2020-06-15 14:18:57 +00:00
|
|
|
|
/*-*- 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/dce.h"
|
|
|
|
|
|
#include "libc/limits.h"
|
|
|
|
|
|
#include "libc/macros.h"
|
|
|
|
|
|
#include "libc/runtime/ring.h"
|
2020-09-03 12:44:37 +00:00
|
|
|
|
#include "libc/runtime/runtime.h"
|
2020-06-15 14:18:57 +00:00
|
|
|
|
#include "libc/str/str.h"
|
|
|
|
|
|
#include "libc/sysv/consts/map.h"
|
|
|
|
|
|
#include "libc/sysv/consts/prot.h"
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
|
* Allocates ring buffer.
|
|
|
|
|
|
*
|
|
|
|
|
|
* Reads/writes wrap around on overflow.
|
|
|
|
|
|
*
|
|
|
|
|
|
* ┌────────────┐
|
|
|
|
|
|
* │ 𝑓₀..𝑓ₙ₋₁ │
|
|
|
|
|
|
* └┬┬──────────┘
|
|
|
|
|
|
* │└────────────┐
|
|
|
|
|
|
* ┌┴────────────┬┴────────────┐
|
|
|
|
|
|
* │ 𝑣₀..𝑣ₙ₋₁ │ 𝑣ₙ..𝑣ₙ*₂₋₁ │
|
|
|
|
|
|
* └─────────────┴─────────────┘
|
|
|
|
|
|
*
|
|
|
|
|
|
* @param r is metadata object owned by caller, initialized to zero
|
|
|
|
|
|
* @param n is byte length
|
|
|
|
|
|
* @return r->p, or NULL w/ errno
|
|
|
|
|
|
* @see ringfree(), balloc()
|
|
|
|
|
|
*/
|
|
|
|
|
|
void *ringalloc(struct RingBuffer *r, size_t n) {
|
|
|
|
|
|
void *a2;
|
|
|
|
|
|
int fd, rc;
|
|
|
|
|
|
size_t grain;
|
|
|
|
|
|
assert(!r->p);
|
|
|
|
|
|
assert(n > 0);
|
|
|
|
|
|
assert(n <= (INT_MAX - FRAMESIZE + 1) / 2);
|
|
|
|
|
|
if ((fd = openanon("ring", 0)) != -1) {
|
|
|
|
|
|
grain = ROUNDUP(n, FRAMESIZE);
|
|
|
|
|
|
rc = ftruncate(fd, grain * 2);
|
|
|
|
|
|
assert(rc != -1);
|
|
|
|
|
|
r->_size = grain * 2;
|
|
|
|
|
|
r->_addr = mmap(NULL, grain, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
|
|
|
|
|
|
if (r->_addr != MAP_FAILED) {
|
|
|
|
|
|
a2 = mmap(r->_addr + grain, grain, PROT_READ | PROT_WRITE,
|
|
|
|
|
|
MAP_SHARED | MAP_FIXED, fd, grain - n);
|
|
|
|
|
|
assert(a2 != MAP_FAILED);
|
|
|
|
|
|
r->p = r->_addr + grain - n;
|
|
|
|
|
|
if (IsWindows()) {
|
|
|
|
|
|
memset(r->p, 0, n); /* @see ftruncate() */
|
|
|
|
|
|
}
|
|
|
|
|
|
}
|
|
|
|
|
|
}
|
|
|
|
|
|
rc = close(fd);
|
|
|
|
|
|
assert(rc != -1);
|
|
|
|
|
|
return r->p;
|
|
|
|
|
|
}
|
