add directory study

study/linux-travel/MINIX-1.5/1.5/Source/commands/atrun.c

@@ -0,0 +1,53 @@
+/* atrun - perform the work 'at' has squirreled away	Author: Jan Looyen */
+
+/*-------------------------------------------------------------------------*
+ *	atrun scans directory /usr/spool/at for 'at' jobs to be executed.  *
+ *	Finished jobs have been moved to directory /usr/spool/at/past.     *
+ *-------------------------------------------------------------------------*/
+#include <sys/types.h>
+#include <sys/dir.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <time.h>
+#include <stdio.h>
+
+main()
+{
+  int fd, nr;
+  char realtime[15], procname[35], procpast[35];
+  struct direct dirbuf;
+  struct tm *p, *localtime();
+  struct stat sbuf;
+  time_t clock;
+
+/*-------------------------------------------------------------------------*
+ *	Compute real time,  move 'at' jobs whose filenames < real time to  *
+ *	/usr/spool/at/past and start a sh for each job.			   *
+ *-------------------------------------------------------------------------*/
+  time(&clock);
+  p = localtime(&clock);
+  sprintf(realtime, "%02d.%03d.%02d%02d.00",
+	p->tm_year % 100, p->tm_yday, p->tm_hour, p->tm_min);
+  if ((fd = open("/usr/spool/at", O_RDONLY)) > 0)
+	while (read(fd, (char *) &dirbuf, sizeof(dirbuf)) > 0)
+		if (dirbuf.d_ino > 0 &&
+		    dirbuf.d_name[0] != '.' &&
+		    dirbuf.d_name[0] != 'p' &&
+		    strncmp(dirbuf.d_name, realtime, 11) <= 0) {
+
+			sprintf(procname, "/usr/spool/at/%.14s", dirbuf.d_name);
+			sprintf(procpast, "/usr/spool/at/past/%.14s", dirbuf.d_name);
+
+			if (fork() == 0)	/* code for child */
+				if (link(procname, procpast) == 0) {	/* link ok? */
+					unlink(procname);
+					stat(procpast, &sbuf);
+					setgid(sbuf.st_uid);
+					setuid(sbuf.st_gid);
+					execl("/bin/sh", "sh", procpast, (char *) 0);
+					fprintf(stderr, "proc %s can't start\n", procpast);
+					exit(1);
+				}
+		}
+}