem_write_buf)
   * [uwr_req_buf_append](#uwr_req_buf_append)
+  * [uwr_req_buf_copy](#uwr_req_buf_copy)
+  * [uwr_mem_splice_file](#uwr_mem_splice_file)
   * [uwr_mem_fill_buf_from_req](#uwr_mem_fill_buf_from_req)
   * [uwr_mem_reset](#uwr_mem_reset)
   * [uwr_http_set_response_status](#uwr_http_set_response_status)
@@ -667,11 +669,12 @@ _Version: 0.2.0_
 ### uwr_get_http_content_len
 
 ```Rust
-pub fn uwr_get_http_content_len(ctx: *const luw_ctx_t) -> usize;
+pub fn uwr_get_http_content_len(ctx: *const luw_ctx_t) -> u64;
 ```
 
 This function returns the size of the overall content. I.e Content-Length.
 
+Prior to version 0.3.0 it returned a usize
 
 ### uwr_get_http_content_sent
 
@@ -686,14 +689,14 @@ split over several calls to luw_request_handler().
 ### uwr_get_http_total_content_sent
 
 ```Rust
-pub fn uwr_get_http_total_content_sent(ctx: *const luw_ctx_t) -> usize;
+pub fn uwr_get_http_total_content_sent(ctx: *const luw_ctx_t) -> u64;
 ```
 
 This function returns the total length of the content that was sent to the
 WebAssembly module so far. Remember, a single HTTP request may be split over
 several calls to luw_request_handler().
 
-_Version: 0.2.0_
+_Version: 0.2.0_ Prior to 0.3.0 it returned a usize
 
 ### uwr_http_is_tls
 
@@ -836,6 +839,70 @@ pub extern "C" fn uwr_request_handler(addr: *mut u8) -> i32 {
 }
 ```
 
+### uwr_req_buf_copy
+
+```Rust
+pub fn uwr_req_buf_copy(ctx: *mut luw_ctx_t, src: *const u8);
+```
+
+This function is analogous to [uwr_req_buf_append](#uwr_req_buf_append) but
+rather than appending the request data contained in _src_ to the previously
+setup *request_buffer* with uwr_set_req_buf(), it simply overwrites what's
+currently there.
+
+This function could be used to handle large requests/uploads that you want to
+save out to disk or some such and can't buffer it all in memory.
+
+### uwr_mem_splice_file
+
+```Rust
+pub fn uwr_mem_splice_file(src: *const u8, f: &mut File) -> isize;
+```
+This function write(2)'s the request data directly from the shared memory
+(_src_) to the file represented by the given _File_ object (_f_).
+
+This can be used as an alternative to [uwr_req_buf_copy](#uwr_req_buf_copy)
+and avoids an extra copying of the request data.
+
+Example
+
+```Rust
+pub extern "C" fn uwr_request_handler(addr: *mut u8) -> i32 {
+    let ctx: *mut luw_ctx_t = unsafe { &mut CTX };
+    let mut f;
+    let bytes_wrote: isize;
+    let mut total = unsafe { TOTAL_BYTES_WROTE };
+
+    if total == 0 {
+        uwr_init_ctx(ctx, addr, 0);
+        uwr_set_req_buf(ctx, unsafe { &mut REQUEST_BUF }, LUW_SRB_NONE);
+
+        f = File::create("/var/tmp/large-file.dat").unwrap();
+    } else {
+        f = File::options()
+            .append(true)
+            .open("/var/tmp/large-file.dat")
+            .unwrap();
+    }
+
+    bytes_wrote = uwr_mem_splice_file(addr, &mut f);
+    if bytes_wrote == -1 {
+        return -1;
+    }
+
+    total += bytes_wrote as u64;
+    if total == uwr_get_http_content_len(ctx) {
+        total = 0;
+
+        uwr_http_response_end();
+    }
+
+    unsafe { TOTAL_BYTES_WROTE = total };
+
+    return 0;
+}
+```
+
 ### uwr_mem_fill_buf_from_req
 
 ```Rust
diff --git a/README.md b/README.md
index 286551a..76dec73 100644
--- a/README.md
+++ b/README.md
@@ -264,7 +264,7 @@ repository root for more details) but will instead assume you already have a
 Unit with the WebAssembly language module already running, perhaps installed
 via a package.
