libwine: Add support for mmap at fixed start addresses on FreeBSD.

The way to implement MAP_TRYFIXED on FreeBSD is call mmap() with MAP_FIXED | MAP_EXCL, which will allocate the mapping from the exact starting address if possible, and if that fails, call mmap() again without them. This gets PE DLLs loading at their correct base addresses, and fixes a FreeBSD-specific problem with Cygwin's fork() caused by cygwin1.dll loading at different base addresses in the parent and child. Signed-off-by: Damjan Jovanovic <damjan.jov@gmail.com> Signed-off-by: Alexandre Julliard <julliard@winehq.org>

libwine: Add support for mmap at fixed start addresses on FreeBSD.
55ba3648 · Damjan Jovanovic · Alexandre Julliard · b9dc3324 · 55ba3648
Commit 55ba3648 authored May 18, 2020 by Damjan Jovanovic Committed by Alexandre Julliard May 20, 2020
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mmap.c libs/wine/mmap.c +8 -5

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--- a/libs/wine/mmap.c
+++ b/libs/wine/mmap.c
@@ -211,18 +211,21 @@ void *wine_anon_mmap( void *start, size_t size, int prot, int flags )

    if (!(flags & MAP_FIXED))
    {
-#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__DragonFly__)
-        /* Even FreeBSD 5.3 does not properly support NULL here. */
-        if( start == NULL ) start = (void *)0x110000;
-#endif
-
 #ifdef MAP_TRYFIXED
        /* If available, this will attempt a fixed mapping in-kernel */
        flags |= MAP_TRYFIXED;
+#elif defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
+        if ( start && mmap( start, size, prot, flags | MAP_FIXED | MAP_EXCL, get_fdzero(), 0 ) )
+            return start;
 #elif defined(__svr4__) || defined(__NetBSD__) || defined(__APPLE__)
        if ( try_mmap_fixed( start, size, prot, flags, get_fdzero(), 0 ) )
            return start;
 #endif
+
+#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__DragonFly__)
+        /* Even FreeBSD 5.3 does not properly support NULL here. */
+        if( start == NULL ) start = (void *)0x110000;
+#endif
    }
    return mmap( start, size, prot, flags, get_fdzero(), 0 );
 }