Function FillBuffer

pg_documentdb/src/infrastructure/cursor_store.c:530–570

* Fills the specified buffer with length bytes from the cursor file. * returns false if the end of the file is reached. */

 * returns false if the end of the file is reached.
 */
static bool
FillBuffer(CursorFileState *cursorFileState, char *buffer, int32_t length)
{
	while (length > 0)
	{
		if (cursorFileState->nbytes == 0)
		{
			int bytesRead = FileRead(cursorFileState->bufFile,
									 cursorFileState->buffer.data, BLCKSZ,
									 cursorFileState->next_offset,
									 WAIT_EVENT_BUFFILE_READ);
			cursorFileState->nbytes += bytesRead;
			cursorFileState->pos = 0;
			if (bytesRead == 0)
			{
				/* There's no more bytes left */
				cursorFileState->cursorComplete = true;
				return false;
			}
		}

		int32_t currentAvailable = cursorFileState->nbytes - cursorFileState->pos;
		if (currentAvailable >= length)
		{
			memcpy(buffer, cursorFileState->buffer.data + cursorFileState->pos, length);
			cursorFileState->pos += length;
			cursorFileState->next_offset += length;
			return true;
		}

		memcpy(buffer, cursorFileState->buffer.data + cursorFileState->pos,
			   currentAvailable);

		cursorFileState->pos = cursorFileState->nbytes = 0;
		cursorFileState->next_offset += currentAvailable;
		buffer += currentAvailable;
		length -= currentAvailable;
	}

	return true;
}


/*