bdlma_guardingallocator.h

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/// @file bdlma_guardingallocator.h
///
/// The content of this file has been pre-processed for Doxygen.
///
 
 
// bdlma_guardingallocator.h                                          -*-C++-*-
#ifndef INCLUDED_BDLMA_GUARDINGALLOCATOR
#define INCLUDED_BDLMA_GUARDINGALLOCATOR
 
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
 
/// @defgroup bdlma_guardingallocator bdlma_guardingallocator
/// @brief  Provide a memory allocator that guards against buffer overruns.
/// @addtogroup bdl
/// @{
/// @addtogroup bdlma
/// @{
/// @addtogroup bdlma_guardingallocator
/// @{
///
/// <h1> Outline </h1>
/// * <a href="#bdlma_guardingallocator-purpose"> Purpose</a>
/// * <a href="#bdlma_guardingallocator-classes"> Classes </a>
/// * <a href="#bdlma_guardingallocator-description"> Description </a>
///   * <a href="#bdlma_guardingallocator-guard-pages"> Guard Pages </a>
///   * <a href="#bdlma_guardingallocator-thread-safety"> Thread Safety </a>
///   * <a href="#bdlma_guardingallocator-usage"> Usage </a>
///     * <a href="#bdlma_guardingallocator-example-1-diagnosing-buffer-overflow"> Example 1: Diagnosing Buffer Overflow </a>
///     * <a href="#bdlma_guardingallocator-example-2-allowing-for-maximal-alignment"> Example 2: Allowing for Maximal Alignment </a>
///
/// # Purpose {#bdlma_guardingallocator-purpose}
/// Provide a memory allocator that guards against buffer overruns.
///
/// # Classes {#bdlma_guardingallocator-classes}
///
/// -  bdlma::GuardingAllocator: memory allocator that detects buffer overruns
///
/// @see  bslma_allocator, bslma_testallocator
///
/// # Description {#bdlma_guardingallocator-description}
/// This component provides a concrete allocation mechanism,
/// `bdlma::GuardingAllocator`, that implements the `bslma::Allocator` protocol
/// and adjoins a read/write protected guard page to each block of memory
/// returned by the `allocate` method.  Each returned block is maximally aligned
/// for the platform.  The guard page is located immediately following (subject
/// to alignment requirements) or immediately preceding the block returned from
/// `allocate` according to an optionally-supplied constructor argument:
/// @code
///  ,------------------------.
/// ( bdlma::GuardingAllocator )
///  `------------------------'
///              |         ctor/dtor
///              V
///     ,----------------.
///    ( bslma::Allocator )
///     `----------------'
///                        allocate
///                        deallocate
/// @endcode
/// *WARNING*: Note that this allocator should *not* be used for production use;
/// it is intended for debugging purposes only.  In particular, clients should
/// be aware that a multiple of the page size is allocated for *each* `allocate`
/// invocation (unless the size of the request is 0).
///
/// Also note that, unlike many other BDE allocators, a `bslma::Allocator *`
/// cannot be (optionally) supplied upon construction of a `GuardingAllocator`;
/// instead, a system facility is used that allocates blocks of memory in
/// multiples of the system page size.
///
/// ## Guard Pages {#bdlma_guardingallocator-guard-pages}
///
///
/// A `GuardingAllocator` may be used to debug buffer overflow (or underflow) by
/// protecting a memory page after (or before) each block of memory returned
/// from `allocate`.  Consequently, certain memory access outside the block
/// returned to the client will trigger a memory protection fault.
///
/// A constructor argument of type `GuardingAllocator::GuardPageLocation`, an
/// enumeration, determines whether guard pages are located following
/// (`e_AFTER_USER_BLOCK`) or preceding (`e_BEFORE_USER_BLOCK`) the user block.
/// If no value is supplied at construction, `e_AFTER_USER_BLOCK` is assumed.
///
/// To illustrate, the following diagram shows the memory layout resulting from
/// an `N`-byte allocation request from a guarding allocator, where `N` is
/// assumed to be less than or equal to the size of a memory page.  Note that
/// two pages of memory are consumed for each such allocation request:
/// @code
/// M  - N rounded up to the least multiple of the maximum alignment
/// A  - address of (2-page) block of memory returned by system allocator
/// U  - address returned from 'allocate' to user
/// G  - address of the guard page
/// PS - page size (in bytes)
///
///                         e_AFTER_USER_BLOCK
///                         ------------------
///
