X.509: Add simple ASN.1 grammar compiler

Add a simple ASN.1 grammar compiler.  This produces a bytecode output that can
be fed to a decoder to inform the decoder how to interpret the ASN.1 stream it
is trying to parse.

Action functions can be specified in the grammar by interpolating:

	({ foo })

after a type, for example:

	SubjectPublicKeyInfo ::= SEQUENCE {
		algorithm		AlgorithmIdentifier,
		subjectPublicKey	BIT STRING ({ do_key_data })
		}

The decoder is expected to call these after matching this type and parsing the
contents if it is a constructed type.

The grammar compiler does not currently support the SET type (though it does
support SET OF) as I can't see a good way of tracking which members have been
encountered yet without using up extra stack space.

Currently, the grammar compiler will fail if more than 256 bytes of bytecode
would be produced or more than 256 actions have been specified as it uses
8-bit jump values and action indices to keep space usage down.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

7 files changed, 1721 insertions, 0 deletions

diff --git a/include/linux/asn1.h b/include/linux/asn1.h
new file mode 100644
index 00000000000..5c3f4e4b9a2
--- /dev/null
+++ b/include/linux/asn1.h
@@ -0,0 +1,67 @@
+/* ASN.1 BER/DER/CER encoding definitions
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#ifndef _LINUX_ASN1_H
+#define _LINUX_ASN1_H
+
+/* Class */
+enum asn1_class {
+	ASN1_UNIV	= 0,	/* Universal */
+	ASN1_APPL	= 1,	/* Application */
+	ASN1_CONT	= 2,	/* Context */
+	ASN1_PRIV	= 3	/* Private */
+};
+#define ASN1_CLASS_BITS	0xc0
+
+
+enum asn1_method {
+	ASN1_PRIM	= 0,	/* Primitive */
+	ASN1_CONS	= 1	/* Constructed */
+};
+#define ASN1_CONS_BIT	0x20
+
+/* Tag */
+enum asn1_tag {
+	ASN1_EOC	= 0,	/* End Of Contents or N/A */
+	ASN1_BOOL	= 1,	/* Boolean */
+	ASN1_INT	= 2,	/* Integer */
+	ASN1_BTS	= 3,	/* Bit String */
+	ASN1_OTS	= 4,	/* Octet String */
+	ASN1_NULL	= 5,	/* Null */
+	ASN1_OID	= 6,	/* Object Identifier  */
+	ASN1_ODE	= 7,	/* Object Description */
+	ASN1_EXT	= 8,	/* External */
+	ASN1_REAL	= 9,	/* Real float */
+	ASN1_ENUM	= 10,	/* Enumerated */
+	ASN1_EPDV	= 11,	/* Embedded PDV */
+	ASN1_UTF8STR	= 12,	/* UTF8 String */
+	ASN1_RELOID	= 13,	/* Relative OID */
+	/* 14 - Reserved */
+	/* 15 - Reserved */
+	ASN1_SEQ	= 16,	/* Sequence and Sequence of */
+	ASN1_SET	= 17,	/* Set and Set of */
+	ASN1_NUMSTR	= 18,	/* Numerical String */
+	ASN1_PRNSTR	= 19,	/* Printable String */
+	ASN1_TEXSTR	= 20,	/* T61 String / Teletext String */
+	ASN1_VIDSTR	= 21,	/* Videotex String */
+	ASN1_IA5STR	= 22,	/* IA5 String */
+	ASN1_UNITIM	= 23,	/* Universal Time */
+	ASN1_GENTIM	= 24,	/* General Time */
+	ASN1_GRASTR	= 25,	/* Graphic String */
+	ASN1_VISSTR	= 26,	/* Visible String */
+	ASN1_GENSTR	= 27,	/* General String */
+	ASN1_UNISTR	= 28,	/* Universal String */
+	ASN1_CHRSTR	= 29,	/* Character String */
+	ASN1_BMPSTR	= 30,	/* BMP String */
+	ASN1_LONG_TAG	= 31	/* Long form tag */
+};
+
+#endif /* _LINUX_ASN1_H */
diff --git a/include/linux/asn1_ber_bytecode.h b/include/linux/asn1_ber_bytecode.h
new file mode 100644
index 00000000000..945d44ae529
--- /dev/null
+++ b/include/linux/asn1_ber_bytecode.h
@@ -0,0 +1,87 @@
+/* ASN.1 BER/DER/CER parsing state machine internal definitions
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#ifndef _LINUX_ASN1_BER_BYTECODE_H
+#define _LINUX_ASN1_BER_BYTECODE_H
+
+#ifdef __KERNEL__
+#include <linux/types.h>
+#endif
+#include <linux/asn1.h>
+
+typedef int (*asn1_action_t)(void *context,
+			     size_t hdrlen, /* In case of ANY type */
+			     unsigned char tag, /* In case of ANY type */
+			     const void *value, size_t vlen);
+
+struct asn1_decoder {
+	const unsigned char *machine;
+	size_t machlen;
+	const asn1_action_t *actions;
+};
+
+enum asn1_opcode {
+	/* The tag-matching ops come first and the odd-numbered slots
+	 * are for OR_SKIP ops.
+	 */
+#define ASN1_OP_MATCH__SKIP		  0x01
+#define ASN1_OP_MATCH__ACT		  0x02
+#define ASN1_OP_MATCH__JUMP		  0x04
+#define ASN1_OP_MATCH__ANY		  0x08
+#define ASN1_OP_MATCH__COND		  0x10
+
+	ASN1_OP_MATCH			= 0x00,
+	ASN1_OP_MATCH_OR_SKIP		= 0x01,
+	ASN1_OP_MATCH_ACT		= 0x02,
+	ASN1_OP_MATCH_ACT_OR_SKIP	= 0x03,
+	ASN1_OP_MATCH_JUMP		= 0x04,
+	ASN1_OP_MATCH_JUMP_OR_SKIP	= 0x05,
+	ASN1_OP_MATCH_ANY		= 0x08,
+	ASN1_OP_MATCH_ANY_ACT		= 0x0a,
+	/* Everything before here matches unconditionally */
+
+	ASN1_OP_COND_MATCH_OR_SKIP	= 0x11,
+	ASN1_OP_COND_MATCH_ACT_OR_SKIP	= 0x13,
+	ASN1_OP_COND_MATCH_JUMP_OR_SKIP	= 0x15,
+	ASN1_OP_COND_MATCH_ANY		= 0x18,
+	ASN1_OP_COND_MATCH_ANY_ACT	= 0x1a,
+
+	/* Everything before here will want a tag from the data */
+#define ASN1_OP__MATCHES_TAG ASN1_OP_COND_MATCH_ANY_ACT
+
+	/* These are here to help fill up space */
+	ASN1_OP_COND_FAIL		= 0x1b,
+	ASN1_OP_COMPLETE		= 0x1c,
+	ASN1_OP_ACT			= 0x1d,
+	ASN1_OP_RETURN			= 0x1e,
+
+	/* The following eight have bit 0 -> SET, 1 -> OF, 2 -> ACT */
+	ASN1_OP_END_SEQ			= 0x20,
+	ASN1_OP_END_SET			= 0x21,
+	ASN1_OP_END_SEQ_OF		= 0x22,
+	ASN1_OP_END_SET_OF		= 0x23,
+	ASN1_OP_END_SEQ_ACT		= 0x24,
+	ASN1_OP_END_SET_ACT		= 0x25,
+	ASN1_OP_END_SEQ_OF_ACT		= 0x26,
+	ASN1_OP_END_SET_OF_ACT		= 0x27,
+#define ASN1_OP_END__SET		  0x01
+#define ASN1_OP_END__OF			  0x02
+#define ASN1_OP_END__ACT		  0x04
+
+	ASN1_OP__NR
+};
+
+#define _tag(CLASS, CP, TAG) ((ASN1_##CLASS << 6) | (ASN1_##CP << 5) | ASN1_##TAG)
+#define _tagn(CLASS, CP, TAG) ((ASN1_##CLASS << 6) | (ASN1_##CP << 5) | TAG)
+#define _jump_target(N) (N)
+#define _action(N) (N)
+
+#endif /* _LINUX_ASN1_BER_BYTECODE_H */
diff --git a/init/Kconfig b/init/Kconfig
index af6c7f8ba01..66cc885abbc 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1612,4 +1612,12 @@ config PADATA
 	depends on SMP
 	bool
 
