perf: eliminate redundant syscalls in "context.IsSet"

[lifubang]

What type of PR is this?

• bug

What this PR does / why we need it:

The lack of an empty check before performing a syscall results in numerous redundant system calls within context.IsSet.

Which issue(s) this PR fixes:

Fix #2282

[yassinebenaid]

Not sure if it's worth it though

[lifubang]

Not sure if it's worth it though

You're right -- the program runs for only tens of milliseconds and performs just ~10 such calls, so the direct performance or CPU cost is negligible. That said, these invalid syscalls still signal a logic flaw (e.g., passing an empty path), which can hurt observability by adding noise to logs, traces, and debugging tools like strace or auditd. They also represent unnecessary resource usage, however small—which adds up in aggregate across many invocations (e.g., in serverless, CI, or containerized environments). Fixing it improves code clarity, maintainability, and system hygiene with minimal effort.

[abitrolly]

a logic flaw (e.g., passing an empty path),

So why eachName passes the empty path?

[dearchap]

@lifubang v1 is in maintenance mode with only security fixes and nothing else. So is v2. v3 is the latest release. if you'd like to port this to v3 I'm fine with reviewing and merging

[lifubang]

v1 is in maintenance mode with only security fixes and nothing else.

Thanks for the context -- I understand the situation.
Let me give it a try to upgrade urfave/cli from v1 to v3 in runc.
It’s likely a sizable effort, but worth doing.