ref: 7f2599254a29c956ac3cdbfc28792a8290312c13
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 .