What causes "Invalid path to YUV file!" in DrKLO/Telegram?

Create the parent directory before invoking: `mkdir -p $(dirname yuv_path)`

Invalid path to YUV file!

Error message

Invalid path to YUV file!

What it means

jpegyuv opens the YUV output file with fopen(yuv_path, "wb") at jpegyuv.c:158. If fopen returns NULL, the output path's parent directory doesn't exist, the process lacks write permission, or the path is invalid. The program frees the YUV buffer and returns 1. Notably, the error message lacks a trailing newline (unlike other messages in the file), which can cause the next shell prompt to appear on the same line.

Source

Thrown at TMessagesProj/jni/mozjpeg/jpegyuv.c:160

    for (y = 0; y < 8 && chroma_scanline + y < chroma_height; y++) {
      for (x = 0; x < chroma_width; x++) {
        yuv_buffer[luma_width*luma_height +
         chroma_width*(chroma_scanline + y) + x] = cbrow_pointer[y][x];
        yuv_buffer[luma_width*luma_height + chroma_width*chroma_height +
         chroma_width*(chroma_scanline + y) + x] = crrow_pointer[y][x];
      }
    }
  }

  jpeg_finish_decompress(&cinfo);
  jpeg_destroy_decompress(&cinfo);

  fclose(jpg_fd);
  free(jpg_buffer);

  yuv_fd = fopen(yuv_path, "wb");
  if (!yuv_fd) {
    fprintf(stderr, "Invalid path to YUV file!");
    free(yuv_buffer);
    return 1;
  }
  if (fwrite(yuv_buffer, yuv_size, 1, yuv_fd) != 1) {
    fprintf(stderr, "Error writing yuv file\n");
  }

  fclose(yuv_fd);
  free(yuv_buffer);

  return 0;
}

View on GitHub (pinned to 45ab8f4308)

Solutions

Create the parent directory before invoking: `mkdir -p $(dirname yuv_path)`
Verify write permission on the output directory
Use the app's internal storage for output
Add the missing newline to the error message in jpegyuv.c for cleaner output

Example fix

// before (JNI)
nativeConvertJpegToYuv(jpgPath, "/sdcard/yuv/output.yuv");

// after
File outDir = context.getFilesDir();
new File(outDir, "yuv").mkdirs();
String yuvPath = new File(outDir, "yuv/output.yuv").getAbsolutePath();
nativeConvertJpegToYuv(jpgPath, yuvPath);

Defensive patterns

Strategy: validation

Validate before calling

// Validate output path and create parent directory before calling jpegyuv
int validate_yuv_output(const char *path) {
    if (path == NULL || path[0] == '\0') return -1;
    // Extract and check/create parent directory
    char dir[4096];
    strncpy(dir, path, sizeof(dir)-1); dir[sizeof(dir)-1] = '\0';
    char *slash = strrchr(dir, '/');
    if (slash) {
        *slash = '\0';
        if (access(dir, W_OK) != 0) {
            // try to create it
            if (mkdir(dir, 0700) != 0 && errno != EEXIST) return -1;
        }
    }
    return 0;
}

Prevention

Create the output directory before invoking jpegyuv
Verify write permission on the output directory
Use the app's internal storage for YUV output files

When it happens

Trigger: Output directory doesn't exist. No write permission on the output directory. The output path is a directory itself. Disk full preventing file creation.

Common situations: JNI caller passes an output path in a directory the native process can't write to. On Android, writing to external storage without proper permissions. Output path points to a read-only filesystem mount.

Related errors

AI-assisted analysis of DrKLO/Telegram@45ab8f4308 (2026-08-14). Data as JSON: /api/errors/00c80f01af2b4313. Report an issue: GitHub.