From 837b77293beafa15f8a125a484a0d17453b021f8 Mon Sep 17 00:00:00 2001
From: Michael Brown
Date: Tue, 29 Apr 2025 09:16:41 +0100
Subject: [xferbuf] Simplify and generalise data transfer buffers

Since all data transfer buffer contents are now accessible via direct
pointer dereferences, remove the unnecessary abstractions for read and
write operations and create two new data transfer buffer types: a
fixed-size buffer, and a void buffer that records its size but can
never receive non-zero lengths of data.  These replace the custom data
buffer types currently implemented for EFI PXE TFTP downloads and for
block device translations.

A new operation xferbuf_detach() is required to take ownership of the
data accumulated in the data transfer buffer, since we no longer rely
on the existence of an independently owned external data pointer for
data transfer buffers allocated via umalloc().

Signed-off-by: Michael Brown <mcb30@ipxe.org>
---
 src/interface/efi/efi_pxe.c | 47 ++-------------------------------------------
 1 file changed, 2 insertions(+), 45 deletions(-)

(limited to 'src/interface/efi')

diff --git a/src/interface/efi/efi_pxe.c b/src/interface/efi/efi_pxe.c
index 732ccdcdf..4ba057019 100644
--- a/src/interface/efi/efi_pxe.c
+++ b/src/interface/efi/efi_pxe.c
@@ -303,48 +303,6 @@ static int efi_pxe_ip_filter ( struct efi_pxe *pxe, EFI_IP_ADDRESS *ip ) {
 	return 0;
 }
 
-/******************************************************************************
- *
- * Data transfer buffer
- *
- ******************************************************************************
- */
-
-/**
- * Reallocate PXE data transfer buffer
- *
- * @v xferbuf		Data transfer buffer
- * @v len		New length (or zero to free buffer)
- * @ret rc		Return status code
- */
-static int efi_pxe_buf_realloc ( struct xfer_buffer *xferbuf __unused,
-				 size_t len __unused ) {
-
-	/* Can never reallocate: return EFI_BUFFER_TOO_SMALL */
-	return -ERANGE;
-}
-
-/**
- * Write data to PXE data transfer buffer
- *
- * @v xferbuf		Data transfer buffer
- * @v offset		Starting offset
- * @v data		Data to copy
- * @v len		Length of data
- */
-static void efi_pxe_buf_write ( struct xfer_buffer *xferbuf, size_t offset,
-				const void *data, size_t len ) {
-
-	/* Copy data to buffer */
-	memcpy ( ( xferbuf->data + offset ), data, len );
-}
-
-/** PXE data transfer buffer operations */
-static struct xfer_buffer_operations efi_pxe_buf_operations = {
-	.realloc = efi_pxe_buf_realloc,
-	.write = efi_pxe_buf_write,
-};
-
 /******************************************************************************
  *
  * (M)TFTP download interface
@@ -966,8 +924,7 @@ efi_pxe_mtftp ( EFI_PXE_BASE_CODE_PROTOCOL *base,
 	pxe->blksize = ( ( callback && blksize ) ? *blksize : -1UL );
 
 	/* Initialise data transfer buffer */
-	pxe->buf.data = data;
-	pxe->buf.len = *len;
+	xferbuf_fixed_init ( &pxe->buf, data, *len );
 
 	/* Open download */
 	if ( ( rc = efi_pxe_tftp_open ( pxe, ip,
@@ -987,6 +944,7 @@ efi_pxe_mtftp ( EFI_PXE_BASE_CODE_PROTOCOL *base,
  err_download:
 	efi_pxe_tftp_close ( pxe, rc );
  err_open:
+	xferbuf_fixed_init ( &pxe->buf, NULL, 0 );
 	efi_snp_release();
  err_opcode:
 	return EFIRC ( rc );
@@ -1611,7 +1569,6 @@ int efi_pxe_install ( EFI_HANDLE handle, struct net_device *netdev ) {
 	pxe->base.Mode = &pxe->mode;
 	memcpy ( &pxe->apple, &efi_apple_net_boot_protocol,
 		 sizeof ( pxe->apple ) );
-	pxe->buf.op = &efi_pxe_buf_operations;
 	intf_init ( &pxe->tftp, &efi_pxe_tftp_desc, &pxe->refcnt );
 	intf_init ( &pxe->udp, &efi_pxe_udp_desc, &pxe->refcnt );
 	INIT_LIST_HEAD ( &pxe->queue );
-- 
cgit v1.2.3-55-g7522