Merge branch 'master' of git://git.etherboot.org/scm/gpxe

9 files changed, 516 insertions, 62 deletions

diff --git a/src/arch/i386/interface/pxe/pxe_call.c b/src/arch/i386/interface/pxe/pxe_call.c
index 1c1b5066c..8f1dd0a22 100644
--- a/src/arch/i386/interface/pxe/pxe_call.c
+++ b/src/arch/i386/interface/pxe/pxe_call.c
@@ -91,6 +91,11 @@ union pxenv_call {
 			( struct s_PXENV_UNDI_GET_IFACE_INFO * );
 	PXENV_EXIT_t ( * undi_get_state ) ( struct s_PXENV_UNDI_GET_STATE * );
 	PXENV_EXIT_t ( * undi_isr ) ( struct s_PXENV_UNDI_ISR * );
+	PXENV_EXIT_t ( * file_open ) ( struct s_PXENV_FILE_OPEN * );
+	PXENV_EXIT_t ( * file_close ) ( struct s_PXENV_FILE_CLOSE * );
+	PXENV_EXIT_t ( * file_select ) ( struct s_PXENV_FILE_SELECT * );
+	PXENV_EXIT_t ( * file_read ) ( struct s_PXENV_FILE_READ * );
+	PXENV_EXIT_t ( * get_file_size ) ( struct s_PXENV_GET_FILE_SIZE * );
 };
 
 /**
@@ -269,6 +274,26 @@ __cdecl void pxe_api_call ( struct i386_all_regs *ix86 ) {
 		pxenv_call.undi_isr = pxenv_undi_isr;
 		param_len = sizeof ( pxenv_any.undi_isr );
 		break;
+	case PXENV_FILE_OPEN:
+		pxenv_call.file_open = pxenv_file_open;
+		param_len = sizeof ( pxenv_any.file_open );
+		break;
+	case PXENV_FILE_CLOSE:
+		pxenv_call.file_close = pxenv_file_close;
+		param_len = sizeof ( pxenv_any.file_close );
+		break;
+	case PXENV_FILE_SELECT:
+		pxenv_call.file_select = pxenv_file_select;
+		param_len = sizeof ( pxenv_any.file_select );
+		break;
+	case PXENV_FILE_READ:
+		pxenv_call.file_read = pxenv_file_read;
+		param_len = sizeof ( pxenv_any.file_read );
+		break;
+	case PXENV_GET_FILE_SIZE:
+		pxenv_call.get_file_size = pxenv_get_file_size;
+		param_len = sizeof ( pxenv_any.get_file_size );
+		break;
 	default:
 		DBG ( "PXENV_UNKNOWN_%hx", opcode );
 		pxenv_call.unknown = pxenv_unknown;
diff --git a/src/core/image.c b/src/core/image.c
index 63c2502bd..440a68c9f 100644
--- a/src/core/image.c
+++ b/src/core/image.c
@@ -237,6 +237,7 @@ int image_autoload ( struct image *image ) {
  * @ret rc		Return status code
  */
 int image_exec ( struct image *image ) {
+	struct uri *old_cwuri;
 	int rc;
 
 	/* Image must be loaded first */
@@ -252,15 +253,23 @@ int image_exec ( struct image *image ) {
 	if ( ! image->type->exec )
 		return -ENOEXEC;
 
+	/* Switch current working directory to be that of the image itself */
+	old_cwuri = uri_get ( cwuri );
+	churi ( image->uri );
+
 	/* Try executing the image */
 	if ( ( rc = image->type->exec ( image ) ) != 0 ) {
 		DBGC ( image, "IMAGE %p could not execute: %s\n",
 		       image, strerror ( rc ) );
-		return rc;
+		goto done;
 	}
 
-	/* Well, some formats might return... */
-	return 0;
+ done:
+	/* Reset current working directory */
+	churi ( old_cwuri );
+	uri_put ( old_cwuri );
+
+	return rc;
 }
 
 /**
diff --git a/src/core/posix_io.c b/src/core/posix_io.c
index 21f818bfa..530ce6511 100644
--- a/src/core/posix_io.c
+++ b/src/core/posix_io.c
@@ -60,12 +60,6 @@ struct posix_file {
 /** List of open files */
 static LIST_HEAD ( posix_files );
 
