Bug#623231: provide "show users with crontab" option for crontab

[Hanno Hecker]

Package: cron
Version: 3.0pl1-105
Severity: wishlist
Tags: patch


The attached patch scans crond's spool dir for user crontabs and prints
them if they have a corresponding password database entry.

diff is against sid's cron

--- cron-3.0pl1.orig/crontab.c	2011-04-18 09:15:39.000000000 +0200
+++ cron-3.0pl1/crontab.c	2011-04-18 09:30:00.088726953 +0200
@@ -47,10 +47,10 @@
 
 #define NHEADER_LINES 3
 
-enum opt_t	{ opt_unknown, opt_list, opt_delete, opt_edit, opt_replace };
+enum opt_t	{ opt_unknown, opt_list, opt_delete, opt_edit, opt_replace, opt_show_users };
 
 #if DEBUGGING
-static char	*Options[] = { "???", "list", "delete", "edit", "replace" };
+static char	*Options[] = { "???", "list", "delete", "edit", "replace", "show" };
 #endif
 
 
@@ -66,6 +66,7 @@
 static	void		list_cmd __P((void)),
 			delete_cmd __P((void)),
 			edit_cmd __P((void)),
+			show_users_cmd __P((void)),
 			poke_daemon __P((void)),
 			check_error __P((char *)),
 			parse_args __P((int c, char *v[]));
@@ -82,11 +83,12 @@
 {
 	fprintf(stderr, "%s: usage error: %s\n", ProgramName, msg);
 	fprintf(stderr, "usage:\t%s [-u user] file\n", ProgramName);
-	fprintf(stderr, "\t%s [ -u user ] [ -i ] { -e | -l | -r }\n", ProgramName);
+	fprintf(stderr, "\t%s [ -u user ] [ -i ] { -e | -l | -r | -s }\n", ProgramName);
 	fprintf(stderr, "\t\t(default operation is replace, per 1003.2)\n");
 	fprintf(stderr, "\t-e\t(edit user's crontab)\n");
 	fprintf(stderr, "\t-l\t(list user's crontab)\n");
 	fprintf(stderr, "\t-r\t(delete user's crontab)\n");
+	fprintf(stderr, "\t-s\t(show all user who have a crontab)\n");
         fprintf(stderr, "\t-i\t(prompt before deleting user's crontab)\n");
 	exit(ERROR_EXIT);
 }
@@ -138,6 +140,8 @@
 				break;
 	case opt_edit:		edit_cmd();
 				break;
+	case opt_show_users:	show_users_cmd();
+				break;
 	case opt_replace:	if (replace_cmd() < 0)
 					exitstatus = ERROR_EXIT;
 				break;
@@ -153,9 +157,9 @@
 }
 	
 #if DEBUGGING
-char *getoptarg = "u:lerix:";
+char *getoptarg = "u:lerisx:";
 #else
-char *getoptarg = "u:leri";
+char *getoptarg = "u:leris";
 #endif
 
 
@@ -229,6 +233,17 @@
 		case 'i':
                         PromptOnDelete = 1;
 			break;
+		case 's':
+			if (getuid() != ROOT_UID)
+			{
+				fprintf(stderr,
+					"must be privileged to use -s\n");
+				exit(ERROR_EXIT);
+			}
+			if (Option != opt_unknown)
+				usage("only one operation permitted");
+			Option = opt_show_users;
+			break;
 		default:
 			usage("unrecognized option");
 		}
@@ -810,6 +825,28 @@
 	exit(1);
 }	
 
+static void
+show_users_cmd() {
+	DIR *dir;
+	struct dirent *dp;
+
+	if (!(dir = opendir(SPOOL_DIR))) {
+		fprintf(stderr, "%s: opendir() of %s failed: %s\n",
+				ProgramName, SPOOL_DIR, strerror(errno));
+		return;
+	}
+	while (dir != NULL && NULL != (dp = readdir(dir))) {
+		char    fname[MAXNAMLEN+1];
+		if (dp->d_name[0] == '.')
+			continue;
+		(void) strcpy(fname, dp->d_name);
+		if ((pw = getpwnam(fname)))
+			fprintf(stdout, "%s\n", fname);
+		else 
+			fprintf(stderr, "%s: WARNING: crontab found with no matching user: %s\n", ProgramName, fname);
+	}
+	return;
+}
 /* returns	0	on success
  *		-1	on syntax error
  *		-2	on install error
--- cron-3.0pl1.orig/crontab.1	2011-04-18 09:15:39.000000000 +0200
+++ cron-3.0pl1/crontab.1	2011-04-18 09:34:24.352726952 +0200
@@ -24,7 +24,7 @@
 .SH SYNOPSIS
 crontab [ \-u user ] file
 .br
-crontab [ \-u user ] [ \-i ] { \-e | \-l | \-r }
+crontab [ \-u user ] [ \-i ] { \-e | \-l | \-r | \-s }
 .SH DESCRIPTION
 .I crontab
 is the program used to install, deinstall or list the tables
@@ -101,6 +101,11 @@
 default editor /usr/bin/editor is used.
 .PP
 The
+.I -s
+option shows all users who have a crontab (and warns about files in the
+spool dir which have no corresponding password database entry).
+.PP
+The
 .I -i
 option modifies the \-r option to prompt the user for a 'y/Y' response
 before actually removing the crontab.