tools/bootconfig: Show bootconfig compact tree from bootconfig file

Show the bootconfig compact tree from the bootconfig file
instead of an initrd if the given file has no magic number
and is smaller than 32KB.

User can use this for checking the syntax error or output
checking before applying the bootconfig to initrd.

Link: https://lkml.kernel.org/r/159704848156.175360.6621139371000789360.stgit@devnote2Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tools/bootconfig/main.c

@@ -195,10 +195,55 @@ int load_xbc_from_initrd(int fd, char **buf)
 	return size;
 }
 
+static void show_xbc_error(const char *data, const char *msg, int pos)
+{
+	int lin = 1, col, i;
+
+	if (pos < 0) {
+		pr_err("Error: %s.\n", msg);
+		return;
+	}
+
+	/* Note that pos starts from 0 but lin and col should start from 1. */
+	col = pos + 1;
+	for (i = 0; i < pos; i++) {
+		if (data[i] == '\n') {
+			lin++;
+			col = pos - i;
+		}
+	}
+	pr_err("Parse Error: %s at %d:%d\n", msg, lin, col);
+
+}
+
+static int init_xbc_with_error(char *buf, int len)
+{
+	char *copy = strdup(buf);
+	const char *msg;
+	int ret, pos;
+
+	if (!copy)
+		return -ENOMEM;
+
+	ret = xbc_init(buf, &msg, &pos);
+	if (ret < 0)
+		show_xbc_error(copy, msg, pos);
+	free(copy);
+
+	return ret;
+}
+
 int show_xbc(const char *path)
 {
 	int ret, fd;
 	char *buf = NULL;
+	struct stat st;
+
+	ret = stat(path, &st);
+	if (ret < 0) {
+		pr_err("Failed to stat %s: %d\n", path, -errno);
+		return -errno;
+	}
 
 	fd = open(path, O_RDONLY);
 	if (fd < 0) {
@@ -207,14 +252,24 @@ int show_xbc(const char *path)
 	}
 
 	ret = load_xbc_from_initrd(fd, &buf);
+	close(fd);
 	if (ret < 0) {
 		pr_err("Failed to load a boot config from initrd: %d\n", ret);
 		goto out;
 	}
+	/* Assume a bootconfig file if it is enough small */
+	if (ret == 0 && st.st_size <= XBC_DATA_MAX) {
+		ret = load_xbc_file(path, &buf);
+		if (ret < 0) {
+			pr_err("Failed to load a boot config: %d\n", ret);
+			goto out;
+		}
+		if (init_xbc_with_error(buf, ret) < 0)
+			goto out;
+	}
 	xbc_show_compact_tree();
 	ret = 0;
 out:
-	close(fd);
 	free(buf);
 
 	return ret;
@@ -251,27 +306,6 @@ int delete_xbc(const char *path)
 	return ret;
 }
 
-static void show_xbc_error(const char *data, const char *msg, int pos)
-{
-	int lin = 1, col, i;
-
-	if (pos < 0) {
-		pr_err("Error: %s.\n", msg);
-		return;
-	}
-
-	/* Note that pos starts from 0 but lin and col should start from 1. */
-	col = pos + 1;
-	for (i = 0; i < pos; i++) {
-		if (data[i] == '\n') {
-			lin++;
-			col = pos - i;
-		}
-	}
-	pr_err("Parse Error: %s at %d:%d\n", msg, lin, col);
-
-}
-
 int apply_xbc(const char *path, const char *xbc_path)
 {
 	u32 size, csum;
@@ -352,11 +386,12 @@ int apply_xbc(const char *path, const char *xbc_path)
 int usage(void)
 {
 	printf("Usage: bootconfig [OPTIONS] <INITRD>\n"
+		"Or     bootconfig <CONFIG>\n"
 		" Apply, delete or show boot config to initrd.\n"
 		" Options:\n"
 		"		-a <config>: Apply boot config to initrd\n"
 		"		-d : Delete boot config file from initrd\n\n"
-		" If no option is given, show current applied boot config.\n");
+		" If no option is given, show the bootconfig in the given file.\n");
 	return -1;
 }