fgetpos failing in iOS 6.1 simulator when opening files in bundles

Question

I'm working on some multiplatform C++ code. Hence the requirement to use fopen, fgetpos, etc. The following was working earlier on iOS and with my update to the latest version it stopped working.

I have a couple of text files Shader.vsh and Shader.fsh in a Shaders folder that is getting copied over to the bundle. In order to open the file, I do the following..

CFBundleRef mainBundle = CFBundleGetMainBundle();

CFStringRef cfstrFilename = CFSTRFromConstCharPtr( "Shader" );
CFStringRef cfstrFileType = CFSTRFromConstCharPtr( "vsh" );
CFStringRef cfstrSubDir = CFSTRFromConstCharPtr( "Shaders" );

CFURLRef resourcesURL = CFBundleCopyResourceURL( mainBundle, cfstrFilename, cfstrFileType, cfstrSubDir );

CFStringRef str = CFURLCopyFileSystemPath( resourcesURL, kCFURLPOSIXPathStyle );
CFRelease( resourcesURL );

char path[ PATH_MAX ];  
CFStringGetCString( str, path, FILENAME_MAX, kCFStringEncodingASCII );

CFRelease( str );

FILE* fp = fopen( path, "rb" );

At this point, fp is Non NULL. So I assume it succeeded. Later, when I try to do

fpos_t pos;
int result = fgetpos( fp, &fpos_t );

result = -1 and errno = 0x2, which I believe is file not found.

As I mentioned earlier, this used to work on a previous version at some point. I started working on this again and in the process updated to the latest XCode, etc and things stopped working.

The path for the file that I pass into fopen turns out to be /Users/shammi/Library/Application Support/iPhone Simulator/6.1/Applications/9132490F-71AC-4C61-A584-E8F6C5B261FF/TestApp.app/Shaders/Shader.vsh I'm able to see and open that file in finder/console and confirmed that its valid.

What am I doing wrong? Is there another alternative that allows me to use portable IO functions?

Wondering if this can be caused by file access permissions somehow being different. Does anyone know if there are any specific requirements for XCode or simulator permissions, etc? — Shammi, Jun 23 '13 at 23:18

score 0 · Answer 1 · answered Jun 24 '13 at 02:08

Found the problem. What I failed to mention here is what happens between the 2 sections of code above. Prior to this, I used to have my own ref counting solution and I recently changed to using shared_ptr. My own ref counting solution allowed for implicit casts. With shared_ptr, you can't do that. So here is the exact code...

std::shared_ptr< BinaryStream > BundleNamespace::OpenStream( const char* _szPath,

BinaryStream::Mode _eMode )
{
    std::shared_ptr< BinaryStream > pStream = __super::OpenStream( _szPath, _eMode );
    if ( !pStream )
    {
        std::string strDir;
        std::string strFile;
        std::string strExt;

        SplitPath( _szPath, strDir, strFile, strExt );

        std::string strFullPath = GetResourcePathFor( strFile.c_str(), strExt.c_str(), strDir.c_str() );

        FILE* fp = fopen( strFullPath.c_str(), _eMode == BinaryStream::Mode_Read ? "r" : "w+b" );

        pStream = std::make_shared<FileStream>( fp, _eMode );
    }

    return pStream;
}

The problem here is with

    pStream = std::make_shared<FileStream>( fp, _eMode );

My FileStream's destructor calls fclose(m_pFile). The fix here is to change it to..

    pStream = std::static_pointer_cast< BinaryStream >( std::make_shared<FileStream>( fp, _eMode ) );`

Also, using perror() proved to be more useful compared to trying to decipher errno.

Spoke a little too soon here with the fix. The problem is that the destructor is getting called. However, even doing this... auto pFileStream = std::make_shared< FileStream >( fp, _eMode ); ends up calling the file stream destructor and I checked that this is the newly constructed object. — Shammi, Jun 24 '13 at 02:16

fgetpos failing in iOS 6.1 simulator when opening files in bundles

1 Answers1