Use stpecpy() where appropriate

This function simplifies the calculation of the bounds of the buffer for
catenating strings.  It would also reduce error checking, but we don't
care about truncation in this specific code. :)

Signed-off-by: Alejandro Colomar <alx@kernel.org>

src/groupmod.c

@@ -35,6 +35,7 @@
 #include "sgroupio.h"
 #endif
 #include "shadowlog.h"
+#include "stpecpy.h"
 #include "stpeprintf.h"
 /*
  * exit status values
@@ -590,42 +591,27 @@ static void prepare_failure_reports (void)
 	                 "group %s/%ju", group_name, (uintmax_t) group_id);
 
 	if (nflg) {
-		strncat (info_group.action, ", new name: ",
+		gr = stpecpy(gr, gr_end, ", new name: ");
-		         511 - strlen (info_group.audit_msg));
+		gr = stpecpy(gr, gr_end, group_newname);
-		strncat (info_group.action, group_newname,
-		         511 - strlen (info_group.audit_msg));
-
 #ifdef	SHADOWGRP
-		strncat (info_gshadow.action, ", new name: ",
+		sgr = stpecpy(sgr, sgr_end, ", new name: ");
-		         511 - strlen (info_gshadow.audit_msg));
+		sgr = stpecpy(sgr, sgr_end, group_newname);
-		strncat (info_gshadow.action, group_newname,
-		         511 - strlen (info_gshadow.audit_msg));
 #endif
-
+		pw = stpecpy(pw, pw_end, ", new name: ");
-		strncat (info_passwd.action, ", new name: ",
+		pw = stpecpy(pw, pw_end, group_newname);
-		         511 - strlen (info_passwd.audit_msg));
-		strncat (info_passwd.action, group_newname,
-		         511 - strlen (info_passwd.audit_msg));
 	}
 	if (pflg) {
-		strncat (info_group.action, ", new password",
+		gr = stpecpy(gr, gr_end, ", new password");
-		         511 - strlen (info_group.audit_msg));
-
 #ifdef	SHADOWGRP
-		strncat (info_gshadow.action, ", new password",
+		sgr = stpecpy(sgr, sgr_end, ", new password");
-		         511 - strlen (info_gshadow.audit_msg));
 #endif
 	}
 	if (gflg) {
-		strncat (info_group.action, ", new gid: ",
+		gr = stpecpy(gr, gr_end, ", new gid: ");
-		         511 - strlen (info_group.audit_msg));
+		stpeprintf(gr, gr_end, "%ju", (uintmax_t) group_newid);
-		stpeprintf(info_group.action+strlen (info_group.action),
-		                 gr_end, "%ju", (uintmax_t) group_newid);
 
-		strncat (info_passwd.action, ", new gid: ",
+		pw = stpecpy(pw, pw_end, ", new gid: ");
-		         511 - strlen (info_passwd.audit_msg));
+		stpeprintf(pw, pw_end, "%ju", (uintmax_t) group_newid);
-		stpeprintf(info_passwd.action+strlen (info_passwd.action),
-		                 pw_end, "%ju", (uintmax_t) group_newid);
 	}
 
 // FIXME: add a system cleanup