From b31b68fc6865ad8a00d3a2e999e28e0f37509fe8 Mon Sep 17 00:00:00 2001
From: Sonika Rathi <sonika.rathi@espressif.com>
Date: Mon, 3 Apr 2023 14:55:37 +0530
Subject: [PATCH] bugfix: fix for fatfs "open("xx",O_CREAT|O_WRONLY,0666)" call
 failure

fatfs 'open' with only O_CREAT flag fails to creat new file

Closes https://github.com/espressif/esp-idf/issues/1817
---
 .../flash_wl/main/test_fatfs_flash_wl.c       |  8 +++++++
 .../test_fatfs_common/test_fatfs_common.c     | 24 +++++++++++++++++++
 .../test_fatfs_common/test_fatfs_common.h     |  4 ++++
 components/fatfs/vfs/vfs_fat.c                |  2 +-
 4 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/components/fatfs/test_apps/flash_wl/main/test_fatfs_flash_wl.c b/components/fatfs/test_apps/flash_wl/main/test_fatfs_flash_wl.c
index 64cf468a0c20..a56b789507de 100644
--- a/components/fatfs/test_apps/flash_wl/main/test_fatfs_flash_wl.c
+++ b/components/fatfs/test_apps/flash_wl/main/test_fatfs_flash_wl.c
@@ -67,6 +67,14 @@ TEST_CASE("(WL) can create and write file", "[fatfs][wear_levelling]")
     test_teardown();
 }
 
+TEST_CASE("(WL) can create and open file with O_CREAT flag", "[fatfs][wear_levelling]")
+{
+    test_setup();
+    test_fatfs_create_file_with_o_creat_flag("/spiflash/hello.txt");
+    test_fatfs_open_file_with_o_creat_flag("/spiflash/hello.txt");
+    test_teardown();
+}
+
 TEST_CASE("(WL) can read file", "[fatfs][wear_levelling]")
 {
     test_setup();
diff --git a/components/fatfs/test_apps/test_fatfs_common/test_fatfs_common.c b/components/fatfs/test_apps/test_fatfs_common/test_fatfs_common.c
index c9b578868e8b..1bc54c7aea8b 100644
--- a/components/fatfs/test_apps/test_fatfs_common/test_fatfs_common.c
+++ b/components/fatfs/test_apps/test_fatfs_common/test_fatfs_common.c
@@ -32,6 +32,30 @@ void test_fatfs_create_file_with_text(const char* name, const char* text)
     TEST_ASSERT_EQUAL(0, fclose(f));
 }
 
+void test_fatfs_create_file_with_o_creat_flag(const char* filename)
+{
+    const int fd = open(filename, O_CREAT|O_WRONLY);
+    TEST_ASSERT_NOT_EQUAL(-1, fd);
+
+    const int r = pwrite(fd, fatfs_test_hello_str, strlen(fatfs_test_hello_str), 0); //offset=0
+    TEST_ASSERT_EQUAL(strlen(fatfs_test_hello_str), r);
+
+    TEST_ASSERT_EQUAL(0, close(fd));
+}
+
+void test_fatfs_open_file_with_o_creat_flag(const char* filename)
+{
+    char buf[32] = { 0 };
+    const int fd = open(filename, O_CREAT|O_RDONLY);
+    TEST_ASSERT_NOT_EQUAL(-1, fd);
+
+    int r = pread(fd, buf, sizeof(buf), 0); // it is a regular read() with offset==0
+    TEST_ASSERT_EQUAL(0, strcmp(fatfs_test_hello_str, buf));
+    TEST_ASSERT_EQUAL(strlen(fatfs_test_hello_str), r);
+
+    TEST_ASSERT_EQUAL(0, close(fd));
+}
+
 void test_fatfs_overwrite_append(const char* filename)
 {
     /* Create new file with 'aaaa' */
diff --git a/components/fatfs/test_apps/test_fatfs_common/test_fatfs_common.h b/components/fatfs/test_apps/test_fatfs_common/test_fatfs_common.h
index 8b2ed0ea3274..dd28211dae0d 100644
--- a/components/fatfs/test_apps/test_fatfs_common/test_fatfs_common.h
+++ b/components/fatfs/test_apps/test_fatfs_common/test_fatfs_common.h
@@ -27,6 +27,10 @@ extern const char* fatfs_test_hello_str_utf;
 
 void test_fatfs_create_file_with_text(const char* name, const char* text);
 
+void test_fatfs_create_file_with_o_creat_flag(const char* filename);
+
+void test_fatfs_open_file_with_o_creat_flag(const char* filename);
+
 void test_fatfs_overwrite_append(const char* filename);
 
 void test_fatfs_read_file(const char* filename);
diff --git a/components/fatfs/vfs/vfs_fat.c b/components/fatfs/vfs/vfs_fat.c
index 6cfd1145c08e..eff73ec359e5 100644
--- a/components/fatfs/vfs/vfs_fat.c
+++ b/components/fatfs/vfs/vfs_fat.c
@@ -264,7 +264,7 @@ static int fat_mode_conv(int m)
         res |= FA_CREATE_NEW;
     } else if ((m & O_CREAT) && (m & O_TRUNC)) {
         res |= FA_CREATE_ALWAYS;
-    } else if (m & O_APPEND) {
+    } else if ((m & O_APPEND) || (m & O_CREAT)) {
         res |= FA_OPEN_ALWAYS;
     } else {
         res |= FA_OPEN_EXISTING;