src/core/posix_io.c - ipxe - Git at Google

 /*
  * 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., 51 Franklin Street, Fifth Floor, Boston, MA
  * 02110-1301, USA.
  *
  * You can also choose to distribute this program under the terms of
  * the Unmodified Binary Distribution Licence (as given in the file
  * COPYING.UBDL), provided that you have satisfied its requirements.
  */

 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );

 #include <stdlib.h>
 #include <string.h>
 #include <errno.h>
 #include <ipxe/list.h>
 #include <ipxe/iobuf.h>
 #include <ipxe/xfer.h>
 #include <ipxe/open.h>
 #include <ipxe/process.h>
 #include <ipxe/posix_io.h>

 /** @file
  *
  * POSIX-like I/O
  *
  * These functions provide traditional blocking I/O semantics.  They
  * are designed to be used by the PXE TFTP API.  Because they block,
  * they may not be used by most other portions of the iPXE codebase.
  */

 /** An open file */
 struct posix_file {
 	/** Reference count for this object */
 	struct refcnt refcnt;
 	/** List of open files */
 	struct list_head list;
 	/** File descriptor */
 	int fd;
 	/** Overall status
 	 *
 	 * Set to -EINPROGRESS while data transfer is in progress.
 	 */
 	int rc;
 	/** Data transfer interface */
 	struct interface xfer;
 	/** Current seek position */
 	size_t pos;
 	/** File size */
 	size_t filesize;
 	/** Received data queue */
 	struct list_head data;
 };

 /** List of open files */
 static LIST_HEAD ( posix_files );

 /**
  * Free open file
  *
  * @v refcnt		Reference counter
  */
 static void posix_file_free ( struct refcnt *refcnt ) {
 	struct posix_file *file =
 		container_of ( refcnt, struct posix_file, refcnt );
 	struct io_buffer *iobuf;
 	struct io_buffer *tmp;

 	list_for_each_entry_safe ( iobuf, tmp, &file->data, list ) {
 		list_del ( &iobuf->list );
 		free_iob ( iobuf );
 	}
 	free ( file );
 }

 /**
  * Terminate file data transfer
  *
  * @v file		POSIX file
  * @v rc		Reason for termination
  */
 static void posix_file_finished ( struct posix_file *file, int rc ) {
 	intf_shutdown ( &file->xfer, rc );
 	file->rc = rc;
 }

 /**
  * Handle deliver_iob() event
  *
  * @v file		POSIX file
  * @v iobuf		I/O buffer
  * @v meta		Data transfer metadata
  * @ret rc		Return status code
  */
 static int posix_file_xfer_deliver ( struct posix_file *file,
 				     struct io_buffer *iobuf,
 				     struct xfer_metadata *meta ) {

 	/* Keep track of file position solely for the filesize */
 	if ( meta->flags & XFER_FL_ABS_OFFSET )
 		file->pos = 0;
 	file->pos += meta->offset;
 	if ( file->filesize < file->pos )
 		file->filesize = file->pos;

 	if ( iob_len ( iobuf ) ) {
 		list_add_tail ( &iobuf->list, &file->data );
 	} else {
 		free_iob ( iobuf );
 	}

 	return 0;
 }

 /** POSIX file data transfer interface operations */
 static struct interface_operation posix_file_xfer_operations[] = {
 	INTF_OP ( xfer_deliver, struct posix_file *, posix_file_xfer_deliver ),
 	INTF_OP ( intf_close, struct posix_file *, posix_file_finished ),
 };

 /** POSIX file data transfer interface descriptor */
 static struct interface_descriptor posix_file_xfer_desc =
 	INTF_DESC ( struct posix_file, xfer, posix_file_xfer_operations );

 /**
  * Identify file by file descriptor
  *
  * @v fd		File descriptor
  * @ret file		Corresponding file, or NULL
  */
 static struct posix_file * posix_fd_to_file ( int fd ) {
 	struct posix_file *file;

 	list_for_each_entry ( file, &posix_files, list ) {
 		if ( file->fd == fd )
 			return file;
 	}
 	return NULL;
 }

 /**
  * Find an available file descriptor
  *
  * @ret fd		File descriptor, or negative error number
  */
 static int posix_find_free_fd ( void ) {
 	int fd;

 	for ( fd = POSIX_FD_MIN ; fd <= POSIX_FD_MAX ; fd++ ) {
 		if ( ! posix_fd_to_file ( fd ) )
 			return fd;
 	}
 	DBG ( "POSIX could not find free file descriptor\n" );
 	return -ENFILE;
 }

 /**
  * Open file
  *
  * @v uri_string	URI string
  * @ret fd		File descriptor, or negative error number
  */
 int open ( const char *uri_string ) {
 	struct posix_file *file;
 	int fd;
 	int rc;

 	/* Find a free file descriptor to use */
 	fd = posix_find_free_fd();
 	if ( fd < 0 )
 		return fd;