+config ASN1
+	tristate
+	help
+	  Build a simple ASN.1 grammar compiler that produces a bytecode output
+	  that can be interpreted by the ASN.1 stream decoder and used to
+	  inform it as to what tags are to be expected in a stream and what
+	  functions to call on what tags.
+
 source "kernel/Kconfig.locks"
diff --git a/scripts/.gitignore b/scripts/.gitignore
index 65f362d931b..fb070fa1038 100644
--- a/scripts/.gitignore
+++ b/scripts/.gitignore
@@ -10,3 +10,4 @@ ihex2fw
 recordmcount
 docproc
 sortextable
+asn1_compiler
diff --git a/scripts/Makefile b/scripts/Makefile
index a55b0067758..01e7adb838d 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -16,8 +16,10 @@ hostprogs-$(CONFIG_VT)           += conmakehash
 hostprogs-$(CONFIG_IKCONFIG)     += bin2c
 hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount
 hostprogs-$(CONFIG_BUILDTIME_EXTABLE_SORT) += sortextable
+hostprogs-$(CONFIG_ASN1)	 += asn1_compiler
 
 HOSTCFLAGS_sortextable.o = -I$(srctree)/tools/include
+HOSTCFLAGS_asn1_compiler.o = -I$(srctree)/include
 
 always		:= $(hostprogs-y) $(hostprogs-m)
 
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index ff1720d28d0..0e801c3cdaf 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -354,6 +354,17 @@ quiet_cmd_cpp_lds_S = LDS     $@
 $(obj)/%.lds: $(src)/%.lds.S FORCE
 	$(call if_changed_dep,cpp_lds_S)
 
+# ASN.1 grammar
+# ---------------------------------------------------------------------------
+quiet_cmd_asn1_compiler = ASN.1   $@
+      cmd_asn1_compiler = $(objtree)/scripts/asn1_compiler $< \
+				$(subst .h,.c,$@) $(subst .c,.h,$@)
+
+.PRECIOUS: $(objtree)/$(obj)/%-asn1.c $(objtree)/$(obj)/%-asn1.h
+
+$(obj)/%-asn1.c $(obj)/%-asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler
+	$(call cmd,asn1_compiler)
+
 # Build the compiled-in targets
 # ---------------------------------------------------------------------------
 