///     [ - - - one memory page  - - - | - - - one memory page  - - - ]
///     ---------------------------------------------------------------
///     |                 |  M  bytes  | ******* R/W protected ****** |
///     ---------------------------------------------------------------
///     ^                 ^            ^
///     A                 U == G - M   G == A + PS
///
///
///                         e_BEFORE_USER_BLOCK
///                         -------------------
///
///     ---------------------------------------------------------------
///     | ******* R/W protected ****** |  M  bytes  |                 |
///     ---------------------------------------------------------------
///     ^                              ^
///     A == G                         U == A + PS
/// @endcode
/// Notice that `M`, the distance from the returned address to the start of the
/// guard page, may be larger than the user requested `N` bytes.  See {Example
/// 2: Allowing for Maximal Alignment}.
///
/// ## Thread Safety {#bdlma_guardingallocator-thread-safety}
///
///
/// The `bdlma::GuardingAllocator` class is fully thread-safe (see
/// @ref bsldoc_glossary ).
///
/// ## Usage {#bdlma_guardingallocator-usage}
///
///
/// This section illustrates intended use of this component.
///
/// ### Example 1: Diagnosing Buffer Overflow {#bdlma_guardingallocator-example-1-diagnosing-buffer-overflow}
///
///
/// Use of a `bdlma::GuardingAllocator` is indicated, for example, if some code
/// under development is suspected of having a buffer overrun (or underrun) bug,
/// and more sophisticated tools that detect such conditions are either not
/// available, or are inconvenient to apply to the situation at hand.
///
/// This usage example illustrates a guarding allocator being brought to bear on
/// a buffer overrun bug.  The bug in question arises in the context of an
/// artificial data handling class, `my_DataHandler`.  This class makes use of a
/// (similarly artificial) data translation utility that translates chunks of
/// data among various data styles.  In our idealized example, we assume that
/// the length of the output resulting from some data translation is precisely
/// determinable from the length of the input data and the respective styles of
/// the input and the (desired) output.  For simplicity, we also assume that
/// input data comes from a trusted source.
///
/// First, we define an enumeration of data styles:
/// @code
/// enum my_DataStyle {
///     e_STYLE_NONE = 0
///   , e_STYLE_A    = 1  // default style
///   , e_STYLE_AA   = 2  // style exactly twice as verbose as 'e_STYLE_A'
///   // etc.
/// };
/// @endcode
/// Next, we define the (elided) interface of our data translation utility:
/// @code
/// /// This `struct` provides a namespace for data translation utilities.
/// struct my_DataTranslationUtil {
///
///     // CLASS METHODS
///
///     /// Return the buffer size (in bytes) required to store the result
///     /// of converting input data of the specified `inputLength` (in
///     /// bytes), in the specified `inputStyle`, into the specified
///     /// `outputStyle`.  The behavior is undefined unless
///     /// `0 <= inputLength`.
///     static int outputSize(my_DataStyle outputStyle,
///                           my_DataStyle inputStyle,
///                           int          inputLength);
///
///     /// Load into the specified `output` buffer the result of converting
///     /// the specified `input` data, in the specified `inputStyle`, into
///     /// the specified `outputStyle`.  Return 0 on success, and a
///     /// non-zero value otherwise.  The behavior is undefined unless
///     /// `output` has sufficient capacity to hold the translated result.
///     /// Note that this method assumes that `input` originated from a
///     /// trusted source.
///     static int translate(char         *output,
///                          my_DataStyle  outputStyle,
///                          const char   *input,
///                          my_DataStyle  inputStyle);
/// };
/// @endcode
/// Next, we define `my_DataHandler`, a simple class that makes use of
/// `my_DataTranslationUtil`:
/// @code
/// /// This `class` provides a basic data handler.
/// class my_DataHandler {
///
///     // DATA
///     my_DataStyle      d_inStyle;     // style of `d_inBuffer` contents
///     char             *d_inBuffer;    // input supplied at construction
///     int               d_inCapacity;  // capacity (in bytes) of `d_inBuffer`