 
-Create the following Unit config
+Create the following Unit config (editing the module paths as appropriate)
 
 ```JSON
 {
@@ -276,7 +276,7 @@ Create the following Unit config
 
     "settings": {
         "http": {
-            "max_body_size": 1073741824
+            "max_body_size": 8589934592
         }
     },
 
@@ -297,6 +297,14 @@ Create the following Unit config
                 "pass": "applications/luw-upload-reflector"
             }
         },
+        {
+            "match": {
+                "uri": "/large-upload*"
+            },
+            "action": {
+                "pass": "applications/large-upload"
+            }
+        },
         {
             "match": {
                 "uri": "/rust-echo*"
@@ -315,7 +323,15 @@ Create the following Unit config
         },
         {
             "match": {
-                "uri": "/hello-world*"
+                "uri": "/rust-large-upload*"
+            },
+            "action": {
+                "pass": "applications/rust-large-upload"
+            }
+        },
+        {
+            "match": {
+                "uri": "/rust-hello-world*"
             },
             "action": {
                 "pass": "applications/rust-hello-world"
@@ -342,6 +358,21 @@ Create the following Unit config
             "request_end_handler": "luw_request_end_handler",
             "response_end_handler": "luw_response_end_handler"
         },
+        "large-upload": {
+            "type": "wasm",
+            "module": "/path/to/unit-wasm/examples/c/large-upload.wasm",
+            "request_handler": "luw_request_handler",
+            "malloc_handler": "luw_malloc_handler",
+            "free_handler": "luw_free_handler",
+            "module_init_handler": "luw_module_init_handler",
+            "module_end_handler": "luw_module_end_handler",
+            "response_end_handler": "luw_response_end_handler",
+            "access": {
+                "filesystem": [
+                    "/var/tmp"
+                ]
+            }
+        },
         "rust-echo-request": {
             "type": "wasm",
             "module": "/path/to/unit-wasm/examples/rust/echo-request/target/wasm32-wasi/debug/rust_echo_request.wasm",
@@ -360,6 +391,21 @@ Create the following Unit config
             "request_end_handler": "uwr_request_end_handler",
             "response_end_handler": "uwr_response_end_handler"
         },
+        "rust-large-upload": {
+            "type": "wasm",
+            "module": "/path/to/src/unit-wasm/examples/rust/large-upload/target/wasm32-wasi/debug/rust_large_upload.wasm",
+            "request_handler": "uwr_request_handler",
+            "malloc_handler": "luw_malloc_handler",
+            "free_handler": "luw_free_handler",
+            "module_init_handler": "uwr_module_init_handler",
+            "module_end_handler": "uwr_module_end_handler",
+            "response_end_handler": "uwr_response_end_handler",
+            "access": {
+                "filesystem": [
+                    "/var/tmp"
+                ]
+            }
+        },
         "rust-hello-world": {
             "type": "wasm",
             "module": "/path/to/unit-wasm/examples/rust/hello-world/target/wasm32-wasi/debug/rust_hello_world.wasm",
diff --git a/examples/c/Makefile b/examples/c/Makefile
index 1b10269..0b0fc31 100644
--- a/examples/c/Makefile
+++ b/examples/c/Makefile
@@ -12,7 +12,9 @@ luw_deps = $(LUW_SRCDIR)/libunit-wasm.a \
 
 examples: examples-luw
 
-examples-luw: luw-echo-request.wasm luw-upload-reflector.wasm
+examples-luw: luw-echo-request.wasm \
+	      luw-upload-reflector.wasm \
+	      large-upload.wasm
 
 examples-raw: echo-request-raw.wasm upload-reflector-raw.wasm
 
@@ -36,5 +38,9 @@ upload-reflector-raw.wasm: upload-reflector-raw.c unit-wasm-raw.o
 	$(PP_CCLNK) $(SDIR)/$@
 	$(v)$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $< unit-wasm-raw.o
 
+large-upload.wasm: large-upload.c $(luw_deps)
+	$(PP_CCLNK) $(SDIR)/$@
+	$(v)$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $< $(LIBS)
+
 clean:
 	rm -f *.wasm *.o *.gch
diff --git a/examples/c/large-upload.c b/examples/c/large-upload.c
new file mode 100644
index 0000000..9d89298
--- /dev/null
+++ b/examples/c/large-upload.c
@@ -0,0 +1,67 @@
+/* SPDX-License-Identifier: Apache-2.0 */
+
+/* examples/c/large-upload.c - Example of handling request payload larger
+ *			       larger than the shared memory
+ *
+ * Copyright (C) Andrew Clayton
+ * Copyright (C) F5, Inc.
