[PATCH 15/39] NLKD - early pseudo-fs

["Jan Beulich" <JBeulich@novell.com>]

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While for limited amounts of configuration information the kernel
command line may be suitable, it isn't when it comes to significant
amounts of configurable entities that need to be set before the full
kernel infrastructure is available. This patch adds functionality to
pass one or more configuration files through the initrd, but without
requiring knowledge of the actual structure (including compression) of
it; the file(s) is/are attached to the end of the already built
initrd (which obviously depends on external scripts not provided
here).

Signed-Off-By: Jan Beulich <jbeulich@novell.com>

(actual patch attached)


[-- Attachment #2: linux-2.6.14-nlkd-early-pseudo-fs.patch --]
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While for limited amounts of configuration information the kernel
command line may be suitable, it isn't when it comes to significant
amounts of configurable entities that need to be set before the full
kernel infrastructure is available. This patch adds functionality to
pass one or more configuration files through the initrd, but without
requiring knowledge of the actual structure (including compression) of
it; the file(s) is/are attached to the end of the already built
initrd (which obviously depends on external scripts not provided
here).

Signed-Off-By: Jan Beulich <jbeulich@novell.com>

Index: 2.6.14-nlkd/include/linux/epfs.h
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ 2.6.14-nlkd/include/linux/epfs.h	2005-06-27 12:48:32.000000000 +0200
@@ -0,0 +1,56 @@
+/*****************************************************************************
+ *
+ *   File Name:      epfs.h
+ *   Created by:     Jan Beulich
+ *   Date created:   28Apr2005
+ *
+ *   %version:       2 %
+ *   %derived_by:    jbeulich %
+ *   %date_modified: Mon Jun 27 04:48:22 2005 %
+ *
+ *****************************************************************************/
+/*****************************************************************************
+ *                                                                           *
+ * Copyright (c) 2005 Novell, Inc. All Rights Reserved.                      *
+ *                                                                           *
+ * This program is free software; you can redistribute it and/or             *
+ * modify it under the terms of version 2 of the GNU General Public License  *
+ * as published by the Free Software Foundation.                             *
+ *                                                                           *
+ * 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, contact Novell, Inc.                     *
+ *                                                                           *
+ * To contact Novell about this file by physical or electronic mail,         *
+ * you may find current contact information at www.novell.com.               *
+ *                                                                           *
+ *****************************************************************************/
+/*****************************************************************************
+ *
+ *	File Description:
+ *
+ *****************************************************************************/
+#ifndef _LINUX_EPFS_H
+
+#include <linux/config.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+
+#if defined(CONFIG_EARLY_PSEUDO_FS) && !defined(MODULE)
+# define EPFS_DECLARE(proto, retval) proto;
+#else
+# define EPFS_DECLARE(proto, retval) static inline proto { return retval; }
+#endif
+
+EPFS_DECLARE(int epfs_open(const char *name), -ENOSYS)
+EPFS_DECLARE(size_t epfs_get_size(int fd), ~(size_t)0)
+EPFS_DECLARE(size_t epfs_read(int fd, size_t pos, void *buf, size_t size), ~(size_t)0)
+EPFS_DECLARE(int epfs_close(int fd), -ENOSYS)
+
+#undef EPFS_DECLARE
+
+#endif /* _LINUX_EPFS_H */
Index: 2.6.14-nlkd/init/Kconfig
===================================================================
--- 2.6.14-nlkd.orig/init/Kconfig	2005-11-09 10:19:35.000000000 +0100
+++ 2.6.14-nlkd/init/Kconfig	2005-11-07 10:51:19.000000000 +0100
@@ -340,6 +340,16 @@ config BASE_FULL
 	  kernel data structures. This saves memory on small machines,
 	  but may reduce performance.
 
+config EARLY_PSEUDO_FS
+	bool "Early pseudo file system support"
+	depends on BLK_DEV_INITRD
+	---help---
+	  This pseudo file system allows access to certain (configuration)
+	  files before any real file system is available. A matching mkinitrd
+	  or similar script is required to actually make use of this.
+
+	  If unsure, say N.
+
 config FUTEX
 	bool "Enable futex support" if EMBEDDED
 	default y
Index: 2.6.14-nlkd/init/Makefile
===================================================================
--- 2.6.14-nlkd.orig/init/Makefile	2005-11-09 10:40:17.000000000 +0100
+++ 2.6.14-nlkd/init/Makefile	2005-11-04 16:19:34.000000000 +0100
@@ -4,6 +4,7 @@
 
 obj-y				:= main.o version.o mounts.o initramfs.o
 obj-$(CONFIG_GENERIC_CALIBRATE_DELAY) += calibrate.o
+obj-$(CONFIG_EARLY_PSEUDO_FS)	+= epfs.o
 
