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| | /*
* Copyright (C) 2012-2020 all contributors <cmogstored-public@yhbt.net>
* License: GPL-3.0+ <https://www.gnu.org/licenses/gpl-3.0.txt>
*/
#include "cmogstored.h"
struct mog_wbuf {
size_t len;
size_t off;
unsigned char buf[FLEXIBLE_ARRAY_MEMBER];
};
static void * wbuf_newv(size_t total, struct iovec *iov, int iovcnt)
{
struct mog_wbuf *wbuf = malloc(sizeof(struct mog_wbuf) + total);
void *dst;
int i;
if (!wbuf) return MOG_WR_ERROR;
dst = wbuf->buf;
wbuf->len = total;
wbuf->off = 0;
for (i = 0; i < iovcnt; i++)
dst = mempcpy(dst, iov[i].iov_base, iov[i].iov_len);
return wbuf;
}
static void * wbuf_new(void *buf, size_t len)
{
struct iovec iov;
iov.iov_base = buf;
iov.iov_len = len;
return wbuf_newv(len, &iov, 1);
}
MOG_NOINLINE static void sysbug(const char *fn, ssize_t bytes)
{
syslog(LOG_ERR, "%s returned %zd bytes written but: %m", fn, bytes);
}
enum mog_write_state mog_tryflush(int fd, struct mog_wbuf **x)
{
struct mog_wbuf *wbuf = *x;
unsigned char *ptr = wbuf->buf + wbuf->off;
size_t len = wbuf->len - wbuf->off;
for (;;) {
ssize_t w = write(fd, ptr, len);
if (w == len) {
mog_free_and_null(x);
return MOG_WRSTATE_DONE;
}
if (w >= 0) {
wbuf->off += w;
ptr += w;
len -= w;
continue;
}
assert(w < 0 && "no error from write(2)");
switch (errno) {
case_EAGAIN: return MOG_WRSTATE_BUSY;
case EINTR: continue;
}
mog_free_and_null(x);
return MOG_WRSTATE_ERR;
}
}
/*
* returns
* - NULL on full write
* - MOG_WR_ERROR on error (and sets errno)
* - address to a new mog_wbuf with unbuffered contents on partial write
*/
void * mog_trywritev(int fd, struct iovec *iov, int iovcnt)
{
ssize_t len = 0;
ssize_t w;
int i;
for (i = 0; i < iovcnt; i++)
len += iov[i].iov_len;
if (len == 0)
return NULL;
retry:
w = writev(fd, iov, iovcnt);
if (w == len) {
return NULL;
} else if (w <= 0) {
switch (errno) {
case_EAGAIN:
TRACE(CMOGSTORED_WRITE_BUFFERED(fd, len));
return wbuf_newv(len, iov, iovcnt);
case EINTR: goto retry;
case 0: sysbug("writev", w);
}
return MOG_WR_ERROR;
} else {
struct iovec *new_iov = iov;
len -= w;
/* skip over iovecs we've already written completely */
for (i = 0; i < iovcnt; i++, new_iov++) {
if (w == 0)
break;
/*
* partially written iovec,
* modify and retry with current iovec in front
*/
if (new_iov->iov_len > (size_t)w) {
unsigned char *base = new_iov->iov_base;
new_iov->iov_len -= w;
base += w;
new_iov->iov_base = (void *)base;
break;
}
w -= new_iov->iov_len;
}
/* retry without the already-written iovecs */
iovcnt -= i;
iov = new_iov;
goto retry;
}
}
/*
* returns
* - NULL on full write
* - MOG_WR_ERROR on error (and sets errno)
* - address to a new mog_wbuf with unbuffered contents on partial write
*/
void * mog_trysend(int fd, void *buf, size_t len, off_t more)
{
if (MOG_MSG_MORE) {
int flags = more > 0 ? MOG_MSG_MORE : 0;
while (len > 0) {
ssize_t w = send(fd, buf, len, flags);
if (w == (ssize_t)len)
return NULL; /* all done */
if (w > 0) {
buf = (char *)buf + w;
len -= w;
continue;
}
/*
* we bail on w == 0, too. send should normally
* return zero, but in case there's a kernel bug
* we should not infinite loop
*/
switch (errno) {
case_EAGAIN:
TRACE(CMOGSTORED_WRITE_BUFFERED(fd, len));
return wbuf_new(buf, len);
case EINTR: continue;
case 0: sysbug("send", w);
}
return MOG_WR_ERROR;
}
return NULL;
} else {
struct iovec iov;
iov.iov_base = buf;
iov.iov_len = len;
return mog_trywritev(fd, &iov, 1);
}
}
|