From 8d6405a610bdbda9f432a700969b4e792f94b074 Mon Sep 17 00:00:00 2001
From: Jonathan Dieter <jdieter@gmail.com>
Date: Mon, 8 Oct 2018 13:57:42 +0100
Subject: [PATCH] Add support for optional flags

Signed-off-by: Jonathan Dieter <jdieter@gmail.com>
---
 src/lib/header.c      | 27 +++++++++++++++++++++++++++
 src/lib/zck_private.h |  1 +
 2 files changed, 28 insertions(+)

diff --git a/src/lib/header.c b/src/lib/header.c
index edefd64..cc402f2 100644
--- a/src/lib/header.c
+++ b/src/lib/header.c
@@ -36,10 +36,14 @@
 static bool check_flags(zckCtx *zck, size_t flags) {
     zck->has_streams = flags & 1;
     if(zck->has_streams) {
+        flags -= 1;
         set_fatal_error(zck,
                         "This version of zchunk doesn't support streams");
         return false;
     }
+    zck->has_optional_flags = flags & 2;
+    if(zck->has_optional_flags)
+        flags -= 2;
     flags = flags & (SIZE_MAX - 1);
     if(flags != 0) {
         set_fatal_error(zck, "Unknown flags(s) set");
@@ -48,6 +52,13 @@ static bool check_flags(zckCtx *zck, size_t flags) {
     return true;
 }
 
+static bool check_optional_flags(zckCtx *zck, size_t flags) {
+    flags = flags & (SIZE_MAX - 1);
+    if(flags != 0)
+        zck_log(ZCK_LOG_WARNING, "Unknown optional flags %i set", flags);
+    return true;
+}
+
 static bool read_header_from_file(zckCtx *zck) {
     /* Allocate header and store any extra bytes at beginning of header */
     zck->header = zrealloc(zck->header, zck->lead_size + zck->header_length);
@@ -128,6 +139,22 @@ static bool read_preface(zckCtx *zck) {
     if(!comp_init(zck))
         return false;
 
+    /* Read optional flags */
+    if(zck->has_optional_flags) {
+        size_t opt_flags = 0;
+        if(!compint_to_size(zck, &opt_flags, header+length, &length,
+                            max_length))
+            return false;
+        if(!check_optional_flags(zck, opt_flags))
+            return false;
+        size_t opt_flag_data_size = 0;
+        if(!compint_to_size(zck, &opt_flag_data_size, header+length, &length,
+                            max_length))
+            return false;
+        if(opt_flag_data_size > 0)
+            length += opt_flag_data_size;
+    }
+
     /* Read and initialize index size */
     if(!compint_to_int(zck, &tmp, header+length, &length, max_length))
         return false;
diff --git a/src/lib/zck_private.h b/src/lib/zck_private.h
index 32b4413..5c40cca 100644
--- a/src/lib/zck_private.h
+++ b/src/lib/zck_private.h
@@ -260,6 +260,7 @@ typedef struct zckCtx {
     zckHash work_index_hash;
     size_t stream;
     int has_streams;
+    int has_optional_flags;
 
     char *read_buf;
     size_t read_buf_size;
-- 
2.30.2