1 files changed, 16 insertions, 0 deletions
diff --git a/sysdeps/generic/mmap_info.h b/sysdeps/generic/mmap_info.h
new file mode 100644
index 0000000..b3087df
--- /dev/null
+++ b/sysdeps/generic/mmap_info.h
@@ -0,0 +1,16 @@
+/* As default architectures with sizeof (off_t) < sizeof (off64_t) the mmap is
+   implemented with __SYS_mmap2 syscall and the offset is represented in
+   multiples of page size.  For offset larger than
+   '1 << (page_shift + 8 * sizeof (off_t))' (that is, 1<<44 on system with
+   page size of 4096 bytes) the system call silently truncates the offset.
+   For this case, glibc mmap implementation returns EINVAL.  */
+
+/* Return the maximum value expected as offset argument in mmap64 call.  */
+static inline uint64_t
+mmap64_maximum_offset (long int page_shift)
+{
+  if (sizeof (off_t) < sizeof (off64_t))
+    return (UINT64_C(1) << (page_shift + (8 * sizeof (off_t)))) - 1;
+  else
+    return UINT64_MAX;
+}