utils: add vbt tool to dump VBT information

meson.build

@@ -27,6 +27,14 @@ sources = files(
 	'src/vbt/vbt.c',
 )
 
+util_vbt_sources = files(
+	'utils/vbt/vbt.c',
+)
+
 include_directories = include_directories('include')
 library = static_library('lil', sources, include_directories: include_directories, pic: false)
 dependency = declare_dependency(link_with: library, include_directories: include_directories)
+
+if get_option('build_utils')
+	util_vbt = executable('vbt', util_vbt_sources, dependencies: dependency, native: true)
+endif

meson_options.txt

@@ -0,0 +1 @@
+option('build_utils', type : 'boolean', value : false)

utils/vbt/vbt.c

@@ -0,0 +1,83 @@
+#include <lil/vbt.h>
+
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+static struct option longopts[] = {
+	{"blocks", no_argument, 0, 'b'},
+	{0, 0, 0, 0},
+};
+
+int main(int argc, char *argv[]) {
+	bool print_blocks = false;
+
+	while(1) {
+		int option_index = 0;
+		int c = getopt_long(argc, argv, "b", longopts, &option_index);
+
+		if(c == -1) {
+			break;
+		}
+
+		switch(c) {
+			case 'b': {
+				print_blocks = true;
+				break;
+			}
+			default: {
+				fprintf(stderr, "getopt_long returned %c\n", c);
+				break;
+			}
+		}
+	}
+
+	if((optind + 1) != argc) {
+		fprintf(stderr, "no file given\n");
+		exit(1);
+	}
+
+	const char *filepath = argv[optind];
+	int fd = open(filepath, O_RDONLY);
+	if(fd < 0) {
+		fprintf(stderr, "could not open file '%s': %s\n", argv[1], strerror(errno));
+		exit(1);
+	}
+
+	struct stat statbuf;
+	int err = fstat(fd, &statbuf);
+	assert(err >= 0);
+
+	void *vbt = mmap(NULL, statbuf.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
+	assert(vbt != MAP_FAILED);
+	close(fd);
+
+	const struct vbt_header *hdr = vbt_get_header(vbt, statbuf.st_size);
+	assert(hdr);
+
+	printf("VBT header version %u.%u\n", hdr->version / 100, hdr->version % 100);
+
+	const struct bdb_header *bdb_hdr = vbt_get_bdb_header(hdr);
+	assert(bdb_hdr);
+
+	if(print_blocks) {
+		printf("Blocks:");
+		for(size_t i = 0; i < 256; i++) {
+			if(vbt_get_bdb_block(hdr, i)) {
+				printf(" %zu", i);
+			}
+		}
+		printf("\n");
+	}
+
+	munmap(vbt, statbuf.st_size);
+
+	return 0;
+}