Merge 56938 - Sbox IPC fix...

sandbox/src/crosscall_params.h

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SANDBOX_SRC_CROSSCALL_PARAMS_H__
 #define SANDBOX_SRC_CROSSCALL_PARAMS_H__
 
 #include <windows.h>
 #include <lmaccess.h>
 
@@ skipping 151 matching lines @@
 // storage allocation that the packed parameters should need.
 // NUMBER_PARAMS: the number of parameters, valid from 1 to N
 // BLOCK_SIZE: the total storage that the NUMBER_PARAMS parameters can take,
 // typically the block size is defined by the channel size of the underlying
 // ipc mechanism.
 // In practice this class is used to levergage C++ capacity to properly
 // calculate sizes and displacements given the possibility of the packed params
 // blob to be complex.
 //
 // As is, this class assumes that the layout of the blob is as follows. Assume
-// that NUMBER_PARAMS = 2:
+// that NUMBER_PARAMS = 2 and a 32-bit build:
 //
-// [ tag              4 bytes]
-// [ IsOnOut          4 bytes]
-// [ call return     52 bytes]
-// [ params count     4 bytes]
-// [ parameter 0 type 4 bytes]
-// [ parameter 0 /\   4 bytes] ---delta to ---\
-// [ parameter 0 size 4 bytes]                |
-// [ parameter 1 type 4 bytes]                |
-// [ parameter 1 /\   4 bytes]                |
-// [ parameter 1 size 4 bytes]                |
-// [ parameter 2 type 4 bytes]                |
-// [ parameter 2 /\   4 bytes] ----------------------\
-// [ parameter 2 size 4 bytes]                |      |
-// |-------------------------|                |      |
-// |                         | <--------------/      |
-// |                         |                       |
-// |                         | <---------------------/
-// |-------------------------|
+// [ tag                4 bytes]
+// [ IsOnOut            4 bytes]
+// [ call return       52 bytes]
+// [ params count       4 bytes]
+// [ parameter 0 type   4 bytes]
+// [ parameter 0 offset 4 bytes] ---delta to ---\
+// [ parameter 0 size   4 bytes]                |
+// [ parameter 1 type   4 bytes]                |
+// [ parameter 1 offset 4 bytes] ---------------|--\
+// [ parameter 1 size   4 bytes]                |  |
+// [ parameter 2 type   4 bytes]                |  |
+// [ parameter 2 offset 4 bytes] ----------------------\
+// [ parameter 2 size   4 bytes]                |  |   |
+// |---------------------------|                |  |   |
+// | value 0     (x bytes)     | <--------------/  |   |
+// | value 1     (y bytes)     | <-----------------/   |
+// |                           |                       |
+// | end of buffer             | <---------------------/
+// |---------------------------|
 //
 // Note that the actual number of params is NUMBER_PARAMS + 1
 // so that the size of each actual param can be computed from the difference
-// between one parameter and the next down
+// between one parameter and the next down. The offset of the last param
+// points to the end of the buffer and the type and size are undefined.
+//
 template <size_t NUMBER_PARAMS, size_t BLOCK_SIZE>
 class ActualCallParams : public CrossCallParams {
  public:
   // constructor. Pass the ipc unique tag as input
   explicit ActualCallParams(uint32 tag)
       : CrossCallParams(tag, NUMBER_PARAMS) {
     param_info_[0].offset_ = parameters_ - reinterpret_cast<char*>(this);
   }
 
   // Testing-only constructor. Allows setting the |number_params| to a
   // wrong value.
   ActualCallParams(uint32 tag, uint32 number_params)
       : CrossCallParams(tag, number_params) {
     param_info_[0].offset_ = parameters_ - reinterpret_cast<char*>(this);
   }
 
+  // Testing-only method. Allows setting the apparent size to a wrong value.
+  // returns the previous size.
+  size_t OverrideSize(size_t new_size) {
+    size_t previous_size = param_info_[NUMBER_PARAMS].offset_;
+    param_info_[NUMBER_PARAMS].offset_ = new_size;
+    return previous_size;
+  }
+
   // Copies each paramter into the internal buffer. For each you must supply:
   // index: 0 for the first param, 1 for the next an so on
   bool CopyParamIn(size_t index, const void* parameter_address, size_t size,
                    bool is_in_out, ArgType type) {
     if (index >= NUMBER_PARAMS) {
       return false;
     }
 
     if (kuint32max == size) {
       // Memory error while getting the size.
@@ skipping 53 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(ActualCallParams);
 };
 
 COMPILE_ASSERT(sizeof(ActualCallParams<1, 1024>) == 1024, bad_size_buffer);
 COMPILE_ASSERT(sizeof(ActualCallParams<2, 1024>) == 1024, bad_size_buffer);
 COMPILE_ASSERT(sizeof(ActualCallParams<3, 1024>) == 1024, bad_size_buffer);
 
 }  // namespace sandbox
 
 #endif  // SANDBOX_SRC_CROSSCALL_PARAMS_H__