--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/predate.c	Fri Oct 19 14:06:22 2007 +0200
@@ -0,0 +1,116 @@
+#include <sys/types.h>
+#include <time.h>
+#include "datetime.h"
+#include "fork.h"
+#include "wait.h"
+#include "fd.h"
+#include "fmt.h"
+#include "strerr.h"
+#include "substdio.h"
+#include "subfd.h"
+#include "readwrite.h"
+#include "exit.h"
+
+#define FATAL "predate: fatal: "
+
+static char *montab[12] = {
+"Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"
+};
+
+char num[FMT_ULONG];
+char outbuf[1024];
+
+void main(argc,argv)
+int argc;
+char **argv;
+{
+  time_t now;
+  struct tm *tm;
+  struct datetime dt;
+  datetime_sec utc;
+  datetime_sec local;
+  int minutes;
+  int pi[2];
+  substdio ss;
+  int wstat;
+  int pid;
+
+  sig_pipeignore();
+
+  if (!argv[1])
+    strerr_die1x(100,"predate: usage: predate child");
+
+  if (pipe(pi) == -1)
+    strerr_die2sys(111,FATAL,"unable to create pipe: ");
+
+  switch(pid = fork()) {
+    case -1:
+      strerr_die2sys(111,FATAL,"unable to fork: ");
+    case 0:
+      close(pi[1]);
+      if (fd_move(0,pi[0]) == -1)
+	strerr_die2sys(111,FATAL,"unable to set up fds: ");
+      sig_pipedefault();
+      execvp(argv[1],argv + 1);
+      strerr_die4sys(111,FATAL,"unable to run ",argv[1],": ");
+  }
+  close(pi[0]);
+  substdio_fdbuf(&ss,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);
+
+  substdio_puts(&ss,"Date: ");
+  substdio_put(&ss,num,fmt_uint(num,dt.mday));
+  substdio_puts(&ss," ");
+  substdio_puts(&ss,montab[dt.mon]);
+  substdio_puts(&ss," ");
+  substdio_put(&ss,num,fmt_uint(num,dt.year + 1900));
+  substdio_puts(&ss," ");
+  substdio_put(&ss,num,fmt_uint0(num,dt.hour,2));
+  substdio_puts(&ss,":");
+  substdio_put(&ss,num,fmt_uint0(num,dt.min,2));
+  substdio_puts(&ss,":");
+  substdio_put(&ss,num,fmt_uint0(num,dt.sec,2));
+
+  if (local < utc) {
+    minutes = (utc - local + 30) / 60;
+    substdio_puts(&ss," -");
+    substdio_put(&ss,num,fmt_uint0(num,minutes / 60,2));
+    substdio_put(&ss,num,fmt_uint0(num,minutes % 60,2));
+  }
+  else {
+    minutes = (local - utc + 30) / 60;
+    substdio_puts(&ss," +");
+    substdio_put(&ss,num,fmt_uint0(num,minutes / 60,2));
+    substdio_put(&ss,num,fmt_uint0(num,minutes % 60,2));
+  }
+
+  substdio_puts(&ss,"\n");
+  substdio_copy(&ss,subfdin);
+  substdio_flush(&ss);
+  close(pi[1]);
+
+  if (wait_pid(&wstat,pid) == -1)
+    strerr_die2sys(111,FATAL,"wait failed: ");
+  if (wait_crashed(wstat))
+    strerr_die2x(111,FATAL,"child crashed");
+  _exit(wait_exitcode(wstat));
+}