From 05352b63e418b03da147557f384ef27e570e6e92 Mon Sep 17 00:00:00 2001
From: Sven Herrmann <sven.herrmann@posteo.de>
Date: Fri, 29 May 2020 16:18:18 +0000
Subject: [PATCH 1/2] tests/pkg_fatfs_vfs: add tests

* vfs_open with `O_WRONLY | O_CREAT` if file exists
* of fopen etc. with newlib
---
 tests/pkg_fatfs_vfs/main.c | 78 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)

diff --git a/tests/pkg_fatfs_vfs/main.c b/tests/pkg_fatfs_vfs/main.c
index fa29c40da834..a81c562fbbc7 100644
--- a/tests/pkg_fatfs_vfs/main.c
+++ b/tests/pkg_fatfs_vfs/main.c
@@ -292,9 +292,84 @@ static void test_create(void)
     nw = vfs_write(fd, test_txt, sizeof(test_txt));
     print_test_result("test_create__write_wo", nw == sizeof(test_txt));
     print_test_result("test_create__close_wo", vfs_close(fd) == 0);
+
+    /* test create if file exists */
+    fd = vfs_open(FULL_FNAME1, O_WRONLY | O_CREAT, 0);
+    print_test_result("test_create__open_wo2", fd >= 0);
+
+    nw = vfs_write(fd, test_txt, sizeof(test_txt));
+    print_test_result("test_create__write_wo2", nw == sizeof(test_txt));
+    print_test_result("test_create__close_wo2", vfs_close(fd) == 0);
+
     print_test_result("test_create__umount", vfs_umount(&_test_vfs_mount) == 0);
 }
 
+#ifdef MODULE_NEWLIB
+static void test_newlib(void)
+{
+    FILE* fl;
+    char buf[sizeof(test_txt) + sizeof(test_txt2)];
+    print_test_result("test_newlib__mount", vfs_mount(&_test_vfs_mount) == 0);
+
+    /* try to open file that doesn't exist */
+    fl = fopen(FULL_FNAME_NXIST, "r");
+    print_test_result("test_newlib__fopen", fl == NULL);
+    if (fl) {
+        fclose(fl);
+    }
+
+    /* create new file write and check content */
+    remove(FULL_FNAME2);
+    fl = fopen(FULL_FNAME2, "w+");
+    print_test_result("test_newlib__fopen_w", fl != NULL);
+    if (fl) {
+        print_test_result("test_newlib__fputs_w", fputs(test_txt, fl) >= 0);
+        rewind(fl);
+        print_test_result("test_newlib__fread_w",
+                fread(buf, sizeof(*buf), sizeof(buf), fl) > 0);
+        print_test_result("test_newlib__strcmp_w", strcmp(test_txt, buf) == 0);
+        print_test_result("test_newlib__fclose_w", fclose(fl) == 0);
+    }
+
+    /* cppcheck-suppress resourceLeak
+     * (reason: cppcheck <2.0 reports a false positive here) */
+    fl = fopen(FULL_FNAME2, "r"); /* open file RO */
+    print_test_result("test_newlib__fopen_r", fl != NULL);
+    if (fl) {
+        print_test_result("test_newlib__fclose_r", fclose(fl) == 0);
+    }
+
+    /* remove file */
+    print_test_result("test_newlib__remove", remove(FULL_FNAME2) == 0);
+
+    /* append to non existing file */
+    fl = fopen(FULL_FNAME2, "a");
+    print_test_result("test_newlib__fopen_a", fl != NULL);
+    if (fl) {
+        print_test_result("test_newlib__fputs_a", fputs(test_txt, fl) >= 0);
+        print_test_result("test_newlib__fclose_a", fclose(fl) == 0);
+    }
+
+    /* append to existing file and check content */
+    fl = fopen(FULL_FNAME2, "a+");
+    print_test_result("test_newlib__fopen_a2", fl != NULL);
+    if (fl) {
+        print_test_result("test_newlib__fputs_a2", fputs(test_txt2, fl) >= 0);
+        rewind(fl);
+        print_test_result("test_newlib__fread_a2",
+                fread(buf, sizeof(*buf), sizeof(buf), fl) > 0);
+        print_test_result("test_newlib__strcmp_a2",
+                strncmp(test_txt, buf, strlen(test_txt)) == 0);
+        print_test_result("test_newlib__strcmp_a2", strncmp(test_txt2,
+                    &buf[strlen(test_txt)], strlen(test_txt2)) == 0);
+        print_test_result("test_newlib__fclose_a2", fclose(fl) == 0);
+    }
+    print_test_result("test_newlib__remove", remove(FULL_FNAME2) == 0);
+
+    print_test_result("test_newlib__umount", vfs_umount(&_test_vfs_mount) == 0);
+}
+#endif
+
 int main(void)
 {
 #if MODULE_MTD_SDCARD
@@ -324,6 +399,9 @@ int main(void)
     test_unlink();
     test_mkrmdir();
     test_create();
+#ifdef MODULE_NEWLIB
+    test_newlib();
+#endif
 
     printf("Test end.\n");
     return 0;

From 4469d8f0fb298de784119943900845d04702f69f Mon Sep 17 00:00:00 2001
From: Sven Herrmann <sven.herrmann@posteo.de>
Date: Fri, 29 May 2020 13:08:43 +0000
Subject: [PATCH 2/2] pkg/fatfs/fatfs_vfs: fix flag translation in _open

---
 pkg/fatfs/fatfs_vfs/fatfs_vfs.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/pkg/fatfs/fatfs_vfs/fatfs_vfs.c b/pkg/fatfs/fatfs_vfs/fatfs_vfs.c
index a41168d1a99b..0892c8ab6b9f 100644
--- a/pkg/fatfs/fatfs_vfs/fatfs_vfs.c
+++ b/pkg/fatfs/fatfs_vfs/fatfs_vfs.c
@@ -151,7 +151,12 @@ static int _open(vfs_file_t *filp, const char *name, int flags, mode_t mode,
         fatfs_flags |= FA_CREATE_ALWAYS;
     }
     if ((flags & O_CREAT) == O_CREAT) {
-        fatfs_flags |= FA_CREATE_NEW;
+        if ((flags & O_EXCL) == O_EXCL) {
+            fatfs_flags |= FA_CREATE_NEW;
+        }
+        else {
+            fatfs_flags |= FA_OPEN_ALWAYS;
+        }
     }
     else {
         fatfs_flags |= FA_OPEN_EXISTING;