Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: Segmentation Fault by memcpy
Top Forums Programming Segmentation Fault by memcpy Post 302425751 by Zykl0n-B on Saturday 29th of May 2010 05:17:14 PM
Old 05-29-2010
Segmentation Fault by memcpy
Hello everybody,
I'm coding a test program for ARP protocol, and i don't know why i'm getting a SIGSEGV, i traced it with gdb and it says it's due to the memcpy function from /lib/libc.so.6.
Code:
Program received signal SIGSEGV, Segmentation fault.
0xb7e9e327 in memcpy () from /lib/libc.so.6

This segmentation fault came when i decided to change the protocol headers, i was using a buffer to store two structures, containing ethernet & arp headers, and i decided to use just one structure, containing both headers structure.

This is the code:
Code:
struct ethernet{
unsigned char target[6];
unsigned char source[6];
unsigned short type;
};

struct arp{
unsigned short ar$hrd;
unsigned short ar$pro;
unsigned char  ar$hln;
unsigned char  ar$pln;
unsigned short ar$op;
unsigned char  ar$sha[6];
unsigned char  ar$spa[4];
unsigned char  ar$tha[6];
unsigned char  ar$tpa[4];
};

struct arpmsg{
struct ethernet ethernet;
struct arp arp;
};

And i get the segmentation fault in the main program when i use memcpy to store the addresses in their respective field, here's an example:

Code:
char mac[]={0x01,0x00,0x5E,0x03,0x03,0x08};
memcpy(arpmsg->arp.ar$sha, mac, 6);

Please, could anyone tell me what am i doing wrong? This is a weird error, gcc gives me no warnings.

Oh!, i changed the memcpy function to strncpy, strcpy, and i keep getting the same SIGSEGV.

I'll appreciate any answers, thank you.
Zykl0n-B
 

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

Segmentation Fault

hello all, I tried a program on an array to intialise array elements from the standard input device.it is an integer array of 5 elements.but after entering the 4th element it throws a message called "Segmentation Fault" and returns to the command prompt without asking for the 5th element. ... (3 Replies)
Discussion started by: compbug
3 Replies

2. AIX

Segmentation fault

Hi , During execution a backup binary i get following error "Program error 11 (Segmentation fault), saving core file in '/usr/datatools" Riyaz (2 Replies)
Discussion started by: rshaikh
2 Replies

3. UNIX for Dummies Questions & Answers

Segmentation Fault

Hi, While comparing primary key data of two tables thr bteq script I am getting this Error. This script is a shell script. *** Error: The following error was encountered on the output file. Script.sh: 3043492 Segmentation fault(coredump) Please let me know how to get through it. ... (5 Replies)
Discussion started by: monika
5 Replies

4. Programming

Segmentation fault in C

i have this code int already_there(char *client_names, char *username) { int i; for(i = 0; i<NUM; i++) { printf("HERE\n"); if (strcmp(client_names, username)==0) return(1); } return(0); } and i get a segmentation fault, whats wrong here? (7 Replies)
Discussion started by: omega666
7 Replies

5. UNIX for Advanced & Expert Users

segmentation fault with ps

What does this mean and why is this happening? $ ps -ef | grep ocular Segmentation fault (core dumped) $ ps -ef | grep ocular Segmentation fault (core dumped) $ ps aux | grep ocular Segmentation fault (core dumped) $ ps Segmentation fault (core dumped) $ pkill okular $ ps... (1 Reply)
Discussion started by: cokedude
1 Replies

6. Programming

Using gdb, ignore beginning segmentation fault until reproduce environment segmentation fault

I use a binary name (ie polo) it gets some parameter , so for debugging normally i do this : i wrote script for watchdog my app (polo) and check every second if it's not running then start it , the problem is , if my app , remain in state of segmentation fault for a while (ie 15 ... (6 Replies)
Discussion started by: pooyair
6 Replies