///     my_DataStyle      d_altStyle;    // alternative style (if requested)
///     char             *d_altBuffer;   // buffer for alternative style
///     bslma::Allocator *d_allocator_p; // memory allocator (held, not owned)
///
///   private:
///     // NOT IMPLEMENTED
///     my_DataHandler(const my_DataHandler&);
///
///   public:
///     // CREATORS
///
///     /// Create a data handler for the specified `input` data, in the
///     /// specified `inputStyle`, having the specified `inputLength` (in
///     /// bytes).  Optionally specify a `basicAllocator` used to supply
///     /// memory.  If `basicAllocator` is 0, the currently installed
///     /// default allocator is used.  The behavior is undefined unless
///     /// `0 <= inputLength`.
///     my_DataHandler(const char       *input,
///                    int               inputLength,
///                    my_DataStyle      inputStyle,
///                    bslma::Allocator *basicAllocator = 0);
///
///     ~my_DataHandler();
///         // Destroy this data handler.
///
///     // ...
///
///     // MANIPULATORS
///
///     /// Generate data for this data handler in the specified
///     /// `alternateStyle`.  Return 0 on success, and a non-zero value
///     /// otherwise.  If `alternateStyle` is the same as the style of data
///     /// supplied at construction, this method returns 0 with no effect.
///     int generateAlternate(my_DataStyle alternateStyle);
///
///     // ...
/// };
/// @endcode
/// Next, we show the definition of the `my_DataHandler` constructor:
/// @code
/// my_DataHandler::my_DataHandler(const char       *input,
///                                int               inputLength,
///                                my_DataStyle      inputStyle,
///                                bslma::Allocator *basicAllocator)
/// : d_inStyle(inputStyle)
/// , d_inBuffer(0)
/// , d_inCapacity(inputLength)
/// , d_altStyle(e_STYLE_NONE)
/// , d_altBuffer(0)
/// , d_allocator_p(bslma::Default::allocator(basicAllocator))
/// {
///     BSLS_ASSERT(0 <= inputLength);
///
///     void *tmp = d_allocator_p->allocate(inputLength);
///     bsl::memcpy(tmp, input, inputLength);
///     d_inBuffer = static_cast<char *>(tmp);
/// }
/// @endcode
/// Next, we show the definition of the `generateAlternate` manipulator.  Note
/// that we have deliberately introduced a bug in `generateAlternate` to cause
/// buffer overrun:
/// @code
/// int my_DataHandler::generateAlternate(my_DataStyle alternateStyle)
/// {
///     if (alternateStyle == d_inStyle) {
///         return 0;                                                 // RETURN
///     }
///
///     int altLength = my_DataTranslationUtil::outputSize(alternateStyle,
///                                                        d_inStyle,
///                                                        d_inCapacity);
///     (void)altLength;
///
///     // Oops!  Should have used 'altLength'.
///     char *tmpAltBuffer = (char *)d_allocator_p->allocate(d_inCapacity);
///     int rc = my_DataTranslationUtil::translate(tmpAltBuffer,
///                                                alternateStyle,
///                                                d_inBuffer,
///                                                d_inStyle);
///
///     if (rc) {
///         d_allocator_p->deallocate(tmpAltBuffer);
///         return rc;                                                // RETURN
///     }
///
///     d_altStyle  = alternateStyle;
///     d_altBuffer = tmpAltBuffer;
///
///     return 0;
/// }
/// @endcode
/// Next, we define some data (in `e_STYLE_A`):
/// @code
/// const char *input = "AAAAAAAAAAAAAAA@";  // data always terminated with '@'
/// @endcode
/// Then, we define a `my_DataHandler` object, `handler`, to process that data:
/// @code
/// my_DataHandler handler(input, 16, e_STYLE_A);
/// @endcode
/// Note that our `handler` object uses the default allocator.
///
/// Next, we request that an alternate data style, `e_STYLE_AA`, be generated by
/// `handler`.  Unfortunately, data in style `e_STYLE_AA` is twice as large as
/// that in style `e_STYLE_A` making it a virtual certainty that the program
/// will crash due to the insufficiently sized buffer that is allocated in the
/// `generateAlternate` method to accommodate the `e_STYLE_AA` data:
/// @code
/// int rc = handler.generateAlternate(e_STYLE_AA);
/// if (!rc) {
///     // use data in alternate style
/// }
/// @endcode
/// Suppose that after performing a brief post-mortem on the resulting core
