discover: Reimplement native-parser as a Bison parser

Occasionally you look at some code and realise that a) this never gets
built, and b) even if it did it would never compile. Today's example is
native-parser.c which we must have just assumed worked for quite a
while.

The native parser has bitrotted entirely and needs to be brought up to
date. While we're here, lets take the chance to implement a proper
grammar for it. This helps us reason more effectively about the parser,
lets us extend it easily in the future, and.. I wanted to write a Bison
parser too.

This implements most of the old functionality, but drops off some
smaller details like settings icons which needs some separate attention
to bring up to date.

Signed-off-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>

5 files changed, 401 insertions, 0 deletions

diff --git a/discover/native/Makefile.am b/discover/native/Makefile.am
new file mode 100644
index 0000000..f120e70
--- /dev/null
+++ b/discover/native/Makefile.am
@@ -0,0 +1,54 @@
+#  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; version 2 of the License.
+#
+#  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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+#
+
+noinst_PROGRAMS += discover/native/native-parser.ro
+
+discover_native_native_parser_ro_SOURCES = \
+	discover/native/native.h \
+	discover/native/native.c \
+	discover/native/native-lexer.l \
+	discover/native/native-parser.y
+
+BUILT_SOURCES += \
+	discover/native/native-parser.c \
+	discover/native/native-parser.h \
+	discover/native/native-lexer.h \
+	discover/native/native-lexer.c
+
+CLEANFILES += \
+	discover/native/native-parser.c \
+	discover/native/native-parser.h \
+	discover/native/native-lexer.c \
+	discover/native/native-lexer.h
+
+discover_native_native_parser_ro_CPPFLAGS = \
+	$(AM_CPPFLAGS) \
+	-I$(top_srcdir)/discover/native \
+	-I$(top_builddir)/discover/native
+
+discover_native_native_parser_ro_LINK = \
+	$(LD) -r -o $@
+
+# ylwrap doesn't handle flex header files well; use our own rule here.
+discover/native/native-lexer.h discover/native/native-lexer.c: \
+		$(top_srcdir)/discover/native/native-lexer.l
+	$(AM_V_LEX)$(LEXCOMPILE) --header-file=discover/native/native-lexer.h \
+				       -o discover/native/native-lexer.c $^
+
+# We need to loosen our warnings for the generated lexer code.
+discover/native/%native-lexer.o discover/native/native-lexer.o: \
+		AM_CFLAGS += -Wno-unused-parameter -Wno-missing-prototypes \
+			       -Wno-missing-declarations -Wno-sign-compare
+
+$(discover_native_native_parser_ro_OBJECTS): discover/native/native-parser.h
diff --git a/discover/native/native-lexer.l b/discover/native/native-lexer.l
new file mode 100644
index 0000000..bf1408a
--- /dev/null
+++ b/discover/native/native-lexer.l
@@ -0,0 +1,65 @@
+%{
+#include "native.h"
+#include "native-parser.h"
+#include <talloc/talloc.h>
+
+#define YYSTYPE NSTYPE
+
+void yyerror(struct native_parser *parser, const char *fmt, ...);
+%}
+
+%option nounput noinput
+%option batch never-interactive
+%option warn
+%option noyywrap
+%option reentrant
+%option bison-bridge
+%option yylineno
+%option noyyalloc noyyfree noyyrealloc
+%option extra-type="struct native_parser *"
+%option prefix="n"
+
+%x label
+%x args
+
+DELIM	[ \t]+
+NUMBER	0|[1-9][0-9]*
+WORDS	[^\n]+
+NEWLINE [\n]+
+
+%%
+
+name		{ BEGIN(label); return TOKEN_NAME; }
+image		{ BEGIN(label); return TOKEN_IMAGE; }
+initrd		{ BEGIN(label); return TOKEN_INITRD; }
+args		{ BEGIN(label); return TOKEN_ARGS; }
+dtb		{ BEGIN(label); return TOKEN_DTB; }
+description	{ BEGIN(label); return TOKEN_DESCRIPTION; }
+default		{ BEGIN(label); return TOKEN_DEFAULT; }
+dev_description { BEGIN(label); return TOKEN_DEV_DESCRIPTION; }
+{DELIM}		{ ; }
+{NEWLINE}	{ ; }
