From c2e49a4196749676ccea31ae645c5d3eb4408520 Mon Sep 17 00:00:00 2001
From: Maxim Dounin <mdounin@mdounin.ru>
Date: Thu, 26 Jun 2014 02:27:21 +0400
Subject: [PATCH] Cache: version in cache files.

This allows to change the structure of cache files without spamming logs
with false alerts.
---
 src/http/ngx_http_cache.h      |  3 +++
 src/http/ngx_http_file_cache.c | 11 ++++++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/http/ngx_http_cache.h b/src/http/ngx_http_cache.h
index 193a35322..1a3117adb 100644
--- a/src/http/ngx_http_cache.h
+++ b/src/http/ngx_http_cache.h
@@ -25,6 +25,8 @@
 
 #define NGX_HTTP_CACHE_KEY_LEN       16
 
+#define NGX_HTTP_CACHE_VERSION       1
+
 
 typedef struct {
     ngx_uint_t                       status;
@@ -97,6 +99,7 @@ struct ngx_http_cache_s {
 
 
 typedef struct {
+    ngx_uint_t                       version;
     time_t                           valid_sec;
     time_t                           last_modified;
     time_t                           date;
diff --git a/src/http/ngx_http_file_cache.c b/src/http/ngx_http_file_cache.c
index 4d9e82235..1eab77215 100644
--- a/src/http/ngx_http_file_cache.c
+++ b/src/http/ngx_http_file_cache.c
@@ -498,6 +498,12 @@ ngx_http_file_cache_read(ngx_http_request_t *r, ngx_http_cache_t *c)
 
     h = (ngx_http_file_cache_header_t *) c->buf->pos;
 
+    if (h->version != NGX_HTTP_CACHE_VERSION) {
+        ngx_log_error(NGX_LOG_INFO, r->connection->log, 0,
+                      "cache file \"%s\" version mismatch", c->file.name.data);
+        return NGX_DECLINED;
+    }
+
     if (h->crc32 != c->crc32) {
         ngx_log_error(NGX_LOG_CRIT, r->connection->log, 0,
                       "cache file \"%s\" has md5 collision", c->file.name.data);
@@ -875,6 +881,7 @@ ngx_http_file_cache_set_header(ngx_http_request_t *r, u_char *buf)
 
     ngx_memzero(h, sizeof(ngx_http_file_cache_header_t));
 
+    h->version = NGX_HTTP_CACHE_VERSION;
     h->valid_sec = c->valid_sec;
     h->last_modified = c->last_modified;
     h->date = c->date;
@@ -1042,7 +1049,8 @@ ngx_http_file_cache_update_header(ngx_http_request_t *r)
         goto done;
     }
 
-    if (h.last_modified != c->last_modified
+    if (h.version != NGX_HTTP_CACHE_VERSION
+        || h.last_modified != c->last_modified
         || h.crc32 != c->crc32
         || h.header_start != c->header_start
         || h.body_start != c->body_start)
@@ -1060,6 +1068,7 @@ ngx_http_file_cache_update_header(ngx_http_request_t *r)
 
     ngx_memzero(&h, sizeof(ngx_http_file_cache_header_t));
 
+    h.version = NGX_HTTP_CACHE_VERSION;
     h.valid_sec = c->valid_sec;
     h.last_modified = c->last_modified;
     h.date = c->date;