diff --git a/scripts/asn1_compiler.c b/scripts/asn1_compiler.c
new file mode 100644
index 00000000000..db0e5cd34c7
--- /dev/null
+++ b/scripts/asn1_compiler.c
@@ -0,0 +1,1545 @@
+/* Simplified ASN.1 notation parser
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <ctype.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <linux/asn1_ber_bytecode.h>
+
+enum token_type {
+	DIRECTIVE_ABSENT,
+	DIRECTIVE_ALL,
+	DIRECTIVE_ANY,
+	DIRECTIVE_APPLICATION,
+	DIRECTIVE_AUTOMATIC,
+	DIRECTIVE_BEGIN,
+	DIRECTIVE_BIT,
+	DIRECTIVE_BMPString,
+	DIRECTIVE_BOOLEAN,
+	DIRECTIVE_BY,
+	DIRECTIVE_CHARACTER,
+	DIRECTIVE_CHOICE,
+	DIRECTIVE_CLASS,
+	DIRECTIVE_COMPONENT,
+	DIRECTIVE_COMPONENTS,
+	DIRECTIVE_CONSTRAINED,
+	DIRECTIVE_CONTAINING,
+	DIRECTIVE_DEFAULT,
+	DIRECTIVE_DEFINED,
+	DIRECTIVE_DEFINITIONS,
+	DIRECTIVE_EMBEDDED,
+	DIRECTIVE_ENCODED,
+	DIRECTIVE_ENCODING_CONTROL,
+	DIRECTIVE_END,
+	DIRECTIVE_ENUMERATED,
+	DIRECTIVE_EXCEPT,
+	DIRECTIVE_EXPLICIT,
+	DIRECTIVE_EXPORTS,
+	DIRECTIVE_EXTENSIBILITY,
+	DIRECTIVE_EXTERNAL,
+	DIRECTIVE_FALSE,
+	DIRECTIVE_FROM,
+	DIRECTIVE_GeneralString,
+	DIRECTIVE_GeneralizedTime,
+	DIRECTIVE_GraphicString,
+	DIRECTIVE_IA5String,
+	DIRECTIVE_IDENTIFIER,
+	DIRECTIVE_IMPLICIT,
+	DIRECTIVE_IMPLIED,
+	DIRECTIVE_IMPORTS,
+	DIRECTIVE_INCLUDES,
+	DIRECTIVE_INSTANCE,
+	DIRECTIVE_INSTRUCTIONS,
+	DIRECTIVE_INTEGER,
+	DIRECTIVE_INTERSECTION,
+	DIRECTIVE_ISO646String,
+	DIRECTIVE_MAX,
+	DIRECTIVE_MIN,
+	DIRECTIVE_MINUS_INFINITY,
+	DIRECTIVE_NULL,
+	DIRECTIVE_NumericString,
+	DIRECTIVE_OBJECT,
+	DIRECTIVE_OCTET,
+	DIRECTIVE_OF,
+	DIRECTIVE_OPTIONAL,
+	DIRECTIVE_ObjectDescriptor,
+	DIRECTIVE_PATTERN,
+	DIRECTIVE_PDV,
+	DIRECTIVE_PLUS_INFINITY,
+	DIRECTIVE_PRESENT,
+	DIRECTIVE_PRIVATE,
+	DIRECTIVE_PrintableString,
+	DIRECTIVE_REAL,
+	DIRECTIVE_RELATIVE_OID,
+	DIRECTIVE_SEQUENCE,
+	DIRECTIVE_SET,
+	DIRECTIVE_SIZE,
+	DIRECTIVE_STRING,
+	DIRECTIVE_SYNTAX,
+	DIRECTIVE_T61String,
+	DIRECTIVE_TAGS,
+	DIRECTIVE_TRUE,
+	DIRECTIVE_TeletexString,
+	DIRECTIVE_UNION,
+	DIRECTIVE_UNIQUE,
+	DIRECTIVE_UNIVERSAL,
+	DIRECTIVE_UTCTime,
+	DIRECTIVE_UTF8String,
+	DIRECTIVE_UniversalString,
+	DIRECTIVE_VideotexString,
+	DIRECTIVE_VisibleString,
+	DIRECTIVE_WITH,
+	NR__DIRECTIVES,
+	TOKEN_ASSIGNMENT = NR__DIRECTIVES,
+	TOKEN_OPEN_CURLY,
+	TOKEN_CLOSE_CURLY,
+	TOKEN_OPEN_SQUARE,
+	TOKEN_CLOSE_SQUARE,
+	TOKEN_OPEN_ACTION,
+	TOKEN_CLOSE_ACTION,
+	TOKEN_COMMA,
+	TOKEN_NUMBER,
+	TOKEN_TYPE_NAME,
+	TOKEN_ELEMENT_NAME,
+	NR__TOKENS
+};
+
+static const unsigned char token_to_tag[NR__TOKENS] = {
+	/* EOC goes first */
+	[DIRECTIVE_BOOLEAN]		= ASN1_BOOL,
+	[DIRECTIVE_INTEGER]		= ASN1_INT,
+	[DIRECTIVE_BIT]			= ASN1_BTS,
+	[DIRECTIVE_OCTET]		= ASN1_OTS,
+	[DIRECTIVE_NULL]		= ASN1_NULL,
+	[DIRECTIVE_OBJECT]		= ASN1_OID,
+	[DIRECTIVE_ObjectDescriptor]	= ASN1_ODE,
+	[DIRECTIVE_EXTERNAL]		= ASN1_EXT,
+	[DIRECTIVE_REAL]		= ASN1_REAL,
+	[DIRECTIVE_ENUMERATED]		= ASN1_ENUM,
+	[DIRECTIVE_EMBEDDED]		= 0,
+	[DIRECTIVE_UTF8String]		= ASN1_UTF8STR,
+	[DIRECTIVE_RELATIVE_OID]	= ASN1_RELOID,
+	/* 14 */
+	/* 15 */
+	[DIRECTIVE_SEQUENCE]		= ASN1_SEQ,
+	[DIRECTIVE_SET]			= ASN1_SET,
+	[DIRECTIVE_NumericString]	= ASN1_NUMSTR,
+	[DIRECTIVE_PrintableString]	= ASN1_PRNSTR,
+	[DIRECTIVE_T61String]		= ASN1_TEXSTR,
+	[DIRECTIVE_TeletexString]	= ASN1_TEXSTR,
+	[DIRECTIVE_VideotexString]	= ASN1_VIDSTR,
+	[DIRECTIVE_IA5String]		= ASN1_IA5STR,
+	[DIRECTIVE_UTCTime]		= ASN1_UNITIM,
+	[DIRECTIVE_GeneralizedTime]	= ASN1_GENTIM,
+	[DIRECTIVE_GraphicString]	= ASN1_GRASTR,
+	[DIRECTIVE_VisibleString]	= ASN1_VISSTR,
+	[DIRECTIVE_GeneralString]	= ASN1_GENSTR,
+	[DIRECTIVE_UniversalString]	= ASN1_UNITIM,
+	[DIRECTIVE_CHARACTER]		= ASN1_CHRSTR,
+	[DIRECTIVE_BMPString]		= ASN1_BMPSTR,
+};
+
+static const char asn1_classes[4][5] = {
+	[ASN1_UNIV]	= "UNIV",
+	[ASN1_APPL]	= "APPL",
+	[ASN1_CONT]	= "CONT",
+	[ASN1_PRIV]	= "PRIV"
+};
+
+static const char asn1_methods[2][5] = {
+	[ASN1_UNIV]	= "PRIM",
+	[ASN1_APPL]	= "CONS"
+};
+
+static const char *const asn1_universal_tags[32] = {
+	"EOC",
+	"BOOL",
+	"INT",
+	"BTS",
+	"OTS",
+	"NULL",
+	"OID",
+	"ODE",
+	"EXT",
+	"REAL",
+	"ENUM",
+	"EPDV",
+	"UTF8STR",
+	"RELOID",
+	NULL,		/* 14 */
+	NULL,		/* 15 */
+	"SEQ",
+	"SET",
+	"NUMSTR",
+	"PRNSTR",
+	"TEXSTR",
+	"VIDSTR",
+	"IA5STR",
+	"UNITIM",
+	"GENTIM",
+	"GRASTR",
+	"VISSTR",
+	"GENSTR",
+	"UNISTR",
+	"CHRSTR",
+	"BMPSTR",
+	NULL		/* 31 */
+};
+
+static const char *filename;
+static const char *grammar_name;
+static const char *outputname;
+static const char *headername;
+
+static const char *const directives[NR__DIRECTIVES] = {
+#define _(X) [DIRECTIVE_##X] = #X
+	_(ABSENT),
+	_(ALL),
+	_(ANY),
+	_(APPLICATION),
+	_(AUTOMATIC),
+	_(BEGIN),
+	_(BIT),
+	_(BMPString),
+	_(BOOLEAN),
+	_(BY),
+	_(CHARACTER),
+	_(CHOICE),
+	_(CLASS),
+	_(COMPONENT),
+	_(COMPONENTS),
+	_(CONSTRAINED),
+	_(CONTAINING),
+	_(DEFAULT),
+	_(DEFINED),
+	_(DEFINITIONS),
+	_(EMBEDDED),
+	_(ENCODED),
+	[DIRECTIVE_ENCODING_CONTROL] = "ENCODING-CONTROL",
+	_(END),
+	_(ENUMERATED),
+	_(EXCEPT),
+	_(EXPLICIT),
+	_(EXPORTS),
+	_(EXTENSIBILITY),
+	_(EXTERNAL),
+	_(FALSE),
+	_(FROM),
+	_(GeneralString),
+	_(GeneralizedTime),
+	_(GraphicString),
+	_(IA5String),
+	_(IDENTIFIER),
+	_(IMPLICIT),
+	_(IMPLIED),
+	_(IMPORTS),
+	_(INCLUDES),
+	_(INSTANCE),
+	_(INSTRUCTIONS),
+	_(INTEGER),
+	_(INTERSECTION),
+	_(ISO646String),
+	_(MAX),
+	_(MIN),
+	[DIRECTIVE_MINUS_INFINITY] = "MINUS-INFINITY",
+	[DIRECTIVE_NULL] = "NULL",
+	_(NumericString),
+	_(OBJECT),
+	_(OCTET),
+	_(OF),
+	_(OPTIONAL),
+	_(ObjectDescriptor),
+	_(PATTERN),
+	_(PDV),
+	[DIRECTIVE_PLUS_INFINITY] = "PLUS-INFINITY",
+	_(PRESENT),
+	_(PRIVATE),
+	_(PrintableString),
+	_(REAL),
+	[DIRECTIVE_RELATIVE_OID] = "RELATIVE-OID",
+	_(SEQUENCE),
+	_(SET),
+	_(SIZE),
+	_(STRING),
+	_(SYNTAX),
+	_(T61String),
+	_(TAGS),
+	_(TRUE),
+	_(TeletexString),
+	_(UNION),
+	_(UNIQUE),
+	_(UNIVERSAL),
+	_(UTCTime),
+	_(UTF8String),
+	_(UniversalString),
+	_(VideotexString),
+	_(VisibleString),
+	_(WITH)
+};
+
+struct action {
