<sys/time.h> gettimeofday conflict with Eth socket sendto
 

Whenever I enable gettimeofday in my code, previous working sendto(raw_eth, buffer, ...)

stopped working and

Error: Bad file descriptor.

Why is that?

the only thing I'm sure is it's not name pollution. Since all the variable defined in main() works if I make the wrap of gettimeofday an empty function.

Thanks,

In the absence of code the only explanation I can come up with is: wizards did it! If you don't wish to share the code of your program, write a different, smaller program which does little more but exemplify the problem you are facing; and post that program instead.

Hi -

It sounds like you might be calling "gettimeofday()" incorrectly?

Does your code resemble this:

Thank you guys for reply,

I have gettimeofday(tv, NULL) wrapped with a function:

int SetTimer(struct timeval *tv, time_t sec)
{
gettimeofday(tv, NULL);

tv->tv_sec+=sec;

return 0;
}

in main()
{
struct timeval *tv;

SetTimer(tv, TIME_OUT);

/* Socket stuff */
...
sendto(...)

}

if I comment out contents in SetTimer, sendto works.

Thank you for posting some code. Unfortunately, it doesn't show enough to exhibit any problem.

So would you be so kind as to do these two things?

1. Post a tiny, complete program which misbehaves, so we can compile it ourselves and watch it misbehave.
2. Surround the code you post with CODE tags. Do this by:
   1. selecting all the code in your post, so it's highlighted; and
   2. pressing the octothorpe (#) icon above your posted text.

legendbb -

Please do what I asked you to above!!!!!

You're declaring a pointer to "struct timeval *" ... but your never ALLOCATING the timeval record that's being pointed to!!!!

Guaranteed segmentation violation ;)

Just declare the variable, and pass "&addressof" into the function. It will make you much happier ;)

PS:
Regrettably, a buffer overrun in one part of the program (e.g. your call time "gettimeofday()" with a bogus pointer) can (and usually will) cause a crash in a completely *different* part of the program (here, "sendto()". But just as easily "printf()", "malloc()" or just about any other standard library function).

My problematic code is 600 lines.

I'll tailor it down until the problem just repeats, and post here is I don't find the answer.

Thank you everyone for your help and time.

paulsm4 is definitely right. I didn't initialize the pointer after declaration.

BTW, what is the proper way of initializing the pointer of such struct if in some scenario I prefer to use pointer.

Simple - you declare the object (variable, struct, malloc() a block of memory - whatever) *first*. Then you can make as many or as few pointers as you want.

If you don't declare anything but a pointer ... well, then, it doesn't have anything to "point to", does it?

'Hope that helps .. PSM

PS:
An equivalent example:
But *why*? Much simpler:
Make sense?

Great thanks,