vfs_fat_sdmmc: if card init fails, fail cleanly

This fixes the issue with sdmmc_host not returned to clean state after
a failed attempt to mount the card, with no SD card in the slot.

components/fatfs/src/vfs_fat_sdmmc.c

@@ -39,14 +39,19 @@ esp_err_t esp_vfs_fat_sdmmc_mount(const char* base_path,
     sdmmc_host_init();
 
     // enable card slot
-    sdmmc_host_init_slot(host_config->slot, slot_config);
+    esp_err_t err = sdmmc_host_init_slot(host_config->slot, slot_config);
+    if (err != ESP_OK) {
+        return err;
+    }
+
     s_card = malloc(sizeof(sdmmc_card_t));
     if (s_card == NULL) {
-        return ESP_ERR_NO_MEM;
+        err = ESP_ERR_NO_MEM;
+        goto fail;
     }
 
     // probe and initialize card
-    esp_err_t err = sdmmc_card_init(host_config, s_card);
+    err = sdmmc_card_init(host_config, s_card);
     if (err != ESP_OK) {
         ESP_LOGD(TAG, "sdmmc_card_init failed 0x(%x)", err);
         goto fail;
@@ -104,6 +109,7 @@ esp_err_t esp_vfs_fat_sdmmc_mount(const char* base_path,
     return ESP_OK;
 
 fail:
+    sdmmc_host_deinit();
     free(workbuf);
     esp_vfs_unregister(base_path);
     free(s_card);

components/fatfs/test/test_fatfs.c

@@ -52,6 +52,25 @@ static void create_file_with_text(const char* name, const char* text)
     TEST_ASSERT_EQUAL(0, fclose(f));
 }
 
+TEST_CASE("Mount fails cleanly without card inserted", "[fatfs][ignore]")
+{
+    HEAP_SIZE_CAPTURE();
+    sdmmc_host_t host = SDMMC_HOST_DEFAULT();
+    sdmmc_slot_config_t slot_config = SDMMC_SLOT_CONFIG_DEFAULT();
+    esp_vfs_fat_sdmmc_mount_config_t mount_config = {
+        .format_if_mount_failed = false,
+        .max_files = 5
+    };
+
+    for (int i = 0; i < 3; ++i) {
+        printf("Initializing card, attempt %d ", i);
+        esp_err_t err = esp_vfs_fat_sdmmc_mount("/sdcard", &host, &slot_config, &mount_config, NULL);
+        printf(" err=%d\n", err);
+        TEST_ESP_ERR(ESP_FAIL, err);
+    }
+    HEAP_SIZE_CHECK(0);
+}
+
 TEST_CASE("can create and write file on sd card", "[fatfs][ignore]")
 {
     HEAP_SIZE_CAPTURE();