[PATCH bpf-next v4 3/8] bpftool: Add gen btf command

@@ -5,6 +5,7 @@
 #define _GNU_SOURCE
 #endif
 #include <ctype.h>
+#include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <linux/err.h>

@@ -1084,6 +1085,7 @@ static int do_help(int argc, char **argv)
 	fprintf(stderr,
 		"Usage: %1$s %2$s object OUTPUT_FILE INPUT_FILE [INPUT_FILE...]\n"
 		"       %1$s %2$s skeleton FILE [name OBJECT_NAME]\n"
+		"       %1$s %2$s btf INPUT OUTPUT OBJECT(S)\n"
 		"       %1$s %2$s help\n"
 		"\n"
 		"       " HELP_SPEC_OPTIONS " |\n"

@@ -1094,9 +1096,124 @@ static int do_help(int argc, char **argv)
 	return 0;
 }
 
+/* Create BTF file for a set of BPF objects */
+static int btfgen(const char *src_btf, const char *dst_btf, const char *objspaths[])
+{
+	return -EOPNOTSUPP;
+}
+
+static int is_file(const char *path)
+{
+	struct stat st;
+
+	if (stat(path, &st) < 0)
+		return -1;
+
+	switch (st.st_mode & S_IFMT) {
+	case S_IFDIR:
+		return 0;
+	case S_IFREG:
+		return 1;
+	default:
+		return -1;
+	}
+}
+
+static int do_gen_btf(int argc, char **argv)
+{
+	char src_btf_path[PATH_MAX], dst_btf_path[PATH_MAX];
+	bool input_is_file, output_is_file = false;
+	const char *input, *output;
+	const char **objs = NULL;
+	struct dirent *dir;
+	DIR *d = NULL;
+	int i, err;
+
+	if (!REQ_ARGS(3)) {
+		usage();
+		return -1;
+	}
+
+	input = GET_ARG();
+	err = is_file(input);
+	if (err < 0) {
+		p_err("failed to stat %s: %s", input, strerror(errno));
+		return err;
+	}
+	input_is_file = err;
+
+	output = GET_ARG();
+	err = is_file(output);
+	if (err != 0)
+		output_is_file = true;
+
+	objs = (const char **) malloc((argc + 1) * sizeof(*objs));
+	if (!objs)
+		return -ENOMEM;
+
+	i = 0;
+	while (argc > 0)
+		objs[i++] = GET_ARG();
+
+	objs[i] = NULL;
+
+	/* single BTF file */
+	if (input_is_file) {
+		printf("SBTF: %s\n", input);
+
+		if (output_is_file) {
+			err = btfgen(input, output, objs);
+			goto out;
+		}
+		snprintf(dst_btf_path, sizeof(dst_btf_path), "%s/%s", output,
+			 basename(input));
+		err = btfgen(input, dst_btf_path, objs);
+		goto out;
+	}
+
+	if (output_is_file) {
+		p_err("can't have just one file as output");
+		err = -EINVAL;
+		goto out;
+	}
+
+	/* directory with BTF files */
+	d = opendir(input);
+	if (!d) {
+		p_err("error opening input dir: %s", strerror(errno));
+		err = -errno;
+		goto out;
+	}
+
+	while ((dir = readdir(d)) != NULL) {
+		if (dir->d_type != DT_REG)
+			continue;
+
+		if (strncmp(dir->d_name + strlen(dir->d_name) - 4, ".btf", 4))
+			continue;
+
+		snprintf(src_btf_path, sizeof(src_btf_path), "%s/%s", input, dir->d_name);
+		snprintf(dst_btf_path, sizeof(dst_btf_path), "%s/%s", output, dir->d_name);
+
+		printf("SBTF: %s\n", src_btf_path);
+
+		err = btfgen(src_btf_path, dst_btf_path, objs);
+		if (err)
+			goto out;
+	}
+
+out:
+	if (!err)
+		printf("STAT: done!\n");
+	free(objs);
+	closedir(d);
+	return err;
+}
+
 static const struct cmd cmds[] = {
 	{ "object",	do_object },
 	{ "skeleton",	do_skeleton },
+	{ "btf",	do_gen_btf},
 	{ "help",	do_help },
 	{ 0 }
 };