a buffer to read data into (which should be at least count bytes long).
location to store the number of bytes that was read from the stream
optional #GCancellable object, %NULL to ignore.
Return: %TRUE on success, %FALSE if there was an error
GException on failure.
Tries to read @count bytes from the stream into the buffer starting at @buffer. Will block during this read.
This function is similar to g_input_stream_read(), except it tries to read as many bytes as requested, only stopping on an error or end of stream.
On a successful read of @count bytes, or if we reached the end of the stream, %TRUE is returned, and @bytes_read is set to the number of bytes read into @buffer.
If there is an error during the operation %FALSE is returned and @error is set to indicate the error status, @bytes_read is updated to contain the number of bytes read into @buffer before the error occurred.