fix: stop UDP xsgetn assembling after buffered residue#41
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PR #37 gated only the count >= N bulk recv path. wait_for()/peek() underflow a short datagram first, so a following read(udp_buffer_size) drained residue with count < N and still assembled forever in the underflow loop. Never cross datagram boundaries in xsgetn for SOCK_DGRAM. Co-authored-by: Kaius Ruokonen <ruoka@users.noreply.github.com>
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PR #37 gated only the count >= N bulk recv path. wait_for()/peek() underflow a short datagram first, so a following read(udp_buffer_size) drained residue with count < N and still assembled forever in the underflow loop. Never cross datagram boundaries in xsgetn for SOCK_DGRAM. Co-authored-by: Cursor Agent <cursoragent@cursor.com> Co-authored-by: Kaius Ruokonen <ruoka@users.noreply.github.com>
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Bug and impact
After PR #37,
endpointbuf::xsgetnstill hung on a common UDP read pattern:wait_for()(or anypeek) followed byread(buf, udp_buffer_size)for a short datagram. The call blocked forever waiting for more bytes, or could merge later datagrams.Root cause
PR #37 only gated the
count >= Nbulk-recvpath.endpointstream::wait_forpeeks first, which underflows the short datagram into the get area. The following max-sizereadthen drained that residue withcount < N, skipped the gate, and entered the underflow assemble loop.Fix
For
SOCK_DGRAM, never cross datagram boundaries inxsgetn: return after draining buffered residue, and after a single underflow fill. TCP short-recv assembly is unchanged.Validation
NET_DISABLE_NETWORK_TESTS=0 tools/CB.sh debug test— both UDP xsgetn scenarios passed; remaining assertion failures are known cloud-fabricconnect_with_timeout/ environment noise unrelated to this change