No need to re-implement realloc(). Just use it

the way the man page says.

ok tb@

diff --git a/sbin/dhclient/options.c b/sbin/dhclient/options.c
index 25d4e6e..197685f 100644 (file)
--- a/sbin/dhclient/options.c
+++ b/sbin/dhclient/options.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: options.c,v 1.112 2018/07/22 08:59:56 krw Exp $       */
+/*     $OpenBSD: options.c,v 1.113 2018/07/22 21:32:04 krw Exp $       */
 
 /* DHCP options parsing and reassembly. */
 
@@ -406,7 +406,7 @@ parse_option_buffer(struct option_data *options, unsigned char *buffer,
 {
        unsigned char   *s, *t, *end;
        char            *name, *fmt;
-       int              len, code;
+       int              code, len, newlen;
 
        s = buffer;
        end = s + length;
@@ -458,36 +458,20 @@ parse_option_buffer(struct option_data *options, unsigned char *buffer,
                }
 
                /*
-                * If we haven't seen this option before, just make
-                * space for it and copy it there.
+                * Concatenate new data + NUL to existing option data.
+                *
+                * Note that the NUL is *not* counted in the len field!
                 */
-               if (options[code].data == NULL) {
-                       t = calloc(1, len + 1);
-                       if (t == NULL)
-                               fatal("option %s", name);
-                       /*
-                        * Copy and NUL-terminate the option (in case
-                        * it's an ASCII string).
-                        */
-                       memcpy(t, &s[2], len);
-                       t[len] = 0;
-                       options[code].len = len;
-                       options[code].data = t;
-               } else {
-                       /*
-                        * If it's a repeat, concatenate it to whatever
-                        * we last saw.
-                        */
-                       t = calloc(1, len + options[code].len + 1);
-                       if (t == NULL)
-                               fatal("option %s concat", name);
-                       memcpy(t, options[code].data, options[code].len);
-                       memcpy(t + options[code].len, &s[2], len);
-                       options[code].len += len;
-                       t[options[code].len] = 0;
-                       free(options[code].data);
-                       options[code].data = t;
-               }
+               newlen = options[code].len + len;
+               if ((t = realloc(options[code].data, newlen + 1)) == NULL)
+                       fatal("option %s", name);
+
+               memcpy(t + options[code].len, &s[2], len);
+               t[newlen] = 0;
+
+               options[code].len = newlen;
+               options[code].data = t;
+
                s += s[1] + 2;
        }