Separate the "is data ready" function of xfer_seek() into an

xfer_window() function, which can return a scalar rather than a
boolean.

diff --git a/src/core/downloader.c b/src/core/downloader.c
index 4a74589f4ad824fdf0af63e4cebd027dd6ed48fd..3726c6e1a8b5aea95a15494f0000cb03d8d972d1 100644 (file)
--- a/src/core/downloader.c
+++ b/src/core/downloader.c
@@ -228,6 +228,7 @@ static struct xfer_interface_operations downloader_xfer_operations = {
        .close          = downloader_xfer_close,
        .vredirect      = xfer_vopen,
        .seek           = downloader_xfer_seek,
+       .window         = unlimited_xfer_window,
        .deliver_iob    = xfer_deliver_as_raw,
        .deliver_raw    = downloader_xfer_deliver_raw,
 };

diff --git a/src/core/hw.c b/src/core/hw.c
index 2cb912b195801837125356b923116e6768853202..3502dbfbc5069126027b43cdad34791f3d15b6ff 100644 (file)
--- a/src/core/hw.c
+++ b/src/core/hw.c
@@ -37,6 +37,7 @@ static struct xfer_interface_operations hw_xfer_operations = {
        .close          = hw_xfer_close,
        .vredirect      = ignore_xfer_vredirect,
        .seek           = ignore_xfer_seek,
+       .window         = unlimited_xfer_window,
        .deliver_iob    = xfer_deliver_as_raw,
        .deliver_raw    = ignore_xfer_deliver_raw,
 };
@@ -45,7 +46,7 @@ static void hw_step ( struct process *process ) {
        struct hw *hw = container_of ( process, struct hw, process );
        int rc;
 
-       if ( xfer_ready ( &hw->xfer ) == 0 ) {
+       if ( xfer_window ( &hw->xfer ) ) {
                rc = xfer_deliver_raw ( &hw->xfer, hw_msg, sizeof ( hw_msg ) );
                hw_finished ( hw, rc );
        }

diff --git a/src/core/posix_io.c b/src/core/posix_io.c
index 03d440a64f76f33cffec56fcd9a86e2d9a5dc070..21f818bfa97c02cccebc01dd15aadddc92aad98f 100644 (file)
--- a/src/core/posix_io.c
+++ b/src/core/posix_io.c
@@ -160,6 +160,7 @@ static struct xfer_interface_operations posix_file_xfer_operations = {
        .close          = posix_file_xfer_close,
        .vredirect      = xfer_vopen,
        .seek           = posix_file_xfer_seek,
+       .window         = unlimited_xfer_window,
        .alloc_iob      = default_xfer_alloc_iob,
        .deliver_iob    = posix_file_xfer_deliver_iob,
        .deliver_raw    = xfer_deliver_as_iob,

diff --git a/src/core/resolv.c b/src/core/resolv.c
index 7ca62cd80db3621999674727e71d8bf0b2a987b1..5c25ddb121c86d51486665ae65564ba6083fb4c4 100644 (file)
--- a/src/core/resolv.c
+++ b/src/core/resolv.c
@@ -308,25 +308,12 @@ struct named_socket {
        int have_local;
 };
 
-/**
- * Handle seek() event
- *
- * @v xfer             Data transfer interface
- * @v offset           Offset to new position
- * @v whence           Basis for new position
- * @ret rc             Return status code
- */
-static int resolv_xfer_seek ( struct xfer_interface *xfer __unused,
-                             off_t offset __unused, int whence __unused ) {
-       /* Never ready to accept data */
-       return -EAGAIN;
-}
-
 /** Named socket opener data transfer interface operations */
 static struct xfer_interface_operations named_xfer_ops = {
        .close          = ignore_xfer_close,
        .vredirect      = ignore_xfer_vredirect,
-       .seek           = resolv_xfer_seek,
+       .seek           = ignore_xfer_seek,
+       .window         = no_xfer_window,
        .alloc_iob      = default_xfer_alloc_iob,
        .deliver_iob    = xfer_deliver_as_raw,
        .deliver_raw    = ignore_xfer_deliver_raw,

diff --git a/src/core/xfer.c b/src/core/xfer.c
index 3e55ebaf7043557a06bb302e367ab12b7ee4ca92..3e6b7eb666c52a70c198a18b5100d1385ea38006 100644 (file)
--- a/src/core/xfer.c
+++ b/src/core/xfer.c
@@ -110,6 +110,22 @@ int xfer_seek ( struct xfer_interface *xfer, off_t offset, int whence ) {
        return rc;
 }
 
