[PATCH 2/2] ntdll: Use the F_PREALLOCATE fcntl(2) on Mac OS when posix_fallocate(2/3) isn't available.

[Chip Davis]

From: Charles Davis

Signed-off-by: Chip Davis 
---
 dlls/ntdll/unix/file.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/dlls/ntdll/unix/file.c b/dlls/ntdll/unix/file.c
index 4286b81aa1f..ea3c947da73 100644
--- a/dlls/ntdll/unix/file.c
+++ b/dlls/ntdll/unix/file.c
@@ -142,6 +142,20 @@ static int posix_fallocate( int fd, off_t offset, off_t len )
     if (fallocate( fd, 0, offset, len ) < 0)
         return errno;
     return 0;
+#elif defined(F_PREALLOCATE)
+    struct fstore fst;
+    struct stat st;
+
+    if (fstat( fd, &st ) < 0)
+        return errno;
+
+    fst.fst_flags = F_ALLOCATECONTIG|F_ALLOCATEALL;
+    fst.fst_posmode = F_PEOFPOSMODE;
+    fst.fst_offset = 0;
+    fst.fst_length = len + offset - st.st_blocks * 512;
+    if (fcntl( fd, F_PREALLOCATE, &fst ) < 0)
+        return errno;
+    return 0;
 #else
     return ENOSYS;
 #endif