+ */
+
+#define _XOPEN_SOURCE	500
+
+#define _FILE_OFFSET_BITS 64
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include "unit/unit-wasm.h"
+
+static luw_ctx_t ctx;
+static u8 *request_buf;
+static unsigned long long total_bytes_wrote;
+static int fd;
+
+__luw_export_name("luw_module_end_handler")
+void luw_module_end_handler(void)
+{
+        free(request_buf);
+}
+
+__luw_export_name("luw_module_init_handler")
+void luw_module_init_handler(void)
+{
+        request_buf = malloc(luw_mem_get_init_size());
+}
+
+__luw_export_name("luw_response_end_handler")
+void luw_response_end_handler(void)
+{
+	close(fd);
+	total_bytes_wrote = 0;
+}
+
+__luw_export_name("luw_request_handler")
+int luw_request_handler(u8 *addr)
+{
+	ssize_t bytes_wrote;
+
+	if (total_bytes_wrote == 0) {
+		luw_init_ctx(&ctx, addr, 0);
+		luw_set_req_buf(&ctx, &request_buf, LUW_SRB_NONE);
+
+		fd = open("/var/tmp/large-file.dat", O_CREAT|O_TRUNC|O_WRONLY,
+			  0666);
+	}
+
+	bytes_wrote = luw_mem_splice_file(addr, fd);
+	if (bytes_wrote == -1)
+		return -1;
+
+	total_bytes_wrote += bytes_wrote;
+	if (total_bytes_wrote == luw_get_http_content_len(&ctx))
+		luw_http_response_end();
+
+	return 0;
+}
diff --git a/examples/c/luw-upload-reflector.c b/examples/c/luw-upload-reflector.c
index 5abce9f..f32b603 100644
--- a/examples/c/luw-upload-reflector.c
+++ b/examples/c/luw-upload-reflector.c
@@ -53,7 +53,7 @@ static int upload_reflector(luw_ctx_t *ctx)
 		const char *ct = luw_http_hdr_get_value(ctx, "Content-Type");
 		char clen[32];
 
-		snprintf(clen, sizeof(clen), "%lu",
+		snprintf(clen, sizeof(clen), "%llu",
 			 luw_get_http_content_len(ctx));
 
 		luw_http_init_headers(ctx, 2, 0);
diff --git a/examples/rust/Makefile b/examples/rust/Makefile
index a000c9c..3d2570d 100644
--- a/examples/rust/Makefile
+++ b/examples/rust/Makefile
@@ -2,7 +2,10 @@ include ../../shared.mk
 
 SDIR = examples/rust
 
-examples: rust-echo-request rust-upload-reflector rust-hello-world
+examples: rust-echo-request \
+	  rust-upload-reflector \
+	  rust-hello-world \
+	  rust-large-upload
 
 rust-echo-request: echo-request/Cargo.toml echo-request/src/lib.rs
 	$(PP_GEN) $(SDIR)/echo-request/target/wasm32-wasi/
@@ -16,6 +19,10 @@ rust-hello-world: hello-world/Cargo.toml hello-world/src/lib.rs
 	$(PP_GEN) $(SDIR)/hello-world/target/wasm32-wasi/
 	$(v)cd hello-world; cargo build --target=wasm32-wasi
 
+rust-large-upload: large-upload/Cargo.toml large-upload/src/lib.rs
+	$(PP_GEN) $(SDIR)/large-upload/target/wasm32-wasi/
+	$(v)cd large-upload; cargo build --target=wasm32-wasi
+
 clean:
 	rm -f */Cargo.lock
 	rm -rf */target
diff --git a/examples/rust/large-upload/Cargo.toml b/examples/rust/large-upload/Cargo.toml
new file mode 100644
index 0000000..b74192e
--- /dev/null
+++ b/examples/rust/large-upload/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "rust-large-upload"
+version = "0.2.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+unit-wasm = { path = "../../../src/rust", version = "0.2.0" }
+
+[lib]
+crate-type = ["cdylib"]
diff --git a/examples/rust/large-upload/src/lib.rs b/examples/rust/large-upload/src/lib.rs
new file mode 100644
index 0000000..a59bdb3
--- /dev/null
+++ b/examples/rust/large-upload/src/lib.rs
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: Apache-2.0 */
+
+/*
+ * Copyright (C) Andrew Clayton
+ * Copyright (C) Timo Stark
+ * Copyright (C) F5, Inc.
