fs: Add fs_file_t_init() function

The fs_file_t_init() function has been added that should be used
for initialization of fs_file_t structures before passing them
to fs_open and other functions.

Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>

include/fs/fs.h

@@ -220,6 +220,20 @@ struct fs_statvfs {
 #define FS_FSTAB_DECLARE_ENTRY(node_id)		\
 	extern struct fs_mount_t FS_FSTAB_ENTRY(node_id)
 
+/**
+ * @brief Initialize fs_file_t object
+ *
+ * Initialized the fs_file_t object; the function needs to be invoked
+ * on object before first use with fs_open.
+ *
+ * @param zfp Pointer to file object
+ *
+ */
+static inline void fs_file_t_init(struct fs_file_t *zfp)
+{
+	*zfp = (struct fs_file_t){ 0 };
+}
+
 /**
  * @brief Open or create file
  *

include/fs/fs_interface.h

@@ -45,6 +45,8 @@ struct fs_mount_t;
 /**
  * @brief File object representing an open file
  *
+ * The object needs to be initialized with function fs_file_t_init().
+ *
  * @param Pointer to FATFS file object structure
  * @param mp Pointer to mount point structure
  */

tests/subsys/fs/common/test_fs_open_flags.c

@@ -141,6 +141,8 @@ void test_fs_open_flags(void)
 	};
 	int block = 1;
 
+	fs_file_t_init(&ts.file);
+
 	ZBEGIN("Attempt open non-existent");
 	ZOPEN(&ts, 0, -ENOENT);
 	ZOPEN(&ts, FS_O_WRITE, -ENOENT);

tests/subsys/fs/fs_api/src/main.c

@@ -72,6 +72,7 @@ void test_main(void)
 			 ztest_unit_test_setup_teardown(test_mount,
 							fs_setup,
 							dummy_teardown),
+			 ztest_unit_test(test_fs_file_t_init),
 			 ztest_unit_test(test_file_statvfs),
 			 ztest_unit_test(test_mkdir),
 			 ztest_unit_test(test_opendir),

tests/subsys/fs/fs_api/src/test_fs.h

@@ -32,6 +32,7 @@ struct test_fs_data {
 	int reserve;
 };
 
+void test_fs_file_t_init(void);
 void test_fs_register(void);
 void test_mount(void);
 void test_file_statvfs(void);

tests/subsys/fs/fs_api/src/test_fs_dir_file.c

@@ -78,6 +78,21 @@ static struct fs_file_t filep;
 static struct fs_file_t err_filep;
 static const char test_str[] = "hello world!";
 
+/**
+ * @brief Test fs_file_t_init initializer
+ */
+void test_fs_file_t_init(void)
+{
+	struct fs_file_t fst;
+
+	memset(&fst, 0xff, sizeof(fst));
+
+	fs_file_t_init(&fst);
+	zassert_equal(fst.mp, NULL, "Expected to be initialized to NULL");
+	zassert_equal(fst.filep, NULL, "Expected to be initialized to NULL");
+	zassert_equal(fst.flags, 0, "Expected to be initialized to 0");
+}
+
 /**
  * @brief Test mount interface of filesystem
  *
@@ -396,6 +411,7 @@ void test_file_open(void)
 	int ret;
 
 	TC_PRINT("\nOpen tests:\n");
+	fs_file_t_init(&filep);
 
 	TC_PRINT("\nOpen a file without a path\n");
 	ret = fs_open(&filep, NULL, FS_O_READ);
@@ -435,7 +451,7 @@ static int _test_file_write(void)
 	TC_PRINT("\nWrite tests:\n");
 
 	TC_PRINT("Write to an unopened file\n");
-	err_filep.mp = NULL;
+	fs_file_t_init(&err_filep);
 	brw = fs_write(&err_filep, (char *)test_str, strlen(test_str));
 	if (brw >= 0) {
 		return TC_FAIL;
@@ -500,7 +516,7 @@ static int _test_file_sync(void)
 	TC_PRINT("\nSync tests:\n");
 
 	TC_PRINT("sync an unopened file\n");
-	err_filep.mp = NULL;
+	fs_file_t_init(&err_filep);
 	ret = fs_sync(&err_filep);
 	if (!ret) {
 		return TC_FAIL;
@@ -513,6 +529,7 @@ static int _test_file_sync(void)
 		return TC_FAIL;
 	}
 
+	fs_file_t_init(&filep);
 	ret = fs_open(&filep, TEST_FILE, FS_O_RDWR);
 
 	for (;;) {
@@ -578,7 +595,7 @@ void test_file_read(void)
 	TC_PRINT("\nRead tests:\n");
 
 	TC_PRINT("Read an unopened file\n");
-	err_filep.mp = NULL;
+	fs_file_t_init(&err_filep);
 	brw = fs_read(&err_filep, read_buff, sz);
 	zassert_false(brw >= 0, "Can't read an unopened file");
 
@@ -637,7 +654,7 @@ static int _test_file_truncate(void)
 	TC_PRINT("\nTruncate tests: max file size is 128byte\n");
 
 	TC_PRINT("\nTruncate, seek, tell an unopened file\n");
-	err_filep.mp = NULL;
+	fs_file_t_init(&err_filep);
 	ret = fs_truncate(&err_filep, 256);
 	if (!ret) {
 		return TC_FAIL;
@@ -798,7 +815,7 @@ void test_file_close(void)
 	TC_PRINT("\nClose tests:\n");
 
 	TC_PRINT("Close an unopened file\n");
-	err_filep.mp = NULL;
+	fs_file_t_init(&err_filep);
 	ret = fs_close(&err_filep);
 	zassert_equal(ret, 0, "Should close an unopened file");
 

tests/subsys/fs/fs_api/src/test_fs_mount_flags.c

@@ -18,7 +18,9 @@ static struct fs_mount_t mp = {
 void test_mount_flags(void)
 {
 	int ret = 0;
-	struct fs_file_t fs = { 0 };
+	struct fs_file_t fs;
+
+	fs_file_t_init(&fs);
 
 	/* Format volume and add some files/dirs to check read-only flag */
 	mp.flags = 0;