 	/* Allocate and initialise structure */
 	file = zalloc ( sizeof ( *file ) );
 	if ( ! file )
 		return -ENOMEM;
 	ref_init ( &file->refcnt, posix_file_free );
 	file->fd = fd;
 	file->rc = -EINPROGRESS;
 	intf_init ( &file->xfer, &posix_file_xfer_desc, &file->refcnt );
 	INIT_LIST_HEAD ( &file->data );

 	/* Open URI on data transfer interface */
 	if ( ( rc = xfer_open_uri_string ( &file->xfer, uri_string ) ) != 0 )
 		goto err;

 	/* Wait for open to succeed or fail */
 	while ( list_empty ( &file->data ) ) {
 		step();
 		if ( file->rc == 0 )
 			break;
 		if ( file->rc != -EINPROGRESS ) {
 			rc = file->rc;
 			goto err;
 		}
 	}

 	/* Add to list of open files.  List takes reference ownership. */
 	list_add ( &file->list, &posix_files );
 	DBG ( "POSIX opened %s as file %d\n", uri_string, fd );
 	return fd;

  err:
 	posix_file_finished ( file, rc );
 	ref_put ( &file->refcnt );
 	return rc;
 }

 /**
  * 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 len;

 	/* Identify file */
 	file = posix_fd_to_file ( fd );
 	if ( ! file )
 		return -EBADF;

 	/* 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 );
 		}
 		file->pos += len;
 		assert ( len != 0 );
 		return len;
 	}

 	/* If file has completed, return (after returning all data) */
 	if ( file->rc != -EINPROGRESS ) {
 		assert ( list_empty ( &file->data ) );
 		return file->rc;
 	}

 	/* No data ready and file still in progress; return -WOULDBLOCK */
 	return -EWOULDBLOCK;
 }

 /**
  * Determine file size
  *
  * @v fd		File descriptor
  * @ret size		File size, or negative error number
  */
 ssize_t fsize ( int fd ) {
 	struct posix_file *file;

 	/* Identify file */
 	file = posix_fd_to_file ( fd );
 	if ( ! file )
 		return -EBADF;

 	return file->filesize;
 }

 /**
  * Close file
  *
  * @v fd		File descriptor
  * @ret rc		Return status code
  */
 int close ( int fd ) {
 	struct posix_file *file;

 	/* Identify file */
 	file = posix_fd_to_file ( fd );
 	if ( ! file )
 		return -EBADF;

 	/* Terminate data transfer */
 	posix_file_finished ( file, 0 );

 	/* Remove from list of open files and drop reference */
 	list_del ( &file->list );
 	ref_put ( &file->refcnt );
 	return 0;
 }
	/*
	* 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., 51 Franklin Street, Fifth Floor, Boston, MA
	* 02110-1301, USA.
	*
	* You can also choose to distribute this program under the terms of
	* the Unmodified Binary Distribution Licence (as given in the file
	* COPYING.UBDL), provided that you have satisfied its requirements.
	*/

	FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );

	#include <stdlib.h>
	#include <string.h>
	#include <errno.h>
	#include <ipxe/list.h>
	#include <ipxe/iobuf.h>
	#include <ipxe/xfer.h>
	#include <ipxe/open.h>
	#include <ipxe/process.h>
	#include <ipxe/posix_io.h>

	/** @file
	*
	* POSIX-like I/O
	*
	* These functions provide traditional blocking I/O semantics. They
	* are designed to be used by the PXE TFTP API. Because they block,
	* they may not be used by most other portions of the iPXE codebase.
	*/

	/** An open file */
	struct posix_file {
	/** Reference count for this object */
	struct refcnt refcnt;
	/** List of open files */
	struct list_head list;
	/** File descriptor */
	int fd;
	/** Overall status
	*
	* Set to -EINPROGRESS while data transfer is in progress.
	*/
	int rc;
	/** Data transfer interface */
	struct interface xfer;
	/** Current seek position */
	size_t pos;
	/** File size */
	size_t filesize;
	/** Received data queue */
	struct list_head data;
	};

	/** List of open files */
	static LIST_HEAD ( posix_files );

	/**
	* Free open file
	*
	* @v refcnt Reference counter
	*/
	static void posix_file_free ( struct refcnt *refcnt ) {
	struct posix_file *file =
	container_of ( refcnt, struct posix_file, refcnt );
	struct io_buffer *iobuf;
	struct io_buffer *tmp;

	list_for_each_entry_safe ( iobuf, tmp, &file->data, list ) {
	list_del ( &iobuf->list );
	free_iob ( iobuf );
	}
	free ( file );
	}

	/**
	* Terminate file data transfer
	*
	* @v file POSIX file
	* @v rc Reason for termination
	*/
	static void posix_file_finished ( struct posix_file *file, int rc ) {
	intf_shutdown ( &file->xfer, rc );
	file->rc = rc;
	}

