Add optional JSON output support

Enable JSON output for efibootmgr. This provides an interface for third
party tools so they do not need to scrap the existing textual output.

This feature is optional and is enabled by using JSON=1 when compiling:

	make ... JSON=1

Add parameter '-j'/--json' to use JSON output. If efibootmgr is not
built with JSON output support it will print out this instead:

	"JSON support is not built-in"

This feature adds a new (optional) dependency with libjansson.

Signed-off-by: Jose M. Guisado <[email protected]>

Author: pvxe

Make.defaults

@@ -46,6 +46,9 @@ cflags	= $(EXTRALIBDIR) $(EXTRAINCDIR) $(CFLAGS) $(SUBDIR_CFLAGS) \
 	$(if $(findstring clang,$(CC)),$(clang_cflags),) \
 	$(if $(findstring gcc,$(CC)),$(gcc_cflags),) \
 	$(call pkg-config-cflags)
+ifdef JSON
+	cflags += -DJSON
+endif
 clang_ccldflags =
 gcc_ccldflags = -fno-merge-constants \
 	-Wl,--fatal-warnings,--no-allow-shlib-undefined \

src/Makefile

@@ -13,14 +13,21 @@ TARGETS=$(BINTARGETS) efibootmgr.8 efibootdump.8
 all : deps $(TARGETS)
 
 EFIBOOTMGR_SOURCES = efibootmgr.c efi.c parse_loader_data.c
+ifdef JSON
+EFIBOOTMGR_SOURCES += json.c
+endif
 EFICONMAN_SOURCES = eficonman.c
 EFIBOOTDUMP_SOURCES = efibootdump.c parse_loader_data.c
 EFIBOOTNEXT_SOURCES = efibootnext.c
 ALL_SOURCES=$(EFIBOOTMGR_SOURCES)
 -include $(call deps-of,$(ALL_SOURCES))
 
+
 efibootmgr : $(call objects-of,$(EFIBOOTMGR_SOURCES))
 efibootmgr : PKGS=efivar efiboot
+ifdef JSON
+efibootmgr : PKGS+=jansson
+endif
 
 eficonman : $(call objects-of,$(EFICONMAN_SOURCES))
 eficonman : PKGS=efivar efiboot popt

src/efibootmgr.c

@@ -55,6 +55,7 @@
 #include "parse_loader_data.h"
 #include "efibootmgr.h"
 #include "error.h"
+#include "json.h"
 
 #ifndef EFIBOOTMGR_VERSION
 #define EFIBOOTMGR_VERSION "unknown (fix Makefile!)"
@@ -1401,6 +1402,7 @@ usage()
 	printf("\t-g | --gpt            Force disk with invalid PMBR to be treated as GPT.\n");
 	printf("\t-i | --iface name     Create a netboot entry for the named interface (IPv4+DHCP support only).\n");
 	printf("\t-I | --index number   When creating an entry, insert it in bootorder at specified position (default: 0).\n");
+	printf("\t-j | --json           Enable JSON output\n");
 	printf("\t     --uri Uri        Specify an Uri (for use with --iface option).\n");
 	printf("\t-l | --loader name     (Defaults to \""DEFAULT_LOADER"\").\n");
 	printf("\t-L | --label label     Boot manager display label (defaults to \"Linux\").\n");
@@ -1472,6 +1474,7 @@ parse_opts(int argc, char **argv)
 			{"gpt",                    no_argument, 0, 'g'},
 			{"iface",            required_argument, 0, 'i'},
 			{"index",            required_argument, 0, 'I'},
+			{"json",                   no_argument, 0, 'j'},
 			{"uri",	             required_argument, 0, 0},
 			{"keep",                   no_argument, 0, 'k'},
 			{"loader",           required_argument, 0, 'l'},
@@ -1498,7 +1501,7 @@ parse_opts(int argc, char **argv)
 		};
 
 		c = getopt_long(argc, argv,
-				"aAb:BcCd:De:E:fFgi:I:kl:L:m:M:n:No:Op:qrt:Tuv::Vwy@:h",
+				"aAb:BcCd:De:E:fFgi:I:j:kl:L:m:M:n:No:Op:qrt:Tuv::Vwy@:h",
 				long_options, &option_index);
 		if (c == -1)
 			break;
@@ -1612,6 +1615,9 @@ parse_opts(int argc, char **argv)
 			}
 			opts.index = (uint16_t)lindex;
 			break;
+		case 'j':
+			opts.json = 1;
+			break;
 		case 'k':
 			opts.keep_old_entries = 1;
 			break;
@@ -1947,7 +1953,7 @@ main(int argc, char **argv)
 		ret=set_mirror(opts.below4g, opts.above4g);
 	}
 
-	if (!opts.quiet && ret == 0) {
+	if (!opts.quiet && !opts.json && ret == 0) {
 		switch (mode) {
 		case boot:
 			num = read_u16("BootNext");
@@ -1976,6 +1982,11 @@ main(int argc, char **argv)
 			break;
 		}
 	}
+
+	if (!opts.quiet && opts.json && ret == 0) {
+		print_json(&entry_list, mode, prefices, order_name);
+	}
+
 	free_vars(&entry_list);
 	free_array(names);
 	if (ret)

src/include/efibootmgr.h

@@ -95,6 +95,7 @@ typedef struct {
 	unsigned int driver:1;
 	unsigned int sysprep:1;
 	unsigned int explicit_label:1;
+	unsigned int json:1;
 	short int timeout;
 	uint16_t index;
 } efibootmgr_opt_t;

