Hi i just whant to update an password entry in /etc/shadow.
But dosen't get it to work. Something is wrong! in this code.

What i try do do is if user kalle exist in shadow.
I whant it to update it's password for just that entry.

#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <pwd.h>
#include <grp.h>
#include <string.h>
#include <shadow.h>
//#include <userpw.h>

int main()
{
// -------------------------- //
// ------- passwd file ------ //
// -------------------------- //
FILE* fp;
struct passwd *p;

memset(&p, 0, sizeof(p));

if (!(fp = fopen("/etc/passwd", "a"))) {
perror("Problem ");
return(1);
}

// --------------------------- //
// ----- Password Crypt ------ //
// --------------------------- //
char salt[2];
char password[8] = "password";
char t[11];

salt[0] = 'W'; salt[1] = 'M';
strcpy(t,(char *)crypt(password, salt));

// --------------------------- //
// ------ shadow file -------- //
// --------------------------- //

FILE* fps;
struct spwd *sp;
memset(&sp, 0, sizeof(sp));
if (!(fps = fopen("/etc/shadow", "rw"))) {
perror("Problem");
return(1);
}

char user[20] = "kalle";

/* Loop thru passwd file */
while ((p = getpwent()) != NULL) {
printf("%s\n",p->pw_name);

//IF user found
if (strcmp(p->pw_name, user) == 0 ) {

if(!(sp=getspnam(p->pw_name))){
printf("user missing in shadow file");
} else {
strcpy(sp->sp_pwdp,t);
prinf("run the train %s\n",sp->sp_pwdp);
putspent(sp,fps);
}


}

}


fclose(fps);

return( EXIT_SUCCESS );
}

Now i got a bit thurder. But have a differnet problem.
In end of the shadow file it writes "GjgGToqZ1:14063:0:99999:7:"
dont understand why!




#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <pwd.h>
#include <grp.h>
#include <string.h>
#include <shadow.h>
//#include <userpw.h>

int main()
{
// -------------------------- //
// ------- passwd file ------ //
// -------------------------- //
FILE* fp;
struct passwd *p;

memset(&p, 0, sizeof(p));

if (!(fp = fopen("/etc/passwd", "r"))) {
perror("Problem ");
return(1);
}

// --------------------------- //
// ------ shadow file -------- //
// --------------------------- //

FILE* fps;

struct spwd *sp;
//char currpass[255];
memset(&sp, 0, sizeof(sp));
//memset(&currpass, 0, sizeof(currpass));
if (!(fps = fopen("/etc/shadow", "r+"))) {
perror("Problem");
return(1);
}



char user[20] = "kalle";
//strcpy(sp->sp_pwdp,t);
//char password[10] = "password";

/* Loop thru passwd file */

while ((sp = getspent()) != NULL) {
if (strcmp(sp->sp_namp,user) == 0 ) {
//if(!(sp=getspnam(sp->sp_namp))) {
// printf("that user does not exist in shadow file\n");
//} else {
strcpy(sp->sp_pwdp,"testpass");
putspent(sp, fps);
}

else {
//strcpy(sp->sp_pwdp,"temp");
putspent(sp,fps);
}
}
fclose(fp);
fclose(fps); return( EXIT_SUCCESS );
}

exit(0);

Problem solved!