/// file, we strongly suspect that a buffer overrun is the root cause, but the
/// program crashed in a context far removed from that of the source of the
/// problem (which is often the case with buffer overrun issues).
///
/// Consequently, we modify the code to supply a guarding allocator to the
/// `handler` object, then rebuild and rerun the program.  We have configured
/// the guarding allocator (below) to place guard pages *after* user blocks.
/// Note that `e_AFTER_USER_BLOCK` is the default, so it need not be specified
/// at construction as we have (pedantically) done here:
/// @code
/// typedef bdlma::GuardingAllocator GA;
/// GA guard(GA::e_AFTER_USER_BLOCK);
///
/// my_DataHandler handler(input, 16, e_STYLE_A, &guard);
/// @endcode
/// With a guarding allocator now in place, a memory fault is triggered when a
/// guard page is overwritten as a result of the buffer overrun bug.  Hence, the
/// program will dump core in a context that is more proximate to the buggy
/// code, resulting in a core file that will be more amenable to revealing the
/// issue when analyzed in a debugger.
///
/// ### Example 2: Allowing for Maximal Alignment {#bdlma_guardingallocator-example-2-allowing-for-maximal-alignment}
///
///
/// The requirement that this allocator always return maximally aligned memory
/// can lead to situations when using `e_AFTER_USER_BLOCK` where there is unused
/// memory between the end of allocated memory and the first address of the
/// guard page.  If so, small memory overruns (e.g., a single byte) will not
/// land on the guard page and go undetected.  Fortunately, users can often
/// compensate for this behavior and position their data adjacent to the guard
/// page.
///
/// Suppose one must test a function, `myIntSort`, having the signature and
/// contract:
/// @code
/// /// Efficiently sort in place the values in the specified range
/// /// `[start .. end - 1]` into ascending order.
/// void myIntSort(int *begin, int *end);
/// @endcode
/// If the `myIntSort` function uses some manner of partitioning algorithm the
/// implementation will involve considerable pointer arithmetic, recursion,
/// etc., then a reasonable test concern would be:
/// @code
///     // Concerns:
///     // 1. The implementation never modifies or even reads data outside of
///     //    the given input range.
///     //
///     // 2. Some other concern.
///     //
///     // 3. Yet another concern.
///     //
///     // 4. ...
/// @endcode
/// Addressing that test concern is ordinarily challenging.  One approach is to
/// bracket the data for each test with data having a distinctive value (e.g.,
/// `0x0BADCAFE`) and then check that the test does not corrupt that pattern
/// (any overwrite being *very* unlikely to preserve the special value).  Tests
/// of reads past the given range are harder to prove.  One could argue that
/// incorporating that data into the sort would corrupt the result but one
/// cannot prove that it was never accessed.  Alternatively, using
/// `bdlma::GuardingAllocator` provides a stronger proof from a simpler test
/// case.  Thus, our test plan would include:
/// @code
///     // Plan:
///     // 1. Test for range overflow and underflow by positioning test data in
///     //    memory obtained from 'bdlma::GuardingAllocator' objects.  Each
///     //    test is run twice, once with the guard page below the test data,
///     //    and again with the guard page above the test data.
/// @endcode
/// First, create a set of test data for thoroughly testing all concerns of
/// `myIntSort`, and a framework for running through those tests:
/// @code
/// /// Thoroughly test the `myIntSort` function using a table-driven
/// /// framework.  Note that the testing concerns were listed above.
/// void testMyIntSort()
/// {
///     const bsl::size_t MAX_NUM_INPUTS = 5;
///     struct {
///         int         d_line;
///         bsl::size_t d_numInputs;
///         int         d_input[MAX_NUM_INPUTS];
///     } DATA [] = {
///         { __LINE__, 1, { 0       } }
///       , { __LINE__, 2, { 2, 1    } }
///
///       // ...
///
///       , { __LINE__, 3, { 2, 1, 3 } }
///
///       // ...
///
///     };
///     const bsl::size_t NUM_DATA = sizeof DATA / sizeof *DATA;
///
///     const int pageSize = myGetPageSize();
///     assert(myIsPowerOfTwo(pageSize));
///
///     for (bsl::size_t ti = 0; ti < NUM_DATA; ++ti) {
///         const int         LINE       = DATA[ti].d_line;  (void) LINE;
