1 files changed, 27 insertions, 0 deletions
diff --git a/src/flatfile.cpp b/src/flatfile.cpp
index 535f4eda91..d9fd4041b7 100644
--- a/src/flatfile.cpp
+++ b/src/flatfile.cpp
@@ -7,6 +7,7 @@
 #include <flatfile.h>
 #include <logging.h>
 #include <tinyformat.h>
+#include <util/system.h>
 
 FlatFileSeq::FlatFileSeq(fs::path dir, const char* prefix, size_t chunk_size) :
     m_dir(std::move(dir)),
@@ -45,3 +46,29 @@ FILE* FlatFileSeq::Open(const CDiskBlockPos& pos, bool fReadOnly)
     }
     return file;
 }
+
+size_t FlatFileSeq::Allocate(const CDiskBlockPos& pos, size_t add_size, bool& out_of_space)
+{
+    out_of_space = false;
+
+    unsigned int n_old_chunks = (pos.nPos + m_chunk_size - 1) / m_chunk_size;
+    unsigned int n_new_chunks = (pos.nPos + add_size + m_chunk_size - 1) / m_chunk_size;
+    if (n_new_chunks > n_old_chunks) {
+        size_t old_size = pos.nPos;
+        size_t new_size = n_new_chunks * m_chunk_size;
+        size_t inc_size = new_size - old_size;
+
+        if (CheckDiskSpace(m_dir, inc_size)) {
+            FILE *file = Open(pos);
+            if (file) {
+                LogPrintf("Pre-allocating up to position 0x%x in %s%05u.dat\n", new_size, m_prefix, pos.nFile);
+                AllocateFileRange(file, pos.nPos, inc_size);
+                fclose(file);
+                return inc_size;
+            }
+        } else {
+            out_of_space = true;
+        }
+    }
+    return 0;
+}