#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include "../git-compat-util.h"

void *gitfakemmap(void *start, size_t length, int prot , int flags, int fd, off_t offset)
{
        int n = 0;
        off_t current_offset = lseek(fd, 0, SEEK_CUR);

        if (start != NULL || !(flags & MAP_PRIVATE))
                die("Invalid usage of gitfakemmap.");

        if (lseek(fd, offset, SEEK_SET) < 0) {
                errno = EINVAL;
                return MAP_FAILED;
        }

        start = xmalloc(length);
        if (start == NULL) {
                errno = ENOMEM;
                return MAP_FAILED;
        }

        while (n < length) {
                int count = read(fd, start+n, length-n);

                if (count == 0) {
                        memset(start+n, 0, length-n);
                        break;
                }

                if (count < 0) {
                        free(start);
                        errno = EACCES;
                        return MAP_FAILED;
                }

                n += count;
        }

        if (current_offset != lseek(fd, current_offset, SEEK_SET)) {
                errno = EINVAL;
                return MAP_FAILED;
        }

        return start;
}

int gitfakemunmap(void *start, size_t length)
{
        free(start);
        return 0;
}