-/** Minimum file descriptor that will ever be allocated */
-#define POSIX_FD_MIN ( 1 )
-
-/** Maximum file descriptor that will ever be allocated */
-#define POSIX_FD_MAX ( 255 )
-
 /**
  * Free open file
  *
@@ -252,53 +246,83 @@ int open ( const char *uri_string ) {
 }
 
 /**
+ * Check file descriptors for readiness
+ *
+ * @v readfds		File descriptors to check
+ * @v wait		Wait until data is ready
+ * @ret nready		Number of ready file descriptors
+ */
+int select ( fd_set *readfds, int wait ) {
+	struct posix_file *file;
+	int fd;
+
+	do {
+		for ( fd = POSIX_FD_MIN ; fd <= POSIX_FD_MAX ; fd++ ) {
+			if ( ! FD_ISSET ( fd, readfds ) )
+				continue;
+			file = posix_fd_to_file ( fd );
+			if ( ! file )
+				return -EBADF;
+			if ( ( list_empty ( &file->data ) ) &&
+			     ( file->rc != -EINPROGRESS ) )
+				continue;
+			/* Data is available or status has changed */
+			FD_ZERO ( readfds );
+			FD_SET ( fd, readfds );
+			return 1;
+		}
+		step();
+	} while ( wait );
+
+	return 0;
+}
+
+/**
  * Read data from file
  *
  * @v buffer		Data buffer
  * @v offset		Starting offset within data buffer
  * @v len		Maximum length to read
  * @ret len		Actual length read, or negative error number
+ *
+ * This call is non-blocking; if no data is available to read then
+ * -EWOULDBLOCK will be returned.
  */
 ssize_t read_user ( int fd, userptr_t buffer, off_t offset, size_t max_len ) {
 	struct posix_file *file;
 	struct io_buffer *iobuf;
-	size_t frag_len;
-	ssize_t len = 0;
+	size_t len;
 
 	/* Identify file */
 	file = posix_fd_to_file ( fd );
 	if ( ! file )
 		return -EBADF;
 
-	while ( 1 ) {
-		/* Try to fetch more data if none available */
-		if ( list_empty ( &file->data ) )
-			step();
-		/* Dequeue at most one received I/O buffer into user buffer */
-		list_for_each_entry ( iobuf, &file->data, list ) {
-			frag_len = iob_len ( iobuf );
-			if ( frag_len > max_len )
-				frag_len = max_len;
-			copy_to_user ( buffer, offset, iobuf->data,
-				       frag_len );
-			iob_pull ( iobuf, frag_len );
-			if ( ! iob_len ( iobuf ) ) {
-				list_del ( &iobuf-> list );
-				free_iob ( iobuf );
-			}
-			file->pos += frag_len;
-			len += frag_len;
-			offset += frag_len;
-			max_len -= frag_len;
-			break;
+	/* Try to fetch more data if none available */
+	if ( list_empty ( &file->data ) )
+		step();
+
+	/* Dequeue at most one received I/O buffer into user buffer */
+	list_for_each_entry ( iobuf, &file->data, list ) {
+		len = iob_len ( iobuf );
+		if ( len > max_len )
+			len = max_len;
+		copy_to_user ( buffer, offset, iobuf->data, len );
+		iob_pull ( iobuf, len );
+		if ( ! iob_len ( iobuf ) ) {
+			list_del ( &iobuf->list );
+			free_iob ( iobuf );
 		}
-		/* If buffer is full, return */
-		if ( ! max_len )
-			return len;
-		/* If file has completed, return */
-		if ( file->rc != -EINPROGRESS )
-			return ( file->rc ? file->rc : len );
+		file->pos += len;
+		return len;
 	}
+
+	/* If file has completed, return (after returning all data) */
+	if ( file->rc != -EINPROGRESS )
+		return file->rc;
+
+	/* No data ready and file still in progress; return -WOULDBLOCK */
+	return -EWOULDBLOCK;
 }
 
