hwclock: simplify save_adjtime() execution flow

Return early to avoid excessive nesting.  In same go remove any chance of
overflow by using appropriate allocation.  And update variable names to be
easier to understand.

Reviewed-by: J William Piggott <elseifthen@gmx.com>
Signed-off-by: Sami Kerola <kerolasa@iki.fi>

diff --git a/sys-utils/hwclock.c b/sys-utils/hwclock.c
index b08bd781a68d1a094474b30bc199f7af9de9558f..c5be96f542ed8209d54410926cd0e01a0d01eea5 100644 (file)
--- a/sys-utils/hwclock.c
+++ b/sys-utils/hwclock.c
@@ -82,6 +82,7 @@
 #include "hwclock.h"
 #include "timeutils.h"
 #include "env.h"
+#include "xalloc.h"
 
 #ifdef HAVE_LIBAUDIT
 #include <libaudit.h>
@@ -1076,57 +1077,42 @@ calculate_adjustment(const struct hwclock_control *ctl,
 static void save_adjtime(const struct hwclock_control *ctl,
                         const struct adjtime *adjtime)
 {
-       char newfile[412];      /* Stuff to write to disk file */
+       char *content;          /* Stuff to write to disk file */
+       FILE *fp;
+       int err = 0;
 
-       if (adjtime->dirty) {
-               /*
-                * snprintf is not always available, but this is safe as
-                * long as libc does not use more than 100 positions for %ld
-                * or %f
-                */
-               sprintf(newfile, "%f %ld %f\n%ld\n%s\n",
-                       adjtime->drift_factor,
-                       adjtime->last_adj_time,
-                       adjtime->not_adjusted,
-                       adjtime->last_calib_time,
-                       (adjtime->local_utc == LOCAL) ? "LOCAL" : "UTC");
+       if (!adjtime->dirty)
+               return;
 
-               if (ctl->testing) {
-                       printf(_
-                              ("Not updating adjtime file because of testing mode.\n"));
-                       printf(_("Would have written the following to %s:\n%s"),
-                              ctl->adj_file_name, newfile);
-               } else {
-                       FILE *adjfile;
-                       int err = 0;
-
-                       adjfile = fopen(ctl->adj_file_name, "w");
-                       if (adjfile == NULL) {
-                               warn(_
-                                    ("Could not open file with the clock adjustment parameters "
-                                     "in it (%s) for writing"), ctl->adj_file_name);
-                               err = 1;
-                       } else {
-                               if (fputs(newfile, adjfile) < 0) {
-                                       warn(_
-                                            ("Could not update file with the clock adjustment "
-                                             "parameters (%s) in it"),
-                                            ctl->adj_file_name);
-                                       err = 1;
-                               }
-                               if (close_stream(adjfile) != 0) {
-                                       warn(_
-                                            ("Could not update file with the clock adjustment "
-                                             "parameters (%s) in it"),
-                                            ctl->adj_file_name);
-                                       err = 1;
-                               }
-                       }
-                       if (err)
-                               warnx(_
-                                     ("Drift adjustment parameters not updated."));
-               }
+       xasprintf(&content, "%f %ld %f\n%ld\n%s\n",
+                 adjtime->drift_factor,
+                 adjtime->last_adj_time,
+                 adjtime->not_adjusted,
+                 adjtime->last_calib_time,
+                 (adjtime->local_utc == LOCAL) ? "LOCAL" : "UTC");
+
+       if (ctl->testing) {
+               printf(_
+                      ("Not updating adjtime file because of testing mode.\n"));
+               printf(_("Would have written the following to %s:\n%s"),
+                      ctl->adj_file_name, content);
+               free(content);
+               return;
+       }
+
+       fp = fopen(ctl->adj_file_name, "w");
+       if (fp == NULL) {
+               warn(_("Could not open file with the clock adjustment parameters "
+                      "in it (%s) for writing"), ctl->adj_file_name);
+               err = 1;
+       } else if (fputs(content, fp) < 0 || close_stream(fp) != 0) {
+               warn(_("Could not update file with the clock adjustment "
+                      "parameters (%s) in it"), ctl->adj_file_name);
+               err = 1;
        }
+       free(content);
+       if (err)
+               warnx(_("Drift adjustment parameters not updated."));
 }
 
 /*