+/**
+ * Check flow control window
+ *
+ * @v xfer             Data transfer interface
+ * @ret len            Length of window
+ */
+size_t xfer_window ( struct xfer_interface *xfer ) {
+       struct xfer_interface *dest = xfer_get_dest ( xfer );
+       size_t len;
+
+       len = dest->op->window ( dest );
+
+       xfer_put ( dest );
+       return len;
+}
+
 /**
  * Test to see if interface is ready to accept data
  *
@@ -297,6 +313,32 @@ int ignore_xfer_seek ( struct xfer_interface *xfer __unused,
        return 0;
 }
 
+/**
+ * Unlimited flow control window
+ *
+ * @v xfer             Data transfer interface
+ * @ret len            Length of window
+ *
+ * This handler indicates that the interface is always ready to accept
+ * data.
+ */
+size_t unlimited_xfer_window ( struct xfer_interface *xfer __unused ) {
+       return ~( ( size_t ) 0 );
+}
+
+/**
+ * No flow control window
+ *
+ * @v xfer             Data transfer interface
+ * @ret len            Length of window
+ *
+ * This handler indicates that the interface is never ready to accept
+ * data.
+ */
+size_t no_xfer_window ( struct xfer_interface *xfer __unused ) {
+       return 0;
+}
+
 /**
  * Allocate I/O buffer
  *
@@ -374,6 +416,7 @@ struct xfer_interface_operations null_xfer_ops = {
        .close          = ignore_xfer_close,
        .vredirect      = ignore_xfer_vredirect,
        .seek           = ignore_xfer_seek,
+       .window         = unlimited_xfer_window,
        .alloc_iob      = default_xfer_alloc_iob,
        .deliver_iob    = xfer_deliver_as_raw,
        .deliver_raw    = ignore_xfer_deliver_raw,