+<label>{DELIM}	{ BEGIN(args); return TOKEN_DELIM; }
+<args>{WORDS}	{ yylval->word = strdup(yytext); return TOKEN_WORD; }
+<args>{NEWLINE}	{ BEGIN(INITIAL); ; }
+
+%%
+
+struct native_parser;
+
+void *yyalloc(size_t bytes, void *yyscanner)
+{
+	struct native_parser *parser = yyget_extra(yyscanner);
+	return talloc_size(parser, bytes);
+}
+
+void *yyrealloc(void *ptr, size_t bytes, void *yyscanner)
+{
+	struct native_parser *parser = yyget_extra(yyscanner);
+	return talloc_realloc_size(parser, ptr, bytes);
+}
+
+void yyfree(void *ptr, void *yyscanner __attribute__((unused)))
+{
+	talloc_free(ptr);
+}
diff --git a/discover/native/native-parser.y b/discover/native/native-parser.y
new file mode 100644
index 0000000..bafcf49
--- /dev/null
+++ b/discover/native/native-parser.y
@@ -0,0 +1,200 @@
+
+%pure-parser
+%lex-param { nscan_t scanner }
+%parse-param { struct native_parser *parser }
+%parse-param { void *scanner }
+%error-verbose
+
+%define api.prefix {n}
+%{
+#include <talloc/talloc.h>
+#include <log/log.h>
+#include "discover/resource.h"
+#include "discover/parser-utils.h"
+
+#include "native.h"
+
+void yyerror(struct native_parser *parser, void *scanner, const char *fmt, ...);
+%}
+
+%union {
+	char	*word;
+	int	num;
+}
+
+%token	<word>	TOKEN_WORD
+%token	<num>	TOKEN_NUMBER
+%token	<num>	TOKEN_DELIM
+
+%token TOKEN_DEFAULT
+%token TOKEN_DEV_DESCRIPTION
+
+%token TOKEN_NAME
+%token TOKEN_IMAGE
+%token TOKEN_INITRD
+%token TOKEN_ARGS
+%token TOKEN_DTB
+%token TOKEN_DESCRIPTION
+%token TOKEN_NEWLINE
+
+%{
+#include "native-lexer.h"
+%}
+
+%%
+
+native:
+      globals boot_options { native_parser_finish(parser); }
+      | boot_options { native_parser_finish(parser); }
+      ;
+
+globals: globals global
+       | global
+       ;
+
+global: TOKEN_DEFAULT delims TOKEN_WORD {
+		if (parser->default_name)
+			pb_log_fn("Duplicate default option, ignoring\n");
+		else
+			parser->default_name = talloc_strdup(parser, $3);
+	}
+	| TOKEN_DEV_DESCRIPTION delims TOKEN_WORD {
+		native_append_string(parser,
+			&parser->ctx->device->device->description, $3);
+	}
+	;
+
+boot_options:
+	    boot_options option
+	    | option
+	    ;
+
+option: name params
+     ;
+
+name: TOKEN_NAME delims TOKEN_WORD {
+		native_parser_create_option(parser, $3);
+	}
+	;
+
+params: params param
+      | param
+      ;
+
+param: TOKEN_IMAGE delims TOKEN_WORD {
+		native_set_resource(parser, &parser->opt->boot_image, $3);
+	}
+	| TOKEN_INITRD delims TOKEN_WORD {
+		native_set_resource(parser, &parser->opt->initrd, $3);
+	}
+	| TOKEN_DTB delims TOKEN_WORD  {
+		native_set_resource(parser, &parser->opt->dtb, $3);
+	}
+	| TOKEN_ARGS delims TOKEN_WORD {
+		native_append_string(parser, &parser->opt->option->boot_args, $3);
+	}
+	| TOKEN_DESCRIPTION delims TOKEN_WORD  {
+		native_append_string(parser, &parser->opt->option->description, $3);
+	}
+	;
+
+delims: delims TOKEN_DELIM
+      | TOKEN_DELIM
+      ;
+
+%%
+
+void yyerror(struct native_parser *parser, void *scanner, const char *fmt, ...)
+{
+	const char *str;
+	va_list ap;
+
+	va_start(ap, fmt);
+	str = talloc_vasprintf(parser, fmt, ap);
+	va_end(ap);
+
+	pb_log("parse error: %d('%s'): %s\n", nget_lineno(scanner),
+					nget_text(scanner), str);
+}
+
+void native_parser_finish(struct native_parser *parser)
+{
+	if (parser->opt) {
+		discover_context_add_boot_option(parser->ctx, parser->opt);
+		parser->opt = NULL;
+	}
+}
+
+void native_set_resource(struct native_parser *parser,
+		struct resource ** resource, const char *path)
+{
+	if (*resource) {
+		pb_log_fn("Duplicate resource at line %d: %s\n",
+			nget_lineno(parser->scanner), path);
+		return;
+	}
+
+	*resource = create_devpath_resource(parser->opt, parser->opt->device,
+					path);
+}
+
+void native_append_string(struct native_parser *parser,
