discover/grub: Add blscfg command support to parse BootLoaderSpec files

The BootLoaderSpec (BLS) defines a file format for boot configurations,
so bootloaders can parse these files and create their boot menu entries
by using the information provided by them [0].

This allow to configure the boot items as drop-in files in a directory
instead of having to parse and modify a bootloader configuration file.

The GRUB 2 bootloader provides a blscfg command that parses these files
and creates menu entries using this information. Add support for it.

[0]: https://www.freedesktop.org/wiki/Specifications/BootLoaderSpec/

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>

13 files changed, 511 insertions, 2 deletions

diff --git a/discover/grub2/Makefile.am b/discover/grub2/Makefile.am
index 130ede8..b240106 100644
--- a/discover/grub2/Makefile.am
+++ b/discover/grub2/Makefile.am
@@ -15,6 +15,7 @@
 noinst_PROGRAMS += discover/grub2/grub2-parser.ro
 
 discover_grub2_grub2_parser_ro_SOURCES = \
+	discover/grub2/blscfg.c \
 	discover/grub2/builtins.c \
 	discover/grub2/env.c \
 	discover/grub2/grub2.h \
diff --git a/discover/grub2/blscfg.c b/discover/grub2/blscfg.c
new file mode 100644
index 0000000..0f69f7e
--- /dev/null
+++ b/discover/grub2/blscfg.c
@@ -0,0 +1,241 @@
+
+#define _GNU_SOURCE
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+#include <dirent.h>
+
+#include <log/log.h>
+#include <file/file.h>
+#include <talloc/talloc.h>
+#include <i18n/i18n.h>
+
+#include "grub2.h"
+#include "discover/parser-conf.h"
+#include "discover/parser.h"
+
+#define BLS_DIR "/loader/entries"
+
+struct bls_state {
+	struct discover_boot_option *opt;
+	struct grub2_script *script;
+	const char *filename;
+	const char *title;
+	const char *version;
+	const char *machine_id;
+	const char *image;
+	const char *initrd;
+	const char *dtb;
+};
+
+static void bls_process_pair(struct conf_context *conf, const char *name,
+			     char *value)
+{
+	struct bls_state *state = conf->parser_info;
+	struct discover_boot_option *opt = state->opt;
+	struct boot_option *option = opt->option;
+	const char *boot_args;
+
+	if (streq(name, "title")) {
+		state->title = talloc_strdup(state, value);
+		return;
+	}
+
+	if (streq(name, "version")) {
+		state->version = talloc_strdup(state, value);
+		return;
+	}
+
+	if (streq(name, "machine-id")) {
+		state->machine_id = talloc_strdup(state, value);
+		return;
+	}
+
+	if (streq(name, "linux")) {
+		state->image = talloc_strdup(state, value);
+		return;
+	}
+
+	if (streq(name, "initrd")) {
+		state->initrd = talloc_strdup(state, value);
+		return;
+	}
+
+	if (streq(name, "devicetree")) {
+		state->dtb = talloc_strdup(state, value);
+		return;
+	}
+
+	if (streq(name, "options")) {
+		if (value[0] == '$') {
+			boot_args = script_env_get(state->script, value + 1);
+			if (!boot_args)
+				return;
+
+			option->boot_args = talloc_strdup(opt, boot_args);
+		} else {
+			option->boot_args = talloc_strdup(opt, value);
+		}
+		return;
+	}
+}
+
+static bool option_is_default(struct grub2_script *script,
+			      struct boot_option *option)
+{
+	const char *var;
+
+	var = script_env_get(script, "default");
+	if (!var)
+		return false;
+
+	if (!strcmp(var, option->id))
+		return true;
+
+	return !strcmp(var, option->name);
+}
+
+static void bls_finish(struct conf_context *conf)
+{
+	struct bls_state *state = conf->parser_info;
+	struct discover_context *dc = conf->dc;
+	struct discover_boot_option *opt = state->opt;
+	struct boot_option *option = opt->option;
+	const char *root;
+	char *filename;
+
+	if (!state->image) {
+		device_handler_status_dev_info(dc->handler, dc->device,
+					       _("linux field not found in %s"),
+					       state->filename);
+		return;
+	}
+
