[PATCH 2/8] man/man7/unix.7: SO_PEERCRED: Also works for SOCK_SEQPACKET

["Günther Noack" <gnoack3000@gmail.com>]

SOCK_SEQPACKET sockets use unix_stream_connect() as their connect
operation (as defined in the ops structure unix_seqpacket_ops in
linux.git net/unix/af_unix.c).  That function records the peer
credentials for both ends for later lookup.

unix_socketpair() records them for socket pairs of every type.

Connected SOCK_DGRAM sockets (unix_dgram_connect()) still don't record
peer credentials, so those remain excluded.

In the code, the function that initializes the peercred is
init_peercred()/update_peercred().

Fixes: 73b3a5686084 (2005-08-16; "Clarified details of use of SO_PEERCRED.")
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Kuniyuki Iwashima <kuniyu@google.com>
Assisted-by: LLM
Signed-off-by: Günther Noack <gnoack3000@gmail.com>
---

Notes:
    Double checked in code.
    
    The unix(7) SOCK_SEQPACKET socket type is also connection-oriented and
    shares the "connect" logic with SOCK_STREAM sockets.

 man/man7/unix.7 | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/man/man7/unix.7 b/man/man7/unix.7
index 1054d7f52a30..d0c1765dfd79 100644
--- a/man/man7/unix.7
+++ b/man/man7/unix.7
@@ -342,9 +342,9 @@ feature test macro to obtain the definition of that structure from
 .IP
 The use of this option is possible only for connected
 .B AF_UNIX
-stream sockets and for
+stream and sequenced-packet sockets, and for
 .B AF_UNIX
-stream and datagram socket pairs created using
+socket pairs created using
 .BR socketpair (2).
 .\"
 .SS Autobind feature
-- 
2.56.0