+	struct action	*next;
+	unsigned char	index;
+	char		name[];
+};
+
+static struct action *action_list;
+static unsigned nr_actions;
+
+struct token {
+	unsigned short	line;
+	enum token_type	token_type : 8;
+	unsigned char	size;
+	struct action	*action;
+	const char	*value;
+	struct type	*type;
+};
+
+static struct token *token_list;
+static unsigned nr_tokens;
+
+static int directive_compare(const void *_key, const void *_pdir)
+{
+	const struct token *token = _key;
+	const char *const *pdir = _pdir, *dir = *pdir;
+	size_t dlen, clen;
+	int val;
+
+	dlen = strlen(dir);
+	clen = (dlen < token->size) ? dlen : token->size;
+
+	//printf("cmp(%*.*s,%s) = ",
+	//       (int)token->size, (int)token->size, token->value,
+	//       dir);
+
+	val = memcmp(token->value, dir, clen);
+	if (val != 0) {
+		//printf("%d [cmp]\n", val);
+		return val;
+	}
+
+	if (dlen == token->size) {
+		//printf("0\n");
+		return 0;
+	}
+	//printf("%d\n", (int)dlen - (int)token->size);
+	return dlen - token->size; /* shorter -> negative */
+}
+
+/*
+ * Tokenise an ASN.1 grammar
+ */
+static void tokenise(char *buffer, char *end)
+{
+	struct token *tokens;
+	char *line, *nl, *p, *q;
+	unsigned tix, lineno;
+
+	/* Assume we're going to have half as many tokens as we have
+	 * characters
+	 */
+	token_list = tokens = calloc((end - buffer) / 2, sizeof(struct token));
+	if (!tokens) {
+		perror(NULL);
+		exit(1);
+	}
+	tix = 0;
+
+	lineno = 0;
+	while (buffer < end) {
+		/* First of all, break out a line */
+		lineno++;
+		line = buffer;
+		nl = memchr(line, '\n', end - buffer);
+		if (!nl) {
+			buffer = nl = end;
+		} else {
+			buffer = nl + 1;
+			*nl = '\0';
+		}
+
+		/* Remove "--" comments */
+		p = line;
+	next_comment:
+		while ((p = memchr(p, '-', nl - p))) {
+			if (p[1] == '-') {
+				/* Found a comment; see if there's a terminator */
+				q = p + 2;
+				while ((q = memchr(q, '-', nl - q))) {
+					if (q[1] == '-') {
+						/* There is - excise the comment */
+						q += 2;
+						memmove(p, q, nl - q);
+						goto next_comment;
+					}
+					q++;
+				}
+				*p = '\0';
+				nl = p;
+				break;
+			} else {
+				p++;
+			}
+		}
+
+		p = line;
+		while (p < nl) {
+			/* Skip white space */
+			while (p < nl && isspace(*p))
+				*(p++) = 0;
+			if (p >= nl)
+				break;
+
+			tokens[tix].line = lineno;
+			tokens[tix].value = p;
+
+			/* Handle string tokens */
+			if (isalpha(*p)) {
+				const char **dir;
+
+				/* Can be a directive, type name or element
+				 * name.  Find the end of the name.
+				 */
+				q = p + 1;
+				while (q < nl && (isalnum(*q) || *q == '-' || *q == '_'))
+					q++;
+				tokens[tix].size = q - p;
+				p = q;
+
+				/* If it begins with a lowercase letter then
+				 * it's an element name
+				 */
+				if (islower(tokens[tix].value[0])) {
+					tokens[tix++].token_type = TOKEN_ELEMENT_NAME;
+					continue;
+				}
+
+				/* Otherwise we need to search the directive
+				 * table
+				 */
+				dir = bsearch(&tokens[tix], directives,
+					      sizeof(directives) / sizeof(directives[1]),
+					      sizeof(directives[1]),
+					      directive_compare);
+				if (dir) {
+					tokens[tix++].token_type = dir - directives;
+					continue;
+				}
+
+				tokens[tix++].token_type = TOKEN_TYPE_NAME;
+				continue;
+			}
+
+			/* Handle numbers */
+			if (isdigit(*p)) {
+				/* Find the end of the number */
+				q = p + 1;
+				while (q < nl && (isdigit(*q)))
+					q++;
+				tokens[tix].size = q - p;
+				p = q;
+				tokens[tix++].token_type = TOKEN_NUMBER;
+				continue;
+			}
+
+			if (nl - p >= 3) {
+				if (memcmp(p, "::=", 3) == 0) {
+					p += 3;
+					tokens[tix].size = 3;
+					tokens[tix++].token_type = TOKEN_ASSIGNMENT;
+					continue;
+				}
+			}
+
+			if (nl - p >= 2) {
+				if (memcmp(p, "({", 2) == 0) {
+					p += 2;
+					tokens[tix].size = 2;
+					tokens[tix++].token_type = TOKEN_OPEN_ACTION;
+					continue;
+				}
+				if (memcmp(p, "})", 2) == 0) {
+					p += 2;
+					tokens[tix].size = 2;
+					tokens[tix++].token_type = TOKEN_CLOSE_ACTION;
+					continue;
+				}
+			}
+
+			if (nl - p >= 1) {
+				tokens[tix].size = 1;
+				switch (*p) {
+				case '{':
+					p += 1;
+					tokens[tix++].token_type = TOKEN_OPEN_CURLY;
+					continue;
+				case '}':
+					p += 1;
+					tokens[tix++].token_type = TOKEN_CLOSE_CURLY;
+					continue;
+				case '[':
+					p += 1;
+					tokens[tix++].token_type = TOKEN_OPEN_SQUARE;
+					continue;
+				case ']':
+					p += 1;
+					tokens[tix++].token_type = TOKEN_CLOSE_SQUARE;
+					continue;
+				case ',':
+					p += 1;
+					tokens[tix++].token_type = TOKEN_COMMA;
+					continue;
+				default:
+					break;
+				}
+			}
+
+			fprintf(stderr, "%s:%u: Unknown character in grammar: '%c'\n",
+				filename, lineno, *p);
+			exit(1);
+		}
+	}
+
+	nr_tokens = tix;
+	printf("Extracted %u tokens\n", nr_tokens);
+
+#if 0
+	{
+		int n;
+		for (n = 0; n < nr_tokens; n++)
+			printf("Token %3u: '%*.*s'\n",
+			       n,
+			       (int)token_list[n].size, (int)token_list[n].size,
+			       token_list[n].value);
+	}
+#endif
+}
+
+static void build_type_list(void);
+static void parse(void);
+static void render(FILE *out, FILE *hdr);
+
+/*
+ *
+ */
+int main(int argc, char **argv)
+{
+	struct stat st;
+	ssize_t readlen;
+	FILE *out, *hdr;
+	char *buffer, *p;
+	int fd;
+
+	if (argc != 4) {
+		fprintf(stderr, "Format: %s <grammar-file> <c-file> <hdr-file>\n",
+			argv[0]);
+		exit(2);
+	}
+
+	filename = argv[1];
+	outputname = argv[2];
+	headername = argv[3];
+
+	fd = open(filename, O_RDONLY);
+	if (fd < 0) {
+		perror(filename);
+		exit(1);
+	}
+
+	if (fstat(fd, &st) < 0) {
+		perror(filename);
+		exit(1);
+	}
+
+	if (!(buffer = malloc(st.st_size + 1))) {
+		perror(NULL);
+		exit(1);
+	}
+
+	if ((readlen = read(fd, buffer, st.st_size)) < 0) {
+		perror(filename);
+		exit(1);
+	}
+
+	if (close(fd) < 0) {
+		perror(filename);
+		exit(1);
+	}
+
+	if (readlen != st.st_size) {
+		fprintf(stderr, "%s: Short read\n", filename);
+		exit(1);
+	}
+