 mounts-y			:= do_mounts.o
 mounts-$(CONFIG_DEVFS_FS)	+= do_mounts_devfs.o
Index: 2.6.14-nlkd/init/epfs.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ 2.6.14-nlkd/init/epfs.c	2005-06-27 16:02:28.000000000 +0200
@@ -0,0 +1,151 @@
+/*****************************************************************************
+ *
+ *   File Name:      epfs.c
+ *   Created by:     Jan Beulich
+ *   Date created:   28Apr2005
+ *
+ *   %version:       2 %
+ *   %derived_by:    jbeulich %
+ *   %date_modified: Mon Jun 27 08:02:17 2005 %
+ *
+ *****************************************************************************/
+/*****************************************************************************
+ *                                                                           *
+ * Copyright (c) 2005 Novell, Inc. All Rights Reserved.                      *
+ *                                                                           *
+ * This program is free software; you can redistribute it and/or             *
+ * modify it under the terms of version 2 of the GNU General Public License  *
+ * as published by the Free Software Foundation.                             *
+ *                                                                           *
+ * 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, contact Novell, Inc.                     *
+ *                                                                           *
+ * To contact Novell about this file by physical or electronic mail,         *
+ * you may find current contact information at www.novell.com.               *
+ *                                                                           *
+ *****************************************************************************/
+/*****************************************************************************
+ *
+ *	File Description:
+ *
+ *****************************************************************************/
+#include <linux/epfs.h>
+#include <linux/init.h>
+#include <linux/initrd.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+
+static inline int __init check_sys(void)
+{
+	return initrd_start && initrd_end > initrd_start;
+}
+
+static const char *__init find(const char *target, int *fd)
+{
+	const char *const start = (char *)initrd_start;
+	const char *ptr = (char *)initrd_end - 1;
+	const char *found = NULL;
+	size_t prev;
+
+	/* check initial link */
+	if (*ptr) {
+		*fd = -ENOSYS;
+		return NULL;
+	}
+	while (--ptr > start)
+		if ((*ptr < '0' || *ptr > '9') && (*ptr < 'A' || *ptr > 'F'))
+			break;
+	if (ptr <= start || *ptr) {
+		*fd = -ENOSYS;
+		return NULL;
+	}
+	if (target)
+		*fd = 0;
+	/* scan list */
+	for (prev = ptr - start; ; ) {
+		char *tail;
+		const size_t cur = simple_strtoul(ptr + 1, &tail, 16);
+		const char *const name = start + cur;
+		size_t size;
+
+		if (!*tail && !cur)
+			break;
+		if (*tail
+		    || cur <= 0
+		    || cur >= prev
+		    || *name != '/'
+		    || (tail = memchr(name, 0, prev - cur)) == NULL
+		    || (ptr = memchr(tail + 1, 0, (prev - cur) - (tail + 1 - name))) == NULL
+		    || (size = simple_strtoul(tail + 1, &tail, 16), tail != ptr)
+		    || (tail = memchr(ptr + 1, 0, (prev - cur) - (ptr + 1 - name))) == NULL
+		    || size + (tail + 1 - name) != prev - cur) {
+			*fd = -ENOSYS;
+			break;
+		}
+		if (!found) {
+			if (target) {
+				++*fd;
+				if(!strcmp(target, name))
+					found = name;
+			}
+			else if (!--*fd)
+				found = name;
+		}
+		prev = cur;
+	}
+	return found;
+}
+
+int __init epfs_open(const char *name)
+{
+	int fd;
+
+	if (!check_sys())
+		return -ENOSYS;
+	if (!name)
+		return -EINVAL;
+	if (!find(name, &fd))
+		return -ENOENT;
+	return fd;
+}
+
+size_t __init epfs_get_size(int fd)
+{
+	const char *start;
+
+	if (!check_sys() || !(start = find(NULL, &fd)))
+		return ~(size_t)0;
+	return simple_strtoul(start + strlen(start) + 1, NULL, 16);
+}
+
+size_t __init epfs_read(int fd, size_t pos, void *buf, size_t len)
+{
+	const char *start;
+	size_t size;
+
+	if (!check_sys() || !(start = find(NULL, &fd)))
+		return ~(size_t)0;
+	size = simple_strtoul(start += strlen(start) + 1, NULL, 16);
+	if (pos >= size)
+		return 0;
+	if (len > size - pos)
+		len = size - pos;
+	start += strlen(start) + 1; /* skip size */
+	start += strlen(start) + 1; /* skip link */
+	memcpy(buf, start + pos, len);
+	return size;
+}
+
+int __init epfs_close(int fd)
+{
+	if (!check_sys())
+		return -ENOSYS;
+	if (!find(NULL, &fd))
+		return -EINVAL;
+	return 0;
+}