+	filename = basename(state->filename);
+	filename[strlen(filename) - strlen(".conf")] = '\0';
+
+	option->id = talloc_strdup(option, filename);
+
+	if (state->title)
+		option->name = talloc_strdup(option, state->title);
+	else if (state->machine_id && state->version)
+		option->name = talloc_asprintf(option, "%s %s",
+					       state->machine_id,
+					       state->version);
+	else if (state->version)
+		option->name = talloc_strdup(option, state->version);
+	else
+		option->name = talloc_strdup(option, state->image);
+
+	root = script_env_get(state->script, "root");
+
+	opt->boot_image = create_grub2_resource(opt, conf->dc->device,
+						root, state->image);
+
+	if (state->initrd)
+		opt->initrd = create_grub2_resource(opt, conf->dc->device,
+						    root, state->initrd);
+
+	if (state->dtb)
+		opt->dtb = create_grub2_resource(opt, conf->dc->device,
+						 root, state->dtb);
+
+	option->is_default = option_is_default(state->script, option);
+
+	discover_context_add_boot_option(dc, opt);
+
+	device_handler_status_dev_info(dc->handler, dc->device,
+				       _("Created menu entry from BLS file %s"),
+				       state->filename);
+}
+
+static int bls_filter(const struct dirent *ent)
+{
+	int offset = strlen(ent->d_name) - strlen(".conf");
+
+	if (offset < 0)
+		return 0;
+
+	return strncmp(ent->d_name + offset, ".conf", strlen(".conf")) == 0;
+}
+
+static int bls_sort(const struct dirent **ent_a, const struct dirent **ent_b)
+{
+	return strverscmp((*ent_b)->d_name, (*ent_a)->d_name);
+}
+
+int builtin_blscfg(struct grub2_script *script,
+		void *data __attribute__((unused)),
+		int argc __attribute__((unused)),
+		char *argv[] __attribute__((unused)));
+
+int builtin_blscfg(struct grub2_script *script,
+		void *data __attribute__((unused)),
+		int argc __attribute__((unused)),
+		char *argv[] __attribute__((unused)))
+{
+	struct discover_context *dc = script->ctx;
+	struct dirent **bls_entries;
+	struct conf_context *conf;
+	struct bls_state *state;
+	char *buf, *filename;
+	int n, len, rc = -1;
+
+	conf = talloc_zero(dc, struct conf_context);
+	if (!conf)
+		return rc;
+
+	conf->dc = dc;
+	conf->get_pair = conf_get_pair_space;
+	conf->process_pair = bls_process_pair;
+	conf->finish = bls_finish;
+
+	n = parser_scandir(dc, BLS_DIR, &bls_entries, bls_filter, bls_sort);
+	if (n <= 0)
+		goto err;
+
+	while (n--) {
+		filename = talloc_asprintf(dc, BLS_DIR"/%s",
+					   bls_entries[n]->d_name);
+		if (!filename)
+			break;
+
+		state = talloc_zero(conf, struct bls_state);
+		if (!state)
+			break;
+
+		state->opt = discover_boot_option_create(dc, dc->device);
+		if (!state->opt)
+			break;
+
+		state->script = script;
+		state->filename = filename;
+		conf->parser_info = state;
+
+		rc = parser_request_file(dc, dc->device, filename, &buf, &len);
+		if (rc)
+			break;
+
+		conf_parse_buf(conf, buf, len);
+
+		talloc_free(buf);
+		talloc_free(state);
+		talloc_free(filename);
+		free(bls_entries[n]);
+	}
+
+	if (n > 0) {
+		device_handler_status_dev_info(dc->handler, dc->device,
+					       _("Scanning %s failed"),
+					       BLS_DIR);
+		do {
+			free(bls_entries[n]);
+		} while (n-- > 0);
+	}
+
+	free(bls_entries);
+err:
+	talloc_free(conf);
+	return rc;
+}
diff --git a/discover/grub2/builtins.c b/discover/grub2/builtins.c
index c16b639..e42821a 100644
--- a/discover/grub2/builtins.c
+++ b/discover/grub2/builtins.c
@@ -330,7 +330,10 @@ extern int builtin_load_env(struct grub2_script *script,
 int builtin_save_env(struct grub2_script *script,
 		void *data __attribute__((unused)),
 		int argc, char *argv[]);
-
+int builtin_blscfg(struct grub2_script *script,
+		void *data __attribute__((unused)),
+		int argc __attribute__((unused)),
+		char *argv[] __attribute__((unused)));
 