src/include/json.h

@@ -0,0 +1,21 @@
+#include <stdio.h>
+
+#include "list.h"
+
+void __print_json(list_t *entry_list, ebm_mode mode,
+			char **prefices, char **order_name);
+
+#ifndef JSON
+#define __unused __attribute__((unused))
+void print_json(list_t __unused *entry_list, ebm_mode __unused mode,
+				char __unused **prefices, char __unused **order_name)
+{
+        printf("JSON support is not built-in\n");
+}
+#else
+static inline void print_json(list_t *entry_list, ebm_mode mode,
+				char **prefices, char **order_name)
+{
+        __print_json(entry_list, mode, prefices, order_name);
+}
+#endif

src/json.c

@@ -0,0 +1,173 @@
+#include <efiboot.h>
+#include <jansson.h>
+
+#include "parse_loader_data.h"
+#include "efibootmgr.h"
+#include "error.h"
+#include "json.h"
+
+static void
+json_fill_bootnext(json_t *root)
+{
+	char s[5] = {};
+	json_t *value;
+	int num;
+
+	num = read_u16("BootNext");
+	cond_warning(opts.verbose >= 2 && num < 0,
+			"Could not read variable 'BootNext'");
+	if (num >= 0) {
+		snprintf(s, sizeof(s), "%04X", num);
+		value = json_string(s);
+		json_object_set_new(root, "BootNext", value);
+	}
+}
+
+static void
+json_fill_bootcurrent(json_t *root)
+{
+	char s[5] = {};
+	json_t *value;
+	int num;
+
+	num = read_u16("BootCurrent");
+	cond_warning(opts.verbose >= 2 && num < 0,
+			"Could not read variable 'BootCurrent'");
+	if (num >= 0) {
+		snprintf(s, sizeof(s), "%04X", num);
+		value = json_string(s);
+		json_object_set_new(root, "BootCurrent", value);
+	}
+}
+
+static void
+json_fill_timeout(json_t *root)
+{
+	json_t *value;
+	int num;
+
+	num = read_u16("Timeout");
+	cond_warning(opts.verbose >= 2 && num < 0,
+			"Could not read variable 'Timeout'");
+	if (num >= 0) {
+		value = json_integer(num);
+		json_object_set_new(root, "Timeout", value);
+	}
+}
+
+static json_t *
+bootorder_json_array(uint16_t *order, int length)
+{
+	json_t *value, *array;
+	char s[5] = {};
+	int i;
+
+	array = json_array();
+	if (!array)
+		return NULL;
+
+	for (i = 0; i < length; i++) {
+		snprintf(s, sizeof(s), "%04X", order[i]);
+		value = json_string(s);
+		json_array_append_new(array, value);
+	}
+
+	return array;
+}
+
+static void
+json_fill_order(json_t *root, const char *name)
+{
+	var_entry_t *order = NULL;
+	uint16_t *data;
+	json_t *array;
+	int rc;
+
+	rc = read_order(name, &order);
+	cond_warning(opts.verbose >= 2 && rc < 0,
+		  "Could not read variable '%s'", name);
+
+	if (rc < 0) {
+		if (errno == ENOENT) {
+			if (!strcmp(name, "BootOrder"))
+				printf("No BootOrder is set; firmware will attempt recovery\n");
+			else
+				printf("No %s is set\n", name);
+		} else
+			perror("json_fill_order()");
+		return;
+	}
+
+	data = (uint16_t *)order->data;
+	if (order->data_size) {
+		array = bootorder_json_array(data,
+					order->data_size / sizeof(uint16_t));
+		if (array != NULL)
+			json_object_set_new(root, name, array);
+		free(order->data);
+	}
+	free(order);
+}
+
+static void
+json_fill_vars(json_t *root, const char *prefix, list_t *entry_list)
+{
+	const unsigned char *description;
+	json_t *boot_json, *vars_json;
+	efi_load_option *load_option;
+	char name[16] = {'\0'};
+	var_entry_t *boot;
+	list_t *pos;
+	int active;
+
+	vars_json = json_array();
+	if (!vars_json)
+		return;
+
+	list_for_each(pos, entry_list) {
+		boot_json = json_object();
+		boot = list_entry(pos, var_entry_t, list);
+		load_option = (efi_load_option *)boot->data;
+		description = efi_loadopt_desc(load_option, boot->data_size);
+		if (boot->name)
+			json_object_set_new(boot_json, "name", json_string(boot->name));
+		else {
+			snprintf(name, sizeof(name), "%s%04X", prefix, boot->num);
+			json_object_set_new(boot_json, "name", json_string(boot->name));
+		}
+
+		active = efi_loadopt_attrs(load_option) & LOAD_OPTION_ACTIVE ? 1 : 0;
+		json_object_set_new(boot_json, "active", json_boolean(active));
+		json_object_set_new(boot_json, "description",
+				json_string((char *)description));
+		json_array_append_new(vars_json, boot_json);
+	}
+
+	json_object_set_new(root, "vars", vars_json);
+}
+
+void
+__print_json(list_t *entry_list, ebm_mode mode, char **prefices, char **order_name)
+{
+	json_t *root = json_object();
+	char *json_str = NULL;
+
+	switch (mode) {
+		case boot:
+			json_fill_bootnext(root);
+			json_fill_bootcurrent(root);
+			json_fill_timeout(root);
+			json_fill_order(root, order_name[mode]);
+			json_fill_vars(root, prefices[mode], entry_list);
+			break;
+		case driver:
+		case sysprep:
+			json_fill_order(root, order_name[mode]);
+			json_fill_vars(root, prefices[mode], entry_list);
+			break;
+	}
+	json_str = json_dumps(root, JSON_COMPACT);
+	printf("%s\n", json_str);
+	free(json_str);
+	json_decref(root);
+}