// miscutilities.c
// Lisa Frye
// October 20, 2000
// Program to show some date/time, user/group, and system
// resource functions for CSC 451

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <pwd.h>
#include <grp.h>
#include <time.h>
#include <sys/systeminfo.h>
#include <sys/utsname.h>
#include <unistd.h>
#include <sys/resource.h>
#include <ulimit.h>

#define TESTFILE1 "/usr/users/staff/frye/csc451/miscutilities.c"
#define TESTFILE2 "/usr/users/staff/frye/csc451"

void time_func();
void print_date(struct tm *tp);
void user_func();
void group_func();
void sys_func();


int main()
{
  time_func();

  user_func();

  group_func();

  sys_func();

  printf("\n=============================================\n\n");
  
  return 0;
}


// Function to demonstrate time functions
void time_func()
{
  time_t clock;
  struct tm *tm;
  struct timeval *tv;
  struct timezone *tz;
  char buf[BUFSIZ];

  printf("\n\n=====================   TIME OUTPUT   ====================\n");

  // Get current time in clock to be used by other functions
  time(&clock);


  // Get GMT time
  tm = gmtime(&clock);
  print_date(tm);

  // Get local time
  tm = localtime(&clock);
  print_date(tm);


  printf("\n======================================================\n");
  printf("%s\n", ctime(&clock));

  printf("\n======================================================\n"); 
  printf("Seconds since 1/1/1970:\t%ld\n", mktime(tm));

  printf("\n======================================================\n");
  strftime(buf, BUFSIZ, "%m/%d/%y %I:%M %p", tm); 
  printf("%s\n", buf);

  return;
}   // end function date_func



// Function to print tm structure
void print_date(struct tm *tp)
{
  char *monstr=(char *)calloc(10, sizeof(char));

  printf("\n======================================================\n");

  // Get string version of month
  switch (tp->tm_mon)
    {
    case 0:
      strcpy(monstr, "January");
      break;
    case 1:
      strcpy(monstr, "February");
      break;
    case 2:
      strcpy(monstr, "March");
      break;
    case 3:
      strcpy(monstr, "April");
      break;
    case 4:
      strcpy(monstr, "May");
      break;
    case 5:
      strcpy(monstr, "June");
      break;
    case 6:
      strcpy(monstr, "July");
      break;
    case 7:
      strcpy(monstr, "August");
      break;
    case 8:
      strcpy(monstr, "September");
      break;
    case 9:
      strcpy(monstr, "October");
      break;
    case 10:
      strcpy(monstr, "November");
      break;
    case 11:
      strcpy(monstr, "December");
      break;
   }

  printf("Month/Day/Year:\t%s %d, %d\n", monstr, tp->tm_mday, tp->tm_year+1900);
  printf("Time\t%d:%d:%d\n", tp->tm_hour, tp->tm_min, tp->tm_sec);
  printf("Day of week:\t");

  // Get day as a string
  switch (tp->tm_wday)
    {
    case 0:
      printf("Sunday\n");
      break;
    case 1:
      printf("Monday\n");
      break;
    case 2:
      printf("Tuesday\n");
      break;
    case 3:
      printf("Wednesday\n");
      break;
    case 4:
      printf("Thursday\n");
      break;
    case 5:
      printf("Friday\n");
      break;
    case 6:
      printf("Saturday\n");
      break;
    }

  printf("Day of Year:\t%d\n", tp->tm_yday);

  // See if it is Daylight Savings Time
  if (tp->tm_isdst != 0)
    printf("Daylight Savings Time is in effect\n"); 
  else
    printf("Daylight Savings Time is not in effect\n"); 

return;
}   // end function print_date



void user_func()
{
  struct passwd *pw;

  printf("\n\n=====================   USER OUTPUT   ====================\n");

  // get uid of process
  printf("Real uid: %d, Effective uid: %d\n", getuid(), geteuid());

  pw = getpwnam("lfrye920");
  printf("\n=============================================\n");
  printf("Name:            %s\n", pw->pw_gecos);
  printf("Login:           %s\n", pw->pw_name);
  printf("uid:             %d\n", pw->pw_uid);
  printf("gif:             %d\n", pw->pw_gid);
  printf("Home Directory:  %s\n", pw->pw_dir);
  printf("Shell:           %s\n", pw->pw_shell);

  pw = getpwent();
  while (pw != NULL)
    {
      if (strncmp(pw->pw_name, "adm", 3) == 0)
	  break;
      printf("\n=============================================\n");
      printf("Name:            %s\n", pw->pw_gecos);
      printf("Login:           %s\n", pw->pw_name);
      printf("uid:             %d\n", pw->pw_uid);
      printf("gif:             %d\n", pw->pw_gid);
      printf("Home Directory:  %s\n", pw->pw_dir);
      printf("Shell:           %s\n", pw->pw_shell);
      pw = getpwent();
    }   // end while loop

  return;
}   // end function user_func



void group_func()
{
  struct group *gr;
  int i = 0;

  printf("\n\n=====================   GROUP OUTPUT   ====================\n");

  // get gid of process
  printf("Real gid: %d, Effective gid: %d\n", getgid(), getegid());

  gr = getgrnam("student");
  printf("\n=============================================\n");
  printf("Group Name:\t%s\n", gr->gr_name);
  printf("gid:\t\t%d\n", gr->gr_gid);
  printf("Members:\t");
  while ((gr->gr_mem[i]) != NULL)
    {
      printf("%s   ", gr->gr_mem[i]);
      i++;
    }   // end while
  printf("\n");

  return;
}   // end function group_func


void sys_func()
{
  struct utsname *info;
  struct rlimit *rp;
  long max_size, val;

  printf("\n\n=====================   SYSTEM OUTPUT   ====================\n");

  // Get system information
  printf("\n=============================================\n");
  if (uname(info) < 0)
    perror("uname");
  else
    {
      printf("Operating System:\t%s\n", info->sysname);
      printf("Hostname:\t\t%s\n", info->nodename);
      printf("OS Release:\t\t%s\n", info->release);
      printf("OS Version:\t\t%s\n", info->version);
      printf("Architecture:\t\t%s\n", info->machine);
    }   // end else


  // Get system limits
  printf("\n=============================================\n");
  val = sysconf(_SC_OPEN_MAX);
  if (val < 0)
    perror("sysconf");
  else
    printf("Max number of open files per process: %d\n", val);

  val = sysconf(_SC_PAGESIZE);
  if (val < 0)
    perror("sysconf");
  else
    printf("System memory page size: %d\n", val);

  val = sysconf(_SC_PHYS_PAGES);
  if (val < 0)
    perror("sysconf");
  else
    printf("Total number of pages of physical memory: %d\n", val);

  val = sysconf(_SC_LOGIN_NAME_MAX);
  if (val < 0)
    perror("sysconf");
  else
    printf("Max length of a login name: %d\n", val);


  // Get system limits associated with specified file
  printf("\n=============================================\n");
  val = pathconf(TESTFILE1, _PC_LINK_MAX);
  if (val < 0)
    perror("pathconf");
  else
    printf("Max number of links to the file: %d\n", val);

  val = pathconf(TESTFILE2, _PC_PATH_MAX);
  if (val < 0)
    perror("pathconf");
  else
    printf("Max number of characters in a pathname: %d\n", val);



  // Get process limits 
  printf("\n=============================================\n");
  max_size = ulimit(UL_GETFSIZE);
  printf("Max file size for process: %ld\n", max_size);
  max_size = ulimit(UL_GDESLIM);
  printf("Max number of open files for process: %ld\n", max_size);


  return;
}   // end function sys_func