Memory Mapped file Support

[abidrahmank]

There was already an issue closed on years ago. #9

Was there any development in this direction (even if it is an additional execution path) ?
As mentioned in the original issue, this would be really helpful for very large ELF files.

[serge1]

Sorry, here goes the right file implementing std::istream() based on memory accesses:

It seems to me that the support of memory mapped files is already in place.
Please find attached a simple implementation of istream interface based on memory buffer.

memory_istream.cpp

After renaming the file to memory_istream.hpp and including it, you will be able to use ELFIO library as usual:

    #include "memory_istream.hpp"
    ...
    ...
    int fd = ::open("/usr/bin/ls", O_RDONLY);
    struct stat st{};
    ::fstat(fd, &st);
    const char* addr = (const char*)::mmap(nullptr, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
    memory_istream elf_file(addr, st.st_size);

    elfio reader;
    if (!reader.load(elf_file)) {
        std::cout << "Can't find or process ELF file " << argv[1] << std::endl;
        return 2;
    }

[sonals]

I believe in this approach elfio would still copy the data over from the stream, elf_file, into sections, hence leading to memory duplication. Shouldn't we add a path in elfio where it does not copy over any section/segment data except if the client is trying to change the sizes of sections thus impacting the layout?