BRK(2) BRK(2)
NAME
brk, sbrk - change memory allocation
SYNOPSIS
#include <u.h>
#include <libc.h>
int brk(void *addr)
void* sbrk(ulong incr)
DESCRIPTION
Brk sets the system's idea of the lowest bss location not
used by the program (called the break) to addr rounded up to
the next multiple of 8 bytes. Locations not less than addr
and below the stack pointer may cause a memory violation if
accessed.
In the alternate function sbrk, incr more bytes are added to
the program's data space and a pointer to the start of the
new area is returned. Rounding occurs as with brk.
When a program begins execution via exec the break is set at
the highest location defined by the program and data storage
areas. Ordinarily, therefore, only programs with growing
data areas need to use brk. A call to sbrk with a zero argu-
ment returns the lowest address in the dynamic segment.
SOURCE
/sys/src/libc/9sys/sbrk.c
SEE ALSO
intro(2), malloc(2), segattach(2), segbrk(2)
DIAGNOSTICS
These functions set errstr.
The error return from sbrk is (void*)-1.
Page 1 Plan 9 (printed 11/23/24)