1 #include <sys/cdefs.h>
2 #include "namespace.h"
3 #include <lib.h>
4
5 #include <string.h>
6 #include <unistd.h>
7
8 #ifdef __weak_alias
9 __weak_alias(brk, _brk)
10 #endif
11
12 extern char *_brksize;
13
14 /* Both OSF/1 and SYSVR4 man pages specify that brk(2) returns int.
15 * However, BSD4.3 specifies that brk() returns char*. POSIX omits
16 * brk() on the grounds that it imposes a memory model on an architecture.
17 * On the other hand, they are so crucial to correct operation of so many
18 * parts of the system, that we have chosen to hide the name brk using _brk,
19 * as with system calls. In this way, if a user inadvertently defines a
20 * procedure brk, MINIX may continue to work because the true call is _brk.
21 */
brk(addr)22 int brk(addr)
23 void *addr;
24 {
25 message m;
26
27 if (addr != _brksize) {
28 memset(&m, 0, sizeof(m));
29 m.m_lc_vm_brk.addr = addr;
30 if (_syscall(VM_PROC_NR, VM_BRK, &m) < 0) return(-1);
31 _brksize = addr;
32 }
33 return(0);
34 }
35
36