 static struct {
 	const char *name;
@@ -380,6 +383,10 @@ static struct {
 		.name = "save_env",
 		.fn = builtin_save_env,
 	},
+	{
+		.name = "blscfg",
+		.fn = builtin_blscfg,
+	}
 };
 
 static const char *nops[] = {
diff --git a/discover/grub2/script.c b/discover/grub2/script.c
index ed81a20..1a802b9 100644
--- a/discover/grub2/script.c
+++ b/discover/grub2/script.c
@@ -103,7 +103,7 @@ static bool is_delim(char c)
 }
 
 static bool option_is_default(struct grub2_script *script,
-		struct discover_boot_option *opt, const char *id)
+			      struct discover_boot_option *opt, const char *id)
 {
 	unsigned int default_idx;
 	const char *var;
diff --git a/discover/parser.c b/discover/parser.c
index 5598f96..9fe1925 100644
--- a/discover/parser.c
+++ b/discover/parser.c
@@ -128,6 +128,22 @@ out:
 	return -1;
 }
 
+int parser_scandir(struct discover_context *ctx, const char *dirname,
+		   struct dirent ***files, int (*filter)(const struct dirent *),
+		   int (*comp)(const struct dirent **, const struct dirent **))
+{
+	char *path;
+	int n;
+
+	path = talloc_asprintf(ctx, "%s%s", ctx->device->mount_path, dirname);
+	if (!path)
+		return -1;
+
+	n = scandir(path, files, filter, comp);
+	talloc_free(path);
+	return n;
+}
+
 void iterate_parsers(struct discover_context *ctx)
 {
 	struct p_item* i;
diff --git a/discover/parser.h b/discover/parser.h
index fc165c5..bff52e3 100644
--- a/discover/parser.h
+++ b/discover/parser.h
@@ -5,6 +5,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
+#include <dirent.h>
 
 #include "device-handler.h"
 
@@ -76,5 +77,12 @@ int parser_request_url(struct discover_context *ctx, struct pb_url *url,
 int parser_stat_path(struct discover_context *ctx,
 		struct discover_device *dev, const char *path,
 		struct stat *statbuf);
+/* Function used to list the files on a directory. The dirname should
+ * be relative to the discover context device mount path. It returns
+ * the number of files returned in files or a negative value on error.
+ */
+int parser_scandir(struct discover_context *ctx, const char *dirname,
+		   struct dirent ***files, int (*filter)(const struct dirent *),
+		   int (*comp)(const struct dirent **, const struct dirent **));
 