+	p = strrchr(argv[1], '/');
+	p = p ? p + 1 : argv[1];
+	grammar_name = strdup(p);
+	if (!p) {
+		perror(NULL);
+		exit(1);
+	}
+	p = strchr(grammar_name, '.');
+	if (p)
+		*p = '\0';
+
+	buffer[readlen] = 0;
+	tokenise(buffer, buffer + readlen);
+	build_type_list();
+	parse();
+
+	out = fopen(outputname, "w");
+	if (!out) {
+		perror(outputname);
+		exit(1);
+	}
+
+	hdr = fopen(headername, "w");
+	if (!out) {
+		perror(headername);
+		exit(1);
+	}
+
+	render(out, hdr);
+
+	if (fclose(out) < 0) {
+		perror(outputname);
+		exit(1);
+	}
+
+	if (fclose(hdr) < 0) {
+		perror(headername);
+		exit(1);
+	}
+
+	return 0;
+}
+
+enum compound {
+	NOT_COMPOUND,
+	SET,
+	SET_OF,
+	SEQUENCE,
+	SEQUENCE_OF,
+	CHOICE,
+	ANY,
+	TYPE_REF,
+	TAG_OVERRIDE
+};
+
+struct element {
+	struct type	*type_def;
+	struct token	*name;
+	struct token	*type;
+	struct action	*action;
+	struct element	*children;
+	struct element	*next;
+	struct element	*render_next;
+	struct element	*list_next;
+	uint8_t		n_elements;
+	enum compound	compound : 8;
+	enum asn1_class	class : 8;
+	enum asn1_method method : 8;
+	uint8_t		tag;
+	unsigned	entry_index;
+	unsigned	flags;
+#define ELEMENT_IMPLICIT	0x0001
+#define ELEMENT_EXPLICIT	0x0002
+#define ELEMENT_MARKED		0x0004
+#define ELEMENT_RENDERED	0x0008
+#define ELEMENT_SKIPPABLE	0x0010
+#define ELEMENT_CONDITIONAL	0x0020
+};
+
+struct type {
+	struct token	*name;
+	struct token	*def;
+	struct element	*element;
+	unsigned	ref_count;
+	unsigned	flags;
+#define TYPE_STOP_MARKER	0x0001
+#define TYPE_BEGIN		0x0002
+};
+
+static struct type *type_list;
+static struct type **type_index;
+static unsigned nr_types;
+
+static int type_index_compare(const void *_a, const void *_b)
+{
+	const struct type *const *a = _a, *const *b = _b;
+
+	if ((*a)->name->size != (*b)->name->size)
+		return (*a)->name->size - (*b)->name->size;
+	else
+		return memcmp((*a)->name->value, (*b)->name->value,
+			      (*a)->name->size);
+}
+
+static int type_finder(const void *_key, const void *_ti)
+{
+	const struct token *token = _key;
+	const struct type *const *ti = _ti;
+	const struct type *type = *ti;
+
+	if (token->size != type->name->size)
+		return token->size - type->name->size;
+	else
+		return memcmp(token->value, type->name->value,
+			      token->size);
+}
+
+/*
+ * Build up a list of types and a sorted index to that list.
+ */
+static void build_type_list(void)
+{
+	struct type *types;
+	unsigned nr, t, n;
+
+	nr = 0;
+	for (n = 0; n < nr_tokens - 1; n++)
+		if (token_list[n + 0].token_type == TOKEN_TYPE_NAME &&
+		    token_list[n + 1].token_type == TOKEN_ASSIGNMENT)
+			nr++;
+
+	if (nr == 0) {
+		fprintf(stderr, "%s: No defined types\n", filename);
+		exit(1);
+	}
+
+	nr_types = nr;
+	types = type_list = calloc(nr + 1, sizeof(type_list[0]));
+	if (!type_list) {
+		perror(NULL);
+		exit(1);
+	}
+	type_index = calloc(nr, sizeof(type_index[0]));
+	if (!type_index) {
+		perror(NULL);
+		exit(1);
+	}
+
+	t = 0;
+	types[t].flags |= TYPE_BEGIN;
+	for (n = 0; n < nr_tokens - 1; n++) {
+		if (token_list[n + 0].token_type == TOKEN_TYPE_NAME &&
+		    token_list[n + 1].token_type == TOKEN_ASSIGNMENT) {
+			types[t].name = &token_list[n];
+			type_index[t] = &types[t];
+			t++;
+		}
+	}
+	types[t].name = &token_list[n + 1];
+	types[t].flags |= TYPE_STOP_MARKER;
+
+	qsort(type_index, nr, sizeof(type_index[0]), type_index_compare);
+
+	printf("Extracted %u types\n", nr_types);
+#if 0
+	for (n = 0; n < nr_types; n++) {
+		struct type *type = type_index[n];
+		printf("- %*.*s\n",
+		       (int)type->name->size,
+		       (int)type->name->size,
+		       type->name->value);
+	}
+#endif
+}
+
+static struct element *parse_type(struct token **_cursor, struct token *stop,
+				  struct token *name);
+
+/*
+ * Parse the token stream
+ */
+static void parse(void)
+{
+	struct token *cursor;
+	struct type *type;
+
+	/* Parse one type definition statement at a time */
+	type = type_list;
+	do {
+		cursor = type->name;
+
+		if (cursor[0].token_type != TOKEN_TYPE_NAME ||
+		    cursor[1].token_type != TOKEN_ASSIGNMENT)
+			abort();
+		cursor += 2;
+
+		type->element = parse_type(&cursor, type[1].name, NULL);
+		type->element->type_def = type;
+
+		if (cursor != type[1].name) {
+			fprintf(stderr, "%s:%d: Parse error at token '%*.*s'\n",
+				filename, cursor->line,
+				(int)cursor->size, (int)cursor->size, cursor->value);
+			exit(1);
+		}
+
+	} while (type++, !(type->flags & TYPE_STOP_MARKER));
+
+	printf("Extracted %u actions\n", nr_actions);
+}
+
+static struct element *element_list;
+
+static struct element *alloc_elem(struct token *type)
+{
+	struct element *e = calloc(1, sizeof(*e));
+	if (!e) {
+		perror(NULL);
+		exit(1);
+	}
+	e->list_next = element_list;
+	element_list = e;
+	return e;
+}
+
+static struct element *parse_compound(struct token **_cursor, struct token *end,
+				      int alternates);
+
+/*
+ * Parse one type definition statement
+ */
+static struct element *parse_type(struct token **_cursor, struct token *end,
+				  struct token *name)
+{
+	struct element *top, *element;
+	struct action *action, **ppaction;
+	struct token *cursor = *_cursor;
+	struct type **ref;
+	char *p;
+	int labelled = 0, implicit = 0;
+
+	top = element = alloc_elem(cursor);
+	element->class = ASN1_UNIV;
+	element->method = ASN1_PRIM;
+	element->tag = token_to_tag[cursor->token_type];
+	element->name = name;
+
+	/* Extract the tag value if one given */
+	if (cursor->token_type == TOKEN_OPEN_SQUARE) {
+		cursor++;
+		if (cursor >= end)
+			goto overrun_error;
+		switch (cursor->token_type) {
+		case DIRECTIVE_UNIVERSAL:
+			element->class = ASN1_UNIV;
+			cursor++;
+			break;
+		case DIRECTIVE_APPLICATION:
+			element->class = ASN1_APPL;
+			cursor++;
+			break;
+		case TOKEN_NUMBER:
+			element->class = ASN1_CONT;
+			break;
+		case DIRECTIVE_PRIVATE:
+			element->class = ASN1_PRIV;
+			cursor++;
+			break;
+		default:
+			fprintf(stderr, "%s:%d: Unrecognised tag class token '%*.*s'\n",
