Opening the help screen corrupts global variables

[r-darwish]

Environment details (Put x in the checkbox along with the information)

• Operating System: macOS 13.6.1 (22G313) (Intel CPU)
• Desktop Environment: macOS
• Terminal Emulator: kitty
• Shell: zsh
• Custom desktop opener (if applicable):
• Program options used: default
• Configuration options set: default
• Plugins are installed: None
• Issue exists on nnn master: yes

Exact steps to reproduce the issue

1. Open nnn
2. Launch the help screen with ?
3. Quit with q

nnn(94221,0x7ff854795700) malloc: *** error for object 0x2020202020202020: pointer being freed was not allocated
nnn(94221,0x7ff854795700) malloc: *** set a breakpoint in malloc_error_break to debug
zsh: abort      ./nnn

The problem occur here:

nnn/src/nnn.c

Lines 5175 to 5186 in 744a755

	for (const char *s = helpstr; s < end; ++s) {
	if (hex) {
	for (int k = 0, n = xchartohex(*s); k < n; ++k) *w++ = ' ';
	} else if (*s == '%') {
	int n = ((s[1] - '0') * 10) + (s[2] - '0');
	for (int k = 0; k < n; ++k) *w++ = ' ';
	s += 2;
	} else {
	*w++ = *s;
	}
	hex = *s == '\n';
	}

as g_buf isn't large enough to contain the entire help output, so it starts overriding the value in other global variables

[N-R-K]

as g_buf isn't large enough to contain the entire help output

What's the size of g_buf for you? I suspect macos has PATH_MAX and/or NAME_MAX set to really low values.

[r-darwish]

1536 bytes

[jarun]

I think we need to have a guard against crossing the length.
Can someone raise a PR?

[N-R-K]

I'll fix it soon and send a PR.