Abort writing cached-microdescs if a failed write has occurred.

Bug 2954; fix on 0.2.2.6-alpha.

changes/bug2954_more

@@ -0,0 +1,4 @@
+  o Minor bugfixes:
+    - If we fail to write a microdescriptor to disk, do not continue
+      replacing the old microdescriptor file. Fix for bug 2954; bugfix
+      on 0.2.2.6-alpha.

src/or/microdesc.c

@@ -80,7 +80,12 @@ dump_microdescriptor(FILE *f, microdesc_t *md, size_t *annotation_len_out)
     char annotation[ISO_TIME_LEN+32];
     format_iso_time(buf, md->last_listed);
     tor_snprintf(annotation, sizeof(annotation), "@last-listed %s\n", buf);
-    fputs(annotation, f);
+    if (fputs(annotation, f) < 0) {
+      log_warn(LD_DIR,
+               "Couldn't write microdescriptor annotation: %s",
+               strerror(ferror(f)));
+      return -1;
+    }
     r += strlen(annotation);
     *annotation_len_out = r;
   } else {
@@ -226,9 +231,10 @@ microdescs_add_list_to_cache(microdesc_cache_t *cache,
       size_t annotation_len;
       size = dump_microdescriptor(f, md, &annotation_len);
       if (size < 0) {
-        /* XXX handle errors from dump_microdescriptor() */
-        /* log?  return -1?  die?  coredump the universe? */
-        continue;
+        /* we already warned in dump_microdescriptor; */
+        abort_writing_to_file(open_file);
+        smartlist_clear(added);
+        return added;
       }
       md->saved_location = SAVED_IN_JOURNAL;
       cache->journal_len += size;