 /**
diff --git a/src/image/script.c b/src/image/script.c
index 2f159c97e..c8821522b 100644
--- a/src/image/script.c
+++ b/src/image/script.c
@@ -27,7 +27,6 @@
 #include <stdlib.h>
 #include <errno.h>
 #include <gpxe/image.h>
-#include <gpxe/uri.h>
 
 struct image_type script_image_type __image_type ( PROBE_NORMAL );
 
@@ -38,7 +37,6 @@ struct image_type script_image_type __image_type ( PROBE_NORMAL );
  * @ret rc		Return status code
  */
 static int script_exec ( struct image *image ) {
-	struct uri *old_cwuri;
 	char cmdbuf[256];
 	size_t offset = 0;
 	size_t remaining;
@@ -53,10 +51,6 @@ static int script_exec ( struct image *image ) {
 	image_get ( image );
 	unregister_image ( image );
 
-	/* Switch current working directory to be that of the script itself */
-	old_cwuri = uri_get ( cwuri );
-	churi ( image->uri );
-
 	while ( offset < image->len ) {
 	
 		/* Read up to cmdbuf bytes from script into buffer */
@@ -93,9 +87,7 @@ static int script_exec ( struct image *image ) {
 
 	rc = 0;
  done:
-	/* Reset current working directory, re-register image and return */
-	churi ( old_cwuri );
-	uri_put ( old_cwuri );
+	/* Re-register image and return */
 	register_image ( image );
 	image_put ( image );
 	return rc;
diff --git a/src/include/gpxe/posix_io.h b/src/include/gpxe/posix_io.h
index a5cf0c753..9984db005 100644
--- a/src/include/gpxe/posix_io.h
+++ b/src/include/gpxe/posix_io.h
@@ -10,13 +10,67 @@
 #include <stdint.h>
 #include <gpxe/uaccess.h>
 
+/** Minimum file descriptor that will ever be allocated */
+#define POSIX_FD_MIN ( 1 )
+
+/** Maximum file descriptor that will ever be allocated */
+#define POSIX_FD_MAX ( 31 )
+
+/** File descriptor set as used for select() */
+typedef uint32_t fd_set;
+
 extern int open ( const char *uri_string );
 extern ssize_t read_user ( int fd, userptr_t buffer,
 			   off_t offset, size_t len );
+extern int select ( fd_set *readfds, int wait );
 extern ssize_t fsize ( int fd );
 extern int close ( int fd );
 
 /**
+ * Zero a file descriptor set
+ *
+ * @v set		File descriptor set
+ */
+static inline __attribute__ (( always_inline )) void
+FD_ZERO ( fd_set *set ) {
+	*set = 0;
+}
+
+/**
+ * Set a bit within a file descriptor set
+ *
+ * @v fd		File descriptor
+ * @v set		File descriptor set
+ */
+static inline __attribute__ (( always_inline )) void
+FD_SET ( int fd, fd_set *set ) {
+	*set |= ( 1 << fd );
+}
+
+/**
+ * Clear a bit within a file descriptor set
+ *
+ * @v fd		File descriptor
+ * @v set		File descriptor set
+ */
+static inline __attribute__ (( always_inline )) void
+FD_CLR ( int fd, fd_set *set ) {
+	*set &= ~( 1 << fd );
+}
+
+/**
+ * Test a bit within a file descriptor set
+ *
+ * @v fd		File descriptor
+ * @v set		File descriptor set
+ * @ret is_set		Corresponding bit is set
+ */
+static inline __attribute__ (( always_inline )) int
+FD_ISSET ( int fd, fd_set *set ) {
+	return ( *set & ( 1 << fd ) );
+}
+
+/**
  * Read data from file
  *
  * @v fd		File descriptor
diff --git a/src/include/pxe.h b/src/include/pxe.h
index 301bb10b8..ecb664d55 100644
--- a/src/include/pxe.h
+++ b/src/include/pxe.h
@@ -58,6 +58,11 @@ union u_PXENV_ANY {
 	struct s_PXENV_UNDI_GET_IFACE_INFO	undi_get_iface_info;
 	struct s_PXENV_UNDI_GET_STATE		undi_get_state;
 	struct s_PXENV_UNDI_ISR			undi_isr;
+	struct s_PXENV_FILE_OPEN		file_open;
+	struct s_PXENV_FILE_CLOSE		file_close;
+	struct s_PXENV_FILE_SELECT		file_select;
+	struct s_PXENV_FILE_READ		file_read;
+	struct s_PXENV_GET_FILE_SIZE		get_file_size;
 };
 
