fix response_type context and duplicate detection

The cache_purge_response_type directive had a flawed duplicate detection
guard that only checked for NGX_HTTP_LOC_CONF. This silently allowed
duplicate directives in http and server contexts to overwrite previous
values without throwing a configuration error. Additionally, a defunct
guard attempting to check for NGX_HTTP_MODULE was comparing context
flags against module-type magic bits, rendering it dead code.

Remove the invalid NGX_HTTP_MODULE check and make duplicate detection
unconditional. The directive is intentionally valid in http, server,
and location contexts, and merge_loc_conf propagates the value downward
appropriately. The README context documentation is updated to reflect
this correctly.

Furthermore, rename the internal configuration variable from resptype
to response_type for clarity. Fix a typo in the response type macro
definitions (NGX_REPONSE_TYPE_* to NGX_CACHE_PURGE_RESPONSE_TYPE_*)
and properly namespace them.

Clarify the documentation and internal comments for the
cache_purge_throttle_ms directive. Bare integers are evaluated as
milliseconds natively to match the directive's name, which differs
from the standard nginx time parser, logging a startup warning.

Add comprehensive test coverage in config.t to ensure proper context
inheritance, duplicate config rejection, and explicit time suffix parsing.

Author: denji

README.md

@@ -138,7 +138,7 @@ Equivalent to `proxy_cache_purge` but for uWSGI cache zones configured with
 ```
 Syntax:  cache_purge_response_type html | json | xml | text
 Default: html
-Context: server, location
+Context: http, server, location
 ```
 
