struct alternates_request {
        struct walker *walker;
        const char *base;
-       char *url;
+       struct strbuf *url;
        struct strbuf *buffer;
        struct active_request_slot *slot;
        int http_specific;
 
                        /* Try reusing the slot to get non-http alternates */
                        alt_req->http_specific = 0;
-                       sprintf(alt_req->url, "%s/objects/info/alternates",
-                               base);
+                       strbuf_reset(alt_req->url);
+                       strbuf_addf(alt_req->url, "%s/objects/info/alternates",
+                                   base);
                        curl_easy_setopt(slot->curl, CURLOPT_URL,
-                                        alt_req->url);
+                                        alt_req->url->buf);
                        active_requests++;
                        slot->in_use = 1;
                        if (slot->finished != NULL)
                        int okay = 0;
                        int serverlen = 0;
                        struct alt_base *newalt;
-                       char *target = NULL;
                        if (data[i] == '/') {
                                /*
                                 * This counts
                        }
                        /* skip "objects\n" at end */
                        if (okay) {
-                               target = xmalloc(serverlen + posn - i - 6);
-                               memcpy(target, base, serverlen);
-                               memcpy(target + serverlen, data + i,
-                                      posn - i - 7);
-                               target[serverlen + posn - i - 7] = 0;
+                               struct strbuf target = STRBUF_INIT;
+                               strbuf_add(&target, base, serverlen);
+                               strbuf_add(&target, data + i, posn - i - 7);
                                if (walker->get_verbosely)
-                                       fprintf(stderr,
-                                               "Also look at %s\n", target);
+                                       fprintf(stderr, "Also look at %s\n",
+                                               target.buf);
                                newalt = xmalloc(sizeof(*newalt));
                                newalt->next = NULL;
-                               newalt->base = target;
+                               newalt->base = strbuf_detach(&target, NULL);
                                newalt->got_indices = 0;
                                newalt->packs = NULL;
 
 static void fetch_alternates(struct walker *walker, const char *base)
 {
        struct strbuf buffer = STRBUF_INIT;
-       char *url;
+       struct strbuf url = STRBUF_INIT;
        struct active_request_slot *slot;
        struct alternates_request alt_req;
        struct walker_data *cdata = walker->data;
        if (walker->get_verbosely)
                fprintf(stderr, "Getting alternates list for %s\n", base);
 
-       url = xmalloc(strlen(base) + 31);
-       sprintf(url, "%s/objects/info/http-alternates", base);
+       strbuf_addf(&url, "%s/objects/info/http-alternates", base);
 
        /*
         * Use a callback to process the result, since another request
 
        curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
        curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
-       curl_easy_setopt(slot->curl, CURLOPT_URL, url);
+       curl_easy_setopt(slot->curl, CURLOPT_URL, url.buf);
 
        alt_req.base = base;
-       alt_req.url = url;
+       alt_req.url = &url;
        alt_req.buffer = &buffer;
        alt_req.http_specific = 1;
        alt_req.slot = slot;
                cdata->got_alternates = -1;
 
        strbuf_release(&buffer);
-       free(url);
+       strbuf_release(&url);
 }
 
 static int fetch_indices(struct walker *walker, struct alt_base *repo)
        return ret;
 }
 
-static int fetch_pack(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
+static int http_fetch_pack(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
 {
        struct packed_git *target;
        int ret;
        if (!fetch_object(walker, altbase, sha1))
                return 0;
        while (altbase) {
-               if (!fetch_pack(walker, altbase, sha1))
+               if (!http_fetch_pack(walker, altbase, sha1))
                        return 0;
                fetch_alternates(walker, data->alt->base);
                altbase = altbase->next;
        struct walker *walker = xmalloc(sizeof(struct walker));
 
        data->alt = xmalloc(sizeof(*data->alt));
-       data->alt->base = xmalloc(strlen(url) + 1);
-       strcpy(data->alt->base, url);
+       data->alt->base = xstrdup(url);
        for (s = data->alt->base + strlen(data->alt->base) - 1; *s == '/'; --s)
                *s = 0;