+				filename, cursor->line,
+				(int)cursor->size, (int)cursor->size, cursor->value);
+			exit(1);
+		}
+
+		if (cursor >= end)
+			goto overrun_error;
+		if (cursor->token_type != TOKEN_NUMBER) {
+			fprintf(stderr, "%s:%d: Missing tag number '%*.*s'\n",
+				filename, cursor->line,
+				(int)cursor->size, (int)cursor->size, cursor->value);
+			exit(1);
+		}
+
+		element->tag &= ~0x1f;
+		element->tag |= strtoul(cursor->value, &p, 10);
+		if (p - cursor->value != cursor->size)
+			abort();
+		cursor++;
+
+		if (cursor >= end)
+			goto overrun_error;
+		if (cursor->token_type != TOKEN_CLOSE_SQUARE) {
+			fprintf(stderr, "%s:%d: Missing closing square bracket '%*.*s'\n",
+				filename, cursor->line,
+				(int)cursor->size, (int)cursor->size, cursor->value);
+			exit(1);
+		}
+		cursor++;
+		if (cursor >= end)
+			goto overrun_error;
+		labelled = 1;
+	}
+
+	/* Handle implicit and explicit markers */
+	if (cursor->token_type == DIRECTIVE_IMPLICIT) {
+		element->flags |= ELEMENT_IMPLICIT;
+		implicit = 1;
+		cursor++;
+		if (cursor >= end)
+			goto overrun_error;
+	} else if (cursor->token_type == DIRECTIVE_EXPLICIT) {
+		element->flags |= ELEMENT_EXPLICIT;
+		cursor++;
+		if (cursor >= end)
+			goto overrun_error;
+	}
+
+	if (labelled) {
+		if (!implicit)
+			element->method |= ASN1_CONS;
+		element->compound = implicit ? TAG_OVERRIDE : SEQUENCE;
+		element->children = alloc_elem(cursor);
+		element = element->children;
+		element->class = ASN1_UNIV;
+		element->method = ASN1_PRIM;
+		element->tag = token_to_tag[cursor->token_type];
+		element->name = name;
+	}
+
+	/* Extract the type we're expecting here */
+	element->type = cursor;
+	switch (cursor->token_type) {
+	case DIRECTIVE_ANY:
+		element->compound = ANY;
+		cursor++;
+		break;
+
+	case DIRECTIVE_NULL:
+	case DIRECTIVE_BOOLEAN:
+	case DIRECTIVE_ENUMERATED:
+	case DIRECTIVE_INTEGER:
+		element->compound = NOT_COMPOUND;
+		cursor++;
+		break;
+
+	case DIRECTIVE_EXTERNAL:
+		element->method = ASN1_CONS;
+
+	case DIRECTIVE_BMPString:
+	case DIRECTIVE_GeneralString:
+	case DIRECTIVE_GraphicString:
+	case DIRECTIVE_IA5String:
+	case DIRECTIVE_ISO646String:
+	case DIRECTIVE_NumericString:
+	case DIRECTIVE_PrintableString:
+	case DIRECTIVE_T61String:
+	case DIRECTIVE_TeletexString:
+	case DIRECTIVE_UniversalString:
+	case DIRECTIVE_UTF8String:
+	case DIRECTIVE_VideotexString:
+	case DIRECTIVE_VisibleString:
+	case DIRECTIVE_ObjectDescriptor:
+	case DIRECTIVE_GeneralizedTime:
+	case DIRECTIVE_UTCTime:
+		element->compound = NOT_COMPOUND;
+		cursor++;
+		break;
+
+	case DIRECTIVE_BIT:
+	case DIRECTIVE_OCTET:
+		element->compound = NOT_COMPOUND;
+		cursor++;
+		if (cursor >= end)
+			goto overrun_error;
+		if (cursor->token_type != DIRECTIVE_STRING)
+			goto parse_error;
+		cursor++;
+		break;
+
+	case DIRECTIVE_OBJECT:
+		element->compound = NOT_COMPOUND;
+		cursor++;
+		if (cursor >= end)
+			goto overrun_error;
+		if (cursor->token_type != DIRECTIVE_IDENTIFIER)
+			goto parse_error;
+		cursor++;
+		break;
+
+	case TOKEN_TYPE_NAME:
+		element->compound = TYPE_REF;
+		ref = bsearch(cursor, type_index, nr_types, sizeof(type_index[0]),
+			      type_finder);
+		if (!ref) {
+			fprintf(stderr, "%s:%d: Type '%*.*s' undefined\n",
+				filename, cursor->line,
+				(int)cursor->size, (int)cursor->size, cursor->value);
+			exit(1);
+		}
+		cursor->type = *ref;
+		(*ref)->ref_count++;
+		cursor++;
+		break;
+
+	case DIRECTIVE_CHOICE:
+		element->compound = CHOICE;
+		cursor++;
+		element->children = parse_compound(&cursor, end, 1);
+		break;
+
+	case DIRECTIVE_SEQUENCE:
+		element->compound = SEQUENCE;
+		element->method = ASN1_CONS;
+		cursor++;
+		if (cursor >= end)
+			goto overrun_error;
+		if (cursor->token_type == DIRECTIVE_OF) {
+			element->compound = SEQUENCE_OF;
+			cursor++;
+			if (cursor >= end)
+				goto overrun_error;
+			element->children = parse_type(&cursor, end, NULL);
+		} else {
+			element->children = parse_compound(&cursor, end, 0);
+		}
+		break;
+
+	case DIRECTIVE_SET:
+		element->compound = SET;
+		element->method = ASN1_CONS;
+		cursor++;
+		if (cursor >= end)
+			goto overrun_error;
+		if (cursor->token_type == DIRECTIVE_OF) {
+			element->compound = SET_OF;
+			cursor++;
+			if (cursor >= end)
+				goto parse_error;
+			element->children = parse_type(&cursor, end, NULL);
+		} else {
+			element->children = parse_compound(&cursor, end, 1);
+		}
+		break;
+
+	default:
+		fprintf(stderr, "%s:%d: Token '%*.*s' does not introduce a type\n",
+			filename, cursor->line,
+			(int)cursor->size, (int)cursor->size, cursor->value);
+		exit(1);
+	}
+
+	/* Handle elements that are optional */
+	if (cursor < end && (cursor->token_type == DIRECTIVE_OPTIONAL ||
+			     cursor->token_type == DIRECTIVE_DEFAULT)
+	    ) {
+		cursor++;
+		top->flags |= ELEMENT_SKIPPABLE;
+	}
+
+	if (cursor < end && cursor->token_type == TOKEN_OPEN_ACTION) {
+		cursor++;
+		if (cursor >= end)
+			goto overrun_error;
+		if (cursor->token_type != TOKEN_ELEMENT_NAME) {
+			fprintf(stderr, "%s:%d: Token '%*.*s' is not an action function name\n",
+				filename, cursor->line,
+				(int)cursor->size, (int)cursor->size, cursor->value);
+			exit(1);
+		}
+
+		action = malloc(sizeof(struct action) + cursor->size + 1);
+		if (!action) {
+			perror(NULL);
+			exit(1);
+		}
+		action->index = 0;
+		memcpy(action->name, cursor->value, cursor->size);
+		action->name[cursor->size] = 0;
+
+		for (ppaction = &action_list;
+		     *ppaction;
+		     ppaction = &(*ppaction)->next
+		     ) {
+			int cmp = strcmp(action->name, (*ppaction)->name);
+			if (cmp == 0) {
+				free(action);
+				action = *ppaction;
+				goto found;
+			}
+			if (cmp < 0) {
+				action->next = *ppaction;
+				*ppaction = action;
+				nr_actions++;
+				goto found;
+			}
+		}
+		action->next = NULL;
+		*ppaction = action;
+		nr_actions++;
+	found:
+
+		element->action = action;
+		cursor->action = action;
+		cursor++;
+		if (cursor >= end)
+			goto overrun_error;
