// SPDX-License-Identifier: MIT
// Author: Giovanni Santini
// Github: @San7o

#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>

// Much faster than read(2) or fread since it does not copy the
// contents in a new buffer. Not portable.
char* mmap_file(const char* filename, size_t* out_size) {
    int fd = open(filename, O_RDONLY);
    if (fd == -1)
    {
        perror("open");
        return NULL;
    }

    struct stat st;
    if (fstat(fd, &st) == -1)
    {
        perror("fstat");
        close(fd);
        return NULL;
    }

    size_t size = st.st_size;
    if (size == 0)
    {
        // empty file
        close(fd);
        if (out_size) *out_size = 0;
        return NULL;
    }

    void* addr = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
    close(fd);
    if (addr == MAP_FAILED)
    {
        perror("mmap");
        return NULL;
    }

    if (out_size)
    {
        *out_size = size;
    }
    return (char*)addr;
}

void unmap_file(char* addr, size_t size) {
    if (addr)
        munmap(addr, size);
}