+ */
+
+use unit_wasm::rusty::*;
+
+use std::fs::File;
+use std::ptr::null_mut;
+
+static mut CTX: luw_ctx_t = UWR_CTX_INITIALIZER();
+static mut REQUEST_BUF: *mut u8 = null_mut();
+static mut TOTAL_BYTES_WROTE: u64 = 0;
+
+#[no_mangle]
+pub extern "C" fn uwr_module_end_handler() {
+    unsafe { uwr_free(REQUEST_BUF); }
+}
+
+#[no_mangle]
+pub extern "C" fn uwr_module_init_handler() {
+    unsafe { REQUEST_BUF = uwr_malloc(uwr_mem_get_init_size()); }
+}
+
+#[no_mangle]
+pub extern "C" fn uwr_response_end_handler() {
+    unsafe { TOTAL_BYTES_WROTE = 0; }
+}
+
+#[no_mangle]
+pub extern "C" fn uwr_request_handler(addr: *mut u8) -> i32 {
+    let ctx: *mut luw_ctx_t = unsafe { &mut CTX };
+    let mut f;
+    let bytes_wrote: isize;
+    let mut total = unsafe { TOTAL_BYTES_WROTE };
+
+    if total == 0 {
+        uwr_init_ctx(ctx, addr, 0);
+        uwr_set_req_buf(ctx, unsafe { &mut REQUEST_BUF }, LUW_SRB_NONE);
+
+        f = File::create("/var/tmp/large-file.dat").unwrap();
+    } else {
+        f = File::options()
+            .append(true)
+            .open("/var/tmp/large-file.dat")
+            .unwrap();
+    }
+
+    bytes_wrote = uwr_mem_splice_file(addr, &mut f);
+    if bytes_wrote == -1 {
+        return -1;
+    }
+
+    total += bytes_wrote as u64;
+    if total == uwr_get_http_content_len(ctx) {
+        uwr_http_response_end();
+    } else {
+        unsafe { TOTAL_BYTES_WROTE = total };
+    }
+
+    return 0;
+}
diff --git a/examples/rust/upload-reflector/src/lib.rs b/examples/rust/upload-reflector/src/lib.rs
index 753ea48..ac48b56 100644
--- a/examples/rust/upload-reflector/src/lib.rs
+++ b/examples/rust/upload-reflector/src/lib.rs
@@ -65,7 +65,8 @@ pub fn upload_reflector(ctx: *mut luw_ctx_t) -> i32 {
 
     uwr_http_send_response(ctx);
 
-    if unsafe { TOTAL_RESPONSE_SENT == uwr_get_http_content_len(ctx) } {
+    if unsafe { TOTAL_RESPONSE_SENT == uwr_get_http_content_len(ctx) as usize }
+    {
         // Tell Unit no more data to send
         uwr_http_response_end();
     }
diff --git a/src/c/include/unit/unit-wasm.h b/src/c/include/unit/unit-wasm.h
index c870e30..c7625de 100644
--- a/src/c/include/unit/unit-wasm.h
+++ b/src/c/include/unit/unit-wasm.h
@@ -84,6 +84,15 @@ typedef enum {
 	LUW_HTTP_GATEWAY_TIMEOUT			= 504,
 } luw_http_status_t;
 
+#if !defined(__DEFINED_ssize_t)
+/*
+ * Match the typedef from wasm32-wasi/include/bits/alltypes.h
+ * without requiring the wasi-sysroot for building the rust
+ * stuff.
