more hacky mmap edits

Author: JacobSzwejbka

extension/data_loader/mman_windows.cpp

@@ -21,6 +21,8 @@
 
 #include <errno.h>
 #include <io.h>
+#include <limits>
+#include <cstdint>
 #include <windows.h>
 
 #ifndef STATUS_SECTION_TOO_BIG
@@ -129,49 +131,42 @@ static DWORD __map_mmap_prot_file(const int prot) {
 
 } // namespace
 
-void* mmap(void* addr, size_t len, int prot, int flags, int fildes, off_t off) {
+void* mmap(
+    void* addr,
+    size_t len,
+    int prot,
+    int flags,
+    int fildes,
+    std::uint64_t off) {
   HANDLE fm, h;
-
   void* map = MAP_FAILED;
 
-#ifdef _MSC_VER
-#pragma warning(push)
-#pragma warning(disable : 4293)
-#endif
-
-  const DWORD dwFileOffsetLow = (sizeof(off_t) <= sizeof(DWORD))
-      ? (DWORD)off
-      : (DWORD)(off & 0xFFFFFFFFL);
-  const DWORD dwFileOffsetHigh = (sizeof(off_t) <= sizeof(DWORD))
-      ? (DWORD)0
-      : (DWORD)((off >> 32) & 0xFFFFFFFFL);
-  const DWORD protect = __map_mmap_prot_page(prot);
-  const DWORD desiredAccess = __map_mmap_prot_file(prot);
-
-  const off_t maxSize = off + (off_t)len;
-
-  const DWORD dwMaxSizeLow = (sizeof(off_t) <= sizeof(DWORD))
-      ? (DWORD)maxSize
-      : (DWORD)(maxSize & 0xFFFFFFFFL);
-  const DWORD dwMaxSizeHigh = (sizeof(off_t) <= sizeof(DWORD))
-      ? (DWORD)0
-      : (DWORD)((maxSize >> 32) & 0xFFFFFFFFL);
-
-#ifdef _MSC_VER
-#pragma warning(pop)
-#endif
-
   errno = 0;
 
   if (len == 0
       /* Unsupported flag combinations */
       || (flags & MAP_FIXED) != 0
-      /* Usupported protection combinations */
+      /* Unsupported protection combinations */
       || prot == PROT_EXEC) {
     errno = EINVAL;
     return MAP_FAILED;
   }
 
+  if (off > std::numeric_limits<std::uint64_t>::max() - len) {
+    errno = EINVAL;
+    return MAP_FAILED;
+  }
+
+  const std::uint64_t maxSize = off + static_cast<std::uint64_t>(len);
+
+  const DWORD dwFileOffsetLow = static_cast<DWORD>(off & 0xFFFFFFFFULL);
+  const DWORD dwFileOffsetHigh = static_cast<DWORD>((off >> 32) & 0xFFFFFFFFULL);
+  const DWORD protect = __map_mmap_prot_page(prot);
+  const DWORD desiredAccess = __map_mmap_prot_file(prot);
+
+  const DWORD dwMaxSizeLow = static_cast<DWORD>(maxSize & 0xFFFFFFFFULL);
+  const DWORD dwMaxSizeHigh = static_cast<DWORD>((maxSize >> 32) & 0xFFFFFFFFULL);
+
   h = ((flags & MAP_ANONYMOUS) == 0) ? (HANDLE)_get_osfhandle(fildes)
                                      : INVALID_HANDLE_VALUE;
 

extension/data_loader/mman_windows.h

@@ -31,6 +31,7 @@
 #endif
 
 #include <sys/types.h>
+#include <cstdint>
 
 #ifdef __cplusplus
 extern "C" {
@@ -56,7 +57,13 @@ extern "C" {
 #define MS_SYNC 2
 #define MS_INVALIDATE 4
 
-void* mmap(void* addr, size_t len, int prot, int flags, int fildes, off_t off);
+void* mmap(
+    void* addr,
+    size_t len,
+    int prot,
+    int flags,
+    int fildes,
+    std::uint64_t off);
 int munmap(void* addr, size_t len);
 int mprotect(void* addr, size_t len, int prot);
 int msync(void* addr, size_t len, int flags);

extension/data_loader/mmap_data_loader.cpp

@@ -11,6 +11,7 @@
 #include <cerrno>
 #include <cstring>
 #include <limits>
+#include <cstdint>
 
 #include <fcntl.h>
 #include <sys/stat.h>
@@ -180,12 +181,6 @@ Error MmapDataLoader::validate_input(size_t offset, size_t size) const {
       offset,
       size,
       file_size_);
-  ET_CHECK_OR_RETURN_ERROR(
-      // Recommended by a lint warning.
-      offset <= std::numeric_limits<off_t>::max(),
-      InvalidArgument,
-      "Offset %zu too large for off_t",
-      offset);
   return Error::Ok;
 }
 
@@ -220,13 +215,19 @@ Result<FreeableBuffer> MmapDataLoader::load(
 
   // Map the pages read-only. Use shared mappings so that other processes
   // can also map the same pages and share the same memory.
+#if defined(_WIN32)
+  const std::uint64_t map_offset = static_cast<std::uint64_t>(range.start);
+#else
+  const off_t map_offset = static_cast<off_t>(range.start);
+#endif
+
   void* pages = ::mmap(
       nullptr,
       map_size,
       PROT_READ,
       MAP_SHARED,
       fd_,
-      static_cast<off_t>(range.start));
+      map_offset);
   ET_CHECK_OR_RETURN_ERROR(
       pages != MAP_FAILED,
       AccessFailed,
@@ -328,13 +329,19 @@ Error MmapDataLoader::load_into(
   // Map the pages read-only. MAP_PRIVATE vs. MAP_SHARED doesn't matter since
   // the data is read-only, but use PRIVATE just to further avoid accidentally
   // modifying the file.
+#if defined(_WIN32)
+  const std::uint64_t map_offset = static_cast<std::uint64_t>(range.start);
+#else
+  const off_t map_offset = static_cast<off_t>(range.start);
+#endif
+
   void* pages = ::mmap(
       nullptr,
       map_size,
       PROT_READ,
       MAP_PRIVATE,
       fd_,
-      static_cast<off_t>(range.start));
+      map_offset);
   ET_CHECK_OR_RETURN_ERROR(
       pages != MAP_FAILED,
       AccessFailed,