predate.c

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#include <sys/types.h>
#include <time.h>
#include <unistd.h>
#include "datetime.h"
#include "wait.h"
#include "fd.h"
#include "fmt.h"
#include "logmsg.h"
#include "buffer.h"
#include "exit.h"
#include "sig.h"
 
#define WHO "predate"
 
static char *montab[12] = {
"Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"
};
 
char num[FMT_ULONG];
char outbuf[1024];
 
int main(int argc, char **argv)
{
  time_t now;
  struct tm *tm;
  struct datetime dt;
  datetime_sec utc;
  datetime_sec local;
  int minutes;
  int pi[2];
  buffer bo;
  int wstat;
  int pid;
 
  sig_pipeignore();
 
  if (!argv[1])
    logmsg(WHO,100,USAGE,"predate child");
 
  if (pipe(pi) == -1)
    logmsg(WHO,111,FATAL,"unable to create pipe");
 
  switch (pid = fork()) {
    case -1:
      logmsg(WHO,111,FATAL,"unable to fork");
    case 0:
      close(pi[1]);
      if (fd_move(0,pi[0]) == -1)
        logmsg(WHO,111,FATAL,"unable to set up fds");
      sig_pipedefault();
      execvp(argv[1],argv + 1);
      logmsg(WHO,111,FATAL,B("unable to run: ",argv[1]));
  }
  close(pi[0]);
  buffer_init(&bo,write,pi[1],outbuf,sizeof(outbuf));
 
  time(&now);
 
  tm = gmtime(&now);
  dt.year = tm->tm_year;
  dt.mon = tm->tm_mon;
  dt.mday = tm->tm_mday;
  dt.hour = tm->tm_hour;
  dt.min = tm->tm_min;
  dt.sec = tm->tm_sec;
  utc = datetime_untai(&dt); /* utc == now, if gmtime ignores leap seconds */
 
  tm = localtime(&now);
  dt.year = tm->tm_year;
  dt.mon = tm->tm_mon;
  dt.mday = tm->tm_mday;
  dt.hour = tm->tm_hour;
  dt.min = tm->tm_min;
  dt.sec = tm->tm_sec;
  local = datetime_untai(&dt);
 
  buffer_puts(&bo,"Date: ");
  buffer_put(&bo,num,fmt_uint(num,dt.mday));
  buffer_puts(&bo," ");
  buffer_puts(&bo,montab[dt.mon]);
  buffer_puts(&bo," ");
  buffer_put(&bo,num,fmt_uint(num,dt.year + 1900));
  buffer_puts(&bo," ");
  buffer_put(&bo,num,fmt_uint0(num,dt.hour,2));
  buffer_puts(&bo,":");
  buffer_put(&bo,num,fmt_uint0(num,dt.min,2));
  buffer_puts(&bo,":");
  buffer_put(&bo,num,fmt_uint0(num,dt.sec,2));
 
  if (local < utc) {
    minutes = (utc - local + 30) / 60;
    buffer_puts(&bo," -");
    buffer_put(&bo,num,fmt_uint0(num,minutes / 60,2));
    buffer_put(&bo,num,fmt_uint0(num,minutes % 60,2));
  }
  else {
    minutes = (local - utc + 30) / 60;
    buffer_puts(&bo," +");
    buffer_put(&bo,num,fmt_uint0(num,minutes / 60,2));
    buffer_put(&bo,num,fmt_uint0(num,minutes % 60,2));
  }
 
  buffer_puts(&bo,"\n");
  buffer_copy(&bo,buffer_0);
  buffer_flush(&bo);
  close(pi[1]);
 
  if (wait_pid(&wstat,pid) == -1)
    logmsg(WHO,111,FATAL,"wait failed");
  if (wait_crashed(wstat))
    logmsg(WHO,111,FATAL,"child crashed");
  _exit(wait_exitcode(wstat));
}