 typedef union u_PXENV_ANY PXENV_ANY_t;
diff --git a/src/include/pxe_api.h b/src/include/pxe_api.h
index e64413254..8dc1607a8 100644
--- a/src/include/pxe_api.h
+++ b/src/include/pxe_api.h
@@ -1555,6 +1555,137 @@ extern PXENV_EXIT_t pxenv_undi_isr ( struct s_PXENV_UNDI_ISR *undi_isr );
 
 /** @} */ /* pxe_undi_api */
 
+/** @defgroup pxe_file_api PXE FILE API
+ *
+ * POSIX-like file operations
+ *
+ * @{
+ */
+
+/** @defgroup pxenv_file_open PXENV_FILE_OPEN
+ *
+ * FILE OPEN
+ *
+ * @{
+ */
+
+/** PXE API function code for pxenv_file_open() */
+#define PXENV_FILE_OPEN			0x00e0
+
+/** Parameter block for pxenv_file_open() */
+struct s_PXENV_FILE_OPEN {
+	PXENV_STATUS_t Status;		/**< PXE status code */
+	UINT16_t FileHandle;		/**< File handle */
+	SEGOFF16_t FileName;		/**< File URL */
+	UINT32_t Reserved;		/**< Reserved */
+} PACKED;
+
+typedef struct s_PXENV_FILE_OPEN PXENV_FILE_OPEN_t;
+
+extern PXENV_EXIT_t pxenv_file_open ( struct s_PXENV_FILE_OPEN *file_open );
+
+/** @} */ /* pxenv_file_open */
+
+/** @defgroup pxenv_file_close PXENV_FILE_CLOSE
+ *
+ * FILE CLOSE
+ *
+ * @{
+ */
+
+/** PXE API function code for pxenv_file_close() */
+#define PXENV_FILE_CLOSE		0x00e1
+
+/** Parameter block for pxenv_file_close() */
+struct s_PXENV_FILE_CLOSE {
+	PXENV_STATUS_t Status;		/**< PXE status code */
+	UINT16_t FileHandle;		/**< File handle */
+} PACKED;
+
+typedef struct s_PXENV_FILE_CLOSE PXENV_FILE_CLOSE_t;
+
+extern PXENV_EXIT_t pxenv_file_close ( struct s_PXENV_FILE_CLOSE
+				       *file_close );
+
+/** @} */ /* pxenv_file_close */
+
+/** @defgroup pxenv_file_select PXENV_FILE_SELECT
+ *
+ * FILE SELECT
+ *
+ * @{
+ */
+
+/** PXE API function code for pxenv_file_select() */
+#define PXENV_FILE_SELECT		0x00e2
+
+/** File is ready for reading */
+#define RDY_READ			0x0001
+
+/** Parameter block for pxenv_file_select() */
+struct s_PXENV_FILE_SELECT {
+	PXENV_STATUS_t Status;		/**< PXE status code */
+	UINT16_t FileHandle;		/**< File handle */
+	UINT16_t Ready;			/**< Indication of readiness */
+} PACKED;
+
+typedef struct s_PXENV_FILE_SELECT PXENV_FILE_SELECT_t;
+
+extern PXENV_EXIT_t pxenv_file_select ( struct s_PXENV_FILE_SELECT
+					*file_select );
+
+/** @} */ /* pxenv_file_select */
+
+/** @defgroup pxenv_file_read PXENV_FILE_READ
+ *
+ * FILE READ
+ *
+ * @{
+ */
+
+/** PXE API function code for pxenv_file_read() */
+#define PXENV_FILE_READ		0x00e3
+
+/** Parameter block for pxenv_file_read() */
+struct s_PXENV_FILE_READ {
+	PXENV_STATUS_t Status;		/**< PXE status code */
+	UINT16_t FileHandle;		/**< File handle */
+	UINT16_t BufferSize;		/**< Data buffer size */
+	SEGOFF16_t Buffer;		/**< Data buffer */
+} PACKED;
+
+typedef struct s_PXENV_FILE_READ PXENV_FILE_READ_t;
+
+extern PXENV_EXIT_t pxenv_file_read ( struct s_PXENV_FILE_READ *file_read );
+
+/** @} */ /* pxenv_file_read */
+
+/** @defgroup pxenv_get_file_size PXENV_GET_FILE_SIZE
+ *
+ * GET FILE SIZE
+ *
+ * @{
+ */
+
+/** PXE API function code for pxenv_get_file_size() */
