1 files changed, 27 insertions, 0 deletions
diff --git a/src/include/port.h b/src/include/port.h
index da18268d17d..3a2601fdc01 100644
--- a/src/include/port.h
+++ b/src/include/port.h
@@ -294,6 +294,33 @@ extern bool rmtree(const char *path, bool rmtopdir);
 #if defined(WIN32) && !defined(__CYGWIN__)
 
 /*
+ * We want the 64-bit variant of lseek().
+ *
+ * For Visual Studio, this must be after <io.h> to avoid messing up its
+ * lseek() and _lseeki64() function declarations.
+ *
+ * For MinGW there is already a macro, so we have to undefine it (depending on
+ * _FILE_OFFSET_BITS, it may point at its own lseek64, but we don't want to
+ * count on that being set).
+ */
+#undef lseek
+#define lseek(a,b,c) _lseeki64((a),(b),(c))
+
+/*
+ * We want the 64-bit variant of chsize().  It sets errno and also returns it,
+ * so convert non-zero result to -1 to match POSIX.
+ *
+ * Prevent MinGW from declaring functions, and undefine its macro before we
+ * define our own.
+ */
+#ifndef _MSC_VER
+#define FTRUNCATE_DEFINED
+#include <unistd.h>
+#undef ftruncate
+#endif
+#define ftruncate(a,b) (_chsize_s((a),(b)) == 0 ? 0 : -1)
+
+/*
  * open() and fopen() replacements to allow deletion of open files and
  * passing of other special options.
  */