+ */
+typedef long	  ssize_t;
+#endif
+
 struct luw_hdr_field {
 	u32 name_off;
 	u32 name_len;
@@ -109,10 +118,10 @@ struct luw_req {
 	u32 server_name_off;
 	u32 server_name_len;
 
-	u32 content_off;
-	u32 content_len;
+	u64 content_len;
+	u64 total_content_sent;
 	u32 content_sent;
-	u32 total_content_sent;
+	u32 content_off;
 
 	u32 request_size;
 
@@ -120,6 +129,8 @@ struct luw_req {
 
 	u32 tls;
 
+	char __pad[4];
+
 	struct luw_hdr_field fields[];
 };
 
@@ -220,9 +231,9 @@ extern const char *luw_get_http_local_addr(const luw_ctx_t *ctx);
 extern const char *luw_get_http_local_port(const luw_ctx_t *ctx);
 extern const char *luw_get_http_server_name(const luw_ctx_t *ctx);
 extern const u8 *luw_get_http_content(const luw_ctx_t *ctx);
-extern size_t luw_get_http_content_len(const luw_ctx_t *ctx);
+extern u64 luw_get_http_content_len(const luw_ctx_t *ctx);
 extern size_t luw_get_http_content_sent(const luw_ctx_t *ctx);
-extern size_t luw_get_http_total_content_sent(const luw_ctx_t *ctx);
+extern u64 luw_get_http_total_content_sent(const luw_ctx_t *ctx);
 extern bool luw_http_is_tls(const luw_ctx_t *ctx);
 extern void luw_http_hdr_iter(luw_ctx_t *ctx,
 			      bool (*luw_http_hdr_iter_func)(luw_ctx_t *ctx,
@@ -236,6 +247,8 @@ extern size_t luw_get_response_data_size(const luw_ctx_t *ctx);
 extern int luw_mem_writep(luw_ctx_t *ctx, const char *fmt, ...);
 extern size_t luw_mem_writep_data(luw_ctx_t *ctx, const u8 *src, size_t size);
 extern void luw_req_buf_append(luw_ctx_t *ctx, const u8 *src);
+extern void luw_req_buf_copy(luw_ctx_t *ctx, const u8 *src);
+extern ssize_t luw_mem_splice_file(const u8 *src, int fd);
 extern size_t luw_mem_fill_buf_from_req(luw_ctx_t *ctx, size_t from);
 extern void luw_mem_reset(luw_ctx_t *ctx);
 extern void luw_http_set_response_status(luw_http_status_t status);
diff --git a/src/c/libunit-wasm.c b/src/c/libunit-wasm.c
index 165dcd7..1b36cf9 100644
--- a/src/c/libunit-wasm.c
+++ b/src/c/libunit-wasm.c
@@ -14,10 +14,16 @@
 #include <stdarg.h>
 #include <string.h>
 #include <strings.h>
+#include <unistd.h>
 #include <errno.h>
 
 #include "unit/unit-wasm.h"
 
+#define MIN(a, b) \
+        ({ __typeof__(a) _a = (a); \
+           __typeof__ (b) _b = (b); \
+         _a < _b ? _a : _b; })
+
 /*
  * Some handlers are required some are optional.