+#define PXENV_GET_FILE_SIZE		0x00e4
+
+/** Parameter block for pxenv_get_file_size() */
+struct s_PXENV_GET_FILE_SIZE {
+	PXENV_STATUS_t Status;		/**< PXE status code */
+	UINT16_t FileHandle;		/**< File handle */
+	UINT32_t FileSize;		/**< File size */
+} PACKED;
+
+typedef struct s_PXENV_GET_FILE_SIZE PXENV_GET_FILE_SIZE_t;
+
+extern PXENV_EXIT_t pxenv_get_file_size ( struct s_PXENV_GET_FILE_SIZE
+					  *get_file_size );
+
+/** @} */ /* pxenv_get_file_size */
+
+/** @} */ /* pxe_file_api */
+
 /** @defgroup pxe_loader_api PXE Loader API
  *
  * The UNDI ROM loader API
diff --git a/src/interface/pxe/pxe_file.c b/src/interface/pxe/pxe_file.c
new file mode 100644
index 000000000..01dac8f7d
--- /dev/null
+++ b/src/interface/pxe/pxe_file.c
@@ -0,0 +1,191 @@
+/** @file
+ *
+ * PXE FILE API
+ *
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <byteswap.h>
+#include <gpxe/uaccess.h>
+#include <gpxe/posix_io.h>
+#include <gpxe/features.h>
+#include <pxe.h>
+
+/*
+ * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+FEATURE ( FEATURE_MISC, "PXEXT", DHCP_EB_FEATURE_PXE_EXT, 1 );
+
+/**
+ * FILE OPEN
+ *
+ * @v file_open				Pointer to a struct s_PXENV_FILE_OPEN
+ * @v s_PXENV_FILE_OPEN::FileName	URL of file to open
+ * @ret #PXENV_EXIT_SUCCESS		File was opened
+ * @ret #PXENV_EXIT_FAILURE		File was not opened
+ * @ret s_PXENV_FILE_OPEN::Status	PXE status code
+ * @ret s_PXENV_FILE_OPEN::FileHandle	Handle of opened file
+ *
+ */
+PXENV_EXIT_t pxenv_file_open ( struct s_PXENV_FILE_OPEN *file_open ) {
+	userptr_t filename;
+	size_t filename_len;
+	int fd;
+
+	DBG ( "PXENV_FILE_OPEN" );
+
+	/* Copy name from external program, and open it */
+	filename = real_to_user ( file_open->FileName.segment,
+			      file_open->FileName.offset );
+	filename_len = strlen_user ( filename, 0 );
+	{
+		char uri_string[ filename_len + 1 ];
+
+		copy_from_user ( uri_string, filename, 0,
+				 sizeof ( uri_string ) );
+		DBG ( " %s", uri_string );
+		fd = open ( uri_string );
+	}
+
+	if ( fd < 0 ) {
+		file_open->Status = PXENV_STATUS ( fd );
+		return PXENV_EXIT_FAILURE;
+	}
+
+	DBG ( " as file %d", fd );
+
+	file_open->FileHandle = fd;
+	file_open->Status = PXENV_STATUS_SUCCESS;
+	return PXENV_EXIT_SUCCESS;
+}
+
+/**
+ * FILE CLOSE
+ *
+ * @v file_close			Pointer to a struct s_PXENV_FILE_CLOSE
+ * @v s_PXENV_FILE_CLOSE::FileHandle	File handle
+ * @ret #PXENV_EXIT_SUCCESS		File was closed
+ * @ret #PXENV_EXIT_FAILURE		File was not closed
+ * @ret s_PXENV_FILE_CLOSE::Status	PXE status code
+ *
+ */
+PXENV_EXIT_t pxenv_file_close ( struct s_PXENV_FILE_CLOSE *file_close ) {
+
+	DBG ( "PXENV_FILE_CLOSE %d", file_close->FileHandle );
+
+	close ( file_close->FileHandle );
+	file_close->Status = PXENV_STATUS_SUCCESS;
+	return PXENV_EXIT_SUCCESS;
+}
+
+/**
+ * FILE SELECT
+ *
+ * @v file_select			Pointer to a struct s_PXENV_FILE_SELECT
+ * @v s_PXENV_FILE_SELECT::FileHandle	File handle
+ * @ret #PXENV_EXIT_SUCCESS		File has been checked for readiness
+ * @ret #PXENV_EXIT_FAILURE		File has not been checked for readiness
