fix read/write big files on linux

Author: malytomas

sources/libcore/filesystem/realFiles.cpp

@@ -179,53 +179,71 @@ namespace cage
 		{
 			CAGE_ASSERT(f);
 #ifdef CAGE_SYSTEM_WINDOWS
-			HANDLE handle = (HANDLE)_get_osfhandle(_fileno(f));
+			const HANDLE handle = (HANDLE)_get_osfhandle(_fileno(f));
 			uint64 off = 0;
 			uint64 s = buffer.size();
 			while (s > 0)
 			{
 				OVERLAPPED o;
 				detail::memset(&o, 0, sizeof(o));
-				uint64 p = at + off;
+				const uint64 p = at + off;
 				o.Offset = (DWORD)p;
 				o.OffsetHigh = (DWORD)((uint64)p >> 32);
-				uint64 k = min(s, (uint64)1024 * 1024 * 1024); // write in chunks of 1 GB
+				const uint64 k = min(s, (uint64)1024 * 1024 * 1024); // read in chunks of 1 GB
 				DWORD r = 0;
 				if (!ReadFile(handle, buffer.data() + off, numeric_cast<DWORD>(k), &r, &o) || r != k)
 					CAGE_THROW_ERROR(SystemError, "ReadFile", GetLastError());
 				off += k;
 				s -= k;
 			}
 #else
-			if (pread(fileno(f), buffer.data(), buffer.size(), at) != buffer.size())
-				CAGE_THROW_ERROR(SystemError, "pread", errno);
+			const int handle = fileno(f);
+			uint64 off = 0;
+			uint64 s = buffer.size();
+			while (s > 0)
+			{
+				const uint64 k = min(s, (uint64)1024 * 1024 * 1024); // read in chunks of 1 GB
+				if (pread(handle, buffer.data() + off, k, at) != k)
+					CAGE_THROW_ERROR(SystemError, "pread", errno);
+				off += k;
+				s -= k;
+			}
 #endif
 		}
 
 		void writeAtImpl(PointerRange<const char> buffer, const uint64 at, FILE *f)
 		{
 			CAGE_ASSERT(f);
 #ifdef CAGE_SYSTEM_WINDOWS
-			HANDLE handle = (HANDLE)_get_osfhandle(_fileno(f));
+			const HANDLE handle = (HANDLE)_get_osfhandle(_fileno(f));
 			uint64 off = 0;
 			uint64 s = buffer.size();
 			while (s > 0)
 			{
 				OVERLAPPED o;
 				detail::memset(&o, 0, sizeof(o));
-				uint64 p = at + off;
+				const uint64 p = at + off;
 				o.Offset = (DWORD)p;
 				o.OffsetHigh = (DWORD)((uint64)p >> 32);
-				uint64 k = min(s, (uint64)1024 * 1024 * 1024); // write in chunks of 1 GB
+				const uint64 k = min(s, (uint64)1024 * 1024 * 1024); // write in chunks of 1 GB
 				DWORD r = 0;
 				if (!WriteFile(handle, buffer.data() + off, numeric_cast<DWORD>(k), &r, &o) || r != k)
 					CAGE_THROW_ERROR(SystemError, "WriteFile", GetLastError());
 				off += k;
 				s -= k;
 			}
 #else
-			if (pwrite(fileno(f), buffer.data(), buffer.size(), at) != buffer.size())
-				CAGE_THROW_ERROR(SystemError, "pwrite", errno);
+			const int handle = fileno(f);
+			uint64 off = 0;
+			uint64 s = buffer.size();
+			while (s > 0)
+			{
+				const uint64 k = min(s, (uint64)1024 * 1024 * 1024); // write in chunks of 1 GB
+				if (pwrite(handle, buffer.data() + off, k, at) != k)
+					CAGE_THROW_ERROR(SystemError, "pwrite", errno);
+				off += k;
+				s -= k;
+			}
 #endif
 		}
 
@@ -322,9 +340,9 @@ namespace cage
 			uint64 size() override
 			{
 				CAGE_ASSERT(f);
-				uint64 pos = ftell(f);
+				const uint64 pos = ftell(f);
 				fseek(f, 0, 2);
-				uint64 siz = ftell(f);
+				const uint64 siz = ftell(f);
 				fseek(f, pos, 0);
 				return siz;
 			}