///         const bsl::size_t NUM_INPUTS = DATA[ti].d_numInputs;
///         const int *const  INPUT      = DATA[ti].d_input;
/// @endcode
/// Then, create a 'bdlma::GuardingAllocator to that will be used to test for
/// under-runs of the given range and, for each data point, run the test on data
/// that will segfault if there is any reference to an address in the page below
/// `begin`, even by a single byte:
/// @code
///         bdlma::GuardingAllocator underRun(
///                             bdlma::GuardingAllocator::e_BEFORE_USER_BLOCK);
///
///         const bsl::size_t  numBytes = NUM_INPUTS * sizeof(int);
///         void              *block    = underRun.allocate(numBytes);
///
///         assert(0 == bsls::AlignmentUtil::calculateAlignmentOffset(
///                                                                 block,
///                                                                 pageSize));
///
///         bsl::memcpy(block, INPUT, numBytes);
///
///         int *begin = static_cast<int *>(block);
///         int *end   = begin + NUM_INPUTS;
///
///         myIntSort(begin, end);                                      // TEST
///
///         assert(myIsIntSorted(begin, end));  // oracle
///
///         underRun.deallocate(block);
/// @endcode
/// Notice that, for expository purposes, we confirmed that the `block` is page
/// aligned.
///
/// Next, we will *rerun* the test using data positioned in memory to catch
/// over-runs of the input range.
/// @code
///         bdlma::GuardingAllocator overRun(
///                              bdlma::GuardingAllocator::e_AFTER_USER_BLOCK);
/// @endcode
/// The step would be to allocate memory and initialize memory as we did
/// before.  The problem is that memory returned from the
/// `bdlma::GuardingAllocator` may not abut the following guard page.
///
/// Consider a platform where:
/// * Maximal alignment is 8 bytes.
/// * `sizeof(int)` is 4 bytes.
///
/// For the data point above consisting of 3 values, the required space is 12
/// bytes (3 * 4) but the maximally aligned address closest to the top of the
/// returned page is 16 bytes (2 * 8) below the page boundary -- a gap of 4
/// bytes.
///
/// We handle this situation by padding our allocation size to the nearest
/// multiple of maximal alignment -- 16 bytes in this case.  That gives us
/// allocated memory that abuts the page boundary.  This allows us to position
/// our test data into the allocated memory so that last element fits in the
/// upper bytes of the returned bytes (i.e., the first 4 bytes of the returned
/// block are not used by this test).
///
/// Now, we calculate the padded allocation size and allocate a block that abuts
/// the page boundary:
/// @code
///         const bsl::size_t paddedSize =
///                   bsls::AlignmentUtil::roundUpToMaximalAlignment(numBytes);
///
///         block = overRun.allocate(paddedSize);
///
///         int *firstProtectedAddress = static_cast<int *>(
///              static_cast<void *>(static_cast<char *>(block) + paddedSize));
///
///         begin = firstProtectedAddress - NUM_INPUTS;
///         end   = firstProtectedAddress;
///
///         assert(0 == bsls::AlignmentUtil::calculateAlignmentOffset(
///                                  block,
///                                  bsls::AlignmentUtil::BSLS_MAX_ALIGNMENT));
///
///         assert(0 == bsls::AlignmentUtil::calculateAlignmentOffset(
///                                                              begin,
///                                                              sizeof(int)));
///
///         assert(0 == bsls::AlignmentUtil::calculateAlignmentOffset(
///                                                                 end,
///                                                                 pageSize));
/// @endcode
/// Notice that again, for purposes of exposition, we have checked the returned
/// addresses and confirmed:
/// * The returned address, `block`, is maximally aligned.
/// * The calculated `begin` is correctly aligned to hold the data value.
/// * The upper end of the returned block, `end`, is page aligned.
///
/// Finally, we load the test data into the carefully positioned memory and
/// rerun the test:
/// @code
///         bsl::memcpy(begin, INPUT, numBytes);
///
///         myIntSort(begin, end);                                      // TEST
///         assert(myIsIntSorted(begin, end));  // oracle
///
///         overRun.deallocate(block);
///     }
/// }
/// @endcode
/// @}
/** @} */
/** @} */
 
