seek(pos, SeekEnd) fails

[mmmilan]

Hi,
I've tracked down a file seeking issue to this:

ESP32, vfs_api.cpp:

bool VFSFileImpl::seek(uint32_t pos, SeekMode mode)
{
    if(_isDirectory || !_f) {
        return false;
    }
    auto rc = fseek(_f, pos, mode);
    return rc == 0;
}

ESP8266, spiffs_api.h:

    bool seek(uint32_t pos, SeekMode mode) override
    {
        CHECKFD();

        int32_t offset = static_cast<int32_t>(pos);
        if (mode == SeekEnd) {
            offset = -offset;
        }
        auto rc = SPIFFS_lseek(_fs->getFs(), _fd, offset, (int) mode);
        if (rc < 0) {
            DEBUGV("SPIFFS_lseek rc=%d\r\n", rc);
            return false;
        }

        return true;
    }

The ESP32 implementation is missing the position to offset conversion (negation) in SeekEnd mode. Could you fix it, please?

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[mmmilan]

The problem still persists.

#ifndef ESP8266
#include "SPIFFS.h"
#endif
#include "FS.h"

const char* testFileName = "/test.txt";

void setup()
{
  Serial.begin(115200);
  Serial.println();
  while (Serial.available())
    Serial.read();
  Serial.println(F("setup begin"));

#ifdef ESP8266
  SPIFFS.begin();
#else
  if (!SPIFFS.begin(true))
    Serial.println(F("begin() failed"));
#endif

  File f = SPIFFS.open(testFileName, "w");
  if (f)
  {
    f.print("abc");
    f.close();
  }
  else
    Serial.println(F("failed to open test file for writing"));
  File r = SPIFFS.open(testFileName, "r");
  if (r)
  {
    r.seek(1, SeekEnd);
    Serial.print(F("position="));
    Serial.println(r.position());
    r.close();
  }
  else
    Serial.println(F("failed to open test file for reading"));
  Serial.println(F("setup end"));
}

void loop()
{  
}

The code above results position=2 on ESP8266 and position=3 on ESP32.

[atanisoft]

@mmmilan please open an issue against ESP-IDF as the arduino side depends on the VFS layer provided by ESP-IDF which you can see the SPIFFS_seek call here. Once ESP-IDF has a fix merged for it and it reaches a stable release version it can be picked up by arduino-esp32.

[mmmilan]

You're referencing code where the offset has a signed type (off_t), not uint32_t, like the Arduino side. It is fine, if it expects negative values for SeekEnd.

[atanisoft]

@mmmilan The arduino side is a wrapper for the underlying VFS layer, nothing more, nothing less. It will require a fix on the IDF side regardless.

[mmmilan]

Why isn't the VFS layer supposed to work like that? "The arduino side is a wrapper for the underlying VFS layer" - then again, the error is in the arduino layer, where the offset is defined unsigned.

[atanisoft]

If you can fix it in the Arduino VFS wrapper send in a PR...

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[STALE_SET] This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 14 days if no further activity occurs. Thank you for your contributions.

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