disklog.c

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/*
 * Copyright (C) 2026 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 );
FILE_SECBOOT ( PERMITTED );
 
#include <assert.h>
#include <errno.h>
#include <string.h>
#include <ipxe/disklog.h>
 
/** @file
 *
 * Disk log console
 *
 */
 
/**
 * Open disk log console
 *
 * @v disklog           Disk log
 * @ret rc              Return status code
 *
 * The data buffer must already contain the initial logical block.
 */
int disklog_open ( struct disklog *disklog ) {
        struct disklog_header *hdr =
                ( ( struct disklog_header * ) disklog->buffer );
 
        /* Sanity checks */
        assert ( disklog->console != NULL );
        assert ( disklog->buffer != NULL );
        assert ( disklog->blksize > 0 );
        assert ( ( disklog->blksize & ( disklog->blksize - 1 ) ) == 0 );
        assert ( disklog->lba <= disklog->max_lba );
        assert ( disklog->op != NULL );
        assert ( disklog->op->write != NULL );
 
        /* Check magic signature */
        if ( ( disklog->blksize < sizeof ( *hdr ) ) ||
             ( memcmp ( hdr->magic, DISKLOG_MAGIC,
                        sizeof ( hdr->magic ) ) != 0 ) ) {
                DBGC ( disklog, "DISKLOG has bad magic signature\n" );
                return -EINVAL;
        }
 
        /* Initialise buffer */
        disklog->offset = sizeof ( *hdr );
        disklog->unwritten = 0;
        memset ( ( disklog->buffer + sizeof ( *hdr ) ), 0,
                 ( disklog->blksize - sizeof ( *hdr ) ) );
 
        /* Enable console */
        disklog->console->disabled = 0;
 
        return 0;
}
 
/**
 * Write character to disk log console
 *
 * @v disklog           Disk log
 * @v character         Character
 */
void disklog_putchar ( struct disklog *disklog, int character ) {
        static int busy;
        int rc;
 
        /* Ignore if we are already mid-logging */
        if ( busy )
                return;
        busy = 1;
 
        /* Sanity checks */
        assert ( disklog->offset < disklog->blksize );
 
        /* Write character to buffer */
        disklog->buffer[disklog->offset++] = character;
        disklog->unwritten++;
 
        /* Write sector to disk, if applicable */
        if ( ( disklog->offset == disklog->blksize ) ||
             ( disklog->unwritten == DISKLOG_MAX_UNWRITTEN ) ||
             ( character == '\n' ) ) {
 
                /* Write sector to disk */
                if ( ( rc = disklog->op->write() ) != 0 ) {
                        DBGC ( disklog, "DISKLOG could not write: %s\n",
                               strerror ( rc ) );
                        /* Ignore and continue; there's nothing we can do */
                }
 
                /* Reset count of unwritten characters */
                disklog->unwritten = 0;
        }
 
        /* Move to next sector, if applicable */
        if ( disklog->offset == disklog->blksize ) {
 
                /* Disable console if we have run out of space */
                if ( disklog->lba >= disklog->max_lba )
                        disklog->console->disabled = 1;
 
                /* Clear log buffer */
                memset ( disklog->buffer, 0, disklog->blksize );
                disklog->offset = 0;
 
                /* Move to next sector */
                disklog->lba++;
        }
 
        /* Clear busy flag */
        busy = 0;
}