Make lexical_cast symmetric

[libs/core.git] / source / io / seekable.cpp

diff --git a/source/io/seekable.cpp b/source/io/seekable.cpp
index 101676e0ef304a5d56efada803808d3e990b5065..35ab5a05104fef55fbe625a3e55cdff2d1b18590 100644 (file)
--- a/source/io/seekable.cpp
+++ b/source/io/seekable.cpp
@@ -1,13 +1,21 @@
-#ifdef WIN32
+#ifndef WIN32
+#define _LARGEFILE64_SOURCE
+#include <cerrno>
+#include <unistd.h>
+#else
 #include <windows.h>
 #endif
-#include <stdexcept>
+#include <msp/core/systemerror.h>
+#include <msp/strings/format.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 +38,46 @@ int sys_seek_type(SeekType st)
        throw invalid_argument("sys_seek_type");
 }
 
+} // namespace
+
+
+namespace Msp {
+namespace IO {
+
+bad_seek::bad_seek(SeekOffset offset, SeekType type):
+       runtime_error(type==S_BEG ? lexical_cast<string>(offset) :
+               type==S_CUR ? format("CUR%+d", offset) :
+               type==S_END ? format("END%+d", offset) :
+               format("SeekType(%d)", type))
+{ }
+
+
+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)
+       {
+               if(errno==EINVAL)
+                       throw bad_seek(offset, type);
+               else
+                       throw system_error("lseek64");
+       }
+
+       return ret;
+#endif
+}
+
 } // namespace IO
 } // namespace Msp