 Sets the `Content-Type` and body format of purge responses. Has no effect on
@@ -197,16 +197,16 @@ Default: 10ms
 Context: http
 ```
 
-Interval between background processing ticks. Also introduces a brief yield
-every 100 files within a single directory walk to limit I/O pressure. Increase
-on constrained or spinning-disk storage; decrease on NVMe. Only meaningful
-when `cache_purge_background_queue on`.
+Interval between background processing ticks. Accepts any nginx time value:
+`10ms`, `500ms`, `1s`, `2s 500ms`. Only meaningful when
+`cache_purge_background_queue on`.
+
+Increase on constrained or spinning-disk storage; decrease on NVMe.
 
-Accepts standard nginx time values with an explicit suffix — `ms` for
-milliseconds, `s` for seconds (e.g. `10ms`, `500ms`, `1s`). A bare integer
-without a suffix is treated as **seconds** by the nginx configuration parser,
-which is almost certainly not what you want for this directive. Always include
-the `ms` suffix when specifying millisecond values.
+**Time-unit note:** a bare integer with no suffix (e.g. `10`) is interpreted
+as milliseconds — matching the `_ms` directive name — and a startup warning is
+logged. Use an explicit `ms` suffix (`10ms`) to silence the warning. This
+differs from most nginx time directives, where a bare integer means seconds.
 
 
 ### `cache_purge_legacy_status`

ngx_cache_purge_module.c

@@ -36,10 +36,10 @@
 # error This module cannot be built against an unknown nginx version.
 #endif
 
-#define NGX_REPONSE_TYPE_HTML  1
-#define NGX_REPONSE_TYPE_XML   2
-#define NGX_REPONSE_TYPE_JSON  3
-#define NGX_REPONSE_TYPE_TEXT  4
+#define NGX_CACHE_PURGE_RESPONSE_TYPE_HTML  1
+#define NGX_CACHE_PURGE_RESPONSE_TYPE_XML   2
+#define NGX_CACHE_PURGE_RESPONSE_TYPE_JSON  3
+#define NGX_CACHE_PURGE_RESPONSE_TYPE_TEXT  4
 
 #define NGX_CACHE_PURGE_QUEUE_SIZE_DEFAULT   1024
 #define NGX_CACHE_PURGE_BATCH_SIZE_DEFAULT   10
@@ -184,7 +184,7 @@ typedef struct {
     ngx_http_cache_purge_conf_t *conf;
     ngx_http_handler_pt          handler;
     ngx_http_handler_pt          original_handler;
-    ngx_uint_t                   resptype;
+    ngx_uint_t                   response_type;
 
 # if (NGX_HTTP_PROXY)
     /*
@@ -258,7 +258,6 @@ char *ngx_http_cache_purge_legacy_status_conf(ngx_conf_t *cf,
     ngx_command_t *cmd, void *conf);
 char *ngx_http_cache_purge_vary_aware_conf(ngx_conf_t *cf,
     ngx_command_t *cmd, void *conf);
-
 static ngx_int_t ngx_http_purge_file_cache_noop(ngx_tree_ctx_t *ctx,
     ngx_str_t *path);
 static ngx_int_t ngx_http_purge_file_cache_delete_file(ngx_tree_ctx_t *ctx,
@@ -365,9 +364,12 @@ static ngx_command_t  ngx_http_cache_purge_module_commands[] = {
       NGX_HTTP_MAIN_CONF_OFFSET,
       offsetof(ngx_http_cache_purge_main_conf_t, batch_size), NULL },
 
-    /* Accepts standard nginx time values: 10ms, 100ms, 1s, 500ms, etc.
-     * Bare integers are treated as SECONDS by ngx_parse_time() — always
-     * include an explicit suffix.  Default (unset): 10ms. */
+    /* Accepts standard nginx time values.  A bare integer means seconds per
+     * the nginx time-value contract; use an explicit suffix for milliseconds:
+     *   cache_purge_throttle_ms 10ms;   -- 10 ms  (correct)
+     *   cache_purge_throttle_ms 10;     -- 10 s   (almost certainly wrong)
+     * Default when directive is absent: 10 ms (set via ngx_conf_init_msec_value,
+     * which bypasses the parser and assigns the raw integer directly). */
     { ngx_string("cache_purge_throttle_ms"),
       NGX_HTTP_MAIN_CONF|NGX_CONF_TAKE1,
       ngx_conf_set_msec_slot,
@@ -2322,30 +2324,24 @@ ngx_http_cache_purge_response_type_conf(ngx_conf_t *cf, ngx_command_t *cmd,
     ngx_http_cache_purge_loc_conf_t *cplcf = conf;
     ngx_str_t                       *value;
 
-    if (cplcf->resptype != NGX_CONF_UNSET_UINT
-        && cf->cmd_type == NGX_HTTP_LOC_CONF)
-    {
+    if (cplcf->response_type != NGX_CONF_UNSET_UINT) {
         return "is duplicate";
     }
 
     if (cf->args->nelts != 2) {
         return "requires exactly one argument: html|json|xml|text";
     }
 
-    if (cf->cmd_type == NGX_HTTP_MODULE) {
-        return "(separate server or location syntax) is not allowed here";
-    }
-
     value = cf->args->elts;
 
     if (ngx_strcmp(value[1].data, "html") == 0) {
-        cplcf->resptype = NGX_REPONSE_TYPE_HTML;
+        cplcf->response_type = NGX_CACHE_PURGE_RESPONSE_TYPE_HTML;
     } else if (ngx_strcmp(value[1].data, "json") == 0) {
-        cplcf->resptype = NGX_REPONSE_TYPE_JSON;
+        cplcf->response_type = NGX_CACHE_PURGE_RESPONSE_TYPE_JSON;
     } else if (ngx_strcmp(value[1].data, "xml") == 0) {
-        cplcf->resptype = NGX_REPONSE_TYPE_XML;
+        cplcf->response_type = NGX_CACHE_PURGE_RESPONSE_TYPE_XML;
