Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

We can put the unsafe keyword as part of the function definition,
getting rid of the unsafe {} blocks in the functions themselves.

Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

In this example we don't need the request buf.

Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

Fixes: 1beab00ac ("Allow to set the HTTP response status")
Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

The programs demonstrate handling requests with payloads larger than
4GiB which means they need to be written out to disk and so also
demonstrates the use of the file-system access mechanism.

Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

uwr_get_http_content_len() & uwr_get_http_total_content_sent() now
return a u64.

Two new functions were added

uwr_req_buf_copy()

Like uwr_req_buf_append() but just copies the data over what's already
there.

uwr_mem_splice_file()

This write(2)'s the request data directly from the shared memory to a
given file.

Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

The types of some of the member of the luw_req structure increased to
64bits to allow for uploads larger than 4GiB.

Two new functions were added

luw_req_buf_copy()

Like luw_req_buf_append() but just copies the data over what's already
there.

luw_mem_splice_file()

This write(2)'s the request data directly from the shared memory to a
given file.

Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

libunit-wasm added two new functions, luw_req_buf_copy() &
luw_mem_splice_file(). See the previous two commits...

This second function takes a file-descriptor as one of its arguments, in
rusty we make this a Rust File object, then pass the underlying fd into
libunit-wasm.

Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

This is inspired by the likes of splice(2) and sendfile(2) in that it
takes data from one place and puts it in another.

This function write(2)'s the request data straight from the shared
memory to a given file (referenced by its file descriptor).

This is an alternative to using luw_req_buf_copy() and avoids an extra
copying of the request data.

E.g

  /* In the request_handler */
  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);
  }

  total_bytes_wrote += luw_mem_splice_file(addr, fd);
  if (total_bytes_wrote == luw_get_http_content_len(&ctx)) {
          close(fd);
          total_bytes_wrote = 0;
          luw_http_response_end();
  }

NOTE:

We include a typedef definition for ssize_t in unit-wasm.h, to avoid
having a dependency on the wasi-sysroot when generating the rust
bindings.

ssize_t is defined in sys/types.h which is provided by libc and not the
compiler.

Signed-off-by: Andrew Clayton <a.clayton@nginx.com>