tools: Add a function to obtain the size of a file

This will be used in mkimage when working out the required size of the FIT
based on the files to be placed into it.

Signed-off-by: Simon Glass <sjg@chromium.org>

doc/mkimage.1

@@ -164,7 +164,7 @@ skipping those for which keys cannot be found. Also add a comment.
 .nf
 .B mkimage -f kernel.its -k /public/signing-keys -K u-boot.dtb \\\\
 .br
-.B -c "Kernel 3.8 image for production devices" kernel.itb
+.B -c """Kernel 3.8 image for production devices""" kernel.itb
 .fi
 
 .P
@@ -175,7 +175,7 @@ with unavailable keys are skipped.
 .nf
 .B mkimage -F -k /secret/signing-keys -K u-boot.dtb \\\\
 .br
-.B -c "Kernel 3.8 image for production devices" kernel.itb
+.B -c """Kernel 3.8 image for production devices""" kernel.itb
 .fi
 
 .SH HOMEPAGE

tools/imagetool.c

@@ -91,3 +91,25 @@ int imagetool_save_subimage(
 
 	return 0;
 }
+
+int imagetool_get_filesize(struct image_tool_params *params, const char *fname)
+{
+	struct stat sbuf;
+	int fd;
+
+	fd = open(fname, O_RDONLY | O_BINARY);
+	if (fd < 0) {
+		fprintf(stderr, "%s: Can't open %s: %s\n",
+			params->cmdname, fname, strerror(errno));
+		return -1;
+	}
+
+	if (fstat(fd, &sbuf) < 0) {
+		fprintf(stderr, "%s: Can't stat %s: %s\n",
+			params->cmdname, fname, strerror(errno));
+		return -1;
+	}
+	close(fd);
+
+	return sbuf.st_size;
+}

tools/imagetool.h

@@ -181,6 +181,18 @@ int imagetool_save_subimage(
 	ulong file_data,
 	ulong file_len);
 
+/**
+ * imagetool_get_filesize() - Utility function to obtain the size of a file
+ *
+ * This function prints a message if an error occurs, showing the error that
+ * was obtained.
+ *
+ * @params:	mkimage parameters
+ * @fname:	filename to check
+ * @return size of file, or -ve value on error
+ */
+int imagetool_get_filesize(struct image_tool_params *params, const char *fname);
+
 /*
  * There is a c file associated with supported image type low level code
  * for ex. default_image.c, fit_image.c