[nginx] Core: made it possible to disable PID files with "pid off".

[Maxim Dounin]

details:   http://freenginx.org/hg/nginx/rev/6a3ee145d0b5
branches:  
changeset: 9268:6a3ee145d0b5
user:      Maxim Dounin <mdounin at mdounin.ru>
date:      Mon May 13 06:13:03 2024 +0300
description:
Core: made it possible to disable PID files with "pid off".

While it is not generally recommended, this might be beneficial in some
configurations, such as with immutable images and direct control by
a service manager.

diffstat:

 src/core/nginx.c                |  35 ++++++++++++++++++++++-------------
 src/core/ngx_cycle.c            |  14 ++++++++++++++
 src/os/unix/ngx_process_cycle.c |   7 ++++---
 3 files changed, 40 insertions(+), 16 deletions(-)

diffs (118 lines):

diff --git a/src/core/nginx.c b/src/core/nginx.c
--- a/src/core/nginx.c
+++ b/src/core/nginx.c
@@ -766,7 +766,9 @@ ngx_exec_new_binary(ngx_cycle_t *cycle, 
 
     ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);
 
-    if (ngx_rename_file(ccf->pid.data, ccf->oldpid.data) == NGX_FILE_ERROR) {
+    if (ccf->pid.len
+        && ngx_rename_file(ccf->pid.data, ccf->oldpid.data) == NGX_FILE_ERROR)
+    {
         ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
                       ngx_rename_file_n " %s to %s failed "
                       "before executing new binary process \"%s\"",
@@ -781,8 +783,9 @@ ngx_exec_new_binary(ngx_cycle_t *cycle, 
     pid = ngx_execute(cycle, &ctx);
 
     if (pid == NGX_INVALID_PID) {
-        if (ngx_rename_file(ccf->oldpid.data, ccf->pid.data)
-            == NGX_FILE_ERROR)
+        if (ccf->pid.len
+            && ngx_rename_file(ccf->oldpid.data, ccf->pid.data)
+               == NGX_FILE_ERROR)
         {
             ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
                           ngx_rename_file_n " %s back to %s failed after "
@@ -1168,20 +1171,26 @@ ngx_core_module_init_conf(ngx_cycle_t *c
         ngx_str_set(&ccf->pid, NGX_PID_PATH);
     }
 
-    if (ngx_conf_full_name(cycle, &ccf->pid, 0) != NGX_OK) {
-        return NGX_CONF_ERROR;
-    }
+    if (ngx_strcmp(ccf->pid.data, "off") == 0) {
+        ngx_str_set(&ccf->pid, "");
+        ngx_str_set(&ccf->oldpid, "");
 
-    ccf->oldpid.len = ccf->pid.len + sizeof(NGX_OLDPID_EXT);
+    } else {
+        if (ngx_conf_full_name(cycle, &ccf->pid, 0) != NGX_OK) {
+            return NGX_CONF_ERROR;
+        }
 
-    ccf->oldpid.data = ngx_pnalloc(cycle->pool, ccf->oldpid.len);
-    if (ccf->oldpid.data == NULL) {
-        return NGX_CONF_ERROR;
+        ccf->oldpid.len = ccf->pid.len + sizeof(NGX_OLDPID_EXT);
+
+        ccf->oldpid.data = ngx_pnalloc(cycle->pool, ccf->oldpid.len);
+        if (ccf->oldpid.data == NULL) {
+            return NGX_CONF_ERROR;
+        }
+
+        ngx_memcpy(ngx_cpymem(ccf->oldpid.data, ccf->pid.data, ccf->pid.len),
+                   NGX_OLDPID_EXT, sizeof(NGX_OLDPID_EXT));
     }
 
-    ngx_memcpy(ngx_cpymem(ccf->oldpid.data, ccf->pid.data, ccf->pid.len),
-               NGX_OLDPID_EXT, sizeof(NGX_OLDPID_EXT));
-
 
 #if !(NGX_WIN32)
 
diff --git a/src/core/ngx_cycle.c b/src/core/ngx_cycle.c
--- a/src/core/ngx_cycle.c
+++ b/src/core/ngx_cycle.c
@@ -1027,6 +1027,10 @@ ngx_create_pidfile(ngx_str_t *name, ngx_
         return NGX_OK;
     }
 
+    if (name->len == 0) {
+        return NGX_OK;
+    }
+
     ngx_memzero(&file, sizeof(ngx_file_t));
 
     file.name = *name;
@@ -1070,6 +1074,10 @@ ngx_delete_pidfile(ngx_cycle_t *cycle)
 
     ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);
 
+    if (ccf->pid.len == 0) {
+        return;
+    }
+
     name = ngx_new_binary ? ccf->oldpid.data : ccf->pid.data;
 
     if (ngx_delete_file(name) == NGX_FILE_ERROR) {
@@ -1092,6 +1100,12 @@ ngx_signal_process(ngx_cycle_t *cycle, c
 
     ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);
 
+    if (ccf->pid.len == 0) {
+        ngx_log_error(NGX_LOG_ERR, cycle->log, 0,
+                      "no PID file configured");
+        return 1;
+    }
+
     ngx_memzero(&file, sizeof(ngx_file_t));
 
     file.name = ccf->pid;
diff --git a/src/os/unix/ngx_process_cycle.c b/src/os/unix/ngx_process_cycle.c
--- a/src/os/unix/ngx_process_cycle.c
+++ b/src/os/unix/ngx_process_cycle.c
@@ -619,9 +619,10 @@ ngx_reap_children(ngx_cycle_t *cycle)
                 ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx,
                                                        ngx_core_module);
 
-                if (ngx_rename_file((char *) ccf->oldpid.data,
-                                    (char *) ccf->pid.data)
-                    == NGX_FILE_ERROR)
+                if (ccf->pid.len
+                    && ngx_rename_file((char *) ccf->oldpid.data,
+                                       (char *) ccf->pid.data)
+                       == NGX_FILE_ERROR)
                 {
                     ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
                                   ngx_rename_file_n " %s back to %s failed "