diff --git a/src/include/gpxe/xfer.h b/src/include/gpxe/xfer.h
index edf553f7ded8fae922ec8d8e92877ebd364a3d03..68c1169e55f1fb9972284737ed0662afaf59c06a 100644 (file)
--- a/src/include/gpxe/xfer.h
+++ b/src/include/gpxe/xfer.h
@@ -39,13 +39,26 @@ struct xfer_interface_operations {
         * @v whence            Basis for new position
         * @ret rc              Return status code
         *
-        * @c whence must be one of @c SEEK_SET or @c SEEK_CUR.  A
-        * successful return indicates that the interface is ready to
-        * immediately accept datagrams; return -EAGAIN if this is not
-        * the case.
+        * @c whence must be one of @c SEEK_SET or @c SEEK_CUR.
         */
        int ( * seek ) ( struct xfer_interface *xfer, off_t offset,
                         int whence );
+       /** Check flow control window
+        *
+        * @v xfer              Data transfer interface
+        * @ret len             Length of window
+        *
+        * Flow control is regarded as advisory but not mandatory.
+        * Users who have control over their own rate of data
+        * generation should perform a flow control check before
+        * generating new data.  Users who have no control (such as
+        * NIC drivers or filter layers) are not obliged to check.
+        *
+        * Data transfer interfaces must be prepared to accept
+        * datagrams even if they are advertising a window of zero
+        * bytes.
+        */
+       size_t ( * window ) ( struct xfer_interface *xfer );
        /** Allocate I/O buffer
         *
         * @v xfer              Data transfer interface
@@ -64,10 +77,6 @@ struct xfer_interface_operations {
         * A data transfer interface that wishes to support only raw
         * data delivery should set this method to
         * xfer_deliver_as_raw().
-        *
-        * Interfaces may not temporarily refuse to accept data by
-        * returning -EAGAIN; such a response may be treated as a
-        * fatal error.
         */
        int ( * deliver_iob ) ( struct xfer_interface *xfer,
                                struct io_buffer *iobuf,
@@ -82,10 +91,6 @@ struct xfer_interface_operations {
         * A data transfer interface that wishes to support only I/O
         * buffer delivery should set this method to
         * xfer_deliver_as_iob().
-        *
-        * Interfaces may not temporarily refuse to accept data by
-        * returning -EAGAIN; such a response may be treated as a
-        * fatal error.
         */
        int ( * deliver_raw ) ( struct xfer_interface *xfer,
                                const void *data, size_t len );
@@ -137,7 +142,7 @@ extern int xfer_vredirect ( struct xfer_interface *xfer, int type,
                            va_list args );
 extern int xfer_redirect ( struct xfer_interface *xfer, int type, ... );
 extern int xfer_seek ( struct xfer_interface *xfer, off_t offset, int whence );
-extern int xfer_ready ( struct xfer_interface *xfer );
+extern size_t xfer_window ( struct xfer_interface *xfer );
 extern struct io_buffer * xfer_alloc_iob ( struct xfer_interface *xfer,
                                           size_t len );
 extern int xfer_deliver_iob ( struct xfer_interface *xfer,
@@ -157,6 +162,8 @@ extern int ignore_xfer_vredirect ( struct xfer_interface *xfer,
                                   int type, va_list args );
 extern int ignore_xfer_seek ( struct xfer_interface *xfer, off_t offset,
                              int whence );
+extern size_t unlimited_xfer_window ( struct xfer_interface *xfer );
+extern size_t no_xfer_window ( struct xfer_interface *xfer );
 extern struct io_buffer * default_xfer_alloc_iob ( struct xfer_interface *xfer,
                                                   size_t len );
 extern int xfer_deliver_as_raw ( struct xfer_interface *xfer,

diff --git a/src/interface/pxe/pxe_udp.c b/src/interface/pxe/pxe_udp.c
index 153d758cc2b05d45619c827c12470a4c72a756d3..745366f242f6db89fa797939a0f5ecfaf40b90b8 100644 (file)
--- a/src/interface/pxe/pxe_udp.c
+++ b/src/interface/pxe/pxe_udp.c
@@ -104,6 +104,7 @@ static struct xfer_interface_operations pxe_udp_xfer_operations = {
        .close          = ignore_xfer_close,
        .vredirect      = ignore_xfer_vredirect,
        .seek           = ignore_xfer_seek,
+       .window         = unlimited_xfer_window,
        .alloc_iob      = default_xfer_alloc_iob,
        .deliver_iob    = pxe_udp_deliver_iob,
        .deliver_raw    = xfer_deliver_as_iob,

diff --git a/src/net/tcp.c b/src/net/tcp.c
index 12ca65a62f5030fc60d338e02a11167211ce3012..410be7374710e3926c32161ec770fa741c570470 100644 (file)
--- a/src/net/tcp.c
+++ b/src/net/tcp.c
@@ -897,31 +897,28 @@ static void tcp_xfer_close ( struct xfer_interface *xfer, int rc ) {
 }
 
 /**
- * Seek to position
+ * Check flow control window
  *
  * @v xfer             Data transfer interface
- * @v offset           Offset to new position
- * @v whence           Basis for new position
- * @ret rc             Return status code
+ * @ret len            Length of window
  */
-static int tcp_xfer_seek ( struct xfer_interface *xfer, off_t offset,
-                          int whence ) {
+static size_t tcp_xfer_window ( struct xfer_interface *xfer ) {
        struct tcp_connection *tcp =
                container_of ( xfer, struct tcp_connection, xfer );
 
-       /* TCP doesn't support seeking to arbitrary positions */
-       if ( ( whence != SEEK_CUR ) || ( offset != 0 ) )
-               return -EINVAL;
-
        /* Not ready if we're not in a suitable connection state */
        if ( ! TCP_CAN_SEND_DATA ( tcp->tcp_state ) )
-               return -EAGAIN;
+               return 0;
 
