ricardgb commented on code in PR #3658:
URL: https://github.com/apache/nuttx-apps/pull/3658#discussion_r4393781164
##########
netutils/telnetd/telnetd_daemon.c:
##########
@@ -115,6 +116,31 @@ int telnetd_daemon(FAR const struct telnetd_config_s
*config)
}
#endif /* CONFIG_SCHED_HAVE_PARENT && CONFIG_ENABLE_ALL_SIGNALS */
+ /* If the daemon was started without standard streams (e.g. spawned by
+ * nsh_telnetstart() before a USB console exists), descriptors 0..2 are
+ * free and any descriptor created below -- the listen socket, an
+ * accepted socket or a session driver -- could be allocated in the
+ * standard-stream range, where the per-session dup2(0..2) would clobber
+ * it. Anchor any free slot in 0..2 to /dev/null first so that can
+ * never happen.
+ */
+
+ for (; ; )
+ {
+ nullfd = open("/dev/null", O_RDWR);
+ if (nullfd < 0)
+ {
+ nerr("ERROR: open(/dev/null) failed: %d\n", errno);
+ goto errout;
Review Comment:
Good catch, thanks. Added `select DEV_NULL` to `NETUTILS_TELNETD`, in the
commit that introduces the `/dev/null` dependency. `moxa:nsh` and
`lm3s6432-s2e:nsh` now resolve to `CONFIG_DEV_NULL=y`, and `lm3s6432-s2e:nsh`
builds with `-Werror` (I could not build `moxa` locally: its assembly needs a
toolchain I do not have). While rewriting, I also brought both commits to the
CONTRIBUTING ยง1.5 form (subjects end with `.`, `Assisted-by:
AGENT_NAME:MODEL_VERSION`). The C code is unchanged.
*Prepared with the assistance of an AI agent (Claude Code).*
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