Update ipv4.c

[LightAutumnMelancholy]

This should fix a ton of the issues that come up in #154

Please look over my work, I'm new in C programming, I've been a shell and python and perl guy most of my career.

[LightAutumnMelancholy]

I took out some obvious white space, but astyle is still catching me somewhere.

[adrienverge]

GitHub is showing the problem to you ;-)

By the way you can run linting scripts locally to identify the problem.

[DimitriPapadopoulos]

Which OS does this patch target exactly?

[LightAutumnMelancholy]

@adrienverge Thanks for that, the build passes now.

So I saw your comments about just calling netstat, I assumed that it was called with system() at some point down the line here.

@DimitriPapadopoulos non-macintosh unix/linux/bsd systems.

[DimitriPapadopoulos]

This part of the code is not executed on non-macintosh unix/linux/bsd systems - hence there isn't anything to fix here.

The "Input/output errors" are unrelated to netstat.

[LightAutumnMelancholy]

#ifndef __APPLE__
	int fd;
	// Cannot stat, mmap not lseek this special /proc file
	fd = open("/proc/net/route", O_RDONLY);
	if (fd == -1)
		return ERR_IPV4_SEE_ERRNO;

	size = read(fd, buffer, sizeof(buffer) - 1);
	if (size == -1) {
		close(fd);
		return ERR_IPV4_SEE_ERRNO;
	}
	close(fd);
#else
	FILE *fp;
	FILE *wnst;
	int len = sizeof(buffer) - 1;
	char *saveptr3 = NULL;

	// Open the command for reading
	wnst = popen("which netstat");
	fp = popen("wnst -f inet -rn", "r");
	if (fp == NULL)
return ERR_IPV4_SEE_ERRNO;

Please excuse me if I have this incorrect, but if the __APPLE__ token is set, this previous block of code executes, else the applicable block is executed?

Do I have this incorrect, can you help me understand if I have this incorrect?

[DimitriPapadopoulos]

These mutliple ifdef/ifndef occurrences are indeed confusing (notice the missing/extra n):

• ifdef __APPLE__ → if on Apple
• ifndef __APPLE__ → if not on Apple

Ideally the code should be rewritten using only ifdef __APPLE__ for the sake of clarity.

[LightAutumnMelancholy]

@DimitriPapadopoulos Thank you for helping me understand. I appreciate your time.