cli/sql: prompting fixes

[knz]

Fixes #102153.
Fixes #105135.
Epic: CRDB-28893

Release note (backwards-incompatible change): When customizing the SQL interactive prompt, the special sequence %M now expands to the full host name instead of the combination of host name and port number. To include the port number explicitly, use %>. The special sequence %m now expands to the host name up to the first period.

Release note (cli change): When customizing the SQL interactive prompt, %M and %m now behave more like psql when connecting over a unix datagram socket.

[cockroach-teamcity]

This change is 

[rafiss]

Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @knz)

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pkg/cli/interactive_tests/test_txn_prompt.tcl line 31 at r1 (raw file):

send "\\set prompt1 abc%mdef\r"
eexpect abc127def

all the logic lgtm, but just a sanity check about what PG is doing: does PG always truncate up to the first period like this? i was wondering if it handled hostnames different from IP addresses.

[knz]

all the logic lgtm, but just a sanity check about what PG is doing: does PG always truncate up to the first period like this?

It's literally in the doc:

The host name of the database server, truncated at the first dot, or [local] if the connection is over a Unix domain socket.

Also in the pg source code, src/bin/psql/prompt.c:

                        /* INET socket */
                        if (host && host[0] && !is_unixsock_path(host))
                        {
                            strlcpy(buf, host, sizeof(buf));
                            if (*p == 'm')
                                buf[strcspn(buf, ".")] = '\0';
                        }

Looks like quite specifically "first dot" to me.

[knz]

bors r=rafiss

[craig]

Build succeeded:

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