nginx unsafe patch for filtering access_log logging by http status

gistfile1.diff

Index: src/http/modules/ngx_http_log_module.c
===================================================================
--- src/http/modules/ngx_http_log_module.c	(revision 4682)
+++ src/http/modules/ngx_http_log_module.c	(working copy)
@@ -52,6 +52,7 @@
     time_t                      disk_full_time;
     time_t                      error_log_time;
     ngx_http_log_fmt_t         *format;
+    ngx_uint_t                  status;
 } ngx_http_log_t;
 
 
@@ -94,6 +95,7 @@
     ngx_http_log_op_t *op);
 static u_char *ngx_http_log_status(ngx_http_request_t *r, u_char *buf,
     ngx_http_log_op_t *op);
+static ngx_uint_t ngx_http_log_get_status(ngx_http_request_t *r);
 static u_char *ngx_http_log_bytes_sent(ngx_http_request_t *r, u_char *buf,
     ngx_http_log_op_t *op);
 static u_char *ngx_http_log_body_bytes_sent(ngx_http_request_t *r,
@@ -136,7 +138,7 @@
 
     { ngx_string("access_log"),
       NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_HTTP_LIF_CONF
-                        |NGX_HTTP_LMT_CONF|NGX_CONF_TAKE123,
+                        |NGX_HTTP_LMT_CONF|NGX_CONF_TAKE1234,
       ngx_http_log_set_log,
       NGX_HTTP_LOC_CONF_OFFSET,
       0,
@@ -239,6 +241,11 @@
     }
 
     log = lcf->logs->elts;
+
+    if (log->status > 0 && log->status != ngx_http_log_get_status(r)) {
+        return NGX_OK;
+    }
+
     for (l = 0; l < lcf->logs->nelts; l++) {
 
         if (ngx_time() == log[l].disk_full_time) {
@@ -577,26 +584,33 @@
 {
     ngx_uint_t  status;
 
-    if (r->err_status) {
-        status = r->err_status;
-
-    } else if (r->headers_out.status) {
-        status = r->headers_out.status;
-
-    } else if (r->http_version == NGX_HTTP_VERSION_9) {
+    if (r->http_version == NGX_HTTP_VERSION_9) {
         *buf++ = '0';
         *buf++ = '0';
         *buf++ = '9';
         return buf;
-
-    } else {
-        status = 0;
     }
 
+    status = ngx_http_log_get_status(r);
+
     return ngx_sprintf(buf, "%03ui", status);
 }
 
+static ngx_uint_t
+ngx_http_log_get_status(ngx_http_request_t *r)
+{
+    if (r->err_status) {
+        return r->err_status;
+    }
 
+    if (r->headers_out.status) {
+        return r->headers_out.status;
+    }
+
+    return 0;
+}
+
+
 static u_char *
 ngx_http_log_bytes_sent(ngx_http_request_t *r, u_char *buf,
     ngx_http_log_op_t *op)
@@ -877,13 +891,14 @@
     ngx_http_log_loc_conf_t *llcf = conf;
 
     ssize_t                     buf;
-    ngx_uint_t                  i, n;
+    ngx_uint_t                  i, n, status;
     ngx_str_t                  *value, name;
     ngx_http_log_t             *log;
     ngx_http_log_fmt_t         *fmt;
     ngx_http_log_main_conf_t   *lmcf;
     ngx_http_script_compile_t   sc;
 
+
     value = cf->args->elts;
 
     if (ngx_strcmp(value[1].data, "off") == 0) {
@@ -974,7 +989,7 @@
 
 buffer:
 
-    if (cf->args->nelts == 4) {
+    if (cf->args->nelts >= 4) {
         if (ngx_strncmp(value[3].data, "buffer=", 7) != 0) {
             ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                "invalid parameter \"%V\"", &value[3]);
@@ -1014,6 +1029,16 @@
         log->file->last = log->file->buffer + buf;
     }
 
+    if (cf->args->nelts == 5) {
+        status = ngx_atoi(value[4].data, value[4].len);
+        if (status <= 0) {
+            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                           "invalid log status \"%V\"", &value[4]);
+            return NGX_CONF_ERROR;
+        }
+        log->status = status;
+    }
+
     return NGX_CONF_OK;
 }