+		if (cursor->token_type != TOKEN_CLOSE_ACTION) {
+			fprintf(stderr, "%s:%d: Missing close action, got '%*.*s'\n",
+				filename, cursor->line,
+				(int)cursor->size, (int)cursor->size, cursor->value);
+			exit(1);
+		}
+		cursor++;
+	}
+
+	*_cursor = cursor;
+	return top;
+
+parse_error:
+	fprintf(stderr, "%s:%d: Unexpected token '%*.*s'\n",
+		filename, cursor->line,
+		(int)cursor->size, (int)cursor->size, cursor->value);
+	exit(1);
+
+overrun_error:
+	fprintf(stderr, "%s: Unexpectedly hit EOF\n", filename);
+	exit(1);
+}
+
+/*
+ * Parse a compound type list
+ */
+static struct element *parse_compound(struct token **_cursor, struct token *end,
+				      int alternates)
+{
+	struct element *children, **child_p = &children, *element;
+	struct token *cursor = *_cursor, *name;
+
+	if (cursor->token_type != TOKEN_OPEN_CURLY) {
+		fprintf(stderr, "%s:%d: Expected compound to start with brace not '%*.*s'\n",
+			filename, cursor->line,
+			(int)cursor->size, (int)cursor->size, cursor->value);
+		exit(1);
+	}
+	cursor++;
+	if (cursor >= end)
+		goto overrun_error;
+
+	if (cursor->token_type == TOKEN_OPEN_CURLY) {
+		fprintf(stderr, "%s:%d: Empty compound\n",
+			filename, cursor->line);
+		exit(1);
+	}
+
+	for (;;) {
+		name = NULL;
+		if (cursor->token_type == TOKEN_ELEMENT_NAME) {
+			name = cursor;
+			cursor++;
+			if (cursor >= end)
+				goto overrun_error;
+		}
+
+		element = parse_type(&cursor, end, name);
+		if (alternates)
+			element->flags |= ELEMENT_SKIPPABLE | ELEMENT_CONDITIONAL;
+
+		*child_p = element;
+		child_p = &element->next;
+
+		if (cursor >= end)
+			goto overrun_error;
+		if (cursor->token_type != TOKEN_COMMA)
+			break;
+		cursor++;
+		if (cursor >= end)
+			goto overrun_error;
+	}
+
+	children->flags &= ~ELEMENT_CONDITIONAL;
+
+	if (cursor->token_type != TOKEN_CLOSE_CURLY) {
+		fprintf(stderr, "%s:%d: Expected compound closure, got '%*.*s'\n",
+			filename, cursor->line,
+			(int)cursor->size, (int)cursor->size, cursor->value);
+		exit(1);
+	}
+	cursor++;
+
+	*_cursor = cursor;
+	return children;
+
+overrun_error:
+	fprintf(stderr, "%s: Unexpectedly hit EOF\n", filename);
+	exit(1);
+}
+
+static void render_element(FILE *out, struct element *e, struct element *tag);
+static void render_out_of_line_list(FILE *out);
+
+static int nr_entries;
+static int render_depth = 1;
+static struct element *render_list, **render_list_p = &render_list;
+
+__attribute__((format(printf, 2, 3)))
+static void render_opcode(FILE *out, const char *fmt, ...)
+{
+	va_list va;
+
+	if (out) {
+		fprintf(out, "\t[%4d] =%*s", nr_entries, render_depth, "");
+		va_start(va, fmt);
+		vfprintf(out, fmt, va);
+		va_end(va);
+	}
+	nr_entries++;
+}
+
+__attribute__((format(printf, 2, 3)))
+static void render_more(FILE *out, const char *fmt, ...)
+{
+	va_list va;
+
+	if (out) {
+		va_start(va, fmt);
+		vfprintf(out, fmt, va);
+		va_end(va);
+	}
+}
+
+/*
+ * Render the grammar into a state machine definition.
+ */
+static void render(FILE *out, FILE *hdr)
+{
+	struct element *e;
+	struct action *action;
+	struct type *root;
+	int index;
+
+	fprintf(hdr, "/*\n");
+	fprintf(hdr, " * Automatically generated by asn1_compiler.  Do not edit\n");
+	fprintf(hdr, " *\n");
+	fprintf(hdr, " * ASN.1 parser for %s\n", grammar_name);
+	fprintf(hdr, " */\n");
+	fprintf(hdr, "#include <linux/asn1_decoder.h>\n");
+	fprintf(hdr, "\n");
+	fprintf(hdr, "extern const struct asn1_decoder %s_decoder;\n", grammar_name);
+	if (ferror(hdr)) {
+		perror(headername);
+		exit(1);
+	}
+
+	fprintf(out, "/*\n");
+	fprintf(out, " * Automatically generated by asn1_compiler.  Do not edit\n");
+	fprintf(out, " *\n");
+	fprintf(out, " * ASN.1 parser for %s\n", grammar_name);
+	fprintf(out, " */\n");
+	fprintf(out, "#include <linux/asn1_ber_bytecode.h>\n");
+	fprintf(out, "#include \"%s-asn1.h\"\n", grammar_name);
+	fprintf(out, "\n");
+	if (ferror(out)) {
+		perror(outputname);
+		exit(1);
+	}
+
+	/* Tabulate the action functions we might have to call */
+	fprintf(hdr, "\n");
+	index = 0;
+	for (action = action_list; action; action = action->next) {
+		action->index = index++;
+		fprintf(hdr,
+			"extern int %s(void *, size_t, unsigned char,"
+			" const void *, size_t);\n",
+			action->name);
+	}
+	fprintf(hdr, "\n");
+
+	fprintf(out, "enum %s_actions {\n", grammar_name);
+	for (action = action_list; action; action = action->next)
+		fprintf(out, "\tACT_%s = %u,\n",
+			action->name, action->index);
+	fprintf(out, "\tNR__%s_actions = %u\n", grammar_name, nr_actions);
+	fprintf(out, "};\n");
+
+	fprintf(out, "\n");
+	fprintf(out, "static const asn1_action_t %s_action_table[NR__%s_actions] = {\n",
+		grammar_name, grammar_name);
+	for (action = action_list; action; action = action->next)
+		fprintf(out, "\t[%4u] = %s,\n", action->index, action->name);
+	fprintf(out, "};\n");
+
+	if (ferror(out)) {
+		perror(outputname);
+		exit(1);
+	}
+
+	/* We do two passes - the first one calculates all the offsets */
+	printf("Pass 1\n");
+	nr_entries = 0;
+	root = &type_list[0];
+	render_element(NULL, root->element, NULL);
+	render_opcode(NULL, "ASN1_OP_COMPLETE,\n");
+	render_out_of_line_list(NULL);
+
+	for (e = element_list; e; e = e->list_next)
+		e->flags &= ~ELEMENT_RENDERED;
+
+	/* And then we actually render */
+	printf("Pass 2\n");
+	fprintf(out, "\n");
+	fprintf(out, "static const unsigned char %s_machine[] = {\n",
+		grammar_name);
+
+	nr_entries = 0;
+	root = &type_list[0];
+	render_element(out, root->element, NULL);
+	render_opcode(out, "ASN1_OP_COMPLETE,\n");
+	render_out_of_line_list(out);
+
+	fprintf(out, "};\n");
+
+	fprintf(out, "\n");
+	fprintf(out, "const struct asn1_decoder %s_decoder = {\n", grammar_name);
+	fprintf(out, "\t.machine = %s_machine,\n", grammar_name);
+	fprintf(out, "\t.machlen = sizeof(%s_machine),\n", grammar_name);
+	fprintf(out, "\t.actions = %s_action_table,\n", grammar_name);
+	fprintf(out, "};\n");
+}
+
+/*
+ * Render the out-of-line elements
+ */
+static void render_out_of_line_list(FILE *out)
+{
