mirror of
https://github.com/systemd/systemd-stable.git
synced 2024-12-22 13:33:56 +03:00
shared: add ring buffer
New "struct ring" object that implements a basic ring buffer for arbitrary byte-streams. A new basic runtime test is also added. This will be needed for our pty helpers for systemd-console and friends.
This commit is contained in:
parent
625e870b4f
commit
e0dd92729e
1
.gitignore
vendored
1
.gitignore
vendored
@ -180,6 +180,7 @@
|
||||
/test-path-util
|
||||
/test-prioq
|
||||
/test-replace-var
|
||||
/test-ring
|
||||
/test-rtnl
|
||||
/test-sched-prio
|
||||
/test-sleep
|
||||
|
@ -801,6 +801,8 @@ libsystemd_shared_la_SOURCES = \
|
||||
src/shared/clean-ipc.c \
|
||||
src/shared/login-shared.c \
|
||||
src/shared/login-shared.h \
|
||||
src/shared/ring.c \
|
||||
src/shared/ring.h \
|
||||
src/shared/async.c \
|
||||
src/shared/async.h
|
||||
|
||||
@ -1198,6 +1200,7 @@ tests += \
|
||||
test-utf8 \
|
||||
test-ellipsize \
|
||||
test-util \
|
||||
test-ring \
|
||||
test-tmpfiles \
|
||||
test-namespace \
|
||||
test-date \
|
||||
@ -1325,6 +1328,12 @@ test_util_SOURCES = \
|
||||
test_util_LDADD = \
|
||||
libsystemd-core.la
|
||||
|
||||
test_ring_SOURCES = \
|
||||
src/test/test-ring.c
|
||||
|
||||
test_ring_LDADD = \
|
||||
libsystemd-core.la
|
||||
|
||||
test_tmpfiles_SOURCES = \
|
||||
src/test/test-tmpfiles.c
|
||||
|
||||
|
208
src/shared/ring.c
Normal file
208
src/shared/ring.c
Normal file
@ -0,0 +1,208 @@
|
||||
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
|
||||
|
||||
/***
|
||||
This file is part of systemd.
|
||||
|
||||
Copyright 2014 David Herrmann <dh.herrmann@gmail.com>
|
||||
|
||||
systemd is free software; you can redistribute it and/or modify it
|
||||
under the terms of the GNU Lesser General Public License as published by
|
||||
the Free Software Foundation; either version 2.1 of the License, or
|
||||
(at your option) any later version.
|
||||
|
||||
systemd 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
|
||||
Lesser General Public License for more details.
|
||||
|
||||
You should have received a copy of the GNU Lesser General Public License
|
||||
along with systemd; If not, see <http://www.gnu.org/licenses/>.
|
||||
***/
|
||||
|
||||
#include <errno.h>
|
||||
#include <inttypes.h>
|
||||
#include <stdlib.h>
|
||||
#include <string.h>
|
||||
#include <sys/uio.h>
|
||||
#include "macro.h"
|
||||
#include "ring.h"
|
||||
|
||||
#define RING_MASK(_r, _v) ((_v) & ((_r)->size - 1))
|
||||
|
||||
void ring_flush(struct ring *r) {
|
||||
assert(r);
|
||||
|
||||
r->start = 0;
|
||||
r->used = 0;
|
||||
}
|
||||
|
||||
void ring_clear(struct ring *r) {
|
||||
free(r->buf);
|
||||
zero(*r);
|
||||
}
|
||||
|
||||
/*
|
||||
* Get data pointers for current ring-buffer data. @vec must be an array of 2
|
||||
* iovec objects. They are filled according to the data available in the
|
||||
* ring-buffer. 0, 1 or 2 is returned according to the number of iovec objects
|
||||
* that were filled (0 meaning buffer is empty).
