Fix failing to create DAG file larger than 2 Gb

Author: S74nk0

ethminer/MinerAux.h

@@ -436,6 +436,20 @@ class MinerCLI
 		{
 			m_minerType = MinerType::Mixed;
 		}
+		else if ((arg == "-D" || arg == "--create-dag") && i + 1 < argc)
+		{
+			string m = boost::to_lower_copy(string(argv[++i]));
+			mode = OperationMode::DAGInit;
+			try
+			{
+				m_initDAG = stol(m);
+			}
+			catch (...)
+			{
+				cerr << "Bad " << arg << " option: " << m << endl;
+				BOOST_THROW_EXCEPTION(BadArgument());
+			}
+		}
 		/*
 		else if (arg == "--current-block" && i + 1 < argc)
 			m_currentBlock = stol(argv[++i]);
@@ -551,6 +565,10 @@ class MinerCLI
 
 	void execute()
 	{
+		if (mode == OperationMode::DAGInit) {
+			doInitDAG(m_initDAG);
+		}
+
 		if (m_shouldListDevices)
 		{
 #if ETH_ETHASHCL || !ETH_TRUE
@@ -1210,6 +1228,8 @@ class MinerCLI
 		}
 	}
 #endif
+	/// DAG initialisation param.
+	unsigned m_initDAG = 0;
 
 	/// Operating mode.
 	OperationMode mode;

libethash/io.c

@@ -91,7 +91,7 @@ enum ethash_io_rc ethash_io_prepare(
 		goto free_memo;
 	}
 	// make sure it's of the proper size
-	if (fseek(f, (long int)(file_size + ETHASH_DAG_MAGIC_NUM_SIZE - 1), SEEK_SET) != 0) {
+	if (ethash_fseek(f, file_size + ETHASH_DAG_MAGIC_NUM_SIZE - 1, SEEK_SET) != 0) {
 		fclose(f);
 		ETHASH_CRITICAL("Could not seek to the end of DAG file: \"%s\". Insufficient space?", tmpfile);
 		goto free_memo;

libethash/io.h

@@ -113,6 +113,16 @@ enum ethash_io_rc ethash_io_prepare(
  */
 FILE* ethash_fopen(char const* file_name, char const* mode);
 
+/**
+ * An fseek wrapper for crossplatform 64-bit seek.
+ *
+ * @param f            The file stream whose fd to get
+ * @param offset       Number of bytes from @a origin
+ * @param origin       Initial position
+ * @return             Current offset or -1 to indicate an error
+ */
+int ethash_fseek(FILE* f, size_t offset, int origin);
+
 /**
  * An strncat wrapper for no-warnings crossplatform strncat.
  *

libethash/io_posix.c

@@ -34,6 +34,11 @@ FILE* ethash_fopen(char const* file_name, char const* mode)
 	return fopen(file_name, mode);
 }
 
+int ethash_fseek(FILE* f, size_t offset, int origin)
+{
+	return fseeko(f, offset, origin);
+}
+
 char* ethash_strncat(char* dest, size_t dest_size, char const* src, size_t count)
 {
 	return strlen(dest) + count + 1 <= dest_size ? strncat(dest, src, count) : NULL;

libethash/io_win32.c

@@ -26,13 +26,19 @@
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <shlobj.h>
+#include <io.h>
 
 FILE* ethash_fopen(char const* file_name, char const* mode)
 {
 	FILE* f;
 	return fopen_s(&f, file_name, mode) == 0 ? f : NULL;
 }
 
+int ethash_fseek(FILE* f, size_t offset, int origin)
+{
+    return _fseeki64(f, offset, origin);
+}
+
 char* ethash_strncat(char* dest, size_t dest_size, char const* src, size_t count)
 {
 	return strncat_s(dest, dest_size, src, count) == 0 ? dest : NULL;