 #endif /* _PARSER_H */
diff --git a/test/parser/Makefile.am b/test/parser/Makefile.am
index a0795db..3479d88 100644
--- a/test/parser/Makefile.am
+++ b/test/parser/Makefile.am
@@ -40,6 +40,11 @@ parser_TESTS = \
 	test/parser/test-grub2-parser-error \
 	test/parser/test-grub2-test-file-ops \
 	test/parser/test-grub2-single-yocto \
+	test/parser/test-grub2-blscfg-default-filename \
+	test/parser/test-grub2-blscfg-default-title \
+	test/parser/test-grub2-blscfg-multiple-bls \
+	test/parser/test-grub2-blscfg-opts-config \
+	test/parser/test-grub2-blscfg-opts-grubenv \
 	test/parser/test-kboot-single \
 	test/parser/test-yaboot-empty \
 	test/parser/test-yaboot-single \
diff --git a/test/parser/test-grub2-blscfg-default-filename.c b/test/parser/test-grub2-blscfg-default-filename.c
new file mode 100644
index 0000000..fb74059
--- /dev/null
+++ b/test/parser/test-grub2-blscfg-default-filename.c
@@ -0,0 +1,29 @@
+#include "parser-test.h"
+
+#if 0 /* PARSER_EMBEDDED_CONFIG */
+set default=6c063c8e48904f2684abde8eea303f41-4.15.2-302.fc28.x86_64
+blscfg
+#endif
+
+void run_test(struct parser_test *test)
+{
+	struct discover_boot_option *opt;
+	struct discover_context *ctx;
+
+	test_add_file_string(test, test->ctx->device,
+			     "/loader/entries/6c063c8e48904f2684abde8eea303f41-4.15.2-302.fc28.x86_64.conf",
+			     "title Fedora (4.15.2-302.fc28.x86_64) 28 (Twenty Eight)\n"
+			     "linux /vmlinuz-4.15.2-302.fc28.x86_64\n"
+			     "initrd /initramfs-4.15.2-302.fc28.x86_64.img\n"
+			     "options root=/dev/mapper/fedora-root ro rd.lvm.lv=fedora/root\n");
+
+	test_read_conf_embedded(test, "/boot/grub2/grub.cfg");
+
+	test_run_parser(test, "grub2");
+
+	ctx = test->ctx;
+
+	opt = get_boot_option(ctx, 0);
+
+	check_is_default(opt);
+}
diff --git a/test/parser/test-grub2-blscfg-default-title.c b/test/parser/test-grub2-blscfg-default-title.c
new file mode 100644
index 0000000..94acf80
--- /dev/null
+++ b/test/parser/test-grub2-blscfg-default-title.c
@@ -0,0 +1,36 @@
+#include "parser-test.h"
+
+#if 0 /* PARSER_EMBEDDED_CONFIG */
+load_env
+set default=${saved_entry}
+blscfg
+#endif
+
+void run_test(struct parser_test *test)
+{
+	struct discover_boot_option *opt;
+	struct discover_context *ctx;
+
+	test_add_file_string(test, test->ctx->device,
+			     "/boot/grub2/grubenv",
+			     "# GRUB Environment Block\n"
+			     "saved_entry=Fedora (4.15.2-302.fc28.x86_64) 28 (Twenty Eight)\n"
+			     "kernelopts=root=/dev/mapper/fedora-root ro rd.lvm.lv=fedora/root\n");
+
+	test_add_file_string(test, test->ctx->device,
+			     "/loader/entries/6c063c8e48904f2684abde8eea303f41-4.15.2-302.fc28.x86_64.conf",
+			     "title Fedora (4.15.2-302.fc28.x86_64) 28 (Twenty Eight)\n"
+			     "linux /vmlinuz-4.15.2-302.fc28.x86_64\n"
+			     "initrd /initramfs-4.15.2-302.fc28.x86_64.img\n"
+			     "options $kernelopts\n");
+
+	test_read_conf_embedded(test, "/boot/grub2/grub.cfg");
+
+	test_run_parser(test, "grub2");
+
+	ctx = test->ctx;
+
+	opt = get_boot_option(ctx, 0);
+
+	check_is_default(opt);
+}
diff --git a/test/parser/test-grub2-blscfg-multiple-bls.c b/test/parser/test-grub2-blscfg-multiple-bls.c
new file mode 100644
index 0000000..8fd218c
--- /dev/null
+++ b/test/parser/test-grub2-blscfg-multiple-bls.c
@@ -0,0 +1,44 @@
+#include "parser-test.h"
+
+#if 0 /* PARSER_EMBEDDED_CONFIG */
+blscfg
+#endif
+
+void run_test(struct parser_test *test)
+{
+	struct discover_boot_option *opt;
+	struct discover_context *ctx;
+
+	test_add_file_string(test, test->ctx->device,
+			     "/loader/entries/6c063c8e48904f2684abde8eea303f41-4.15.2-302.fc28.x86_64.conf",
+			     "title Fedora (4.15.2-302.fc28.x86_64) 28 (Twenty Eight)\n"
