NAME

get_end, get_etext, get_edata - get values of UNIX link editor defined symbols

SYNOPSIS

#include <mach-o/getsect.h>

unsigned long get_end();
unsigned long get_etext();
unsigned long get_edata();

DESCRIPTION

These routines provide a stopgap measure to programs that use the UNIX link-editor defined symbols. Use of these routines is very strongly discouraged. The problem is that any program that is using UNIX link editor defined symbols (_end, _etext or _edata) is making assumptions that the program has the memory layout of a UNIX program.

This is an incorrect assumption for a program built by the Mach-O link editor. The reason that these routines are provided is that if very minimal assumptions about the layout are used and the default format and memory layout of the Mach-O link editor is used to build the program, some things may work by using the values returned by these routines in place of the addresses of their UNIX link-editor defined symbols. So use at your own risk, and only if you know what your doing. Or better yet, convert the program to use the appropriate Mach or Mach-O functions. If you are trying to allocate memory use vm_allocate(2), if you are trying to find out about your address space use vm_region(2) and if you are trying to find out where your program is loaded use the dyld(3) functions.

The values of the UNIX link-editor defined symbols _etext, _edata and _end are returned by the routines get_etext, get_edata, and get_end respectively. In a Mach-O file they have the following values: get_etext returns the first address after the (__TEXT,__text) section, note this my or may not be the only section in the __TEXT segment. get_edata returns the first address after the (__DATA,__data) section, note this my or may not be the last non-zero fill section in the __DATA segment. get_end returns the first address after the last segment in the executable, note a shared library may be loaded at this address.

SEE ALSO

ld(1), dyld(3)