--- /dev/null
+/*
+ * 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 (at your option) 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 <errno.h>
+#include <ipxe/ansiesc.h>
+#include <ipxe/settings.h>
+#include <ipxe/console.h>
+
+/** @file
+ *
+ * In-memory ring buffer console
+ *
+ */
+
+/* Set default console usage if applicable */
+#if ! ( defined ( CONSOLE_DMESG ) && CONSOLE_EXPLICIT ( CONSOLE_DMESG ) )
+#undef CONSOLE_DMESG
+#define CONSOLE_DMESG ( CONSOLE_USAGE_ALL & ~CONSOLE_USAGE_TUI )
+#endif
+
+/** Size of ring buffer */
+#define DMESG_LEN 8192
+
+/** Ring buffer */
+static char dmesg[DMESG_LEN];
+
+/** Offset within ring buffer */
+static unsigned int dmesg_offset;
+
+/** Ring buffer ANSI escape sequence handlers */
+static struct ansiesc_handler dmesg_ansiesc_handlers[] = {
+ { 0, NULL }
+};
+
+/** Ring buffer ANSI escape sequence context */
+static struct ansiesc_context dmesg_ansiesc_ctx = {
+ .handlers = dmesg_ansiesc_handlers,
+};
+
+/**
+ * Print a character to the ring buffer
+ *
+ * @v character Character to be printed
+ */
+static void dmesg_putchar ( int character ) {
+
+ /* Strip ANSI escape sequences */
+ character = ansiesc_process ( &dmesg_ansiesc_ctx, character );
+ if ( character < 0 )
+ return;
+
+ /* Handle backspace characters */
+ if ( character == '\b' ) {
+ if ( dmesg_offset )
+ dmesg_offset--;
+ return;
+ }
+
+ /* Record character */
+ dmesg[ dmesg_offset++ % DMESG_LEN ] = character;
+}
+
+/** Ring buffer console driver */
+struct console_driver dmesg_console __console_driver = {
+ .putchar = dmesg_putchar,
+ .usage = CONSOLE_DMESG,
+};
+
+/**
+ * Fetch ring buffer setting
+ *
+ * @v data Buffer to fill with setting data
+ * @v len Length of buffer
+ * @ret len Length of setting data, or negative error
+ */
+static int dmesg_fetch ( void *data, size_t len ) {
+ uint8_t *bytes = data;
+ size_t max;
+ unsigned int offset;
+
+ /* Calculate length */
+ max = dmesg_offset;
+ if ( max > DMESG_LEN )
+ max = DMESG_LEN;
+ if ( len > max )
+ len = max;
+
+ /* Copy data */
+ offset = ( dmesg_offset - len );
+ while ( len-- )
+ *(bytes++) = dmesg[ offset++ % DMESG_LEN ];
+
+ return max;
+}
+
+/**
+ * Store ring buffer setting
+ *
+ * @v data Setting data, or NULL to clear setting
+ * @v len Length of setting data
+ * @ret rc Return status code
+ */
+static int dmesg_store ( const void *data __unused, size_t len ) {
+
+ /* Only clearing the log is supported */
+ if ( len )
+ return -ENOTSUP;
+
+ /* Clear log */
+ dmesg_offset = 0;
+
+ return 0;
+}
+
+/** Ring buffer setting */
+const struct setting dmesg_setting __setting ( SETTING_MISC, dmesg ) = {
+ .name = "dmesg",
+ .description = "Ring buffer",
+ .type = &setting_type_string,
+ .scope = &builtin_scope,
+};
+
+/** Ring buffer built-in setting */
+struct builtin_setting dmesg_builtin_setting __builtin_setting = {
+ .setting = &dmesg_setting,
+ .fetch = dmesg_fetch,
+ .store = dmesg_store,
+};
projects / thirdparty / ipxe.git / commitdiff
