From a56e05106571f28dc3044296849ccd5127d7d859 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sat, 11 Jun 2011 20:16:33 +0300
Subject: [PATCH] Wrap seek in a helper function and make it compatible with
 64-bit offsets

---
 source/io/file.cpp     | 31 +++++--------------------------
 source/io/file.h       |  4 ++--
 source/io/memory.cpp   |  2 +-
 source/io/memory.h     |  4 ++--
 source/io/seekable.cpp | 40 +++++++++++++++++++++++++++++++++++++---
 source/io/seekable.h   | 17 +++++++++++++----
 6 files changed, 60 insertions(+), 38 deletions(-)

diff --git a/source/io/file.cpp b/source/io/file.cpp
index 1b207a2..0f5652a 100644
--- a/source/io/file.cpp
+++ b/source/io/file.cpp
@@ -156,43 +156,22 @@ void File::sync()
 #endif
 }
 
-unsigned File::seek(int off, SeekType st)
+SeekOffset File::seek(SeekOffset off, SeekType type)
 {
 	check_access(M_NONE);
 
 	signal_flush_required.emit();
-
-	int type = sys_seek_type(st);
-#ifdef WIN32
-	DWORD ret = SetFilePointer(*handle, off, 0, type);
-	if(ret==INVALID_SET_FILE_POINTER)
-		throw system_error("SetFilePointer");
-#else
-	off_t ret = lseek(*handle, off, type);
-	if(ret==(off_t)-1)
-		throw system_error("lseek");
-#endif
-
+	off = sys_seek(handle, off, type);
 	eof_flag = false;
 
-	return ret;
+	return off;
 }
 
-unsigned File::tell() const
+SeekOffset File::tell() const
 {
 	check_access(M_NONE);
 
-#ifdef WIN32
-	DWORD ret = SetFilePointer(*handle, 0, 0, FILE_CURRENT);
-	if(ret==INVALID_SET_FILE_POINTER)
-		throw system_error("SetFilePointer");
-#else
-	off_t ret = lseek(*handle, 0, SEEK_CUR);
-	if(ret==(off_t)-1)
-		throw system_error("lseek");
-#endif
-
-	return ret;
+	return sys_seek(const_cast<Handle &>(handle), 0, S_CUR);
 }
 
 void File::check_access(Mode m) const
diff --git a/source/io/file.h b/source/io/file.h
index ed0a3f8..ee83554 100644
--- a/source/io/file.h
+++ b/source/io/file.h
@@ -56,8 +56,8 @@ protected:
 public:
 	virtual void sync();
 
-	virtual unsigned seek(int, SeekType);
-	virtual unsigned tell() const;
+	virtual SeekOffset seek(SeekOffset, SeekType);
+	virtual SeekOffset tell() const;
 
 private:
 	void check_access(Mode) const;
diff --git a/source/io/memory.cpp b/source/io/memory.cpp
index af6ef3d..4a6296b 100644
--- a/source/io/memory.cpp
+++ b/source/io/memory.cpp
@@ -88,7 +88,7 @@ int Memory::get()
 	return static_cast<unsigned char>(*pos++);
 }
 
-unsigned Memory::seek(int off, SeekType type)
+SeekOffset Memory::seek(SeekOffset off, SeekType type)
 {
 	char *new_pos;
 	if(type==S_BEG)
diff --git a/source/io/memory.h b/source/io/memory.h
index ebd57ed..ca92a75 100644
--- a/source/io/memory.h
+++ b/source/io/memory.h
@@ -28,8 +28,8 @@ public:
 	virtual bool getline(std::string &);
 	virtual int get();
 
-	virtual unsigned seek(int, SeekType);
-	virtual unsigned tell() const { return pos-begin; }
+	virtual SeekOffset seek(SeekOffset, SeekType);
+	virtual SeekOffset tell() const { return pos-begin; }
 
 private:
 	void check_mode(Mode) const;
diff --git a/source/io/seekable.cpp b/source/io/seekable.cpp
index 101676e..12ff6aa 100644
--- a/source/io/seekable.cpp
+++ b/source/io/seekable.cpp
@@ -1,13 +1,19 @@
-#ifdef WIN32
+#ifndef WIN32
+#define _LARGEFILE64_SOURCE
+#else
 #include <windows.h>
 #endif
 #include <stdexcept>
+#include <msp/core/systemerror.h>
+#include "handle.h"
+#include "handle_private.h"
 #include "seekable.h"
 
 using namespace std;
 
-namespace Msp {
-namespace IO {
+namespace {
+
+using namespace Msp::IO;
 
 int sys_seek_type(SeekType st)
 {
@@ -30,5 +36,33 @@ int sys_seek_type(SeekType st)
 	throw invalid_argument("sys_seek_type");
 }
 
+} // namespace
+
+
+namespace Msp {
+namespace IO {
+
+SeekOffset sys_seek(Handle &handle, SeekOffset offset, SeekType type)
+{
+#ifdef WIN32
+	LONG high = offset>>32;
+	DWORD ret = SetFilePointer(*handle, offset, &high, sys_seek_type(type));
+	if(ret==INVALID_SET_FILE_POINTER)
+	{
+		DWORD err = GetLastError();
+		if(err!=NO_ERROR)
+			throw system_error("SetFilePointer");
+	}
+
+	return (SeekOffset(high)<<32) | ret;
+#else
+	off64_t ret = lseek64(*handle, offset, sys_seek_type(type));
+	if(ret==(off64_t)-1)
+		throw system_error("lseek64");
+
+	return ret;
+#endif
+}
+
 } // namespace IO
 } // namespace Msp
diff --git a/source/io/seekable.h b/source/io/seekable.h
index cabb9dc..9522311 100644
--- a/source/io/seekable.h
+++ b/source/io/seekable.h
@@ -6,6 +6,14 @@
 namespace Msp {
 namespace IO {
 
+class Handle;
+
+#ifdef MSVC
+typedef __int64 SeekOffset;
+#else
+typedef long long SeekOffset;
+#endif
+
 enum SeekType
 {
 	S_BEG,
@@ -13,8 +21,6 @@ enum SeekType
 	S_END
 };
 
-int sys_seek_type(SeekType);
-
 
 class Seekable: public Base
 {
@@ -23,12 +29,15 @@ protected:
 
 public:
 	/** Changes the read/write offset.  Returns the new offset. */
-	virtual unsigned seek(int, SeekType) = 0;
+	virtual SeekOffset seek(SeekOffset, SeekType) = 0;
 	
 	/** Returns the current read/write offset. */
-	virtual unsigned tell() const = 0;
+	virtual SeekOffset tell() const = 0;
 };
 
+
+SeekOffset sys_seek(Handle &, SeekOffset, SeekType);
+
 } // namespace IO
 } // namespace Msp
 
-- 
2.43.0