CODEWITHSUNDEEP
cunixmemory
bombax
bombax

Reputation: 1219

Both MAP_ANON and MAP_ANONYMOUS undeclared for sys/mmap in C

This is my mman.h file included from /usr/include/sys/:

http://pastebin.com/FZpHwKMC

Somehow mmap() seems to be defined (and can be used with flags 0 and read/write protection), but not MAP_ANON or MAP_ANONYMOUS as indicated below:

#include <sys/mman.h>

int a = MAP_ANON; /* compile error */
int b = MAP_ANONYMOUS; /* also compile error */

I'm at a loss of what could be wrong. I'm compiling using this makefile:

http://pastebin.com/R1V2edmf

EDIT: It turns out the MAP_ANONYMOUS macro is defined in /usr/include/bits/mman.h but only if __USE_MISC is defined...

Any help would be terrific!

Upvotes: 4

Views: 5869

Answers (1)

CmdrMoozy
CmdrMoozy

Reputation: 3931

If you're using GCC, a common reason for this to occur is that you're not using a GNU C standard. Try compiling with, e.g., -std=gnu11, and see if that fixes the problem.

More information about GCC's language standards can be found here.

GCC also provides a very exhaustive list of exactly what extensions they provide here.

Also, as a side note, it's preferrable to use MAP_ANONYMOUS instead of MAP_ANON, as the latter is deprecated (according to man mmap).

Upvotes: 6

Related Questions