[Fontconfig] how to read config file from current dir (relative to a binary using the lib)

[Pavel Koshevoy]

On 09/02/2012 03:41 AM, Raimund Steger wrote:
> Helmut Tessarek wrote:
>>> How can I make fontconfig look for the config files in the local directory?
>>
>> After going through the entire mail thread again...
>>
>> Don't you think, it might be a good idea to give fontconfig the option to
>> search in ./fontconfig/ first, before looking in PREFIX/etc or --sysconfdir?
>
> Having objects make any assumptions about the location in the file system 
> they're stored in would be very uncommon on Unix. I. e. there is no POSIX 
> equivalent of Win32's GetModuleFileName.


It's common on OSX (some QuickTime plug-ins do this), and it can be done on 
Linux.  I have some sample C++ code in case you are interested.

bool GetCurrentExecutableAbsoluteFileName(std::string & exePathUTF8)
{
     bool ok = false;

#ifdef _WIN32
     wchar_t path[_MAX_PATH] = { 0 };
     unsigned long pathLen = sizeof(path) / sizeof(wchar_t);
     if (GetModuleFileNameW(0, path, pathLen) != 0)
     {
         exePathUTF8 = utf16_to_utf8(std::wstring(path));
         ok = true;
     }
#elif defined(__APPLE__)
     CFBundleRef mainBundle = CFBundleGetMainBundle();
     if (mainBundle)
     {
         CFURLRef cfUrl = CFBundleCopyExecutableURL(mainBundle);

         if (cfUrl)
         {
             CFStringRef cfStr = CFURLCopyFileSystemPath(cfUrl, kCFURLPOSIXPathStyle);

             char txt[1024] = { 0 };
             if (cfStr)
             {
                 if (CFStringGetCString(cfStr, txt, sizeof(txt), kCFStringEncodingUTF8))
                 {
                     exePathUTF8.assign(txt);
                     ok = true;
                 }

                 CFRelease(cfStr);
             }

             CFRelease(cfUrl);
         }
     }
#else
     char path[PATH_MAX + 1] = { 0 };
     if (readlink("/proc/self/exe", path, sizeof(path)) > 0)
     {
         exePathUTF8.assign(path);
         ok = true;
     }
#endif

     assert(!exePathUTF8.empty());
     return ok;
}



I've seen this issue brought up on the ffmpeg-devel mailing list, and here.  I 
hope there will be a positive resolution.  If relative-to-exe fontconfig search 
path is not possible perhaps ffmpeg developers will be more amiable to adding a 
fontconfig configuration parameter to the drawtext filter (so it can pass 
correct fonts.conf file path to libass, which will in turn initialize fontconfig).

Hope this helps,
     Pavel.