7. Homework & Coursework Questions

Segmentation Fault

this is a network programming code to run a rock paper scissors in a client and server. I completed it and it was working without any error. After I added the findWinner function to the server code it starts giving me segmentation fault. -the segmentation fault is fixed Current problem -Also... (3 Replies)
Discussion started by: femchi
3 Replies

8. Solaris

Segmentation fault

Hi Guys, I just installed and booted a zone called testzone. When I logged in remotely and tried changing to root user I get this error: "Segmentation fault" Can someone please help me resolve this? Thanks alot (2 Replies)
Discussion started by: cjashu
2 Replies

9. Programming

Segmentation fault

I keep getting this fault on a lot of the codes I write, I'm not exactly sure why so I'd really appreciate it if someone could explain the idea to me. For example this code #include <stdio.h> main() { unsigned long a=0; unsigned long b=0; int z; { printf("Enter two... (2 Replies)
Discussion started by: sizzler786
2 Replies

10. Programming

C. To segmentation fault or not to segmentation fault, that is the question.

Oddities with gcc, 2.95.3 for the AMIGA and 4.2.1 for MY current OSX 10.14.1... I am creating a basic calculator for the AMIGA ADE *NIX emulator in C as it does not have one. Below are two very condensed snippets of which I have added the results inside the each code section. IMPORTANT!... (11 Replies)
Discussion started by: wisecracker
11 Replies

LEARN ABOUT CENTOS

outb

OUTB(2) 						     Linux Programmer's Manual							   OUTB(2)

NAME

       outb, outw, outl, outsb, outsw, outsl, inb, inw, inl, insb, insw, insl, outb_p, outw_p, outl_p, inb_p, inw_p, inl_p - port I/O

SYNOPSIS

       #include <sys/io.h>

       unsigned char inb(unsigned short int port);
       unsigned char inb_p(unsigned short int port);
       unsigned short int inw(unsigned short int port);
       unsigned short int inw_p(unsigned short int port);
       unsigned int inl(unsigned short int port);
       unsigned int inl_p(unsigned short int port);

       void outb(unsigned char value, unsigned short int port);
       void outb_p(unsigned char value, unsigned short int port);
       void outw(unsigned short int value, unsigned short int port);
       void outw_p(unsigned short int value, unsigned short int port);
       void outl(unsigned int value, unsigned short int port);
       void outl_p(unsigned int value, unsigned short int port);

       void insb(unsigned short int port, void *addr,
		  unsigned long int count);
       void insw(unsigned short int port, void *addr,
		  unsigned long int count);
       void insl(unsigned short int port, void *addr,
		  unsigned long int count);
       void outsb(unsigned short int port, const void *addr,
		  unsigned long int count);
       void outsw(unsigned short int port, const void *addr,
		  unsigned long int count);
       void outsl(unsigned short int port, const void *addr,
		  unsigned long int count);

DESCRIPTION

       This  family  of  functions  is	used  to do low-level port input and output.  The out* functions do port output, the in* functions do port
       input; the b-suffix functions are byte-width and the w-suffix functions word-width; the _p-suffix functions pause until the I/O completes.

       They are primarily designed for internal kernel use, but can be used from user space.

       You must compile with -O or -O2 or similar.  The functions are defined as inline macros, and will not be substituted in	without  optimiza-
       tion enabled, causing unresolved references at link time.

       You  use  ioperm(2)  or	alternatively  iopl(2) to tell the kernel to allow the user space application to access the I/O ports in question.
       Failure to do this will cause the application to receive a segmentation fault.

CONFORMING TO

       outb() and friends are hardware-specific.  The value argument is passed first and the port argument is passed second, which is the opposite
       order from most DOS implementations.

SEE ALSO

       ioperm(2), iopl(2)

COLOPHON

       This  page is part of release 3.53 of the Linux man-pages project.  A description of the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

Linux								    2012-12-31								   OUTB(2)
All times are GMT -4. The time now is 05:09 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy