Author Archives: dmitriano

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22
07
19
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Compiling OpenSSL 1.1 with MSVC2017 for using with QT 5.13

Posted by | QT, Win32 | Tagged |

QT does not work with OpenSSL 1.0 anymore. Versions QT 5.12.4 and above require OpenSSL 1.1, but fortunately OpenSSL 1.1 can be easily compiled with MS2017 as follows:

set PATH=%PATH%;C:\Perl64\bin
set PATH=%PATH%;C:\PFiles\nasm-2.14.02-win64
perl Configure VC-WIN64A
nmake

The key to the success is using ‘VS2017 x64 Native Tools Command Prompt‘, but not ‘VS2017 Developer Command Prompt’.

To make QT use OpenSSL, two dlls

libcrypto-1_1-x64.dll
libssl-1_1-x64.dll

should be copied to QT binary directory, for example, C:\Qt\Qt5.13.0\5.13.0\msvc2017_64\bin

05
07
19
 1 Comment

Oracle Database user and role IDs

Posted by | Oracle |

Below I provided the results of two following queries:

SELECT USERNAME, USER_ID FROM DBA_USERS ORDER BY USER_ID DESC;
SELECT ROLE, ROLE_ID FROM DBA_ROLES ORDER BY ROLE_ID DESC;

that display Oracle Database 18 users, roles and their IDs:

(more…)
21
06
19
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How to change MySQL 5.7 root password

Posted by | MySQL |

First, check MySQL version:

SHOW VARIABLES LIKE "%version%";

+-------------------------+-------------------------+
| Variable_name           | Value                   |
+-------------------------+-------------------------+
| innodb_version          | 5.7.25                  |
| protocol_version        | 10                      |
| slave_type_conversions  |                         |
| tls_version             | TLSv1,TLSv1.1           |
| version                 | 5.7.25-0ubuntu0.16.04.2 |
| version_comment         | (Ubuntu)                |
| version_compile_machine | x86_64                  |
| version_compile_os      | Linux                   |
+-------------------------+-------------------------+
(more…)
18
06
19
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Different type names in different C++ compilers.

Posted by | C++ |

The string representation of a type is implementation defined in C++, for example the following code produce the different output with MSVC, GCC and CLang:

#include <string>
#include <iostream>

struct A {};
class B {};

namespace ns
{
    struct X {};
}

int main()
{
    std::cout << typeid(A).name() << ", " << typeid(B).name() << ", " << typeid(ns::X).name() << ", " << typeid(std::string).name() << std::endl;
    return 0;
}
(more…)
29
05
19
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Determining .NET Framework version from the native C++ code.

Posted by | .NET |

.NET Framework version 4.5 and higher can be determined with the following C++ code:

#include <windows.h>

bool IsDotNet45Installed()
{
    DWORD value{};
    DWORD dataSize = sizeof(value);
        
    const LONG retCode = ::RegGetValue(
        HKEY_LOCAL_MACHINE,
        L"SOFTWARE\\Microsoft\\NET Framework Setup\\NDP\\v4\\Full\\",
        L"Release",
        RRF_RT_REG_DWORD,
        nullptr,
        &value,
        &dataSize
    );

    if (retCode != ERROR_SUCCESS)
    {
        return false;
    }

    return value >= 378389;
}
(more…)
28
05
19
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Handling errors at compile time in C++

Posted by | C++ |

We had a discussion with colleagues on why in the following code we cannot simply use

static_assert(false)

but need to do a trick with ‘always_false’: 

#include <type_traits>

template<typename>
struct always_false : std::false_type {};

template<typename Type>
constexpr int Get()
{
    if constexpr (std::is_same_v<Type, int>)
    {
        return 1;
    }
    else if constexpr (std::is_same_v<Type, bool>)
    {
        return 2;
    }
    else {
        static_assert(always_false<Type>::value);
    }
}
(more…)
27
05
19
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Accessing Oracle Database in C++ with MS VS2017.

Posted by | Oracle |

Download binaries (redistributables) and C++ SDK from Oracle website. For 64bit platform they are respectively:

instantclient-basic-windows.x64-18.5.0.0.0dbru.zip
instantclient-sdk-windows.x64-18.5.0.0.0dbru.zip

Extract them, create a C++ project in VS2017 and link oraocci18.lib in Release configuration and oraocci18d.lib in Debug configuration.

(more…)
22
05
19
 2 Comments

Making SyntaxHighlighter plugin display “>” symbol correctly.

Posted by | WordPress |

My SyntaxHighlighter plugin started to display “>” as “ = & g t ;” after I updated my WordPress to a version where blocks were added. To fix the plugin I added the following line to wp-content/plugins/syntaxhighlighter/syntaxhighlighter.php:

$code = preg_replace( '#<pre [^>]+>([^<]+)?</pre>#', '$1', $content );

// Undo escaping done by WordPress
$code = htmlspecialchars_decode( $code );

return $this->shortcode_callback( $attributes, $code, 'code' );
(more…)
14
05
19
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How to get all the privileges of an Oracle database user.

Posted by | Oracle |

While investigating of how to get all the privileges of an Oracle database user I played with the following queries:

select COUNT(*) from DICTIONARY;
select USERNAME from SYS.ALL_USERS;

select * from DBA_USERS;
select * from DBA_ROLES;
select * from DBA_SYS_PRIVS where grantee = 'CONNECT';
select * from DBA_SYS_PRIVS where grantee = 'RESOURCE';
select * from DBA_SYS_PRIVS;
select * from SESSION_PRIVS;
select * from DBA_TAB_PRIVS where GRANTEE <> 'PUBLIC';
select count(*) from DBA_TAB_PRIVS;
select * from DBA_COL_PRIVS;
select * from ROLE_TAB_PRIVS;
(more…)
08
05
19
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Timed out waiting for device dev-disk-by/… while booting Ubuntu 18.04 up.

Posted by | Ubuntu |

My Ubuntu 18.04 installed in Windows 10 HyperV virtual machine stopped booting up with the following errors:

(more…)
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