+		char **str, const char *append)
+{
+	if (*str)
+		*str = talloc_asprintf_append(*str, "%s", append);
+	else
+		*str = talloc_strdup(parser->opt, append);
+}
+
+void native_parser_create_option(struct native_parser *parser, const char *name)
+{
+	struct discover_boot_option *opt = parser->opt;
+
+	if (opt)
+		native_parser_finish(parser);
+
+	opt = discover_boot_option_create(parser->ctx, parser->ctx->device);
+	opt->option->name = talloc_strdup(opt, name);
+	opt->option->id = talloc_asprintf(opt, "%s@%p",
+			parser->ctx->device->device->id, opt);
+	opt->option->type = DISCOVER_BOOT_OPTION;
+	opt->option->is_default = parser->default_name &&
+				streq(parser->default_name, name);
+	parser->opt = opt;
+	return;
+}
+
+struct native_parser *native_parser_create(struct discover_context *ctx)
+{
+	struct native_parser *parser;
+
+	parser = talloc_zero(ctx, struct native_parser);
+	parser->ctx = ctx;
+	nlex_init_extra(parser, &parser->scanner);
+
+	return parser;
+}
+
+void native_parser_parse(struct native_parser *parser, const char *filename,
+	char *buf, int len)
+{
+	YY_BUFFER_STATE bufstate;
+	int rc;
+
+	if (!len)
+		return;
+
+	parser->filename = filename;
+
+	bufstate = n_scan_bytes(buf, len - 1, parser->scanner);
+	nset_lineno(1, parser->scanner);
+
+	rc = nparse(parser, parser->scanner);
+
+	if (rc)
+		pb_log("Failed to parse %s\n", filename);
+
+	n_delete_buffer(bufstate, parser->scanner);
+}
+
diff --git a/discover/native/native.c b/discover/native/native.c
new file mode 100644
index 0000000..964ad1d
--- /dev/null
+++ b/discover/native/native.c
@@ -0,0 +1,55 @@
+#include <assert.h>
+#include <string.h>
+#include <i18n/i18n.h>
+
+#include <talloc/talloc.h>
+#include <url/url.h>
+
+#include <discover/resource.h>
+#include <discover/parser.h>
+#include <discover/parser-utils.h>
+
+#include "native.h"
+
+static const char *const native_conf_files[] = {
+	"/boot/petitboot.conf",
+	"/petitboot.conf",
+	NULL
+};
+
+static int native_parse(struct discover_context *dc)
+{
+	const char * const *filename;
+	struct native_parser *parser;
+	int len, rc;
+	char *buf;
+
+	/* Support block device boot only at present */
+	if (dc->event)
+		return -1;
+
+	for (filename = native_conf_files; *filename; filename++) {
+		rc = parser_request_file(dc, dc->device, *filename, &buf, &len);
+		if (rc)
+			continue;
+
+		parser = native_parser_create(dc);
+		native_parser_parse(parser, *filename, buf, len);
+		device_handler_status_dev_info(dc->handler, dc->device,
+				_("Parsed native configuration from %s"),
+				*filename);
+		talloc_free(buf);
+		talloc_free(parser);
+		break;
+	}
+
+	return 0;
+}
+
+static struct parser native_parser = {
+	.name			= "native",
+	.parse			= native_parse,
+	.resolve_resource	= resolve_devpath_resource,
+};
+
+register_parser(native_parser);
diff --git a/discover/native/native.h b/discover/native/native.h
new file mode 100644
index 0000000..1cf7d6a
--- /dev/null
+++ b/discover/native/native.h
@@ -0,0 +1,27 @@
+#ifndef NATIVE_H
+#define NATIVE_H
+
+#include <discover/device-handler.h>
+
+struct native_parser {
+	struct discover_context		*ctx;
+	struct discover_boot_option 	*opt;
+	void				*scanner;
+	const char			*filename;
+	char				*default_name;
+};
+
+void native_parser_finish(struct native_parser *parser);
+void native_set_resource(struct native_parser *parser, struct resource **,
+		const char *path);
+void native_append_string(struct native_parser *parser,
+		char **str, const char *append);
+void native_parser_create_option(struct native_parser *parser,
+		const char *name);
+
+/* external parser api */
+struct native_parser *native_parser_create(struct discover_context *ctx);
+void native_parser_parse(struct native_parser *parser, const char *filename,
+		char *buf, int len);
+#endif /* NATIVE_H */
+