text: /*
   * 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;
  }
  