-       /* Not ready if data queue is non-empty */
+       /* Not ready if data queue is non-empty.  This imposes a limit
+        * of only one unACKed packet in the TX queue at any time; we
+        * do this to conserve memory usage.
+        */
        if ( ! list_empty ( &tcp->queue ) )
-               return -EAGAIN;
+               return 0;
 
-       return 0;
+       /* Return TCP window length */
+       return tcp->snd_win;
 }
 
 /**
@@ -951,7 +948,8 @@ static int tcp_xfer_deliver_iob ( struct xfer_interface *xfer,
 static struct xfer_interface_operations tcp_xfer_operations = {
        .close          = tcp_xfer_close,
        .vredirect      = ignore_xfer_vredirect,
-       .seek           = tcp_xfer_seek,
+       .seek           = ignore_xfer_seek,
+       .window         = tcp_xfer_window,
        .alloc_iob      = default_xfer_alloc_iob,
        .deliver_iob    = tcp_xfer_deliver_iob,
        .deliver_raw    = xfer_deliver_as_iob,

diff --git a/src/net/tcp/ftp.c b/src/net/tcp/ftp.c
index 6c09edff15c29707923f7f3b50300bd22203b578..646638aba76cbc9612f1ef451b9737aad6d151e0 100644 (file)
--- a/src/net/tcp/ftp.c
+++ b/src/net/tcp/ftp.c
@@ -297,6 +297,7 @@ static struct xfer_interface_operations ftp_control_operations = {
        .close          = ftp_control_close,
        .vredirect      = xfer_vopen,
        .seek           = ignore_xfer_seek,
+       .window         = unlimited_xfer_window,
        .alloc_iob      = default_xfer_alloc_iob,
        .deliver_iob    = xfer_deliver_as_raw,
        .deliver_raw    = ftp_control_deliver_raw,
@@ -361,6 +362,7 @@ static struct xfer_interface_operations ftp_data_operations = {
        .close          = ftp_data_closed,
        .vredirect      = xfer_vopen,
        .seek           = ignore_xfer_seek,
+       .window         = unlimited_xfer_window,
        .alloc_iob      = default_xfer_alloc_iob,
        .deliver_iob    = ftp_data_deliver_iob,
        .deliver_raw    = xfer_deliver_as_iob,
@@ -393,6 +395,7 @@ static struct xfer_interface_operations ftp_xfer_operations = {
        .close          = ftp_xfer_closed,
        .vredirect      = ignore_xfer_vredirect,
        .seek           = ignore_xfer_seek,
+       .window         = unlimited_xfer_window,
        .alloc_iob      = default_xfer_alloc_iob,
        .deliver_iob    = xfer_deliver_as_raw,
        .deliver_raw    = ignore_xfer_deliver_raw,

diff --git a/src/net/tcp/http.c b/src/net/tcp/http.c
index 287a56a069e0c7d5c1c6ba7568a1710644677fc0..0c0164139451d06da778f8740806b545c7834eb3 100644 (file)
--- a/src/net/tcp/http.c
+++ b/src/net/tcp/http.c
@@ -388,7 +388,7 @@ static void http_step ( struct process *process ) {
        const char *query = http->uri->query;
        int rc;
 
-       if ( xfer_ready ( &http->socket ) == 0 ) {
+       if ( xfer_window ( &http->socket ) ) {
                process_del ( &http->process );
                if ( ( rc = xfer_printf ( &http->socket,
                                          "GET %s%s%s HTTP/1.1\r\n"
@@ -425,6 +425,7 @@ static struct xfer_interface_operations http_socket_operations = {
        .close          = http_socket_close,
        .vredirect      = xfer_vopen,
        .seek           = ignore_xfer_seek,
+       .window         = unlimited_xfer_window,
        .alloc_iob      = default_xfer_alloc_iob,
        .deliver_iob    = http_socket_deliver_iob,
        .deliver_raw    = xfer_deliver_as_iob,
@@ -451,6 +452,7 @@ static struct xfer_interface_operations http_xfer_operations = {
        .close          = http_xfer_close,
        .vredirect      = ignore_xfer_vredirect,
        .seek           = ignore_xfer_seek,
+       .window         = unlimited_xfer_window,
        .alloc_iob      = default_xfer_alloc_iob,
        .deliver_iob    = xfer_deliver_as_raw,
        .deliver_raw    = ignore_xfer_deliver_raw,

