localtime() function is having problem

[lovelylinux]

Hello to all,

I am using localtime() funtion to get information of of time.

But the program is having segmentation fault.

It gives the following type of error from debugger.

/************************************************** ****************/

Program received signal SIGSEGV, Segmentation fault.
0x00a46100 in getenv () from /lib/tls/libc.so.6

#0 0x00a46100 in getenv () from /lib/tls/libc.so.6
#1 0x00aafbcf in tzset_internal () from /lib/tls/libc.so.6
#2 0x00ab07a8 in __tz_convert () from /lib/tls/libc.so.6

/************************************************** ****************/

My Program for the reference point is as per Below.

Same problem is there is I am using either ctime() or gmtime().

So what should I have to use instead of these function to get time.

Or What precautions I have to take.

Please help me if possible.

Any good reply is apprecialble.

Thanking You in advance.

/************************************************** ********************/

#include <stdio.h>
#include <string.h>
#include <utmp.h>
#include <paths.h>
#include <time.h>

struct login
{
char username[20];
char logintime[30];
char logouttime[30];
}user[100];

int main(int argc, char *argv[])
{
int i = 0;
char cTime[64] = { '\0' };
struct tm *Time;
struct utmp *entry;
utmpname(_PATH_WTMP);
setutent();

while(entry = getutent())
{
if( strcmp(entry->ut_line,":0") == 0)
{
Time = localtime(&(entry->ut_time));// with localtime the program is having problem as mentioned above
strftime(cTime,sizeof cTime,"%F %T",Time);
if(strcmp(entry->ut_user,"\0") != 0)
{
strcpy(user[i].username, "");
strcpy(user[i].logintime, "");
strcpy(user[i].username, entry->ut_user);
strcpy(user[i].logintime, cTime);
}
else
{
strcpy(user[i].logouttime, "");
strcpy(user[i].logouttime, cTime);
i++;
}
}
}
int p;
for(p = 0 ; p < i ; p++)
{
printf(" %s\t\t %s\t\t %s\n", user[p].username, user[p].logintime, user[p].logouttime);
}
endutent();
return 0;
}

/************************************************** ************************/

[likwid]

Looks like you haven't allocated any memory for the Time struct.

you need to do something like

Time = (tm *)malloc(sizeof(tm));

if (Time == NULL) {
   fprintf(stderr, "Error allocating memory for Time, Exiting.");
   exit(-1);
}

Then assign values to members of time

--EDIT--

Actually I guess Entry is the struct you need memory for and Time is actually just going to be a pointer. IDK what exactly you're doing. You might want to compile it with -ggdb and set a breakpoint for the first line and just type 'step' to go through each line of code until it segfaults. That'll give you a more clear indication of what's happening.

[Selenita]

I am having the same problem as you, and i tryed the suggestion, but i couldŕ solve it.

what i get debugging is:


.gdbinit: No such file or directory.

Stopped due to shared library event
Stopped due to shared library event
Cannot access memory at address 0x4d348b74

Thanks in advance

[oz]

Hello and welcome to the forums!

Please start a new thread of your own if you wish. This thread is over 3 years old, so locking.

Thank you.