brk, sbrk - change data segment size
int brk(void *end_data_segment);
void *sbrk(ptrdiff_t increment);
brk sets the end of the data segment to the value specified by end_data_segment, when that value is reasonable, the system does have enough memory and the process does not exceed its max data size (see
sbrk increments the program's data space by increment bytes. sbrk isn't a system call, it is just a C library wrapper. Calling sbrk with an increment of 0 can be used to find the current location of
the program break.
On success, brk returns zero, and sbrk returns a pointer to the start of the new area. On error, -1 is returned, and errno is set to ENOMEM.
brk and sbrk are not defined in the C Standard and are deliberately excluded from the POSIX.1 standard (see paragraphs B.22.214.171.124 and B.8.3.3).
execve(2), getrlimit(2), malloc(3)