int v1, v2;
  int isPatch = P("patch")!=0;
  int diffType;          /* 0: none, 1: unified,  2: side-by-side */
  char *zV1;
  char *zV2;
  const char *zRe;
  ReCompiled *pRe = 0;
  u64 diffFlags;
  u32 objdescFlags = 0;
  int verbose = PB("verbose");
  DiffConfig DCfg;

  login_check_credentials();
  if( !g.perm.Read ){ login_needed(g.anon.Read); return; }
  diff_config_init(&DCfg, 0);
  diffType = preferred_diff_type();
  if( P("from") && P("to") ){
    v1 = artifact_from_ci_and_filename("from");
    v2 = artifact_from_ci_and_filename("to");
  }else{
    Stmt q;
    v1 = name_to_rid_www("v1");

  if( zRe ) re_compile(&pRe, zRe, 0);
  if( verbose ) objdescFlags |= OBJDESC_DETAIL;
  if( isPatch ){
    Blob c1, c2, *pOut;
    DiffConfig DCfg;
    pOut = cgi_output_blob();
    cgi_set_content_type("text/plain");
    diffFlags = DIFF_VERBOSE;
    DCfg.diffFlags = DIFF_VERBOSE;
    content_get(v1, &c1);
    content_get(v2, &c2);
    diff_config_init(&DCfg, diffFlags);
    DCfg.pRe = pRe;
    text_diff(&c1, &c2, pOut, &DCfg);
    blob_reset(&c1);
    blob_reset(&c2);
    return;
  }