PhysFS corrupting first few bytes of data

Question

So, this PhysFS class I'm writing seems to be corrupting the first few characters of all the data it reads. The rest of the data seems fine...

Here is the code being called:

std::vector<uint8_t> FileIO::vectorFromFile(std::string fileName)
{
    auto buffer = std::make_shared<std::vector<uint8_t> > (*new std::vector<uint8_t>);
    if(PHYSFS_exists(fileName.c_str()))
    {
        PHYSFS_File* filenameHandle = PHYSFS_openRead(fileName.c_str());
        if (filenameHandle != 0)
        {
            bufferSize = PHYSFS_fileLength(filenameHandle);
            buffer->resize(bufferSize);
            PHYSFS_read (filenameHandle, &buffer->front(), sizeof(uint8_t), bufferSize);
            PHYSFS_close(filenameHandle);
        }
    }
    else
    {
        std::cerr << fileName << " doesn't exist.";
    }
    buffer->push_back((uint8_t) '\0');
    return *buffer;
}

SimpleFile FileIO::getSimpleFile(std::string fileName)
{
    SimpleFile file;
    std::vector<uint8_t> dataVector = vectorFromFile(fileName);
    file.data = &(dataVector[0]);
    file.sizeInBytes = dataVector.size();

    return file;
}

And this example outputs:

─ s  9c rsion="1.0" encoding="UTF-8"?>
<map version="1.0" orientation="orthogonal" width="40" height="40" tilewidth="32
" tileheight="32">
 <tileset firstgid="1" name="Desert" tilewidth="32" tileheight

When it should be:

<?xml version="1.0" encoding="UTF-8"?>
<map version="1.0" orientation="orthogonal" width="40" height="40" tilewidth="32"
tileheight="32">
 <tileset firstgid="1" name="Desert" tilewidth="32" tileheight

Sorry about the pastebin.

I'm a bit new to reading from filesystems and PhysFS, so forgive me if I made an obvious mistake.

EDIT: The header:

#ifndef FILEIO_H
#define FILEIO_H

#include <string>
#include <vector>

struct SimpleFile;

class FileIO
{
private:
    int bufferSize = 0;
public:
    FileIO();
    ~FileIO();
    std::vector<uint8_t> vectorFromFile(std::string fileName);
    SimpleFile getSimpleFile(std::string fileName);
};

struct SimpleFile
{
    uint8_t* data;
    int sizeInBytes;
};

#endif // FILEIO_H

Answer 1

I think your data is just going out of scope and being reused for something else:

SimpleFile FileIO::getSimpleFile(std::string fileName)
{
    SimpleFile file;
    std::vector<uint8_t> dataVector = vectorFromFile(fileName);
    file.data = &(dataVector[0]);
    file.sizeInBytes = dataVector.size();
    return file;
}

Once the function returns dataVector is gone so file.data is an invalid pointer. Of course I do not know much about the C++11 new features that could override that.