sendrecv: split the I/O handling into private handler

Howard Chu brought the bulk work of this patch that properly
moves out the sending and recving of data to the parts of the
code that are properly responsible for the various ways of doing
so.

Daniel Stenberg assisted with polishing a few bits and fixed some
minor flaws in the original patch.

Another upside of this patch is that we now abuse CURLcodes less
with the "magic" -1 return codes and instead use CURLE_AGAIN more
consistently.

1 files changed, 17 insertions, 0 deletions

diff --git a/lib/urldata.h b/lib/urldata.h
index 7e3afee7c..efc56d7b0 100644
--- a/lib/urldata.h
+++ b/lib/urldata.h
@@ -650,6 +650,20 @@ struct Curl_handler {
   long protocol;      /* PROT_* flags concerning the protocol set */
 };
 
+/* return the count of bytes sent, or -1 on error */
+typedef ssize_t (Curl_send)(struct connectdata *conn, /* connection data */
+                            int sockindex,            /* socketindex */
+                            const void *buf,          /* data to write */
+                            size_t len,               /* max amount to write */
+                            CURLcode *err);           /* error to return */
+
+/* return the count of bytes read, or -1 on error */
+typedef ssize_t (Curl_recv)(struct connectdata *conn, /* connection data */
+                            int sockindex,            /* socketindex */
+                            char *buf,                /* store data here */
+                            size_t len,               /* max amount to read */
+                            CURLcode *err);           /* error to return */
+
 /*
  * The connectdata struct contains all fields and variables that should be
  * unique for an entire connection.
@@ -746,6 +760,9 @@ struct connectdata {
   curl_socket_t sock[2]; /* two sockets, the second is used for the data
                             transfer when doing FTP */
 
+  Curl_recv *recv;
+  Curl_send *send;
+
   struct ssl_connect_data ssl[2]; /* this is for ssl-stuff */
   struct ssl_config_data ssl_config;