mman.h does import mmap function but fails to import mremap

Question

So I wanted to use the mremap function to more easily work with memory mapped files but an implicit declaration error is raised

addr = mremap(addr, len, len_file, MREMAP_MAYMOVE);

I do include the required libraries, if i didnt the line

addr = mmap(NULL, len_file, PROT_WRITE|PROT_READ, MAP_SHARED, fd, 0);

would raise the same error.

My current header has the libraries that are pointed as required

#include <sys/mman.h>
#define _GNU_SOURCE

You need to `#define _GNU_SOURCE` before including any headers. — melpomene, Dec 11 '16 at 18:18

score 2 · Accepted Answer · edited Dec 11 '16 at 18:23

2

The order is incorrect here:

#include <sys/mman.h>
#define _GNU_SOURCE

You must define _GNU_SOURCE before including the headers:

#define _GNU_SOURCE
#include <sys/mman.h>

edited Dec 11 '16 at 18:23

melpomene

answered Dec 11 '16 at 18:22

P.P

1 Answers1