+ * @ret s_PXENV_FILE_SELECT::Status	PXE status code
+ * @ret s_PXENV_FILE_SELECT::Ready	Indication of readiness
+ *
+ */
+PXENV_EXIT_t pxenv_file_select ( struct s_PXENV_FILE_SELECT *file_select ) {
+	fd_set fdset;
+	int ready;
+
+	DBG ( "PXENV_FILE_SELECT %d", file_select->FileHandle );
+
+	FD_ZERO ( &fdset );
+	FD_SET ( file_select->FileHandle, &fdset );
+	if ( ( ready = select ( &fdset, 0 ) ) < 0 ) {
+		file_select->Status = PXENV_STATUS ( ready );
+		return PXENV_EXIT_FAILURE;
+	}
+
+	file_select->Ready = ( ready ? RDY_READ : 0 );
+	file_select->Status = PXENV_STATUS_SUCCESS;
+	return PXENV_EXIT_SUCCESS;
+}
+
+/**
+ * FILE READ
+ *
+ * @v file_read				Pointer to a struct s_PXENV_FILE_READ
+ * @v s_PXENV_FILE_READ::FileHandle	File handle
+ * @v s_PXENV_FILE_READ::BufferSize	Size of data buffer
+ * @v s_PXENV_FILE_READ::Buffer		Data buffer
+ * @ret #PXENV_EXIT_SUCCESS		Data has been read from file
+ * @ret #PXENV_EXIT_FAILURE		Data has not been read from file
+ * @ret s_PXENV_FILE_READ::Status	PXE status code
+ * @ret s_PXENV_FILE_READ::Ready	Indication of readiness
+ * @ret s_PXENV_FILE_READ::BufferSize	Length of data read
+ *
+ */
+PXENV_EXIT_t pxenv_file_read ( struct s_PXENV_FILE_READ *file_read ) {
+	userptr_t buffer;
+	ssize_t len;
+
+	DBG ( "PXENV_FILE_READ %d to %04x:%04x+%04x", file_read->FileHandle,
+	      file_read->Buffer.segment, file_read->Buffer.offset,
+	      file_read->BufferSize );
+
+	buffer = real_to_user ( file_read->Buffer.segment,
+				file_read->Buffer.offset );
+	if ( ( len = read_user ( file_read->FileHandle, buffer, 0,
+				file_read->BufferSize ) ) < 0 ) {
+		file_read->Status = PXENV_STATUS ( len );
+		return PXENV_EXIT_FAILURE;
+	}
+
+	DBG ( " read %04zx", ( ( size_t ) len ) );
+
+	file_read->BufferSize = len;
+	file_read->Status = PXENV_STATUS_SUCCESS;
+	return PXENV_EXIT_SUCCESS;
+}
+
+/**
+ * GET FILE SIZE
+ *
+ * @v get_file_size			Pointer to a struct s_PXENV_GET_FILE_SIZE
+ * @v s_PXENV_GET_FILE_SIZE::FileHandle	File handle
+ * @ret #PXENV_EXIT_SUCCESS		File size has been determined
+ * @ret #PXENV_EXIT_FAILURE		File size has not been determined
+ * @ret s_PXENV_GET_FILE_SIZE::Status	PXE status code
+ * @ret s_PXENV_GET_FILE_SIZE::FileSize	Size of file
+ */
+PXENV_EXIT_t pxenv_get_file_size ( struct s_PXENV_GET_FILE_SIZE
+				   *get_file_size ) {
+	ssize_t filesize;
+
+	DBG ( "PXENV_GET_FILE_SIZE %d", get_file_size->FileHandle );
+
+	filesize = fsize ( get_file_size->FileHandle );
+	if ( filesize < 0 ) {
+		get_file_size->Status = PXENV_STATUS ( filesize );
+		return PXENV_EXIT_FAILURE;
+	}
+
+	DBG ( " is %zd", ( ( size_t ) filesize ) );
+
+	get_file_size->FileSize = filesize;
+	get_file_size->Status = PXENV_STATUS_SUCCESS;
+	return PXENV_EXIT_SUCCESS;
+}
diff --git a/src/interface/pxe/pxe_tftp.c b/src/interface/pxe/pxe_tftp.c
index 5197a6310..64f7ffd51 100644
--- a/src/interface/pxe/pxe_tftp.c
+++ b/src/interface/pxe/pxe_tftp.c
@@ -79,6 +79,37 @@ static void pxe_tftp_build_uri ( char *uri_string,
 }
 
