Bug #4707: Library libsaxonhec.dll is not present in the system (Windows) - SaxonC - Saxonica Developer Community

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Bug #4707

closed

Library libsaxonhec.dll is not present in the system (Windows)

Added by O'Neil Delpratt about 4 years ago. Updated almost 2 years ago.

Status:

Closed

Priority:

Normal

Assignee:

O'Neil Delpratt

Category:

Windows

Start date:

2020-09-02

Due date:

% Done:

Estimated time:

Applies to branch:

Fix Committed on Branch:

Fixed in Maintenance Release:

Found in version:

1.2.1

Fixed in version:

11.1

SaxonC Languages:

SaxonC Platforms:

SaxonC Architecture:

Description

Reported by user:

When I create my new project I always got error message that library libsaxonhec.dll is not present in the system despite the path was correct and the library was in the appropriate directory.

Finally I found, that the problem is when compiling and define –DUNICODE is present. In this case this makes type mixture between const char* and const wchar_t* in macro LoadLibrary(…). Please see the file SaxonCGlue.c from line 137:

I have changed the code to (see below) and the problem disappeared (I’m running Win7 64bit and IDE is MS Visual Studio 2017):

#if !(defined (__linux__) || (defined (__APPLE__) && defined(__MACH__)))
#ifdef UNICODE
  wchar_t* wc = malloc(sizeof(wchar_t)*(strlen(name)+1));
  size_t convertedChars = 0;
  mbstowcs_s( &convertedChars, wc, strlen(name)+1, name, _TRUNCATE );
  HANDLE hDll = LoadLibraryW(wc); // Used for windows only
  free(wc);
#else
  HANDLE hDll = LoadLibraryA(name); // Used for windows only
#endif
#else
  HANDLE hDll = LoadLibraryA(name);
#endif

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Updated by O'Neil Delpratt about 4 years ago

Status changed from New to In Progress

I have applied the suggested fix in the function loadDll of the SaxonGlue.h file. Change made in Saxon/C 1.2 and on the trunk.

Although it is not clear to me that the following part is in the second preprocessor else branch required changing from LoadLibrary(name) to LoadLibraryA(name) therefore I have only made the following change:

#if !(defined (__linux__) || (defined (__APPLE__) && defined(__MACH__)))
#ifdef UNICODE
  wchar_t* wc = malloc(sizeof(wchar_t)*(strlen(name)+1));
  size_t convertedChars = 0;
  mbstowcs_s( &convertedChars, wc, strlen(name)+1, name, _TRUNCATE );
  HANDLE hDll = LoadLibraryW(wc); // Used for windows only
  free(wc);
#else
  HANDLE hDll = LoadLibraryA(name); // Used for windows only
#endif
#else
	HANDLE hDll = LoadLibrary(name);
#endif

Testing required.

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Updated by O'Neil Delpratt over 3 years ago

Has duplicate Bug #4953: SaxonCGlue - C/C++ UNICODE Interop - add doc somewhere added

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Updated by Martin Ba over 3 years ago

I like to note here that the use of mbstowcs here is 99.9% superfluous.

The whole point of the LoadLibrary/A/W thing (*) is that the LoadLibraryA function does the CP_ACP conversion for you. LoadLibrary is just a macro that points to either LoadLibraryA or LoadLibraryW.

So, unless one has any reason to need to work with the active C locale encoding explicitly instead of the CP_ACP, using the extra 4 lines for mbctowcs does not buy anything.

Any code passing a char* should just use LoadLibraryA and be done with it.

(*) See also: https://docs.microsoft.com/en-us/windows/win32/api/libloaderapi/nf-libloaderapi-loadlibrarya https://docs.microsoft.com/en-us/windows/win32/intl/conventions-for-function-prototypes

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