/**
 * @file SharedMemory.cpp
 * @author apio (cloudapio.eu)
 * @brief Create and map areas of memory shared between processes.
 *
 * @copyright Copyright (c) 2023, the Luna authors.
 *
 */

#include <errno.h>
#include <luna/Alignment.h>
#include <os/File.h>
#include <os/SharedMemory.h>
#include <string.h>
#include <sys/mman.h>
#include <unistd.h>

namespace os::SharedMemory
{
    Result<u8*> create(StringView path, usize size)
    {
        int fd = shm_open(path.chars(), O_RDWR | O_CREAT | O_EXCL, 0660);
        if (fd < 0)
        {
            int olderr = errno;
            os::eprintln("os: could not create shared memory region: shm_open failed (%s) - %s", path,
                         strerror(olderr));
            return err(olderr);
        }

        size = align_up<PAGE_SIZE>(size);

        if (ftruncate(fd, size) < 0)
        {
            int olderr = errno;
            os::eprintln("os: could not create shared memory region: ftruncate failed (%d, %zu) - %s", fd, size,
                         strerror(olderr));
            shm_unlink(path.chars());
            close(fd);
            return err(olderr);
        }

        void* p = mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
        if (p == MAP_FAILED)
        {
            int olderr = errno;
            os::eprintln("os: could not create shared memory region: mmap failed (%zu, %d) - %s", size, fd,
                         strerror(olderr));
            shm_unlink(path.chars());
            close(fd);
            return err(olderr);
        }

        close(fd);
        return (u8*)p;
    }

    Result<u8*> adopt(StringView path, usize size, bool delete_fs)
    {
        int fd = shm_open(path.chars(), O_RDWR, 0660);
        if (delete_fs) shm_unlink(path.chars());
        if (fd < 0) return err(errno);

        void* p = mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
        if (p == MAP_FAILED)
        {
            int olderr = errno;
            os::eprintln("os: could not adopt shared memory region: mmap failed (%zu, %d) - %s", size, fd,
                         strerror(olderr));
            close(fd);
            return 0;
        }

        close(fd);
        return (u8*)p;
    }
}