+			     "linux /vmlinuz-4.15.2-302.fc28.x86_64\n"
+			     "initrd /initramfs-4.15.2-302.fc28.x86_64.img\n"
+			     "options root=/dev/mapper/fedora-root ro rd.lvm.lv=fedora/root\n\n");
+
+	test_add_file_string(test, test->ctx->device,
+			     "/loader/entries/6c063c8e48904f2684abde8eea303f41-4.14.18-300.fc28.x86_64.conf",
+			     "title Fedora (4.14.18-300.fc28.x86_64) 28 (Twenty Eight)\n"
+			     "linux /vmlinuz-4.14.18-300.fc28.x86_64\n"
+			     "initrd /initramfs-4.14.18-300.fc28.x86_64.img\n"
+			     "options root=/dev/mapper/fedora-root ro rd.lvm.lv=fedora/root\n");
+
+	test_read_conf_embedded(test, "/boot/grub2/grub.cfg");
+
+	test_run_parser(test, "grub2");
+
+	ctx = test->ctx;
+
+	check_boot_option_count(ctx, 2);
+	opt = get_boot_option(ctx, 0);
+
+	check_name(opt, "Fedora (4.15.2-302.fc28.x86_64) 28 (Twenty Eight)");
+	check_resolved_local_resource(opt->boot_image, ctx->device,
+			"/vmlinuz-4.15.2-302.fc28.x86_64");
+
+	opt = get_boot_option(ctx, 1);
+
+	check_name(opt, "Fedora (4.14.18-300.fc28.x86_64) 28 (Twenty Eight)");
+	check_resolved_local_resource(opt->initrd, ctx->device,
+			"/initramfs-4.14.18-300.fc28.x86_64.img");
+}
diff --git a/test/parser/test-grub2-blscfg-opts-config.c b/test/parser/test-grub2-blscfg-opts-config.c
new file mode 100644
index 0000000..856aae2
--- /dev/null
+++ b/test/parser/test-grub2-blscfg-opts-config.c
@@ -0,0 +1,29 @@
+#include "parser-test.h"
+
+#if 0 /* PARSER_EMBEDDED_CONFIG */
+set kernelopts=root=/dev/mapper/fedora-root ro rd.lvm.lv=fedora/root
+blscfg
+#endif
+
+void run_test(struct parser_test *test)
+{
+	struct discover_boot_option *opt;
+	struct discover_context *ctx;
+
+	test_add_file_string(test, test->ctx->device,
+			     "/loader/entries/6c063c8e48904f2684abde8eea303f41-4.15.2-302.fc28.x86_64.conf",
+			     "title Fedora (4.15.2-302.fc28.x86_64) 28 (Twenty Eight)\n"
+			     "linux /vmlinuz-4.15.2-302.fc28.x86_64\n"
+			     "initrd /initramfs-4.15.2-302.fc28.x86_64.img\n"
+			     "options $kernelopts\n");
+
+	test_read_conf_embedded(test, "/boot/grub2/grub.cfg");
+
+	test_run_parser(test, "grub2");
+
+	ctx = test->ctx;
+
+	opt = get_boot_option(ctx, 0);
+
+	check_args(opt, "root=/dev/mapper/fedora-root ro rd.lvm.lv=fedora/root");
+}
diff --git a/test/parser/test-grub2-blscfg-opts-grubenv.c b/test/parser/test-grub2-blscfg-opts-grubenv.c
new file mode 100644
index 0000000..c77c589
--- /dev/null
+++ b/test/parser/test-grub2-blscfg-opts-grubenv.c
@@ -0,0 +1,34 @@
+#include "parser-test.h"
+
+#if 0 /* PARSER_EMBEDDED_CONFIG */
+load_env
+blscfg
+#endif
+
+void run_test(struct parser_test *test)
+{
+	struct discover_boot_option *opt;
+	struct discover_context *ctx;
+
+	test_add_file_string(test, test->ctx->device,
+			     "/boot/grub2/grubenv",
+			     "# GRUB Environment Block\n"
+			     "kernelopts=root=/dev/mapper/fedora-root ro rd.lvm.lv=fedora/root\n");
+
+	test_add_file_string(test, test->ctx->device,
+			     "/loader/entries/6c063c8e48904f2684abde8eea303f41-4.15.2-302.fc28.x86_64.conf",
+			     "title Fedora (4.15.2-302.fc28.x86_64) 28 (Twenty Eight)\n"
+			     "linux /vmlinuz-4.15.2-302.fc28.x86_64\n"
+			     "initrd /initramfs-4.15.2-302.fc28.x86_64.img\n"
+			     "options $kernelopts\n");
+
+	test_read_conf_embedded(test, "/boot/grub2/grub.cfg");
+
+	test_run_parser(test, "grub2");
+
+	ctx = test->ctx;
+
+	opt = get_boot_option(ctx, 0);
+
+	check_args(opt, "root=/dev/mapper/fedora-root ro rd.lvm.lv=fedora/root");
+}
diff --git a/test/parser/utils.c b/test/parser/utils.c
index 47779c8..394efb3 100644
--- a/test/parser/utils.c
+++ b/test/parser/utils.c
@@ -309,6 +309,65 @@ int parser_replace_file(struct discover_context *ctx,
 	return 0;
 }
 
