new file mode 100644
--- /dev/null
+++ b/src/core/ngx_buf.c
@@ -0,0 +1,162 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+
+
+ngx_buf_t *ngx_create_temp_buf(ngx_pool_t *pool, size_t size)
+{
+    ngx_buf_t *b;
+
+    if (!(b = ngx_calloc_buf(pool))) {
+        return NULL;
+    }
+
+    if (!(b->start = ngx_palloc(pool, size))) {
+        return NULL;
+    }
+
+    b->pos = b->start;
+    b->last = b->start;
+    b->end = b->last + size;
+    b->temporary = 1;
+
+    /*
+
+    b->file_pos = 0;
+    b->file_last = 0;
+
+    b->file = NULL;
+    b->shadow = NULL;
+
+    b->tag = 0;
+
+     */
+
+    return b;
+}
+
+
+ngx_chain_t *ngx_create_chain_of_bufs(ngx_pool_t *pool, ngx_bufs_t *bufs)
+{
+    u_char       *p;
+    ngx_int_t     i;
+    ngx_buf_t    *b;
+    ngx_chain_t  *chain, *cl, **ll;
+
+    if (!(p = ngx_palloc(pool, bufs->num * bufs->size))) {
+        return NULL;
+    }
+
+    ll = &chain;
+
+    for (i = 0; i < bufs->num; i++) {
+        if (!(b = ngx_calloc_buf(pool))) {
+            return NULL;
+        }
+
+        b->pos = p;
+        b->last = p;
+        b->temporary = 1;
+
+        b->start = p;
+        p += bufs->size;
+        b->end = p;
+
+        /*
+        b->file_pos = 0;
+        b->file_last = 0;
+
+        b->file = NULL;
+        b->shadow = NULL;
+        b->tag = 0;
+        */
+
+        if (!(cl = ngx_alloc_chain_link(pool))) {
+            return NULL;
+        }
+
+        cl->buf = b;
+        *ll = cl;
+        ll = &cl->next;
+    }
+
+    *ll = NULL;
+
+    return chain;
+}
+
+
+ngx_int_t ngx_chain_add_copy(ngx_pool_t *pool, ngx_chain_t **chain,
+                             ngx_chain_t *in)
+{
+    ngx_chain_t  *cl, **ll;
+
+    ll = chain;
+
+    for (cl = *chain; cl; cl = cl->next) {
+        ll = &cl->next;
+    }
+
+    while (in) {
+        ngx_test_null(cl, ngx_alloc_chain_link(pool), NGX_ERROR);
+
+        cl->buf = in->buf;
+        *ll = cl;
+        ll = &cl->next;
+        in = in->next;
+    }
+
+    *ll = NULL;
+
+    return NGX_OK;
+}
+
+
+void ngx_chain_update_chains(ngx_chain_t **free, ngx_chain_t **busy,
+                             ngx_chain_t **out, ngx_buf_tag_t tag)
+{
+    ngx_chain_t  *tl;
+
+    if (*busy == NULL) {
+        *busy = *out;
+
+    } else {
+        for (tl = *busy; /* void */ ; tl = tl->next) {
+            if (tl->next == NULL) {
+                tl->next = *out;
+                break;
+            }
+        }
+    }
+
+    *out = NULL;
+
+    while (*busy) {
+        if (ngx_buf_size((*busy)->buf) != 0) {
+            break;
+        }
+
+#if (HAVE_WRITE_ZEROCOPY)
+        if ((*busy)->buf->zerocopy_busy) {
+            break;
+        }
+#endif
+
+        if ((*busy)->buf->tag != tag) {
+            *busy = (*busy)->next;
+            continue;
+        }
+
+        (*busy)->buf->pos = (*busy)->buf->last = (*busy)->buf->start;
+
+        tl = *busy;
+        *busy = (*busy)->next;
+        tl->next = *free;
+        *free = tl;
+    }
+}