utilfdt_read: pass back up the length of data read

For a follow up commit, we want to be able to scan the buffer that was
returned to us.  In order to do that safely, we need to know how big
the buffer actually is, so create a new set of funcs to pass that back.

Acked-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/util.c b/util.c
index 4cdad10..350cf8b 100644
--- a/util.c
+++ b/util.c
@@ -198,7 +198,7 @@
 	return val;
 }
 
-int utilfdt_read_err(const char *filename, char **buffp)
+int utilfdt_read_err_len(const char *filename, char **buffp, off_t *len)
 {
 	int fd = 0;	/* assume stdin */
 	char *buf = NULL;
@@ -239,13 +239,20 @@
 		free(buf);
 	else
 		*buffp = buf;
+	*len = bufsize;
 	return ret;
 }
 
-char *utilfdt_read(const char *filename)
+int utilfdt_read_err(const char *filename, char **buffp)
+{
+	off_t len;
+	return utilfdt_read_err_len(filename, buffp, &len);
+}
+
+char *utilfdt_read_len(const char *filename, off_t *len)
 {
 	char *buff;
-	int ret = utilfdt_read_err(filename, &buff);
+	int ret = utilfdt_read_err_len(filename, &buff, len);
 
 	if (ret) {
 		fprintf(stderr, "Couldn't open blob from '%s': %s\n", filename,
@@ -256,6 +263,12 @@
 	return buff;
 }
 
+char *utilfdt_read(const char *filename)
+{
+	off_t len;
+	return utilfdt_read_len(filename, &len);
+}
+
 int utilfdt_write_err(const char *filename, const void *blob)
 {
 	int fd = 1;	/* assume stdout */
diff --git a/util.h b/util.h
index 3f02cd8..95ae531 100644
--- a/util.h
+++ b/util.h
@@ -85,6 +85,13 @@
 char *utilfdt_read(const char *filename);
 
 /**
+ * Like utilfdt_read(), but also passes back the size of the file read.
+ *
+ * @param len		If non-NULL, the amount of data we managed to read
+ */
+char *utilfdt_read_len(const char *filename, off_t *len);
+
+/**
  * Read a device tree file into a buffer. Does not report errors, but only
  * returns them. The value returned can be passed to strerror() to obtain
  * an error message for the user.
@@ -95,6 +102,12 @@
  */
 int utilfdt_read_err(const char *filename, char **buffp);
 
+/**
+ * Like utilfdt_read_err(), but also passes back the size of the file read.
+ *
+ * @param len		If non-NULL, the amount of data we managed to read
+ */
+int utilfdt_read_err_len(const char *filename, char **buffp, off_t *len);
 
 /**
  * Write a device tree buffer to a file. This will report any errors on