ref: 2fe3b28f86ed4aa291fb8a620b948abe9c6a1f84
dir: /sys/man/2/brk/
.TH BRK 2 .SH NAME brk, sbrk \- change memory allocation .SH SYNOPSIS .B #include <u.h> .br .B #include <libc.h> .PP .ta \w'\fLvoid* 'u .B int brk(void *addr) .PP .B void* sbrk(ulong incr) .SH DESCRIPTION .I Brk sets the system's idea of the lowest bss location not used by the program (called the break) to .I addr rounded up to the next multiple of 8 bytes. Locations not less than .I addr and below the stack pointer may cause a memory violation if accessed. .PP In the alternate function .IR sbrk , .I 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 .IR brk . .PP When a program begins execution via .I 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 .IR brk . A call to .I sbrk with a zero argument returns the lowest address in the dynamic segment. .SH SOURCE .B /sys/src/libc/9sys/sbrk.c .SH SEE ALSO .IR intro (2), .IR malloc (2), .IR segattach (2), .IR segbrk (2) .SH DIAGNOSTICS These functions set .IR errstr . .PP The error return from .I sbrk is .BR (void*)-1 .