[BUG] -t | -w suppress warning message, but help text is still shown

[PeterPitterling]

Describe the bug
-t | -w suppress warning message, but help text is still shown

To Reproduce
Steps to reproduce the behavior:

1. Run 'lsof -t -D /non_existent_folder'
2. shows helptext

Expected behavior
no warning and no help text should be written

Program output

$ lsof +D /test
lsof: WARNING: can't stat(/test): No such file or directory
lsof 4.93.2
 latest revision: https://github.com/lsof-org/lsof
 latest FAQ: https://github.com/lsof-org/lsof/blob/master/00FAQ
 latest (non-formatted) man page: https://github.com/lsof-org/lsof/blob/master/Lsof.8
 usage: [-?abhKlnNoOPRtUvVX] [+|-c c] [+|-d s] [+D D] [+|-E] [+|-e s] [+|-f[gG]]
 [-F [f]] [-g [s]] [-i [i]] [+|-L [l]] [+m [m]] [+|-M] [-o [o]] [-p s]
 [+|-r [t]] [-s [p:s]] [-S [t]] [-T [t]] [-u s] [+|-w] [-x [fl]] [--] [names]
Use the ``-h'' option to get more help information.

$ lsof -w +D /test
lsof 4.93.2
 latest revision: https://github.com/lsof-org/lsof
 latest FAQ: https://github.com/lsof-org/lsof/blob/master/00FAQ
 latest (non-formatted) man page: https://github.com/lsof-org/lsof/blob/master/Lsof.8
 usage: [-?abhKlnNoOPRtUvVX] [+|-c c] [+|-d s] [+D D] [+|-E] [+|-e s] [+|-f[gG]]
 [-F [f]] [-g [s]] [-i [i]] [+|-L [l]] [+m [m]] [+|-M] [-o [o]] [-p s]
 [+|-r [t]] [-s [p:s]] [-S [t]] [-T [t]] [-u s] [+|-w] [-x [fl]] [--] [names]
Use the ``-h'' option to get more help information.

Environment (please complete the following information):

• Kernel: all
• OS: all
• lsof Version: all
• Origin: all

[jiegec]

I think it is probably a issue of lsof +D /nonexistent printing help text?

[kurok]

I've investigated this and traced the root cause.

What happens: In src/main.c:369-372, when +D is processed, enter_dir() is called. If it fails (e.g. path doesn't exist), err is set to 1. After all argument processing, main.c:1181-1182
calls usage() whenever err is set — and usage() doesn't check -w/-t (Fwarn/Fterse) at all.

Root cause: enter_dir() (src/arg.c:841) returns 1 for two fundamentally different failure modes:

1. Syntax error — no path provided (line 863): +d not followed by a directory path → usage text is appropriate
2. Runtime error — path doesn't exist / stat fails (line 871) → usage text is NOT appropriate

The caller in main.c can't distinguish these, so both trigger usage().

As @jiegec noted, the real issue is that lsof +D /nonexistent shouldn't print help text at all. A non-existent directory is a runtime error, not a usage error.

Suggested fix: Have enter_dir() return different values for syntax errors vs. runtime errors. Only syntax errors should set err = 1 (which triggers usage()). Runtime errors (stat failure,
not a directory, etc.) should be handled differently — print the warning (unless -w), exit with non-zero status, but don't show help text.

The same pattern applies to +d (line 358) which also calls enter_dir().