Don't lose pointer to first nonempty buf in ngx_*_sendfile_chain().

In ngx_*_sendfile_chain() when calculating pointer to a first
non-zero sized buf, use "in" as iterator.  This fixes processing
of zero sized buf(s) after EINTR.  Otherwise function can return
zero sized buf to caller, and later ngx_http_write_filter()
logs warning.

1 files changed, 14 insertions, 16 deletions

diff --git a/src/os/unix/ngx_linux_sendfile_chain.c b/src/os/unix/ngx_linux_sendfile_chain.c
index 643855ed9..8c4d59c22 100644
--- a/src/os/unix/ngx_linux_sendfile_chain.c
+++ b/src/os/unix/ngx_linux_sendfile_chain.c
@@ -325,9 +325,9 @@ ngx_linux_sendfile_chain(ngx_connection_t *c, ngx_chain_t *in, off_t limit)
 
         c->sent += sent;
 
-        for (cl = in; cl; cl = cl->next) {
+        for ( /* void */ ; in; in = in->next) {
 
-            if (ngx_buf_special(cl->buf)) {
+            if (ngx_buf_special(in->buf)) {
                 continue;
             }
 
@@ -335,28 +335,28 @@ ngx_linux_sendfile_chain(ngx_connection_t *c, ngx_chain_t *in, off_t limit)
                 break;
             }
 
-            size = ngx_buf_size(cl->buf);
+            size = ngx_buf_size(in->buf);
 
             if (sent >= size) {
                 sent -= size;
 
-                if (ngx_buf_in_memory(cl->buf)) {
-                    cl->buf->pos = cl->buf->last;
+                if (ngx_buf_in_memory(in->buf)) {
+                    in->buf->pos = in->buf->last;
                 }
 
-                if (cl->buf->in_file) {
-                    cl->buf->file_pos = cl->buf->file_last;
+                if (in->buf->in_file) {
+                    in->buf->file_pos = in->buf->file_last;
                 }
 
                 continue;
             }
 
-            if (ngx_buf_in_memory(cl->buf)) {
-                cl->buf->pos += (size_t) sent;
+            if (ngx_buf_in_memory(in->buf)) {
+                in->buf->pos += (size_t) sent;
             }
 
-            if (cl->buf->in_file) {
-                cl->buf->file_pos += sent;
+            if (in->buf->in_file) {
+                in->buf->file_pos += sent;
             }
 
             break;
@@ -368,13 +368,11 @@ ngx_linux_sendfile_chain(ngx_connection_t *c, ngx_chain_t *in, off_t limit)
 
         if (!complete) {
             wev->ready = 0;
-            return cl;
+            return in;
         }
 
-        if (send >= limit || cl == NULL) {
-            return cl;
+        if (send >= limit || in == NULL) {
+            return in;
         }
-
-        in = cl;
     }
 }