|
||||
*
|
||||
* Hint: "struct iovec" is defined in <sys/uio.h> and looks like this:
|
||||
* struct iovec {
|
||||
* void *iov_base;
|
||||
* size_t iov_len;
|
||||
* };
|
||||
*/
|
||||
size_t ring_peek(struct ring *r, struct iovec *vec) {
|
||||
assert(r);
|
||||
|
||||
if (r->used == 0) {
|
||||
return 0;
|
||||
} else if (r->start + r->used <= r->size) {
|
||||
if (vec) {
|
||||
vec[0].iov_base = &r->buf[r->start];
|
||||
vec[0].iov_len = r->used;
|
||||
}
|
||||
return 1;
|
||||
} else {
|
||||
if (vec) {
|
||||
vec[0].iov_base = &r->buf[r->start];
|
||||
vec[0].iov_len = r->size - r->start;
|
||||
vec[1].iov_base = r->buf;
|
||||
vec[1].iov_len = r->used - (r->size - r->start);
|
||||
}
|
||||
return 2;
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Copy data from the ring buffer into the linear external buffer @buf. Copy
|
||||
* at most @size bytes. If the ring buffer size is smaller, copy less bytes and
|
||||
* return the number of bytes copied.
|
||||
*/
|
||||
size_t ring_copy(struct ring *r, void *buf, size_t size) {
|
||||
size_t l;
|
||||
|
||||
assert(r);
|
||||
assert(buf);
|
||||
|
||||
if (size > r->used)
|
||||
size = r->used;
|
||||
|
||||
if (size > 0) {
|
||||
l = r->size - r->start;
|
||||
if (size <= l) {
|
||||
memcpy(buf, &r->buf[r->start], size);
|
||||
} else {
|
||||
memcpy(buf, &r->buf[r->start], l);
|
||||
memcpy((uint8_t*)buf + l, r->buf, size - l);
|
||||
}
|
||||
}
|
||||
|
||||
return size;
|
||||
}
|
||||
|
||||
/*
|
||||
* Resize ring-buffer to size @nsize. @nsize must be a power-of-2, otherwise
|
||||
* ring operations will behave incorrectly.
|
||||
*/
|
||||
static int ring_resize(struct ring *r, size_t nsize) {
|
||||
uint8_t *buf;
|
||||
size_t l;
|
||||
|
||||
assert(r);
|
||||
assert(nsize > 0);
|
||||
|
||||
buf = malloc(nsize);
|
||||
if (!buf)
|
||||
return -ENOMEM;
|
||||
|
||||
if (r->used > 0) {
|
||||
l = r->size - r->start;
|
||||
if (r->used <= l) {
|
||||
memcpy(buf, &r->buf[r->start], r->used);
|
||||
} else {
|
||||
memcpy(buf, &r->buf[r->start], l);
|
||||
memcpy(&buf[l], r->buf, r->used - l);
|
||||
}
|
||||
}
|
||||
|
||||
free(r->buf);
|
||||
r->buf = buf;
|
||||
r->size = nsize;
|
||||
r->start = 0;
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
/*
|
||||
* Resize ring-buffer to provide enough room for @add bytes of new data. This
|
||||
* resizes the buffer if it is too small. It returns -ENOMEM on OOM and 0 on
|
||||
* success.
|
||||
*/
|
||||
static int ring_grow(struct ring *r, size_t add) {
|
||||
size_t need;
|
||||
|
||||
assert(r);
|
||||
|
||||
if (r->size - r->used >= add)
|
||||
return 0;
|
||||
|
||||
need = r->used + add;
|
||||
if (need <= r->used)
|
||||
return -ENOMEM;
|
||||
else if (need < 4096)
|
||||
need = 4096;
|
||||
|
||||
need = ALIGN_POWER2(need);
|
||||
if (need == 0)
|
||||
return -ENOMEM;
|
||||
|
||||
return ring_resize(r, need);
|
||||
}
|
||||
|
||||
/*
|
||||
* Push @len bytes from @u8 into the ring buffer. The buffer is resized if it
|
||||
* is too small. -ENOMEM is returned on OOM, 0 on success.
|
||||
*/
|
||||
int ring_push(struct ring *r, const void *u8, size_t size) {
|
||||
int err;
|
||||
size_t pos, l;
|
||||
|
||||
assert(r);
|
||||
assert(u8);
|
||||
|
||||
if (size == 0)
|
||||
return 0;
|
||||
|
||||
err = ring_grow(r, size);
|
||||
if (err < 0)
|
||||
return err;
|
||||
|
||||
pos = RING_MASK(r, r->start + r->used);
|
||||
l = r->size - pos;
|
||||
if (l >= size) {
|
||||
memcpy(&r->buf[pos], u8, size);
|
||||
} else {
|
||||
memcpy(&r->buf[pos], u8, l);
|
||||
memcpy(r->buf, (const uint8_t*)u8 + l, size - l);
|
||||
}
|
||||
|
||||
r->used += size;
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
/*
|
||||
* Remove @len bytes from the start of the ring-buffer. Note that we protect
|
||||
* against overflows so removing more bytes than available is safe.
