Core: fixed handling of "stderr" in error_log.

If "stderr" was specified in one of the "error_log" directives,
stderr is not redirected to the first error_log on startup,
configuration reload, and reopening log files.

src/core/nginx.c

diff --git a/src/core/nginx.c b/src/core/nginx.c
index 94df9bf..796717a 100644
--- a/src/core/nginx.c
+++ b/src/core/nginx.c
@@ -387,7 +387,7 @@
         return 1;
     }
 
-    if (cycle->log->file->fd != ngx_stderr) {
+    if (!cycle->log_use_stderr && cycle->log->file->fd != ngx_stderr) {
 
         if (ngx_set_stderr(cycle->log->file->fd) == NGX_FILE_ERROR) {
             ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno,

src/core/ngx_cycle.c

diff --git a/src/core/ngx_cycle.c b/src/core/ngx_cycle.c
index 40b8562..de81775 100644
--- a/src/core/ngx_cycle.c
+++ b/src/core/ngx_cycle.c
@@ -582,8 +582,9 @@
 
     /* commit the new cycle configuration */
 
-    if (!ngx_use_stderr && cycle->log->file->fd != ngx_stderr) {
-
+    if (!ngx_use_stderr && !cycle->log_use_stderr
+        && cycle->log->file->fd != ngx_stderr)
+    {
         if (ngx_set_stderr(cycle->log->file->fd) == NGX_FILE_ERROR) {
             ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
                           ngx_set_stderr_n " failed");
@@ -1228,7 +1229,7 @@
         file[i].fd = fd;
     }
 
-    if (cycle->log->file->fd != ngx_stderr) {
+    if (!cycle->log_use_stderr && cycle->log->file->fd != ngx_stderr) {
 
         if (ngx_set_stderr(cycle->log->file->fd) == NGX_FILE_ERROR) {
             ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,

src/core/ngx_cycle.h

diff --git a/src/core/ngx_cycle.h b/src/core/ngx_cycle.h
index 2e4bc4b..21bf5ca 100644
--- a/src/core/ngx_cycle.h
+++ b/src/core/ngx_cycle.h
@@ -41,6 +41,8 @@
     ngx_log_t                *log;
     ngx_log_t                 new_log;
 
+    ngx_uint_t                log_use_stderr;  /* unsigned  log_use_stderr:1; */
+
     ngx_connection_t        **files;
     ngx_connection_t         *free_connections;
     ngx_uint_t                free_connection_n;

src/core/ngx_log.c

diff --git a/src/core/ngx_log.c b/src/core/ngx_log.c
index d7830fb..20f5097 100644
--- a/src/core/ngx_log.c
+++ b/src/core/ngx_log.c
@@ -438,6 +438,7 @@
 
     if (ngx_strcmp(value[1].data, "stderr") == 0) {
         ngx_str_null(&name);
+        cf->cycle->log_use_stderr = 1;
 
     } else {
         name = value[1];

src/http/ngx_http_core_module.c

diff --git a/src/http/ngx_http_core_module.c b/src/http/ngx_http_core_module.c
index 25d3dc9..4403fa3 100644
--- a/src/http/ngx_http_core_module.c
+++ b/src/http/ngx_http_core_module.c
@@ -4898,6 +4898,7 @@
 
     if (ngx_strcmp(value[1].data, "stderr") == 0) {
         ngx_str_null(&name);
+        cf->cycle->log_use_stderr = 1;
 
     } else {
         name = value[1];