cosmopolitan/libc/intrin/extend.c
Jōshin e16a7d8f3b
flip et / noet in modelines
`et` means `expandtab`.

```sh
rg 'vi: .* :vi' -l -0 | \
  xargs -0 sed -i '' 's/vi: \(.*\) et\(.*\)  :vi/vi: \1 xoet\2:vi/'
rg 'vi: .*  :vi' -l -0 | \
  xargs -0 sed -i '' 's/vi: \(.*\)noet\(.*\):vi/vi: \1et\2  :vi/'
rg 'vi: .*  :vi' -l -0 | \
  xargs -0 sed -i '' 's/vi: \(.*\)xoet\(.*\):vi/vi: \1noet\2:vi/'
```
2023-12-07 22:17:11 -05:00

110 lines
4.4 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2022 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/calls/calls.h"
#include "libc/calls/struct/sigset.internal.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/intrin/asan.internal.h"
#include "libc/intrin/asancodes.h"
#include "libc/intrin/describebacktrace.internal.h"
#include "libc/intrin/directmap.internal.h"
#include "libc/log/libfatal.internal.h"
#include "libc/macros.internal.h"
#include "libc/runtime/memtrack.internal.h"
#include "libc/sysv/consts/map.h"
#include "libc/sysv/consts/prot.h"
#define G FRAMESIZE
static void *_mapframe_impl(void *p, int f) {
int rc, prot, flags;
struct DirectMap dm;
prot = PROT_READ | PROT_WRITE;
flags = f | MAP_ANONYMOUS | MAP_FIXED;
if ((dm = sys_mmap(p, G, prot, flags, -1, 0)).addr == p) {
rc = __track_memory(&_mmi, (uintptr_t)p >> 16, (uintptr_t)p >> 16,
dm.maphandle, prot, flags, false, false, 0, G);
if (!rc) {
return p;
} else {
return 0;
}
} else {
return 0;
}
}
static void *_mapframe(void *p, int f) {
void *res;
// mmap isn't required to be @asyncsignalsafe but this is
BLOCK_SIGNALS;
__mmi_lock();
res = _mapframe_impl(p, f);
__mmi_unlock();
ALLOW_SIGNALS;
return res;
}
/**
* Extends static allocation.
*
* This simple fixed allocator has unusual invariants
*
* !(p & 0xffff) && !(((p >> 3) + 0x7fff8000) & 0xffff)
*
* which must be the case when selecting a starting address. We also
* make the assumption that allocations can only grow monotonically.
* Furthermore allocations shall never be removed or relocated.
*
* @param p points to start of memory region
* @param n specifies how many bytes are needed
* @param e points to end of memory that's allocated
* @param h is highest address to which `e` may grow
* @param f should be `MAP_PRIVATE` or `MAP_SHARED`
* @return new value for `e` or null w/ errno
* @raise ENOMEM if we require more vespene gas
* @asyncsignalsafe
*/
void *_extend(void *p, size_t n, void *e, int f, intptr_t h) {
char *q;
#ifndef NDEBUG
if ((uintptr_t)SHADOW(p) & (G - 1)) notpossible;
if ((uintptr_t)p + (G << kAsanScale) > h) notpossible;
#endif
// TODO(jart): Make this spin less in non-ASAN mode.
for (q = e; q < ((char *)p + n); q += 8) {
if (!((uintptr_t)q & (G - 1))) {
#ifndef NDEBUG
if (q + G > (char *)h) notpossible;
#endif
if (!_mapframe(q, f)) return 0;
if (IsAsan()) {
if (!((uintptr_t)SHADOW(q) & (G - 1))) {
if (!_mapframe(SHADOW(q), f)) return 0;
__asan_poison(q, G << kAsanScale, kAsanProtected);
}
}
}
if (IsAsan()) {
*SHADOW(q) = 0;
}
}
return q;
}