src/lib/mmap-util.c

	mmap-util.c revision 61fb6ead42247d9bf7e2521ab1e0902c76fccff1
/* Copyright (c) 2002-2003 Timo Sirainen */

#include "lib.h"
#include "mmap-util.h"

#include <sys/stat.h>

void *mmap_file(int fd, size_t *length, int prot)
{
    struct stat st;

    if (fstat(fd, &st) < 0)
        return MAP_FAILED;

    if (st.st_size > SSIZE_T_MAX) {
        /* too large file to map into memory */
        errno = EFBIG;
        return MAP_FAILED;
    }

    *length = (size_t)st.st_size;
    if (*length == 0)
        return NULL;

    i_assert(*length > 0 && *length < SSIZE_T_MAX);

    return mmap(NULL, *length, prot, MAP_SHARED, fd, 0);
}

void *mmap_ro_file(int fd, size_t *length)
{
    return mmap_file(fd, length, PROT_READ);
}

void *mmap_rw_file(int fd, size_t *length)
{
    return mmap_file(fd, length, PROT_READ | PROT_WRITE);
}

#ifndef HAVE_MADVISE
int my_madvise(void *start __attr_unused__, size_t length __attr_unused__,
           int advice __attr_unused__)
{
    return 0;
}
#endif

size_t mmap_get_page_size(void)
{
    static size_t size = 0;

    if (size != 0)
        return size;
    size = getpagesize();
    return size;
}