minix/lib/libc/sys-minix/brk.c
2014-07-28 17:06:22 +02:00

35 lines
912 B
C

#include <sys/cdefs.h>
#include "namespace.h"
#include <lib.h>
#include <string.h>
#include <unistd.h>
#ifdef __weak_alias
__weak_alias(brk, _brk)
#endif
extern char *_brksize;
/* Both OSF/1 and SYSVR4 man pages specify that brk(2) returns int.
* However, BSD4.3 specifies that brk() returns char*. POSIX omits
* brk() on the grounds that it imposes a memory model on an architecture.
* On the other hand, they are so crucial to correct operation of so many
* parts of the system, that we have chosen to hide the name brk using _brk,
* as with system calls. In this way, if a user inadvertently defines a
* procedure brk, MINIX may continue to work because the true call is _brk.
*/
int brk(addr)
void *addr;
{
message m;
if (addr != _brksize) {
memset(&m, 0, sizeof(m));
m.m_lc_vm_brk.addr = addr;
if (_syscall(VM_PROC_NR, VM_BRK, &m) < 0) return(-1);
_brksize = addr;
}
return(0);
}