httpc: allow streaming of PUT and POST request bodies

This is a must when uploading large bodies that are to large to store
in a string or binary.

Besides a string or binary, a body can now be a function and
an accumulator.

Example:

-module(httpc_post_stream_test).
-compile(export_all).

-define(LEN, 1024 * 1024).

prepare_data() ->
    {ok, Fd} = file:open("test_data.dat", [binary, write]),
    ok = file:write(Fd, lists:duplicate(?LEN, "1")),
    ok = file:close(Fd).

test() ->
    inets:start(),
    ok = prepare_data(),
    {ok, Fd1} = file:open("test_data.dat", [binary, read]),
    BodyFun = fun(Fd) ->
        case file:read(Fd, 512) of
        eof ->
            eof;
        {ok, Data} ->
            {ok, Data, Fd}
        end
    end,
    {ok, {{_,200,_}, _, _}} = httpc:request(post, {"http://localhost:8888",
        [{"content-length", integer_to_list(?LEN)}], "text/plain", {BodyFun, Fd1}}, [], []),
    ok = file:close(Fd1).

1 files changed, 3 insertions, 1 deletions

diff --git a/lib/inets/doc/src/httpc.xml b/lib/inets/doc/src/httpc.xml
index 9c8df28fec..df333074cd 100644
--- a/lib/inets/doc/src/httpc.xml
+++ b/lib/inets/doc/src/httpc.xml
@@ -89,7 +89,9 @@ headers()       = [header()]
 header()        = {field(), value()}
 field()         = string() 
 value()         = string() 
-body()          = string() | binary() 
+body()            = string() | binary() | {fun(acc()) -> send_fun_result(), acc()}
+send_fun_result() = eof | {ok, iolist(), acc()}
+acc()             = term()
 filename()      = string() 
     ]]></code>