Changeset ef28d8

Timestamp:

02/04/08 14:43:17 (4 years ago)

Author:

Tomash Brechko <tomash.brechko@…>

Branches:

master-v0.7, gunzip, master-v0.6, memcached_gzip, upstream_count_limit

Children:

ec81a7

Parents:

2bbdb3

git-author:

Tomash Brechko <tomash.brechko@…> (02/04/08 14:43:17)

git-committer:

Tomash Brechko <tomash.brechko@…> (02/04/08 14:43:17)

Message:

Workaround for the infinite loop that is caused by empty input buffer.

File:

• server/src/http/modules/ngx_http_gzip_filter_module.c (modified) (2 diffs)

server/src/http/modules/ngx_http_gzip_filter_module.c

@@ -456 +456 @@
 
                 if (ctx->in_buf->last_buf) {
-                    ctx->flush = Z_FINISH;
+                    /*
+                     * We use Z_BLOCK below for the following reason:
+                     * if we would use Z_FINISH, then decompression
+                     * may return Z_BUF_ERROR, meaning there wasn't
+                     * enough room for decompressed data.  This error
+                     * is not fatal according to zlib.h, however
+                     * ignoring it is dangerous and may mask real
+                     * bugs.  For instance, sometimes completely empty
+                     * last buffer is passed to this filter, and
+                     * decompression would enter the infinite loop: no
+                     * progress is possible because input is void and
+                     * Z_BUF_ERROR is ignored.  We can't use
+                     * Z_NO_FLUSH, because it will never return
+                     * Z_STREAM_END.  We can't use Z_SYNC_FLUSH,
+                     * because it has a special meaning.  So we use
+                     * Z_BLOCK, which eventually would return
+                     * Z_STREAM_END.
+                     *
+                     * Perhaps the above is also true for compression,
+                     * but right now we won't try to change the old
+                     * behaviour.
+                     */
+                    ctx->flush = (!r->gunzip ? Z_FINISH : Z_BLOCK);
 
                 } else if (ctx->in_buf->flush) {
@@ -515 +537 @@
             }
 
-            if (rc != Z_OK && rc != Z_STREAM_END && rc != Z_BUF_ERROR) {
+            if (rc != Z_OK && rc != Z_STREAM_END) {
                 ngx_log_error(NGX_LOG_ALERT, r->connection->log, 0,
                               "deflate() failed: %d, %d", ctx->flush, rc);