  *
@@ -196,7 +202,7 @@ const u8 *luw_get_http_content(const luw_ctx_t *ctx)
 }
 
 /* Returns the size of the overall content length */
-size_t luw_get_http_content_len(const luw_ctx_t *ctx)
+u64 luw_get_http_content_len(const luw_ctx_t *ctx)
 {
 	return ctx->req->content_len;
 }
@@ -208,7 +214,7 @@ size_t luw_get_http_content_sent(const luw_ctx_t *ctx)
 }
 
 /* Returns the size of the overall content sent so far */
-size_t luw_get_http_total_content_sent(const luw_ctx_t *ctx)
+u64 luw_get_http_total_content_sent(const luw_ctx_t *ctx)
 {
 	return ctx->req->total_content_sent;
 }
@@ -304,6 +310,40 @@ void luw_req_buf_append(luw_ctx_t *ctx, const u8 *src)
 	ctx->req->total_content_sent = req->total_content_sent;
 }
 
+/* Copy data from the request to the previously setup request_buffer. */
+void luw_req_buf_copy(luw_ctx_t *ctx, const u8 *src)
+{
+	struct luw_req *req = (struct luw_req *)src;
+
+	memcpy(ctx->reqp + ctx->req->content_off, src + req->content_off,
+	       req->request_size);
+	ctx->req->content_sent = req->content_sent;
+	ctx->req->total_content_sent = req->total_content_sent;
+}
+
+/* Copy data from the request to a given file-descriptor. */
+ssize_t luw_mem_splice_file(const u8 *src, int fd)
+{
+	struct luw_req *req = (struct luw_req *)src;
+	size_t written = 0;
+	size_t bytes_splice = 1024 * 128; /* It's what cp(1) uses */
+
+	do {
+		ssize_t bytes_wrote;
+
+		bytes_splice = MIN(bytes_splice, req->content_sent - written);
+
+		bytes_wrote = write(fd, src + req->content_off + written,
+				    bytes_splice);
+		if (bytes_wrote == -1)
+			return -1;
+
+		written += bytes_wrote;
+	} while (written < req->content_sent);
+
+	return written;
+}
+
 /*
  * Convenience function to fill the response buffer with data from
  * the request buffer.
diff --git a/src/rust/unit-wasm-sys/rusty.rs b/src/rust/unit-wasm-sys/rusty.rs
index 5d1fbad..8132ef0 100644
--- a/src/rust/unit-wasm-sys/rusty.rs
+++ b/src/rust/unit-wasm-sys/rusty.rs
@@ -8,6 +8,8 @@
 use std::ffi::c_char;
 use std::ffi::c_void;
 use std::ffi::CStr;
+use std::fs::File;
+use std::os::fd::{AsRawFd, RawFd};
 use std::ptr::null_mut;
 use std::slice;
 use std::str;
@@ -95,7 +97,7 @@ pub fn uwr_get_http_server_name(ctx: *const luw_ctx_t) -> &'static str {
     C2S!(luw_get_http_server_name(ctx))
 }
 
-pub fn uwr_get_http_content_len(ctx: *const luw_ctx_t) -> usize {
+pub fn uwr_get_http_content_len(ctx: *const luw_ctx_t) -> u64 {
     unsafe { luw_get_http_content_len(ctx) }
 }
 
@@ -103,7 +105,7 @@ pub fn uwr_get_http_content_sent(ctx: *const luw_ctx_t) -> usize {
     unsafe { luw_get_http_content_sent(ctx) }
 }
 
-pub fn uwr_get_http_total_content_sent(ctx: *const luw_ctx_t) -> usize {
+pub fn uwr_get_http_total_content_sent(ctx: *const luw_ctx_t) -> u64 {
     unsafe { luw_get_http_total_content_sent(ctx) }
 }
 
@@ -115,7 +117,7 @@ pub fn uwr_get_http_content_str(ctx: *const luw_ctx_t) -> &'static str {
     unsafe {
         let slice = slice::from_raw_parts(
             uwr_get_http_content(ctx),
-            uwr_get_http_total_content_sent(ctx),
+            uwr_get_http_total_content_sent(ctx).try_into().unwrap(),
         );
         str::from_utf8(slice).unwrap()
     }
@@ -158,9 +160,15 @@ pub fn uwr_mem_write_str(ctx: *mut luw_ctx_t, src: &str) -> usize {
 pub fn uwr_mem_write_buf(
     ctx: *mut luw_ctx_t,
     src: *const u8,
-    size: usize,
+    size: u64,
 ) -> usize {
-    unsafe { luw_mem_writep_data(ctx, src, size) }
+    /*
+     * We're dealing with a 32bit address space, but we allow
+     * size to come from the output of uwr_get_http_content_len()
+     * which returns a u64 to allow for larger than memory uploads.
