minix/servers/vm/break.c
David van Moolenbroek 24ec0d73b5 Clean up interface to PM and VFS
- introduce new call numbers, names, and field aliases;
- initialize request messages to zero for all ABI calls;
- format callnr.h in the same way as com.h;
- redo call tables in both servers;
- remove param.h namespace pollution in the servers;
- make brk(2) go to VM directly, rather than through PM;
- remove obsolete BRK, UTIME, and WAIT calls;
- clean up path copying routine in VFS;
- move remaining system calls from libminlib to libc;
- correct some errno-related mistakes in libc routines.

Change-Id: I2d8ec5d061cd7e0b30c51ffd77aa72ebf84e2565
2014-03-01 09:05:01 +01:00

70 lines
2.2 KiB
C

/* The MINIX model of memory allocation reserves a fixed amount of memory for
* the combined text, data, and stack segments. The amount used for a child
* process created by FORK is the same as the parent had. If the child does
* an EXEC later, the new size is taken from the header of the file EXEC'ed.
*
* The layout in memory consists of the text segment, followed by the data
* segment, followed by a gap (unused memory), followed by the stack segment.
* The data segment grows upward and the stack grows downward, so each can
* take memory from the gap. If they meet, the process must be killed. The
* procedures in this file deal with the growth of the data and stack segments.
*
* The entry points into this file are:
* do_brk: BRK/SBRK system calls to grow or shrink the data segment
*/
#define _SYSTEM 1
#include <minix/callnr.h>
#include <minix/com.h>
#include <minix/config.h>
#include <minix/const.h>
#include <minix/ds.h>
#include <minix/endpoint.h>
#include <minix/minlib.h>
#include <minix/type.h>
#include <minix/ipc.h>
#include <minix/sysutil.h>
#include <minix/syslib.h>
#include <minix/bitmap.h>
#include <errno.h>
#include <env.h>
#include "glo.h"
#include "vm.h"
#include "proto.h"
#include "util.h"
#define DATA_CHANGED 1 /* flag value when data segment size changed */
#define STACK_CHANGED 2 /* flag value when stack size changed */
/*===========================================================================*
* do_brk *
*===========================================================================*/
int do_brk(message *msg)
{
/* Perform the brk(addr) system call.
* The parameter, 'addr' is the new virtual address in D space.
*/
int proc;
if (vm_isokendpt(msg->m_source, &proc) != OK) {
printf("VM: bogus endpoint VM_BRK %d\n", msg->m_source);
return EINVAL;
}
return real_brk(&vmproc[proc], (vir_bytes) msg->VMB_ADDR);
}
/*===========================================================================*
* real_brk *
*===========================================================================*/
int real_brk(struct vmproc *vmp, vir_bytes v)
{
if(map_region_extend_upto_v(vmp, v) == OK) {
return OK;
}
return(ENOMEM);
}