 /**
+ * Read as much as possible from file
+ *
+ * @v fd				File descriptor
+ * @v buffer				Data buffer
+ * @v max_len				Maximum length to read
+ * @ret len				Actual length read, or negative error
+ */
+static ssize_t pxe_tftp_read_all ( int fd, userptr_t buffer,
+				   size_t max_len ) {
+	fd_set fdset;
+	off_t offset = 0;
+	int ready;
+	ssize_t len;
+
+	do {
+		FD_ZERO ( &fdset );
+		FD_SET ( fd, &fdset );
+		ready = select ( &fdset, 1 );
+		if ( ready < 0 )
+			return ready;
+		len = read_user ( fd, buffer, offset, max_len );
+		if ( len < 0 )
+			return len;
+		offset += len;
+	        max_len -= len;
+	} while ( max_len && len );
+
+	return offset;
+}
+
+/**
  * TFTP OPEN
  *
  * @v tftp_open				Pointer to a struct s_PXENV_TFTP_OPEN
@@ -251,11 +282,12 @@ PXENV_EXIT_t pxenv_tftp_read ( struct s_PXENV_TFTP_READ *tftp_read ) {
 
 	buffer = real_to_user ( tftp_read->Buffer.segment,
 				tftp_read->Buffer.offset );
-	len = read_user ( pxe_single_fd, buffer, 0, pxe_single_blksize );
+	len = pxe_tftp_read_all ( pxe_single_fd, buffer, pxe_single_blksize );
 	if ( len < 0 ) {
 		tftp_read->Status = PXENV_STATUS ( len );
 		return PXENV_EXIT_FAILURE;
 	}
+
 	tftp_read->BufferSize = len;
 	tftp_read->PacketNumber = ++pxe_single_blkidx;
 
@@ -359,10 +391,8 @@ PXENV_EXIT_t pxenv_tftp_read_file ( struct s_PXENV_TFTP_READ_FILE
 	char uri_string[PXE_URI_LEN];
 	int fd;
 	userptr_t buffer;
-	size_t max_len;
-	ssize_t frag_len;
-	size_t len = 0;
-	int rc = -ENOBUFS;
+	ssize_t len;
+	int rc = 0;
 
 	DBG ( "PXENV_TFTP_READ_FILE" );
 
@@ -384,16 +414,9 @@ PXENV_EXIT_t pxenv_tftp_read_file ( struct s_PXENV_TFTP_READ_FILE
 
 	/* Read file */
 	buffer = phys_to_user ( tftp_read_file->Buffer );
-	max_len = tftp_read_file->BufferSize;
-	while ( max_len ) {
-		frag_len = read_user ( fd, buffer, len, max_len );
-		if ( frag_len <= 0 ) {
-			rc = frag_len;
-			break;
-		}
-		len += frag_len;
-		max_len -= frag_len;
-	}
+	len = pxe_tftp_read_all ( fd, buffer, tftp_read_file->BufferSize );
+	if ( len < 0 )
+		rc = len;
 
 	close ( fd );
 	tftp_read_file->BufferSize = len;