From d38c8fb27f7f94d81ec546bff6c306e21f949d0e Mon Sep 17 00:00:00 2001
From: Aldo Mazzeo <gbmaster@users.noreply.github.com>
Date: Thu, 7 Mar 2019 02:05:26 +0100
Subject: [PATCH] Don't duplicate a uc_mem_map_ptr'd memory region when
 splitting it (#1028) (#1030)

---
 uc.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 52 insertions(+), 16 deletions(-)

diff --git a/uc.c b/uc.c
index 56166cce..11399017 100644
--- a/uc.c
+++ b/uc.c
@@ -801,6 +801,8 @@ static bool split_region(struct uc_struct *uc, MemoryRegion *mr, uint64_t addres
     uint32_t perms;
     uint64_t begin, end, chunk_end;
     size_t l_size, m_size, r_size;
+    RAMBlock *block = NULL;
+    bool prealloc = false;
 
     chunk_end = address + size;
 
@@ -817,10 +819,27 @@ static bool split_region(struct uc_struct *uc, MemoryRegion *mr, uint64_t addres
         // impossible case
         return false;
 
-    backup = copy_region(uc, mr);
-    if (backup == NULL)
+    QTAILQ_FOREACH(block, &uc->ram_list.blocks, next) {
+        if (block->offset <= mr->addr && block->length >= (mr->end - mr->addr)) {
+            break;
+        }
+    }
+
+    if (block == NULL)
         return false;
 
+    // RAM_PREALLOC is not defined outside exec.c and I didn't feel like
+    // moving it
+	prealloc = !!(block->flags & 1);
+
+    if (block->flags & 1) {
+        backup = block->host;
+    } else {
+        backup = copy_region(uc, mr);
+        if (backup == NULL)
+            return false;
+    }
+
     // save the essential information required for the split before mr gets deleted
     perms = mr->perms;
     begin = mr->addr;
@@ -853,31 +872,48 @@ static bool split_region(struct uc_struct *uc, MemoryRegion *mr, uint64_t addres
     // allocation just failed so no guarantee that we can recover the original
     // allocation at this point
     if (l_size > 0) {
-        if (uc_mem_map(uc, begin, l_size, perms) != UC_ERR_OK)
-            goto error;
-        if (uc_mem_write(uc, begin, backup, l_size) != UC_ERR_OK)
-            goto error;
+        if (!prealloc) {
+            if (uc_mem_map(uc, begin, l_size, perms) != UC_ERR_OK)
+                goto error;
+            if (uc_mem_write(uc, begin, backup, l_size) != UC_ERR_OK)
+                goto error;
+        } else {
+            if (uc_mem_map_ptr(uc, begin, l_size, perms, backup) != UC_ERR_OK)
+                goto error;
+        }
     }
 
     if (m_size > 0 && !do_delete) {
-        if (uc_mem_map(uc, address, m_size, perms) != UC_ERR_OK)
-            goto error;
-        if (uc_mem_write(uc, address, backup + l_size, m_size) != UC_ERR_OK)
-            goto error;
+        if (!prealloc) {
+            if (uc_mem_map(uc, address, m_size, perms) != UC_ERR_OK)
+                goto error;
+            if (uc_mem_write(uc, address, backup + l_size, m_size) != UC_ERR_OK)
+                goto error;
+        } else {
+            if (uc_mem_map_ptr(uc, address, m_size, perms, backup + l_size) != UC_ERR_OK)
+                goto error;
+        }
     }
 
     if (r_size > 0) {
-        if (uc_mem_map(uc, chunk_end, r_size, perms) != UC_ERR_OK)
-            goto error;
-        if (uc_mem_write(uc, chunk_end, backup + l_size + m_size, r_size) != UC_ERR_OK)
-            goto error;
+        if (!prealloc) {
+            if (uc_mem_map(uc, chunk_end, r_size, perms) != UC_ERR_OK)
+                goto error;
+            if (uc_mem_write(uc, chunk_end, backup + l_size + m_size, r_size) != UC_ERR_OK)
+                goto error;
+        } else {
+            if (uc_mem_map_ptr(uc, chunk_end, r_size, perms, backup + l_size + m_size) != UC_ERR_OK)
+                goto error;
+        }
     }
 
-    free(backup);
+    if (!prealloc)
+        free(backup);
     return true;
 
 error:
-    free(backup);
+    if (!prealloc)
+        free(backup);
     return false;
 }