LittleFS missing availableForWrite()

[CapnBry]

Basic Infos

• This issue complies with the issue POLICY doc.
• I have read the documentation at readthedocs and the issue is not addressed there.
• I have tested that the issue is present in current master branch (aka latest git).
• I have searched the issue tracker for a similar issue.
• If there is a stack dump, I have decoded it.
• I have filled out all fields below.

Platform

• Hardware: [ESP-12F]
• Core Version: [3.0.2]
• Development Env: [VSMicro]
• Operating System: [Windows]

Settings in IDE

• Module: [LOLIN(WEMOS) D1 D2 & mini]
• Flash Mode: [DIO]
• Flash Size: [4MB]
• lwip Variant: [Higher Bandwidth]
• Reset Method: [nodemcu]
• Flash Frequency: [40Mhz]
• CPU Frequency: [80Mhz]
• Upload Using: [SERIAL]
• Upload Speed: [921600] (serial upload only)

Problem Description

Attempting to use HTTPClient to stream directly to a LittleFS File times out with error code -11. This is due to the LittleFSFileImpl not implementing availableForWrite(), so the base implementation returns 0 and the streaming can't write and times out. I added this implementation but I do not know if this is the right thing to return. It probably isn't but hey it works! It would probably work even if I returned 1 so I'm not going to throw myself a parade or anything for getting it working.

// in LittleFS.h LittleFSFileImpl
    int availableForWrite() override {
      if (!_opened || !_fd) {
        return 0;
      }
      return _fs->_lfs_cfg.block_size;
    }

MCVE Sketch

void taskcbIcsCheck(void)
{
  Serial.println(F("Performing ICS check..."));

  WiFiClient *client;
  if (strncmp(ICS_URL, "https://", 8) == 0)
  {
    client = new BearSSL::WiFiClientSecure();
    ((BearSSL::WiFiClientSecure *)client)->setInsecure();
  }
  else
    client = new WiFiClient();

  HTTPClient *https = new HTTPClient();
  int httpCode = -1;
  if (https->begin(*client, ICS_URL))
  {
    https->setUserAgent("Google-Calendar-Importer");
    https->setFollowRedirects(HTTPC_FORCE_FOLLOW_REDIRECTS);
    httpCode = https->GET();
    Serial.print(F("Response code ")); Serial.println(httpCode, DEC);

    if (httpCode == HTTP_CODE_OK) {
      File f = LittleFS.open("cal.ics", "w");
      int n = https->writeToStream(&f);
      f.close();
      Serial.print("Download complete n="); Serial.println(n, DEC);

      g_IcsLastCheck = time(nullptr);
      taskIcsRead.restartDelayed(100);
    }
    https->end();
  }
  else
    Serial.print("Connect failed");

  delete https;
  delete client;
}

Debug Messages

[HTTP-Client][handleHeaderResponse] RX: ''
[HTTP-Client][handleHeaderResponse] code: 200
[HTTP-Client][handleHeaderResponse] size: 8718
// and then nothing, return code -11

[d-a-v]

@CapnBry thanks for reporting this issue to us.
LittleFS wrapper indeed lacks of this implementation.
Returning block_size unlocks Stream*Send() methods but this may be a little too rough.
We'll address a fix very soon.

[CapnBry]

Awesome, thanks for the reply. Yeah I wasn't sure what value to return considering it could be up to the remaining space of the entire partition! Or be really inefficient and return as low as 1 haha.

Appreciate you putting this on your radar for a proper fox and thanks so much for all the other tons of code that makes my projects just an include and a few lines.