     } else if (ngx_strcmp(value[1].data, "text") == 0) {
-        cplcf->resptype = NGX_REPONSE_TYPE_TEXT;
+        cplcf->response_type = NGX_CACHE_PURGE_RESPONSE_TYPE_TEXT;
     } else {
         ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
             "invalid parameter \"%V\", expected html|json|xml|text",
@@ -2495,27 +2491,27 @@ ngx_http_cache_purge_send_response(ngx_http_request_t *r, ngx_str_t *status)
     ngx_memcpy(buf_keydata, key[0].data, key[0].len);
     /* buf_keydata[key[0].len] is already '\0' from ngx_pcalloc */
 
-    switch (cplcf->resptype) {
-    case NGX_REPONSE_TYPE_JSON:
+    switch (cplcf->response_type) {
+    case NGX_CACHE_PURGE_RESPONSE_TYPE_JSON:
         resp_ct        = ngx_http_cache_purge_content_type_json;
         resp_ct_size   = ngx_http_cache_purge_content_type_json_size;
         resp_body      = ngx_http_cache_purge_body_templ_json;
         resp_body_size = ngx_http_cache_purge_body_templ_json_size;
         break;
-    case NGX_REPONSE_TYPE_XML:
+    case NGX_CACHE_PURGE_RESPONSE_TYPE_XML:
         resp_ct        = ngx_http_cache_purge_content_type_xml;
         resp_ct_size   = ngx_http_cache_purge_content_type_xml_size;
         resp_body      = ngx_http_cache_purge_body_templ_xml;
         resp_body_size = ngx_http_cache_purge_body_templ_xml_size;
         break;
-    case NGX_REPONSE_TYPE_TEXT:
+    case NGX_CACHE_PURGE_RESPONSE_TYPE_TEXT:
         resp_ct        = ngx_http_cache_purge_content_type_text;
         resp_ct_size   = ngx_http_cache_purge_content_type_text_size;
         resp_body      = ngx_http_cache_purge_body_templ_text;
         resp_body_size = ngx_http_cache_purge_body_templ_text_size;
         break;
     default:
-    case NGX_REPONSE_TYPE_HTML:
+    case NGX_CACHE_PURGE_RESPONSE_TYPE_HTML:
         resp_ct        = ngx_http_cache_purge_content_type_html;
         resp_ct_size   = ngx_http_cache_purge_content_type_html_size;
         resp_body      = ngx_http_cache_purge_body_templ_html;
@@ -3023,7 +3019,7 @@ ngx_http_cache_purge_create_loc_conf(ngx_conf_t *cf)
     conf->uwsgi.enable   = NGX_CONF_UNSET;
 # endif
 
-    conf->resptype = NGX_CONF_UNSET_UINT;
+    conf->response_type = NGX_CONF_UNSET_UINT;
     conf->conf     = NGX_CONF_UNSET_PTR;
 
     return conf;
@@ -3038,8 +3034,8 @@ ngx_http_cache_purge_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
 
     clcf = ngx_http_conf_get_module_loc_conf(cf, ngx_http_core_module);
 
-    ngx_conf_merge_uint_value(conf->resptype, prev->resptype,
-                              NGX_REPONSE_TYPE_HTML);
+    ngx_conf_merge_uint_value(conf->response_type, prev->response_type,
+                              NGX_CACHE_PURGE_RESPONSE_TYPE_HTML);
 
 # if (NGX_HTTP_FASTCGI)
     ngx_http_cache_purge_merge_conf(&conf->fastcgi, &prev->fastcgi);

t/config.t

@@ -101,3 +101,61 @@ PURGE /purge/test*
 --- error_code: 202
 --- response_headers
 Content-Type: text/plain
+
+=== TEST 5a: throttle_ms with explicit ms suffix — accepted
+--- http_config
+    cache_purge_background_queue on;
+    cache_purge_throttle_ms 10ms;
+--- config
+    location /health { return 200 "ok"; }
+--- request
+GET /health
+--- error_code: 200
+
+=== TEST 5b: throttle_ms with s suffix — 1s accepted
+--- http_config
+    cache_purge_background_queue on;
+    cache_purge_throttle_ms 1s;
+--- config
+    location /health { return 200 "ok"; }
+--- request
+GET /health
+--- error_code: 200
+
+=== TEST 6a: response_type set in http{} context — accepted and inherited (Bug 1 + Bug 2)
+# The C type includes NGX_HTTP_MAIN_CONF, so http{} is valid.
+# The defunct NGX_HTTP_MODULE guard would have rejected this if it had ever fired.
+--- http_config
+    proxy_cache_path $TEST_NGINX_SERVROOT/cache keys_zone=rt_zone:1m;
+    cache_purge_background_queue on;
+    cache_purge_response_type json;
+--- config
+    location /purge { proxy_cache_purge rt_zone "$uri"; }
+--- request
+PURGE /purge/test*
+--- error_code: 202
+--- response_headers
+Content-Type: application/json
+
+=== TEST 6b: duplicate response_type in server{} context causes config error (Bug 3)
+# Before the fix, duplicates in server{} were silently swallowed.
+--- http_config
+    proxy_cache_path $TEST_NGINX_SERVROOT/cache keys_zone=rt2_zone:1m;
+--- config eval
+"cache_purge_response_type html;\n    cache_purge_response_type json;"
+--- must_die
+--- error_log eval
+qr/is duplicate/
+
+=== TEST 6c: response_type set in server{} context inherits into location (Bug 1)
+--- http_config
+    proxy_cache_path $TEST_NGINX_SERVROOT/cache keys_zone=rt3_zone:1m;
+    cache_purge_background_queue on;
+--- config
+    cache_purge_response_type xml;
+    location /purge { proxy_cache_purge rt3_zone "$uri"; }
+--- request
+PURGE /purge/test*
+--- error_code: 202
+--- response_headers
+Content-Type: text/xml