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#include <string.h>
#include <ipc.h>
#include <mutex.h>
#include <thread.h>
static size_t channel_read(fs_node_ptr c, size_t offset, size_t len, char* buf);
static size_t channel_write(fs_node_ptr c, size_t offset, size_t len, const char* buf);
static bool channel_stat(fs_node_ptr c, stat_t *st);
static void channel_close(fs_node_ptr c);
static fs_node_ops_t channel_ops = {
.read = channel_read,
.write = channel_write,
.close = channel_close,
.open = 0,
.readdir = 0,
.ioctl = 0,
.stat = channel_stat,
.walk = 0,
.create = 0,
.move = 0,
.delete = 0,
.dispose = 0,
};
typedef struct channel {
struct channel *other_side;
mutex_t lock;
char buf[CHANNEL_BUFFER_SIZE];
size_t buf_use_begin, buf_used; // circular buffer
} channel_t;
fs_handle_pair_t make_channel() {
fs_handle_pair_t ret = { .a = 0, .b = 0 };
channel_t *a = 0, *b = 0;
a = (channel_t*)malloc(sizeof(channel_t));
if (a == 0) goto error;
b = (channel_t*)malloc(sizeof(channel_t));
if (b == 0) goto error;
ret.a = (fs_handle_t*)malloc(sizeof(fs_handle_t));
if (ret.a == 0) goto error;
ret.b = (fs_handle_t*)malloc(sizeof(fs_handle_t));
if (ret.b == 0) goto error;
a->other_side = b;
b->other_side = a;
a->lock = b->lock = MUTEX_UNLOCKED;
a->buf_use_begin = a->buf_used = 0;
b->buf_use_begin = b->buf_used = 0;
ret.a->fs = ret.b->fs = 0;
ret.a->node = ret.b->node = 0;
ret.a->ops = ret.b->ops = &channel_ops;
ret.a->data = a;
ret.b->data = b;
ret.a->refs = ret.b->refs = 1;
ret.a->mode = ret.b->mode = FM_READ | FM_WRITE;
return ret;
error:
if (a) free(a);
if (b) free(b);
if (ret.a) free(ret.a);
if (ret.b) free(ret.b);
ret.a = ret.b = 0;
return ret;
}
size_t channel_read(fs_node_ptr ch, size_t offset, size_t len, char* buf) {
channel_t *c = (channel_t*)ch;
mutex_lock(&c->lock);
if (c->buf_used < len) len = c->buf_used;
if (len) {
size_t len0 = len, len1 = 0;
if (c->buf_use_begin + len > CHANNEL_BUFFER_SIZE) {
len0 = CHANNEL_BUFFER_SIZE - c->buf_use_begin;
len1 = len - len0;
}
memcpy(buf, c->buf + c->buf_use_begin, len0);
if (len1) memcpy(buf + len0, c->buf, len1);
c->buf_use_begin = (c->buf_use_begin + len) % CHANNEL_BUFFER_SIZE;
c->buf_used -= len;
if (c->buf_used == 0) c->buf_use_begin = 0;
}
mutex_unlock(&c->lock);
return len;
}
size_t channel_write(fs_node_ptr ch, size_t offset, size_t len, const char* buf) {
channel_t *tc = (channel_t*)ch;
channel_t *c = tc->other_side;
if (c == 0) return 0;
while (!mutex_try_lock(&c->lock)) {
yield();
if (tc->other_side == 0) return 0;
}
if (c->buf_used + len > CHANNEL_BUFFER_SIZE) len = CHANNEL_BUFFER_SIZE - c->buf_used;
if (len) {
size_t len0 = len, len1 = 0;
if (c->buf_use_begin + c->buf_used + len > CHANNEL_BUFFER_SIZE) {
len0 = CHANNEL_BUFFER_SIZE - c->buf_use_begin - c->buf_used;
len1 = len - len0;
}
memcpy(c->buf + c->buf_use_begin + c->buf_used, buf, len0);
if (len1) memcpy(c->buf, buf + len0, len1);
c->buf_used += len;
}
mutex_unlock(&c->lock);
if (len) resume_on(c); // notify processes that may be waiting for data
return len;
}
bool channel_stat(fs_node_ptr ch, stat_t *st) {
channel_t *c = (channel_t*)ch;
mutex_lock(&c->lock);
st->type = FT_CHANNEL;
st->size = c->buf_used;
st->access = FM_READ | FM_WRITE;
mutex_unlock(&c->lock);
return true;
}
void channel_close(fs_node_ptr ch) {
channel_t *c = (channel_t*)ch;
mutex_lock(&c->lock);
c->other_side->other_side = 0;
free(c);
}
/* vim: set ts=4 sw=4 tw=0 noet :*/
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