diff --git a/src/net/udp.c b/src/net/udp.c
index 3e33ff175b68ac496ab6173bfc08194d44961e4e..b4cd8e6b29aa79d733b4c00dcead7944dff1365a 100644 (file)
--- a/src/net/udp.c
+++ b/src/net/udp.c
@@ -415,6 +415,7 @@ static struct xfer_interface_operations udp_xfer_operations = {
        .close          = udp_xfer_close,
        .vredirect      = ignore_xfer_vredirect,
        .seek           = ignore_xfer_seek,
+       .window         = unlimited_xfer_window,
        .alloc_iob      = udp_alloc_iob,
        .deliver_iob    = udp_xfer_deliver_iob,
        .deliver_raw    = xfer_deliver_as_iob,

diff --git a/src/net/udp/dhcp.c b/src/net/udp/dhcp.c
index 5a8203a1936245ee53388ea019398dc3ac015e9a..26059341cea72abb0dc26c97583ff4b6c9da7992 100644 (file)
--- a/src/net/udp/dhcp.c
+++ b/src/net/udp/dhcp.c
@@ -722,6 +722,7 @@ static struct xfer_interface_operations dhcp_xfer_operations = {
        .close          = ignore_xfer_close,
        .vredirect      = xfer_vopen,
        .seek           = ignore_xfer_seek,
+       .window         = unlimited_xfer_window,
        .deliver_iob    = xfer_deliver_as_raw,
        .deliver_raw    = dhcp_deliver_raw,
 };

diff --git a/src/net/udp/dns.c b/src/net/udp/dns.c
index 76d5dd7a1cfcc1276b7c34b9d1c1eec51ca9e7c0..aab9cfc27e485e411871928ab0fc52692d1689c2 100644 (file)
--- a/src/net/udp/dns.c
+++ b/src/net/udp/dns.c
@@ -433,6 +433,7 @@ static struct xfer_interface_operations dns_socket_operations = {
        .close          = dns_xfer_close,
        .vredirect      = xfer_vopen,
        .seek           = ignore_xfer_seek,
+       .window         = unlimited_xfer_window,
        .alloc_iob      = default_xfer_alloc_iob,
        .deliver_iob    = xfer_deliver_as_raw,
        .deliver_raw    = dns_xfer_deliver_raw,

diff --git a/src/net/udp/tftp.c b/src/net/udp/tftp.c
index 03a51f9a2d910c64d2289c81418fd6c28077b8f3..106c70475a29d530b2cdf2cf8ea6a3c56c1c4d4b 100644 (file)
--- a/src/net/udp/tftp.c
+++ b/src/net/udp/tftp.c
@@ -583,6 +583,7 @@ static struct xfer_interface_operations tftp_socket_operations = {
        .close          = tftp_socket_close,
        .vredirect      = xfer_vopen,
        .seek           = ignore_xfer_seek,
+       .window         = unlimited_xfer_window,
        .alloc_iob      = default_xfer_alloc_iob,
        .deliver_iob    = tftp_socket_deliver_iob,
        .deliver_raw    = xfer_deliver_as_iob,
@@ -609,6 +610,7 @@ static struct xfer_interface_operations tftp_xfer_operations = {
        .close          = tftp_xfer_close,
        .vredirect      = ignore_xfer_vredirect,
        .seek           = ignore_xfer_seek,
+       .window         = unlimited_xfer_window,
        .alloc_iob      = default_xfer_alloc_iob,
        .deliver_iob    = xfer_deliver_as_raw,
        .deliver_raw    = ignore_xfer_deliver_raw,