3 files changed, 47 insertions, 8 deletions
diff --git a/src/daemon/command_parser_executor.cpp b/src/daemon/command_parser_executor.cpp
index 17b945c9a..a8a3db45a 100644
--- a/src/daemon/command_parser_executor.cpp
+++ b/src/daemon/command_parser_executor.cpp
@@ -672,11 +672,38 @@ bool t_command_parser_executor::alt_chain_info(const std::vector<std::string>& a
 {
   if(args.size() > 1)
   {
-    std::cout << "usage: alt_chain_info [block_hash]" << std::endl;
+    std::cout << "usage: alt_chain_info [block_hash|>N|-N]" << std::endl;
     return false;
   }
 
-  return m_executor.alt_chain_info(args.size() == 1 ? args[0] : "");
+  std::string tip;
+  size_t above = 0;
+  uint64_t last_blocks = 0;
+  if (args.size() == 1)
+  {
+    if (args[0].size() > 0 && args[0][0] == '>')
+    {
+      if (!epee::string_tools::get_xtype_from_string(above, args[0].c_str() + 1))
+      {
+        std::cout << "invalid above parameter" << std::endl;
+        return false;
+      }
+    }
+    else if (args[0].size() > 0 && args[0][0] == '-')
+    {
+      if (!epee::string_tools::get_xtype_from_string(last_blocks, args[0].c_str() + 1))
+      {
+        std::cout << "invalid last_blocks parameter" << std::endl;
+        return false;
+      }
+    }
+    else
+    {
+      tip = args[0];
+    }
+  }
+
+  return m_executor.alt_chain_info(tip, above, last_blocks);
 }
 
 bool t_command_parser_executor::print_blockchain_dynamic_stats(const std::vector<std::string>& args)
diff --git a/src/daemon/rpc_command_executor.cpp b/src/daemon/rpc_command_executor.cpp
index 054b956ab..51fbd8628 100644
--- a/src/daemon/rpc_command_executor.cpp
+++ b/src/daemon/rpc_command_executor.cpp
@@ -1823,7 +1823,7 @@ bool t_rpc_command_executor::print_coinbase_tx_sum(uint64_t height, uint64_t cou
   return true;
 }
 
-bool t_rpc_command_executor::alt_chain_info(const std::string &tip)
+bool t_rpc_command_executor::alt_chain_info(const std::string &tip, size_t above, uint64_t last_blocks)
 {
   cryptonote::COMMAND_RPC_GET_INFO::request ireq;
   cryptonote::COMMAND_RPC_GET_INFO::response ires;
@@ -1860,12 +1860,24 @@ bool t_rpc_command_executor::alt_chain_info(const std::string &tip)
 
   if (tip.empty())
   {
-    tools::msg_writer() << boost::lexical_cast<std::string>(res.chains.size()) << " alternate chains found:";
     auto chains = res.chains;
     std::sort(chains.begin(), chains.end(), [](const cryptonote::COMMAND_RPC_GET_ALTERNATE_CHAINS::chain_info &info0, cryptonote::COMMAND_RPC_GET_ALTERNATE_CHAINS::chain_info &info1){ return info0.height < info1.height; });
-    for (const auto &chain: chains)
-    {
-      uint64_t start_height = (chain.height - chain.length + 1);
+    std::vector<size_t> display;
+    for (size_t i = 0; i < chains.size(); ++i)
+    {
+      const auto &chain = chains[i];
+      if (chain.length <= above)
+        continue;
+      const uint64_t start_height = (chain.height - chain.length + 1);
+      if (last_blocks > 0 && ires.height - 1 - start_height >= last_blocks)
+        continue;
+      display.push_back(i);
+    }
+    tools::msg_writer() << boost::lexical_cast<std::string>(display.size()) << " alternate chains found:";
+    for (const size_t idx: display)
+    {
+      const auto &chain = chains[idx];
+      const uint64_t start_height = (chain.height - chain.length + 1);
       tools::msg_writer() << chain.length << " blocks long, from height " << start_height << " (" << (ires.height - start_height - 1)
           << " deep), diff " << chain.difficulty << ": " << chain.block_hash;
     }
diff --git a/src/daemon/rpc_command_executor.h b/src/daemon/rpc_command_executor.h
index 3c2686b3f..96e742e1b 100644
--- a/src/daemon/rpc_command_executor.h
+++ b/src/daemon/rpc_command_executor.h
@@ -145,7 +145,7 @@ public:
 
   bool print_coinbase_tx_sum(uint64_t height, uint64_t count);
 
-  bool alt_chain_info(const std::string &tip);
+  bool alt_chain_info(const std::string &tip, size_t above, uint64_t last_blocks);
 
   bool print_blockchain_dynamic_stats(uint64_t nblocks);