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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
 

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LEARN ABOUT CENTOS

hwloc_obj_attr_u_hwloc_pcidev_attr_s

hwloc_obj_attr_u::hwloc_pcidev_attr_s(3)		     Hardware Locality (hwloc)			  hwloc_obj_attr_u::hwloc_pcidev_attr_s(3)

NAME

       hwloc_obj_attr_u::hwloc_pcidev_attr_s -

SYNOPSIS

       #include <hwloc.h>

   Data Fields
       unsigned short domain
       unsigned char bus
       unsigned char dev
       unsigned char func
       unsigned short class_id
       unsigned short vendor_id
       unsigned short device_id
       unsigned short subvendor_id
       unsigned short subdevice_id
       unsigned char revision
       float linkspeed

Detailed Description
       PCI Device specific Object Attributes.

Field Documentation
   unsigned char hwloc_obj_attr_u::hwloc_pcidev_attr_s::bus
   unsigned short hwloc_obj_attr_u::hwloc_pcidev_attr_s::class_id
   unsigned char hwloc_obj_attr_u::hwloc_pcidev_attr_s::dev
   unsigned short hwloc_obj_attr_u::hwloc_pcidev_attr_s::device_id
   unsigned short hwloc_obj_attr_u::hwloc_pcidev_attr_s::domain
   unsigned char hwloc_obj_attr_u::hwloc_pcidev_attr_s::func
   float hwloc_obj_attr_u::hwloc_pcidev_attr_s::linkspeed
   unsigned char hwloc_obj_attr_u::hwloc_pcidev_attr_s::revision
   unsigned short hwloc_obj_attr_u::hwloc_pcidev_attr_s::subdevice_id
   unsigned short hwloc_obj_attr_u::hwloc_pcidev_attr_s::subvendor_id
   unsigned short hwloc_obj_attr_u::hwloc_pcidev_attr_s::vendor_id
Author
       Generated automatically by Doxygen for Hardware Locality (hwloc) from the source code.

Version 1.7							  Sun Apr 7 2013			  hwloc_obj_attr_u::hwloc_pcidev_attr_s(3)
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