mkimage: Set up a file size parameter and keep it updated

Some functions called by mkimage would like to know the output file size.
Initially this is the same as the input file size, but it may be affected by
adding headers, etc.

Add this information to the image parameters.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

tools/imagetool.h

@@ -59,6 +59,7 @@ struct image_tool_params {
 	const char *keydest;	/* Destination .dtb for public key */
 	const char *comment;	/* Comment to add to signature node */
 	int require_keys;	/* 1 to mark signing keys as 'required' */
+	int file_size;		/* Total size of output file */
 };
 
 /*

tools/mkimage.c

@@ -75,6 +75,7 @@ int main(int argc, char **argv)
 	int retval = 0;
 	struct image_type_params *tparams = NULL;
 	int pad_len = 0;
+	int dfd;
 
 	params.cmdname = *argv;
 	params.addr = params.ep = 0;
@@ -310,6 +311,22 @@ NXTARG:		;
 		exit (retval);
 	}
 
+	dfd = open(params.datafile, O_RDONLY | O_BINARY);
+	if (dfd < 0) {
+		fprintf(stderr, "%s: Can't open %s: %s\n",
+			params.cmdname, params.datafile, strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+
+	if (fstat(dfd, &sbuf) < 0) {
+		fprintf(stderr, "%s: Can't stat %s: %s\n",
+			params.cmdname, params.datafile, strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+
+	params.file_size = sbuf.st_size + tparams->header_size;
+	close(dfd);
+
 	/*
 	 * In case there an header with a variable
 	 * length will be added, the corresponding
@@ -409,6 +426,7 @@ NXTARG:		;
 			params.cmdname, params.imagefile, strerror(errno));
 		exit (EXIT_FAILURE);
 	}
+	params.file_size = sbuf.st_size;
 
 	ptr = mmap(0, sbuf.st_size, PROT_READ|PROT_WRITE, MAP_SHARED, ifd, 0);
 	if (ptr == MAP_FAILED) {