+int parser_scandir(struct discover_context *ctx, const char *dirname,
+		   struct dirent ***files, int (*filter)(const struct dirent *)
+		   __attribute__((unused)),
+		   int (*comp)(const struct dirent **, const struct dirent **)
+		   __attribute__((unused)))
+{
+	struct parser_test *test = ctx->test_data;
+	struct test_file *f;
+	char *filename;
+	struct dirent **dirents = NULL, **new_dirents;
+	int n = 0, namelen;
+
+	list_for_each_entry(&test->files, f, list) {
+		if (f->dev != ctx->device)
+			continue;
+
+		filename = strrchr(f->name, '/');
+		if (!filename)
+			continue;
+
+		namelen = strlen(filename);
+
+		if (strncmp(f->name, dirname, strlen(f->name) - namelen))
+			continue;
+
+		if (!dirents) {
+			dirents = malloc(sizeof(struct dirent *));
+		} else {
+			new_dirents = realloc(dirents, sizeof(struct dirent *)
+					      * (n + 1));
+			if (!new_dirents)
+				goto err_cleanup;
+
+			dirents = new_dirents;
+		}
+
+		dirents[n] = malloc(sizeof(struct dirent) + namelen + 1);
+
+		if (!dirents[n])
+			goto err_cleanup;
+
+		strcpy(dirents[n]->d_name, filename + 1);
+		n++;
+	}
+
+	*files = dirents;
+
+	return n;
+
+err_cleanup:
+	do {
+		free(dirents[n]);
+	} while (n-- > 0);
+
+	free(dirents);
+
+	return -1;
+}
+
 struct load_url_result *load_url_async(void *ctx, struct pb_url *url,
 		load_url_complete async_cb, void *async_data,
 		waiter_cb stdout_cb, void *stdout_data)