|
||||
*/
|
||||
void ring_pull(struct ring *r, size_t size) {
|
||||
assert(r);
|
||||
|
||||
if (size > r->used)
|
||||
size = r->used;
|
||||
|
||||
r->start = RING_MASK(r, r->start + size);
|
||||
r->used -= size;
|
||||
}
|
59
src/shared/ring.h
Normal file
59
src/shared/ring.h
Normal file
@ -0,0 +1,59 @@
|
||||
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
|
||||
|
||||
#pragma once
|
||||
|
||||
/***
|
||||
This file is part of systemd.
|
||||
|
||||
Copyright 2014 David Herrmann <dh.herrmann@gmail.com>
|
||||
|
||||
systemd is free software; you can redistribute it and/or modify it
|
||||
under the terms of the GNU Lesser General Public License as published by
|
||||
the Free Software Foundation; either version 2.1 of the License, or
|
||||
(at your option) any later version.
|
||||
|
||||
systemd 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
|
||||
Lesser General Public License for more details.
|
||||
|
||||
You should have received a copy of the GNU Lesser General Public License
|
||||
along with systemd; If not, see <http://www.gnu.org/licenses/>.
|
||||
***/
|
||||
|
||||
#include <errno.h>
|
||||
#include <inttypes.h>
|
||||
#include <stdlib.h>
|
||||
#include <string.h>
|
||||
#include <sys/uio.h>
|
||||
|
||||
struct ring {
|
||||
uint8_t *buf; /* buffer or NULL */
|
||||
size_t size; /* actual size of @buf */
|
||||
size_t start; /* start position of ring */
|
||||
size_t used; /* number of actually used bytes */
|
||||
};
|
||||
|
||||
/* flush buffer so it is empty again */
|
||||
void ring_flush(struct ring *r);
|
||||
|
||||
/* flush buffer, free allocated data and reset to initial state */
|
||||
void ring_clear(struct ring *r);
|
||||
|
||||
/* get pointers to buffer data and their length */
|
||||
size_t ring_peek(struct ring *r, struct iovec *vec);
|
||||
|
||||
/* copy data into external linear buffer */
|
||||
size_t ring_copy(struct ring *r, void *buf, size_t size);
|
||||
|
||||
/* push data to the end of the buffer */
|
||||
int ring_push(struct ring *r, const void *u8, size_t size);
|
||||
|
||||
/* pull data from the front of the buffer */
|
||||
void ring_pull(struct ring *r, size_t size);
|
||||
|
||||
/* return size of occupied buffer in bytes */
|
||||
static inline size_t ring_get_size(struct ring *r)
|
||||
{
|
||||
return r->used;
|
||||
}
|
135
src/test/test-ring.c
Normal file
135
src/test/test-ring.c
Normal file
@ -0,0 +1,135 @@
|
||||
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
|
||||
|
||||
/***
|
||||
This file is part of systemd.
|
||||
|
||||
Copyright 2014 David Herrmann <dh.herrmann@gmail.com>
|
||||
|
||||
systemd is free software; you can redistribute it and/or modify it
|
||||
under the terms of the GNU Lesser General Public License as published by
|
||||
the Free Software Foundation; either version 2.1 of the License, or
|
||||
(at your option) any later version.
|
||||
|
||||
systemd 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
|
||||
Lesser General Public License for more details.
|
||||
|
||||
You should have received a copy of the GNU Lesser General Public License
|
||||
along with systemd; If not, see <http://www.gnu.org/licenses/>.
