Issue #19012 has been updated by zverok (Victor Shepelev). Should the docs for [BasicSocket#recv_nonblock](https://docs.ruby-lang.org/en/master/BasicSocket.html#method-i-recv_nonblock) be updated? Now they state
When recvfrom(2) returns 0, Socket#recv_nonblock returns an empty string as data. The meaning depends on the socket: EOF on TCP, empty packet on UDP, etc.
I am not sure whether the change affects all the cases (this thing about datagrams got me confused). Other affected methods don't have a similar clause, but this one seems to directly contradict the implemented behavior now. ---------------------------------------- Bug #19012: BasicSocket#recv* methods return an empty packet instead of nil on closed connections https://bugs.ruby-lang.org/issues/19012#change-105705 * Author: byroot (Jean Boussier) * Status: Closed * Priority: Normal * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN ---------------------------------------- `man recvmsg(2)` states:
Return Value These calls return the number of bytes received, or -1 if an error occurred. The return value will be 0 when the peer has performed an orderly shutdown.
But somehow the entire `receiv` family of methods in Ruby seem to interpret `0` as empty string instead of "EOF". ```ruby require 'socket' puts "=== pipes ===" r, w = IO.pipe r.read_nonblock(1, exception: false) # => :wait_readable w.close r.read_nonblock(1, exception: false) # => nil (EOF) puts "=== sockets ====" r, w = UNIXSocket.socketpair r.read_nonblock(1, exception: false) # => :wait_readable r.recvmsg_nonblock(1, exception: false) # => :wait_readable r.recv_nonblock(1, exception: false) # => :wait_readable w.close r.read_nonblock(1, exception: false) # => nil (EOF) r.recvmsg_nonblock(1, exception: false) # => ["", #<Addrinfo: empty-sockaddr SOCK_STREAM>, 128]] r.recvmsg # => ["", #<Addrinfo: empty-sockaddr SOCK_STREAM>, 0]] r.recv_nonblock(1, exception: false) # => "" ``` ### Expected behavior I would expect `recvmsg_nonblock`, `recvmsg`, `recv_nonblock` and `recv` to return `nil` when the connection is closed. -- https://bugs.ruby-lang.org/