get_end(3) get_end(3)
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 pro-
gram, some things may work by using the values returned by these rou-
tines in place of the addresses of their UNIX link-editor defined sym-
bols. 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)
Apple Computer, Inc. April 10, 1998 get_end(3)
Mac OS X 10.6 - Generated Thu Sep 17 20:20:00 CDT 2009