cosmopolitan/libc/runtime/munmap.c

107 lines
4.3 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/calls/calls.h"
#include "libc/calls/internal.h"
#include "libc/dce.h"
#include "libc/nt/memory.h"
#include "libc/nt/runtime.h"
#include "libc/runtime/mappings.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/fileno.h"
/**
* Releases memory pages.
*
* @param addr is a pointer within any memory mapped region the process
* has permission to control, such as address ranges returned by
* mmap(), the program image itself, etc.
* @param size is the amount of memory to unmap, which should be a
* multiple of PAGESIZE, and may be a subset of that which was
* mapped previously
* @return 0 on success, or -1 w/ errno
*/
int __munmap(void *addr, size_t size) {
int rc;
intptr_t p;
size_t i, j;
struct AddrSize a;
struct MemoryCoord c, m;
p = (intptr_t)addr;
assert(!(0 < p && p < 0x200000));
assert(-0x800000000000L <= p && p <= 0x7fffffffffffL);
if (!size) return 0;
if (!addr || addr == MAP_FAILED) return 0;
if (addr == NULL && size <= 0x200000) return 0;
addr = (void *)ROUNDDOWN((intptr_t)addr, FRAMESIZE);
size = ROUNDUP(size, FRAMESIZE);
rc = 0;
c = ADDRSIZE_TO_COORD(addr, size);
j = findmapping(c.y);
for (i = j; i; --i) {
m = _mm.p[i - 1];
assert(m.x <= m.y);
assert(c.y >= m.x);
if (c.x > m.y) {
break;
} else if (c.x > m.x && c.y < m.y) {
/* remove middle portion */
assert(!"map hole punching not implemented");
} else if (c.x > m.x && c.y >= m.y) {
/* remove righthand portion */
assert(!"map hole punching not implemented");
/* _mm.p[i - 1].y = c.x - 1; */
/* i++; */
/* break; */
} else if (c.x <= m.x && c.y < m.y) {
/* remove lefthand portion */
assert(!"map hole punching not implemented");
/* _mm.p[i - 1].x = c.y + 1; */
/* j--; */
} else if ((m.x >= c.x && m.x <= c.y) && (m.y >= c.x && m.y <= c.y)) {
a = COORD_TO_ADDRSIZE(m);
if (!IsWindows()) {
rc |= munmap$sysv(a.addr, a.size);
} else {
if (!UnmapViewOfFile(a.addr)) rc = -1;
if (!CloseHandle(_mm.h[i - 1])) rc = -1;
}
} else {
assert(!"wut");
}
}
if (i < j) {
if (j < _mm.i) {
memmove(&_mm.p[i], &_mm.p[j],
(intptr_t)&_mm.p[_mm.i] - (intptr_t)&_mm.p[j]);
memmove(&_mm.h[i], &_mm.h[j],
(intptr_t)&_mm.h[_mm.i] - (intptr_t)&_mm.h[j]);
}
_mm.i -= j - i;
}
return rc;
}