e.patch

diff --git a/lib/core/logconf.c b/lib/core/logconf.c
index 1f8b30d8..b1b85e4f 100644
--- a/lib/core/logconf.c
+++ b/lib/core/logconf.c
@@ -34,6 +34,7 @@ enum {
     ELEMENT_TYPE_METHOD,                        /* %m */
     ELEMENT_TYPE_LOCAL_PORT,                    /* %p, %{local}p */
     ELEMENT_TYPE_REMOTE_PORT,                   /* %{remote}p */
+    ELEMENT_TYPE_ENV_VAR,                       /* %{..}e */
     ELEMENT_TYPE_QUERY,                         /* %q */
     ELEMENT_TYPE_REQUEST_LINE,                  /* %r */
     ELEMENT_TYPE_STATUS,                        /* %s */
@@ -150,6 +151,13 @@ h2o_logconf_t *h2o_logconf_compile(const char *fmt, int escape, char *errbuf)
                         goto Error;
                     }
                     break;
+                case 'e':
+                    {
+                        h2o_iovec_t name = h2o_strdup(NULL, pt, quote_end - pt);
+                        NEW_ELEMENT(ELEMENT_TYPE_ENV_VAR);
+                        LAST_ELEMENT()->data.name = name;
+                    }
+                    break;
                 case 't':
                     if (h2o_memis(pt, quote_end - pt, H2O_STRLIT("sec"))) {
                         NEW_ELEMENT(ELEMENT_TYPE_TIMESTAMP_SEC_SINCE_EPOCH);
@@ -213,7 +221,7 @@ h2o_logconf_t *h2o_logconf_compile(const char *fmt, int escape, char *errbuf)
 #undef MAP_EXT_TO_PROTO
                     break;
                 default:
-                    sprintf(errbuf, "failed to compile log format: header name is not followed by either `i`, `o`, `x`");
+                    sprintf(errbuf, "failed to compile log format: header name is not followed by either `i`, `o`, `x`, `e`");
                     goto Error;
                 }
                 pt = quote_end + 2;
@@ -232,6 +240,7 @@ h2o_logconf_t *h2o_logconf_compile(const char *fmt, int escape, char *errbuf)
                     TYPE_MAP('l', ELEMENT_TYPE_LOGNAME);
                     TYPE_MAP('m', ELEMENT_TYPE_METHOD);
                     TYPE_MAP('p', ELEMENT_TYPE_LOCAL_PORT);
+                    TYPE_MAP('e', ELEMENT_TYPE_ENV_VAR);
                     TYPE_MAP('q', ELEMENT_TYPE_QUERY);
                     TYPE_MAP('r', ELEMENT_TYPE_REQUEST_LINE);
                     TYPE_MAP('s', ELEMENT_TYPE_STATUS);
@@ -487,6 +496,15 @@ char *h2o_log_request(h2o_logconf_t *logconf, h2o_req_t *req, size_t *len, char
             RESERVE(sizeof(H2O_UINT16_LONGEST_STR) - 1);
             pos = append_port(pos, req->conn->callbacks->get_peername, req->conn, nullexpr);
             break;
+        case ELEMENT_TYPE_ENV_VAR:  /* %{..}e */  {
+            //read env variable
+            sprintf(stdout, "getting enf"  );
+            h2o_iovec_t *env_var = h2o_req_getenv(req, element->data.name.base, element->data.name.len, 0);
+            if (env_var == NULL)
+                goto EmitNull;
+            RESERVE(env_var->len * unsafe_factor);
+            pos = append_unsafe_string(pos, env_var->base, env_var->len);
+            } break;
         case ELEMENT_TYPE_QUERY: /* %q */
             if (req->input.query_at != SIZE_MAX) {
                 size_t len = req->input.path.len - req->input.query_at;