brk, sbrk - change core allocation
The system call sets the system's idea of the lowest data segment loca‐
tion not used by the program (called the break) to addr (rounded up to
the next multiple of the system's page size). Locations greater than
addr and below the stack pointer are not in the address space and will
thus cause a memory violation if accessed.
In the alternate function incr more bytes are added to the program's
data space and a pointer to the start of the new area is returned.
When a program begins execution using 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
The system call may be used to determine the maximum permissible size
of the data segment. It will not be possible to set the break beyond
the rlim_max value returned from a call to for example, etext + rlp
-rlim_max. See for the definition of etext.
If the call is successful, returns a 0 value. If the program requests
more memory than the system limit, returns -1. If the break could not
be set, returns -1.
Setting the break may fail due to a temporary lack of swap space. It
is not possible to distinguish this from a failure caused by exceeding
the maximum size of the data segment without consulting
The call fails and no additional memory is allocated under the follow‐
[ENOMEM] The limit, as set by is exceeded.
[ENOMEM] The maximum possible size of a data segment (compiled
into the system) is exceeded.
[ENOMEM] Insufficient space exists in the swap area to support
See Alsoexecve(2), getrlimit(2), setrlimit(2), end(3), malloc(3)