Exiv2

It should be possible to access an image that is write-protected as long as no attempt is made to write to it.

KALANAG> chmod -w table.jpg
KALANAG> ./exifprint.exe table.jpg
Caught Exiv2 exception 'table.jpg: Failed to open the data source: Permission denied (13)'

Additional information:

By default, a FileIo is opened in read and write mode:

int FileIo::open()
    {
        // Default open is in read-write binary mode
        return open("r+b");
    }

This should only be "rb". However, the switching from read to write mode would also need to be changed.