From 1a44ef32379039f7d0d828d9d190aa94da02b1ee Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?R=C3=A9mi=20Bernon?= <rbernon@codeweavers.com>
Date: Thu, 26 Dec 2019 22:27:27 +0100
Subject: [PATCH] ntdll: Replace incorrect find_free_reserved_area function
 call.
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This introduces map_free_area function which tries mapping the expected
free areas until it finds one that succeeds. It now also works for
memory regions outside of the reserved region, but could probably be
improved.

Signed-off-by: Rémi Bernon <rbernon@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>
---
 dlls/ntdll/virtual.c | 99 +++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 93 insertions(+), 6 deletions(-)

diff --git a/dlls/ntdll/virtual.c b/dlls/ntdll/virtual.c
index 1fe173825da..953cf589017 100644
--- a/dlls/ntdll/virtual.c
+++ b/dlls/ntdll/virtual.c
@@ -535,6 +535,90 @@ static struct wine_rb_entry *find_view_inside_range( void **base_ptr, void **end
 }
 
 
+/***********************************************************************
+ *           try_map_free_area
+ *
+ * Try mmaping some expected free memory region, eventually stepping and
+ * retrying inside it, and return where it actually succeeded, or NULL.
+ */
+static void* try_map_free_area( void *base, void *end, ptrdiff_t step,
+                                void *start, size_t size, int unix_prot )
+{
+    void *ptr;
+
+    while (start && base <= start && (char*)start + size <= (char*)end)
+    {
+        if ((ptr = wine_anon_mmap( start, size, unix_prot, 0 )) == start)
+            return start;
+        TRACE( "Found free area is already mapped, start %p.\n", start );
+
+        if (ptr != (void *)-1)
+            munmap( ptr, size );
+
+        if ((step > 0 && (char *)end - (char *)start < step) ||
+            (step < 0 && (char *)start - (char *)base < -step) ||
+            step == 0)
+            break;
+        start = (char *)start + step;
+    }
+
+    return NULL;
+}
+
+
+/***********************************************************************
+ *           map_free_area
+ *
+ * Find a free area between views inside the specified range and map it.
+ * The csVirtual section must be held by caller.
+ */
+static void *map_free_area( void *base, void *end, size_t size, size_t mask, int top_down,
+                             int unix_prot )
+{
+    struct wine_rb_entry *first = find_view_inside_range( &base, &end, top_down );
+    ptrdiff_t step = top_down ? -(mask + 1) : (mask + 1);
+    void *start;
+
+    if (top_down)
+    {
+        start = ROUND_ADDR( (char *)end - size, mask );
+        if (start >= end || start < base) return NULL;
+
+        while (first)
+        {
+            struct file_view *view = WINE_RB_ENTRY_VALUE( first, struct file_view, entry );
+            if ((start = try_map_free_area( (char *)view->base + view->size, (char *)start + size, step,
+                                            start, size, unix_prot ))) break;
+            start = ROUND_ADDR( (char *)view->base - size, mask );
+            /* stop if remaining space is not large enough */
+            if (!start || start >= end || start < base) return NULL;
+            first = wine_rb_prev( first );
+        }
+    }
+    else
+    {
+        start = ROUND_ADDR( (char *)base + mask, mask );
+        if (!start || start >= end || (char *)end - (char *)start < size) return NULL;
+
+        while (first)
+        {
+            struct file_view *view = WINE_RB_ENTRY_VALUE( first, struct file_view, entry );
+            if ((start = try_map_free_area( start, view->base, step,
+                                            start, size, unix_prot ))) break;
+            start = ROUND_ADDR( (char *)view->base + view->size + mask, mask );
+            /* stop if remaining space is not large enough */
+            if (!start || start >= end || (char *)end - (char *)start < size) return NULL;
+            first = wine_rb_next( first );
+        }
+    }
+
+    if (!first)
+        return try_map_free_area( base, end, step, start, size, unix_prot );
+
+    return start;
+}
+
+
 /***********************************************************************
  *           find_reserved_free_area
  *
@@ -1181,14 +1265,17 @@ static NTSTATUS map_view( struct file_view **view_ret, void *base, size_t size,
             goto done;
         }
 
+        if (zero_bits_64)
+        {
+            if (!(ptr = map_free_area( (void*)0, alloc.limit, size, mask, top_down, VIRTUAL_GetUnixProt(vprot) )))
+                return STATUS_NO_MEMORY;
+            TRACE( "got mem with map_free_area %p-%p\n", ptr, (char *)ptr + size );
+            goto done;
+        }
+
         for (;;)
         {
-            if (!zero_bits_64)
-                ptr = NULL;
-            else if (!(ptr = find_reserved_free_area( (void*)0, alloc.limit, view_size, mask, top_down )))
-                return STATUS_NO_MEMORY;
-
-            if ((ptr = wine_anon_mmap( ptr, view_size, VIRTUAL_GetUnixProt(vprot), ptr ? MAP_FIXED : 0 )) == (void *)-1)
+            if ((ptr = wine_anon_mmap( NULL, view_size, VIRTUAL_GetUnixProt(vprot), 0 )) == (void *)-1)
             {
                 if (errno == ENOMEM) return STATUS_NO_MEMORY;
                 return STATUS_INVALID_PARAMETER;