|
||||
***/
|
||||
|
||||
#include <string.h>
|
||||
#include <unistd.h>
|
||||
#include <fcntl.h>
|
||||
#include <locale.h>
|
||||
#include <errno.h>
|
||||
|
||||
#include "def.h"
|
||||
#include "ring.h"
|
||||
#include "util.h"
|
||||
|
||||
static void test_ring(void) {
|
||||
static const char buf[8192];
|
||||
struct ring r;
|
||||
size_t l;
|
||||
struct iovec vec[2];
|
||||
int s;
|
||||
|
||||
memset(&r, 0, sizeof(r));
|
||||
|
||||
l = ring_peek(&r, vec);
|
||||
assert_se(l == 0);
|
||||
|
||||
s = ring_push(&r, buf, 2048);
|
||||
assert_se(!s);
|
||||
assert_se(ring_get_size(&r) == 2048);
|
||||
|
||||
l = ring_peek(&r, vec);
|
||||
assert_se(l == 1);
|
||||
assert_se(vec[0].iov_len == 2048);
|
||||
assert_se(!memcmp(vec[0].iov_base, buf, vec[0].iov_len));
|
||||
assert_se(ring_get_size(&r) == 2048);
|
||||
|
||||
ring_pull(&r, 2048);
|
||||
assert_se(ring_get_size(&r) == 0);
|
||||
|
||||
l = ring_peek(&r, vec);
|
||||
assert_se(l == 0);
|
||||
assert_se(ring_get_size(&r) == 0);
|
||||
|
||||
s = ring_push(&r, buf, 2048);
|
||||
assert_se(!s);
|
||||
assert_se(ring_get_size(&r) == 2048);
|
||||
|
||||
l = ring_peek(&r, vec);
|
||||
assert_se(l == 1);
|
||||
assert_se(vec[0].iov_len == 2048);
|
||||
assert_se(!memcmp(vec[0].iov_base, buf, vec[0].iov_len));
|
||||
assert_se(ring_get_size(&r) == 2048);
|
||||
|
||||
s = ring_push(&r, buf, 1);
|
||||
assert_se(!s);
|
||||
assert_se(ring_get_size(&r) == 2049);
|
||||
|
||||
l = ring_peek(&r, vec);
|
||||
assert_se(l == 2);
|
||||
assert_se(vec[0].iov_len == 2048);
|
||||
assert_se(vec[1].iov_len == 1);
|
||||
assert_se(!memcmp(vec[0].iov_base, buf, vec[0].iov_len));
|
||||
assert_se(!memcmp(vec[1].iov_base, buf, vec[1].iov_len));
|
||||
assert_se(ring_get_size(&r) == 2049);
|
||||
|
||||
ring_pull(&r, 2048);
|
||||
assert_se(ring_get_size(&r) == 1);
|
||||
|
||||
l = ring_peek(&r, vec);
|
||||
assert_se(l == 1);
|
||||
assert_se(vec[0].iov_len == 1);
|
||||
assert_se(!memcmp(vec[0].iov_base, buf, vec[0].iov_len));
|
||||
assert_se(ring_get_size(&r) == 1);
|
||||
|
||||
ring_pull(&r, 1);
|
||||
assert_se(ring_get_size(&r) == 0);
|
||||
|
||||
s = ring_push(&r, buf, 2048);
|
||||
assert_se(!s);
|
||||
assert_se(ring_get_size(&r) == 2048);
|
||||
|
||||
s = ring_push(&r, buf, 2049);
|
||||
assert_se(!s);
|
||||
assert_se(ring_get_size(&r) == 4097);
|
||||
|
||||
l = ring_peek(&r, vec);
|
||||
assert_se(l == 1);
|
||||
assert_se(vec[0].iov_len == 4097);
|
||||
assert_se(!memcmp(vec[0].iov_base, buf, vec[0].iov_len));
|
||||
assert_se(ring_get_size(&r) == 4097);
|
||||
|
||||
ring_pull(&r, 1);
|
||||
assert_se(ring_get_size(&r) == 4096);
|
||||
|
||||
s = ring_push(&r, buf, 4096);
|
||||
assert_se(!s);
|
||||
assert_se(ring_get_size(&r) == 8192);
|
||||
|
||||
l = ring_peek(&r, vec);
|
||||
assert_se(l == 2);
|
||||
assert_se(vec[0].iov_len == 8191);
|
||||
assert_se(vec[1].iov_len == 1);
|
||||
assert_se(!memcmp(vec[0].iov_base, buf, vec[0].iov_len));
|
||||
assert_se(!memcmp(vec[1].iov_base, buf, vec[1].iov_len));
|
||||
assert_se(ring_get_size(&r) == 8192);
|
||||
|
||||
ring_clear(&r);
|
||||
assert_se(ring_get_size(&r) == 0);
|
||||
}
|
||||
|
||||
int main(int argc, char *argv[]) {
|
||||
log_parse_environment();
|
||||
log_open();
|
||||
|
||||
test_ring();
|
||||
|
||||
return 0;
|
||||
}
|
Loading…
Reference in New Issue
Block a user