Large File Support for native Windows platforms.

[gnulib.git] / m4 / largefile.m4

diff --git a/m4/largefile.m4 b/m4/largefile.m4
index 1369bbe..a159f4a 100644 (file)
--- a/m4/largefile.m4
+++ b/m4/largefile.m4
@@ -102,3 +102,48 @@ fi
 ])# AC_SYS_LARGEFILE
 
 ])# m4_version_prereq 2.69
+
+# Enable large files on systems where this is implemented by Gnulib, not by the
+# system headers.
+# Set the variables WINDOWS_64_BIT_OFF_T, WINDOWS_64_BIT_ST_SIZE if Gnulib
+# overrides ensure that off_t or 'struct size.st_size' are 64-bit, respectively.
+AC_DEFUN([gl_LARGEFILE],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  case "$host_os" in
+    mingw*)
+      dnl Native Windows.
+      dnl mingw64 defines off_t to a 64-bit type already, if
+      dnl _FILE_OFFSET_BITS=64, which is ensured by AC_SYS_LARGEFILE.
+      AC_CACHE_CHECK([for 64-bit off_t], [gl_cv_type_off_t_64],
+        [AC_COMPILE_IFELSE(
+           [AC_LANG_PROGRAM(
+              [[#include <sys/types.h>
+                int verify_off_t_size[sizeof (off_t) >= 8 ? 1 : -1];
+              ]],
+              [[]])],
+           [gl_cv_type_off_t_64=yes], [gl_cv_type_off_t_64=no])
+        ])
+      if test $gl_cv_type_off_t_64 = no; then
+        WINDOWS_64_BIT_OFF_T=1
+      else
+        WINDOWS_64_BIT_OFF_T=0
+      fi
+      dnl But all native Windows platforms (including mingw64) have a 32-bit
+      dnl st_size member in 'struct stat'.
+      WINDOWS_64_BIT_ST_SIZE=1
+      ;;
+    *)
+      dnl Nothing to do on gnulib's side.
+      dnl A 64-bit off_t is
+      dnl   - already the default on MacOS X, FreeBSD, NetBSD, OpenBSD, IRIX,
+      dnl     OSF/1, Cygwin,
+      dnl   - enabled by _FILE_OFFSET_BITS=64 (ensured by AC_SYS_LARGEFILE) on
+      dnl     glibc, HP-UX, Solaris,
+      dnl   - enabled by _LARGE_FILES=1 (ensured by AC_SYS_LARGEFILE) on AIX,
+      dnl   - impossible to achieve on Minix 3.1.8.
+      WINDOWS_64_BIT_OFF_T=0
+      WINDOWS_64_BIT_ST_SIZE=0
+      ;;
+  esac
+])