Cannot read file on SD card even though the file is readable outside of the library

[DaGigabyte]

I have encountered a similar problem problem as #128. But I think our cases are different.
Firstly, I am able to read from my file on SD card using the following code in setup().

    uint8_t *buf = nullptr;
    buf = reinterpret_cast<uint8_t *>(malloc(2048));
    int toSend = 2048;
    myFile = SD.open(FILE_NAME, FILE_READ);
    toSend = myFile.read(buf, toSend);
    ESP_LOGE("File", "Read %d bytes", toSend);

Output: [ 5222][E][main.cpp:170] setup(): [File] Read 2048 bytes

However, when trying to print the toSend of reading the same file in the AsyncClient.h, toSend is zero. However, the file.size() and filename are valid.

Line 377-393 in AsyncClient.h that I modified.

                {
                    size_t filesize = sData->request.file_data.file.size();
                    // toSend = filesize;
                    toSend = sData->request.file_data.file.read(buf, toSend);
                    ESP_LOGE("sendBuff", "filename: %s", sData->request.file_data.filename.c_str());
                    ESP_LOGE("sendBuff", "filesize: %d", filesize);
                    ESP_LOGE("sendBuff", "toSend: %d", toSend);
                    if (toSend == 0)
                    {
                        // In case file read error.
                        ESP_LOGE("sendBuff", "file read error");
                        setAsyncError(sData, state, FIREBASE_ERROR_FILE_READ, !sData->sse, true);
                        ret = function_return_type_failure;
                        goto exit;
                    }
                }

Result:

Upload file...
fileCallback called for: /sailing_data_1999_0_0_0_0_0.csv, mode: 0
fileCallback called for: /sailing_data_1999_0_0_0_0_0.csv, mode: 0
[  6984][E][AsyncClient.h:373] sendBuff(): [sendBuff] allocate buf as: 2048
[  6984][E][AsyncClient.h:382] sendBuff(): [sendBuff] filename: /sailing_data_1999_0_0_0_0_0.csv
[  6988][E][AsyncClient.h:383] sendBuff(): [sendBuff] filesize: 1452984
[  6994][E][AsyncClient.h:384] sendBuff(): [sendBuff] toSend: 0
[  7000][E][AsyncClient.h:388] sendBuff(): [sendBuff] file read error
Event task: task_6228, msg: ready, code: 10
Debug task: task_6228, msg: Connecting to server...
Error task: task_6228, msg: error reading file, code: -104

This is the fileCallback used.

void fileCallback(File &file, const char *filename, file_operating_mode mode)
{
    Serial.printf("fileCallback called for: %s, mode: %d\n", filename, mode);

    switch (mode)
    {
    case file_mode_open_read:
        myFile = SD.open(filename, FILE_READ);

        break;
    case file_mode_open_write:
        myFile = SD.open(filename, FILE_WRITE);
        break;
    case file_mode_open_append:
        myFile = SD.open(filename, FILE_APPEND);
        break;
    case file_mode_remove:
        SD.remove(filename);
        break;
    default:
        Serial.println("Unknown file operation mode");
        break;
    }
    // Set the internal FS object with global File object.
    file = myFile;
}

Strangely, I am able to read the file in setup but not in the library. I don't see a problem in the filecallback function though...

[mobizt]

If you use ESP32, this is the issue in ESP32 filsystems core library since v3.x.x.

If your ESP32 core SDK is up to dated, the current version of library examples that using global defined File object should work normally.

FirebaseClient/examples/Storage/Async/Callback/Download/Download.ino

Lines 219 to 242 in f700d7e

	void fileCallback(File &file, const char *filename, file_operating_mode mode)
	{
	// FILE_OPEN_MODE_READ, FILE_OPEN_MODE_WRITE and FILE_OPEN_MODE_APPEND are defined in this library
	// MY_FS is defined in this example
	switch (mode)
	{
	case file_mode_open_read:
	myFile = MY_FS.open(filename, FILE_OPEN_MODE_READ);
	break;
	case file_mode_open_write:
	myFile = MY_FS.open(filename, FILE_OPEN_MODE_WRITE);
	break;
	case file_mode_open_append:
	myFile = MY_FS.open(filename, FILE_OPEN_MODE_APPEND);
	break;
	case file_mode_remove:
	MY_FS.remove(filename);
	break;
	default:
	break;
	}
	// Set the internal FS object with global File object.
	file = myFile;
	}

If you are using outdated ESP32 core SDK (v2,x.x), you should follow the old examples that using library local defined File object like this.

FirebaseClient/examples/Storage/Async/Callback/Download/Download.ino

Lines 220 to 241 in 0bd66fb

	void fileCallback(File &file, const char *filename, file_operating_mode mode)
	{
	// FILE_OPEN_MODE_READ, FILE_OPEN_MODE_WRITE and FILE_OPEN_MODE_APPEND are defined in this library
	// MY_FS is defined in this example
	switch (mode)
	{
	case file_mode_open_read:
	file = MY_FS.open(filename, FILE_OPEN_MODE_READ);
	break;
	case file_mode_open_write:
	file = MY_FS.open(filename, FILE_OPEN_MODE_WRITE);
	break;
	case file_mode_open_append:
	file = MY_FS.open(filename, FILE_OPEN_MODE_APPEND);
	break;
	case file_mode_remove:
	MY_FS.remove(filename);
	break;
	default:
	break;
	}
	}

This issue only existed in ESP32 core only.