--- sysctl.c
+++ sysctl.c	2008-02-14 12:04:36.000000000 +0100
@@ -128,6 +128,7 @@ static int ReadSetting(const char *restr
    char *restrict outname;
    char inbuf[1025];
    FILE *restrict fp;
+   struct stat ts;
 
    if (!name || !*name) {
       fprintf(stderr, ERR_INVALID_KEY, name);
@@ -144,6 +145,23 @@ static int ReadSetting(const char *restr
    outname = strdup(name);
    slashdot(outname,'/','.'); /* change / to . */
 
+   if (stat(tmpname, &ts) < 0) {
+      perror(tmpname);
+      rc = -1;
+      goto out;
+   }
+   if ((ts.st_mode & S_IRUSR) == 0)
+      goto out;
+
+   if (S_ISDIR(ts.st_mode)) {
+      size_t len;
+      len = strlen(tmpname);
+      tmpname[len] = '/';
+      tmpname[len+1] = '\0';
+      rc = DisplayAll(tmpname);
+      goto out;
+   }
+
    fp = fopen(tmpname, "r");
 
    if (!fp) {
@@ -164,6 +182,7 @@ static int ReadSetting(const char *restr
          break;
       }
    } else {
+      errno = 0;
       if(fgets(inbuf, sizeof inbuf - 1, fp)) {
          // this loop is required, see
          // /sbin/sysctl -a | egrep -6 dev.cdrom.info
@@ -194,18 +213,20 @@ static int ReadSetting(const char *restr
             len = strlen(tmpname);
             tmpname[len] = '/';
             tmpname[len+1] = '\0';
+            fclose(fp);
             rc = DisplayAll(tmpname);
-            break;
+            goto out;
          }
          default:
             fprintf(stderr, ERR_UNKNOWN_READING, strerror(errno), outname);
             rc = -1;
+         case 0:
             break;
          }
       }
       fclose(fp);
    }
-
+out:
    free(tmpname);
    free(outname);
    return rc;
@@ -265,8 +286,9 @@ static int WriteSetting(const char *sett
    const char *value;
    const char *equals;
    char *tmpname;
-   FILE *fp;
    char *outname;
+   FILE *fp;
+   struct stat ts;
 
    if (!name) {        /* probably don't want to display this err */
       return 0;
@@ -299,6 +321,22 @@ static int WriteSetting(const char *sett
    outname[equals-name] = 0;
    slashdot(outname,'/','.'); /* change / to . */
  
+   if (stat(tmpname, &ts) < 0) {
+      perror(tmpname);
+      rc = -1;
+      goto out;
+   }
+
+   if ((ts.st_mode & S_IWUSR) == 0) {
+      fprintf(stderr, ERR_UNKNOWN_WRITING, strerror(EACCES), outname);
+      goto out;
+   }
+
+   if (S_ISDIR(ts.st_mode)) {
+      fprintf(stderr, ERR_UNKNOWN_WRITING, strerror(EACCES), outname);
+      goto out;
+   }
+
    fp = fopen(tmpname, "w");
 
    if (!fp) {
@@ -343,7 +381,7 @@ static int WriteSetting(const char *sett
          }
       }
    }
-
+out:
    free(tmpname);
    free(outname);
    return rc;