	/**
	* Handle deliver_iob() event
	*
	* @v file POSIX file
	* @v iobuf I/O buffer
	* @v meta Data transfer metadata
	* @ret rc Return status code
	*/
	static int posix_file_xfer_deliver ( struct posix_file *file,
	struct io_buffer *iobuf,
	struct xfer_metadata *meta ) {

	/* Keep track of file position solely for the filesize */
	if ( meta->flags & XFER_FL_ABS_OFFSET )
	file->pos = 0;
	file->pos += meta->offset;
	if ( file->filesize < file->pos )
	file->filesize = file->pos;

	if ( iob_len ( iobuf ) ) {
	list_add_tail ( &iobuf->list, &file->data );
	} else {
	free_iob ( iobuf );
	}

	return 0;
	}

	/** POSIX file data transfer interface operations */
	static struct interface_operation posix_file_xfer_operations[] = {
	INTF_OP ( xfer_deliver, struct posix_file *, posix_file_xfer_deliver ),
	INTF_OP ( intf_close, struct posix_file *, posix_file_finished ),
	};

	/** POSIX file data transfer interface descriptor */
	static struct interface_descriptor posix_file_xfer_desc =
	INTF_DESC ( struct posix_file, xfer, posix_file_xfer_operations );

	/**
	* Identify file by file descriptor
	*
	* @v fd File descriptor
	* @ret file Corresponding file, or NULL
	*/
	static struct posix_file * posix_fd_to_file ( int fd ) {
	struct posix_file *file;

	list_for_each_entry ( file, &posix_files, list ) {
	if ( file->fd == fd )
	return file;
	}
	return NULL;
	}

	/**
	* Find an available file descriptor
	*
	* @ret fd File descriptor, or negative error number
	*/
	static int posix_find_free_fd ( void ) {
	int fd;

	for ( fd = POSIX_FD_MIN ; fd <= POSIX_FD_MAX ; fd++ ) {
	if ( ! posix_fd_to_file ( fd ) )
	return fd;
	}
	DBG ( "POSIX could not find free file descriptor\n" );
	return -ENFILE;
	}

	/**
	* Open file
	*
	* @v uri_string URI string
	* @ret fd File descriptor, or negative error number
	*/
	int open ( const char *uri_string ) {
	struct posix_file *file;
	int fd;
	int rc;

	/* Find a free file descriptor to use */
	fd = posix_find_free_fd();
	if ( fd < 0 )
	return fd;

	/* Allocate and initialise structure */
	file = zalloc ( sizeof ( *file ) );
	if ( ! file )
	return -ENOMEM;
	ref_init ( &file->refcnt, posix_file_free );
	file->fd = fd;
	file->rc = -EINPROGRESS;
	intf_init ( &file->xfer, &posix_file_xfer_desc, &file->refcnt );
	INIT_LIST_HEAD ( &file->data );

	/* Open URI on data transfer interface */
	if ( ( rc = xfer_open_uri_string ( &file->xfer, uri_string ) ) != 0 )
	goto err;

	/* Wait for open to succeed or fail */
	while ( list_empty ( &file->data ) ) {
	step();
	if ( file->rc == 0 )
	break;
	if ( file->rc != -EINPROGRESS ) {
	rc = file->rc;
	goto err;
	}
	}

	/* Add to list of open files. List takes reference ownership. */
	list_add ( &file->list, &posix_files );
	DBG ( "POSIX opened %s as file %d\n", uri_string, fd );
	return fd;

	err:
	posix_file_finished ( file, rc );
	ref_put ( &file->refcnt );
	return rc;
	}

	/**
	* 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 len;

	/* Identify file */
	file = posix_fd_to_file ( fd );
	if ( ! file )
	return -EBADF;

	/* 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 );
	}
	file->pos += len;
	assert ( len != 0 );
	return len;
	}

	/* If file has completed, return (after returning all data) */
	if ( file->rc != -EINPROGRESS ) {
	assert ( list_empty ( &file->data ) );
	return file->rc;
	}

	/* No data ready and file still in progress; return -WOULDBLOCK */
	return -EWOULDBLOCK;
	}

	/**
	* Determine file size
	*
	* @v fd File descriptor
	* @ret size File size, or negative error number
	*/
	ssize_t fsize ( int fd ) {
	struct posix_file *file;

	/* Identify file */
	file = posix_fd_to_file ( fd );
	if ( ! file )
	return -EBADF;

	return file->filesize;
	}

	/**
	* Close file
	*
	* @v fd File descriptor
	* @ret rc Return status code
	*/
	int close ( int fd ) {
	struct posix_file *file;

	/* Identify file */
	file = posix_fd_to_file ( fd );
	if ( ! file )
	return -EBADF;

	/* Terminate data transfer */
	posix_file_finished ( file, 0 );

	/* Remove from list of open files and drop reference */
	list_del ( &file->list );
	ref_put ( &file->refcnt );
	return 0;
	}