tests/lib: Factor out file related functions

Signed-off-by: Maximilian Brune <maximilian.brune@9elements.com>
Change-Id: I5c22913b35848c5ea32d6805ea081abefd3380bf
Reviewed-on: https://review.coreboot.org/c/coreboot/+/82237
Reviewed-by: Julius Werner <jwerner@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Jakub Czapiga <czapiga@google.com>

tests/helpers/file.c

@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <fcntl.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+/*
+ * Get the file size of a given file
+ *
+ * @params fname  name of the file relative to the __TEST_DATA_DIR__ directory
+ *
+ * @return  On success file size in bytes is returned. On failure -1 is returned.
+ */
+int test_get_file_size(const char *fname)
+{
+	char path[strlen(__TEST_DATA_DIR__) + strlen(fname) + 2];
+	sprintf(path, "%s/%s", __TEST_DATA_DIR__, fname);
+
+	struct stat st;
+	if (stat(path, &st) == -1)
+		return -1;
+	return st.st_size;
+}
+
+/*
+ * Read a file and write its contents into a buffer
+ *
+ * @params fname  name of the file relative to the __TEST_DATA_DIR__ directory
+ * @params buf    buffer to write file contents into
+ * @params size   size of buf
+ *
+ * @return  On success number of bytes read is returned. On failure -1 is returned.
+ */
+int test_read_file(const char *fname, uint8_t *buf, size_t size)
+{
+	char path[strlen(__TEST_DATA_DIR__) + strlen(fname) + 2];
+	sprintf(path, "%s/%s", __TEST_DATA_DIR__, fname);
+
+	int f = open(path, O_RDONLY);
+	if (f == -1)
+		return -1;
+
+	int read_size = read(f, buf, size);
+
+	close(f);
+	return read_size;
+}