+     */
+    let sz = size as usize;
+    unsafe { luw_mem_writep_data(ctx, src, sz) }
 }
 
 pub fn uwr_req_buf_append(ctx: *mut luw_ctx_t, src: *const u8) {
@@ -169,6 +177,17 @@ pub fn uwr_req_buf_append(ctx: *mut luw_ctx_t, src: *const u8) {
     }
 }
 
+pub fn uwr_req_buf_copy(ctx: *mut luw_ctx_t, src: *const u8) {
+    unsafe {
+        luw_req_buf_copy(ctx, src);
+    }
+}
+
+pub fn uwr_mem_splice_file(src: *const u8, f: &mut File) -> isize {
+    let fd: RawFd = f.as_raw_fd();
+    unsafe { luw_mem_splice_file(src, fd) }
+}
+
 pub fn uwr_mem_fill_buf_from_req(ctx: *mut luw_ctx_t, from: usize) -> usize {
     unsafe { luw_mem_fill_buf_from_req(ctx, from) }
 }
diff --git a/unit-wasm-conf.json b/unit-wasm-conf.json
index ac17693..719cd67 100644
--- a/unit-wasm-conf.json
+++ b/unit-wasm-conf.json
@@ -7,7 +7,7 @@
 
     "settings": {
         "http": {
-            "max_body_size": 1073741824
+            "max_body_size": 8589934592
         }
     },
 
@@ -28,6 +28,14 @@
                 "pass": "applications/luw-upload-reflector"
             }
         },
+        {
+            "match": {
+                "uri": "/large-upload*"
+            },
+            "action": {
+                "pass": "applications/large-upload"
+            }
+        },
         {
             "match": {
                 "uri": "/rust-echo*"
@@ -44,6 +52,14 @@
                 "pass": "applications/rust-upload-reflector"
             }
         },
+        {
+            "match": {
+                "uri": "/rust-large-upload*"
+            },
+            "action": {
+                "pass": "applications/rust-large-upload"
+            }
+        },
         {
             "match": {
                 "uri": "/rust-hello-world*"
@@ -73,6 +89,21 @@
             "request_end_handler": "luw_request_end_handler",
             "response_end_handler": "luw_response_end_handler"
         },
+        "large-upload": {
+            "type": "wasm",
+            "module": "/path/to/unit-wasm/examples/c/large-upload.wasm",
+            "request_handler": "luw_request_handler",
+            "malloc_handler": "luw_malloc_handler",
+            "free_handler": "luw_free_handler",
+            "module_init_handler": "luw_module_init_handler",
+            "module_end_handler": "luw_module_end_handler",
+            "response_end_handler": "luw_response_end_handler",
+            "access": {
+                "filesystem": [
+                    "/var/tmp"
+                ]
+            }
+        },
         "rust-echo-request": {
             "type": "wasm",
             "module": "/path/to/unit-wasm/examples/rust/echo-request/target/wasm32-wasi/debug/rust_echo_request.wasm",
@@ -91,6 +122,21 @@
             "request_end_handler": "uwr_request_end_handler",
             "response_end_handler": "uwr_response_end_handler"
         },
+        "rust-large-upload": {
+            "type": "wasm",
+            "module": "/path/to/src/unit-wasm/examples/rust/large-upload/target/wasm32-wasi/debug/rust_large_upload.wasm",
+            "request_handler": "uwr_request_handler",
+            "malloc_handler": "luw_malloc_handler",
+            "free_handler": "luw_free_handler",
+            "module_init_handler": "uwr_module_init_handler",
+            "module_end_handler": "uwr_module_end_handler",
+            "response_end_handler": "uwr_response_end_handler",
+            "access": {
+                "filesystem": [
+                    "/var/tmp"
+                ]
+            }
+        },
         "rust-hello-world": {
             "type": "wasm",
             "module": "/path/to/unit-wasm/examples/rust/hello-world/target/wasm32-wasi/debug/rust_hello_world.wasm",