+	struct element *e, *ce;
+	const char *act;
+	int entry;
+
+	while ((e = render_list)) {
+		render_list = e->render_next;
+		if (!render_list)
+			render_list_p = &render_list;
+
+		render_more(out, "\n");
+		e->entry_index = entry = nr_entries;
+		render_depth++;
+		for (ce = e->children; ce; ce = ce->next)
+			render_element(out, ce, NULL);
+		render_depth--;
+
+		act = e->action ? "_ACT" : "";
+		switch (e->compound) {
+		case SEQUENCE:
+			render_opcode(out, "ASN1_OP_END_SEQ%s,\n", act);
+			break;
+		case SEQUENCE_OF:
+			render_opcode(out, "ASN1_OP_END_SEQ_OF%s,\n", act);
+			render_opcode(out, "_jump_target(%u),\n", entry);
+			break;
+		case SET:
+			render_opcode(out, "ASN1_OP_END_SET%s,\n", act);
+			break;
+		case SET_OF:
+			render_opcode(out, "ASN1_OP_END_SET_OF%s,\n", act);
+			render_opcode(out, "_jump_target(%u),\n", entry);
+			break;
+		}
+		if (e->action)
+			render_opcode(out, "_action(ACT_%s),\n",
+				      e->action->name);
+		render_opcode(out, "ASN1_OP_RETURN,\n");
+	}
+}
+
+/*
+ * Render an element.
+ */
+static void render_element(FILE *out, struct element *e, struct element *tag)
+{
+	struct element *ec;
+	const char *cond, *act;
+	int entry, skippable = 0, outofline = 0;
+
+	if (e->flags & ELEMENT_SKIPPABLE ||
+	    (tag && tag->flags & ELEMENT_SKIPPABLE))
+		skippable = 1;
+
+	if ((e->type_def && e->type_def->ref_count > 1) ||
+	    skippable)
+		outofline = 1;
+
+	if (e->type_def && out) {
+		render_more(out, "\t// %*.*s\n",
+			    (int)e->type_def->name->size, (int)e->type_def->name->size,
+			    e->type_def->name->value);
+	}
+
+	/* Render the operation */
+	cond = (e->flags & ELEMENT_CONDITIONAL ||
+		(tag && tag->flags & ELEMENT_CONDITIONAL)) ? "COND_" : "";
+	act = e->action ? "_ACT" : "";
+	switch (e->compound) {
+	case ANY:
+		render_opcode(out, "ASN1_OP_%sMATCH_ANY%s,", cond, act);
+		if (e->name)
+			render_more(out, "\t\t// %*.*s",
+				    (int)e->name->size, (int)e->name->size,
+				    e->name->value);
+		render_more(out, "\n");
+		goto dont_render_tag;
+
+	case TAG_OVERRIDE:
+		render_element(out, e->children, e);
+		return;
+
+	case SEQUENCE:
+	case SEQUENCE_OF:
+	case SET:
+	case SET_OF:
+		render_opcode(out, "ASN1_OP_%sMATCH%s%s,",
+			      cond,
+			      outofline ? "_JUMP" : "",
+			      skippable ? "_OR_SKIP" : "");
+		break;
+
+	case CHOICE:
+		goto dont_render_tag;
+
+	case TYPE_REF:
+		if (e->class == ASN1_UNIV && e->method == ASN1_PRIM && e->tag == 0)
+			goto dont_render_tag;
+	default:
+		render_opcode(out, "ASN1_OP_%sMATCH%s%s,",
+			      cond, act,
+			      skippable ? "_OR_SKIP" : "");
+		break;
+	}
+
+	if (e->name)
+		render_more(out, "\t\t// %*.*s",
+			    (int)e->name->size, (int)e->name->size,
+			    e->name->value);
+	render_more(out, "\n");
+
+	/* Render the tag */
+	if (!tag)
+		tag = e;
+	if (tag->class == ASN1_UNIV &&
+	    tag->tag != 14 &&
+	    tag->tag != 15 &&
+	    tag->tag != 31)
+		render_opcode(out, "_tag(%s, %s, %s),\n",
+			      asn1_classes[tag->class],
+			      asn1_methods[tag->method | e->method],
+			      asn1_universal_tags[tag->tag]);
+	else
+		render_opcode(out, "_tagn(%s, %s, %2u),\n",
+			      asn1_classes[tag->class],
+			      asn1_methods[tag->method | e->method],
+			      tag->tag);
+	tag = NULL;
+dont_render_tag:
+
+	/* Deal with compound types */
+	switch (e->compound) {
+	case TYPE_REF:
+		render_element(out, e->type->type->element, tag);
+		if (e->action)
+			render_opcode(out, "ASN1_OP_ACT,\n");
+		break;
+
+	case SEQUENCE:
+		if (outofline) {
+			/* Render out-of-line for multiple use or
+			 * skipability */
+			render_opcode(out, "_jump_target(%u),", e->entry_index);
+			if (e->type_def && e->type_def->name)
+				render_more(out, "\t\t// --> %*.*s",
+					    (int)e->type_def->name->size,
+					    (int)e->type_def->name->size,
+					    e->type_def->name->value);
+			render_more(out, "\n");
+			if (!(e->flags & ELEMENT_RENDERED)) {
+				e->flags |= ELEMENT_RENDERED;
+				*render_list_p = e;
+				render_list_p = &e->render_next;
+			}
+			return;
+		} else {
+			/* Render inline for single use */
+			render_depth++;
+			for (ec = e->children; ec; ec = ec->next)
+				render_element(out, ec, NULL);
+			render_depth--;
+			render_opcode(out, "ASN1_OP_END_SEQ%s,\n", act);
+		}
+		break;
+
+	case SEQUENCE_OF:
+	case SET_OF:
+		if (outofline) {
+			/* Render out-of-line for multiple use or
+			 * skipability */
+			render_opcode(out, "_jump_target(%u),", e->entry_index);
+			if (e->type_def && e->type_def->name)
+				render_more(out, "\t\t// --> %*.*s",
+					    (int)e->type_def->name->size,
+					    (int)e->type_def->name->size,
+					    e->type_def->name->value);
+			render_more(out, "\n");
+			if (!(e->flags & ELEMENT_RENDERED)) {
+				e->flags |= ELEMENT_RENDERED;
+				*render_list_p = e;
+				render_list_p = &e->render_next;
+			}
+			return;
+		} else {
+			/* Render inline for single use */
+			entry = nr_entries;
+			render_depth++;
+			render_element(out, e->children, NULL);
+			render_depth--;
+			if (e->compound == SEQUENCE_OF)
+				render_opcode(out, "ASN1_OP_END_SEQ_OF%s,\n", act);
+			else
+				render_opcode(out, "ASN1_OP_END_SET_OF%s,\n", act);
+			render_opcode(out, "_jump_target(%u),\n", entry);
+		}
+		break;
+
+	case SET:
+		/* I can't think of a nice way to do SET support without having
+		 * a stack of bitmasks to make sure no element is repeated.
+		 * The bitmask has also to be checked that no non-optional
+		 * elements are left out whilst not preventing optional
+		 * elements from being left out.
+		 */
+		fprintf(stderr, "The ASN.1 SET type is not currently supported.\n");
+		exit(1);
+
+	case CHOICE:
+		for (ec = e->children; ec; ec = ec->next)
+			render_element(out, ec, NULL);
+		if (!skippable)
+			render_opcode(out, "ASN1_OP_COND_FAIL,\n");
+		if (e->action)
+			render_opcode(out, "ASN1_OP_ACT,\n");
+		break;
+
+	default:
+		break;
+	}
+
+	if (e->action)
+		render_opcode(out, "_action(ACT_%s),\n", e->action->name);
+}