/** @addtogroup bdl
 * @{
 */
/** @addtogroup bdlma
 * @{
 */
/** @addtogroup bdlma_guardingallocator
 * @{
 */
 
#include <bdlscm_version.h>
 
#include <bslma_allocator.h>
 
#include <bsls_keyword.h>
#include <bsls_types.h>
 
 
namespace bdlma {
 
                         // -----------------------
                         // class GuardingAllocator
                         // -----------------------
 
/// This class defines a concrete thread-safe "guarding" allocator mechanism
/// that implements the `bslma::Allocator` protocol, and adjoins a
/// read/write protected guard page to each block of memory returned by the
/// `allocate` method.  The guard page is placed immediately before or
/// immediately following the block returned from `allocate` according to
/// the `GuardPageLocation` enumerator value (optionally) supplied at construction.  
/// 
/// \note Note that,   unlike many other allocators, an allocator
/// cannot be (optionally) supplied at construction; instead, a system
/// facility is used that allocates blocks of memory in multiples of the
/// system page size.  Also note that this allocator is intended for
/// debugging purposes *only*.
///
/// See @ref bdlma_guardingallocator 
class GuardingAllocator : public bslma::Allocator {
 
  public:
    // TYPES
 
    /// Enumerate the configuration options for `GuardingAllocator` that may
    /// be (optionally) supplied at construction.
    enum GuardPageLocation {
        e_AFTER_USER_BLOCK,  // locate the guard page after the user block
        e_BEFORE_USER_BLOCK  // locate the guard page before the user block
    };
 
  private:
    // DATA
    GuardPageLocation d_guardPageLocation;  // if `e_AFTER_USER_BLOCK`, place
                                            // the read/write protected guard
                                            // page after the user block;
                                            // otherwise, place it before the
                                            // block (`e_BEFORE_USER_BLOCK`)
 
  private:
    // NOT IMPLEMENTED
    GuardingAllocator(const GuardingAllocator&);
    GuardingAllocator& operator=(const GuardingAllocator&);
 
  public:
    // CREATORS
 
    /// Create a guarding allocator.  Optionally specify a `guardLocation`
    /// indicating where read/write protected guard pages should be placed
    /// with respect to the memory blocks returned by the `allocate` method.
    /// If `guardLocation` is not specified, guard pages are placed
    /// immediately following the memory blocks returned by `allocate`.
    explicit
    GuardingAllocator(GuardPageLocation guardLocation = e_AFTER_USER_BLOCK);
 
    /// Destroy this allocator object.  
    /// \note Note that  destroying this allocator
    /// has no effect on any outstanding allocated memory.
    ~GuardingAllocator() BSLS_KEYWORD_OVERRIDE;
 
    // MANIPULATORS
 
    /// Return a newly-allocated maximally-aligned block of memory of the
    /// specified `size` (in bytes) that has a read/write protected guard
    /// page located immediately before or after it according to the
    /// `GuardPageLocation` indicated at construction.  If `size` is 0, no memory is allocated and 0 is returned.  
    /// 
    /// \note Note that   a multiple of the
    /// platform's memory page size is allocated for *every* call to this
    /// method.
    void *allocate(bsls::Types::size_type size) BSLS_KEYWORD_OVERRIDE;
 
    /// Return the memory block at the specified `address` back to this
    /// allocator.  If `address` is 0, this method has no effect.
    /// Otherwise, the guard page associated with `address` is unprotected and also deallocated.  
    /// 
    /// \pre The behavior is undefined   unless `address`
    /// was returned by `allocate` and has not already been deallocated.
    void deallocate(void *address) BSLS_KEYWORD_OVERRIDE;
};
 
// ============================================================================
//                             INLINE DEFINITIONS
// ============================================================================
 
                         // -----------------------
                         // class GuardingAllocator
                         // -----------------------
 
// CREATORS
inline
GuardingAllocator::GuardingAllocator(GuardPageLocation guardLocation)
: d_guardPageLocation(guardLocation)
{
}
 
}  // close package namespace
 
 
#endif
 
// ----------------------------------------------------------------------------
// Copyright 2016 Bloomberg Finance L.P.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ----------------------------- END-OF-FILE ----------------------------------
 
/** @} */
/** @} */
/** @} */