MSGWAITALL
MSGWAITALL is a flag used with the recv() system call on Linux that requests the kernel to block until the full amount of data requested by the caller has been received. When this flag is set, the function does not return until either exactly the specified number of bytes has been read, an error occurs, or a signal interrupts the call. It is primarily used with stream-oriented sockets (such as TCP) to avoid partial reads when the caller needs a complete payload.
Behavior and semantics: With MSG_WAITALL, recv() will attempt to fill the user-provided buffer up to the requested
Portability and availability: MSG_WAITALL is a Linux-specific flag. It is not defined in the POSIX standard