1 files changed, 98 insertions, 0 deletions
diff --git a/src/flatfile.cpp b/src/flatfile.cpp
new file mode 100644
index 0000000000..8a8f7b681c
--- /dev/null
+++ b/src/flatfile.cpp
@@ -0,0 +1,98 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2019 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <stdexcept>
+
+#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)),
+    m_prefix(prefix),
+    m_chunk_size(chunk_size)
+{
+    if (chunk_size == 0) {
+        throw std::invalid_argument("chunk_size must be positive");
+    }
+}
+
+std::string FlatFilePos::ToString() const
+{
+    return strprintf("FlatFilePos(nFile=%i, nPos=%i)", nFile, nPos);
+}
+
+fs::path FlatFileSeq::FileName(const FlatFilePos& pos) const
+{
+    return m_dir / strprintf("%s%05u.dat", m_prefix, pos.nFile);
+}
+
+FILE* FlatFileSeq::Open(const FlatFilePos& pos, bool read_only)
+{
+    if (pos.IsNull()) {
+        return nullptr;
+    }
+    fs::path path = FileName(pos);
+    fs::create_directories(path.parent_path());
+    FILE* file = fsbridge::fopen(path, read_only ? "rb": "rb+");
+    if (!file && !read_only)
+        file = fsbridge::fopen(path, "wb+");
+    if (!file) {
+        LogPrintf("Unable to open file %s\n", path.string());
+        return nullptr;
+    }
+    if (pos.nPos && fseek(file, pos.nPos, SEEK_SET)) {
+        LogPrintf("Unable to seek to position %u of %s\n", pos.nPos, path.string());
+        fclose(file);
+        return nullptr;
+    }
+    return file;
+}
+
+size_t FlatFileSeq::Allocate(const FlatFilePos& 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;
+}
+
+bool FlatFileSeq::Flush(const FlatFilePos& pos, bool finalize)
+{
+    FILE* file = Open(FlatFilePos(pos.nFile, 0)); // Avoid fseek to nPos
+    if (!file) {
+        return error("%s: failed to open file %d", __func__, pos.nFile);
+    }
+    if (finalize && !TruncateFile(file, pos.nPos)) {
+        fclose(file);
+        return error("%s: failed to truncate file %d", __func__, pos.nFile);
+    }
+    if (!FileCommit(file)) {
+        fclose(file);
+        return error("%s: failed to commit file %d", __func__, pos.nFile);
+    }
+
+    fclose(file);
+    return true;
+}