often bigger) so even if we are reading while the subprocess is still going, we
should never have only a partial item in the buffer.
+hs12: This assumption is not true anymore, since we got quit large items (certificate
+information and such)
+
Argument:
poffset the offset of the parlist item
eop TRUE if the process has completed
address_item *addr = p->addr;
pid_t pid = p->pid;
int fd = p->fd;
-uschar *endptr = big_buffer;
-uschar *ptr = endptr;
+int required = PIPE_HEADER_SIZE; /* size including id, subid and length */
+
uschar *msg = p->msg;
BOOL done = p->done;
BOOL finished = FALSE;
-/* minimum size to read is header size including id, subid and length */
-int required = PIPE_HEADER_SIZE;
/* Loop through all items, reading from the pipe when necessary. The pipe
-is set up to be non-blocking, but there are two different Unix mechanisms in
-use. Exim uses O_NONBLOCK if it is defined. This returns 0 for end of file,
-and EAGAIN for no more data. If O_NONBLOCK is not defined, Exim uses O_NDELAY,
-which returns 0 for both end of file and no more data. We distinguish the
-two cases by taking 0 as end of file only when we know the process has
-completed.
-
-Each separate item is written to the pipe in a single write(), and as they are
-all short items, the writes will all be atomic and we should never find
-ourselves in the position of having read an incomplete item. "Short" in this
-case can mean up to about 1K in the case when there is a long error message
-associated with an address.
-
-write(3) [Linux] says that atomic writes are not interleaved with each other.
-Not more.
+used to be non-blocking. But I do not see a reason for using non-blocking I/O
+here, as the preceding select() tells us, if data is available for reading.
+
+A read() on a "selected" handle should never block, but(!) it may return
+less data then we expected. (The buffer size we pass to read() shouldn't be
+understood as a "request", but as a "limit".)
+
+Each separate item is written to the pipe in a timely manner. But, especially for
+larger items, the read(2) may already return partial data from the write(2).
+
+The write is atomic mostly (depending on the amount written), but atomic does
+not imply "all or noting", it just is "not intermixed" with other writes on the
+same channel (pipe).
*/
DEBUG(D_deliver) debug_printf("reading pipe for subprocess %d (%s)\n",
- (int)p->pid, eop? "ended" : "not ended");
+ (int)p->pid, eop? "ended" : "not ended yet");
while (!done)
{
retry_item *r, **rp;
- int remaining = endptr - ptr;
- uschar header[PIPE_HEADER_SIZE + 1];
- uschar id, subid;
- uschar *endc;
-
- /* Read (first time) or top up the chars in the buffer if necessary.
- There will be only one read if we get all the available data (i.e. don't
- fill the buffer completely). */
-
- if (remaining < required && !finished)
- {
- int len;
- int available = big_buffer_size - remaining;
-
- if (remaining > 0) memmove(big_buffer, ptr, remaining);
-
- ptr = big_buffer;
- endptr = big_buffer + remaining;
- len = read(fd, endptr, available);
-
- DEBUG(D_deliver) debug_printf("read() yielded %d\n", len);
-
- /* If the result is EAGAIN and the process is not complete, just
- stop reading any more and process what we have already. */
-
- if (len < 0)
- {
- if (!eop && errno == EAGAIN) len = 0; else
- {
- msg = string_sprintf("failed to read pipe from transport process "
- "%d for transport %s: %s", pid, addr->transport->driver_name,
- strerror(errno));
- break;
- }
- }
-
- /* If the length is zero (eof or no-more-data), just process what we
- already have. Note that if the process is still running and we have
- read all the data in the pipe (but less that "available") then we
- won't read any more, as "finished" will get set. */
-
- endptr += len;
- remaining += len;
- finished = len != available;
+ uschar pipeheader[PIPE_HEADER_SIZE+1];
+ uschar *id = &pipeheader[0];
+ uschar *subid = &pipeheader[1];
+ uschar *ptr = big_buffer;
+ size_t required = PIPE_HEADER_SIZE; /* first the pipehaeder, later the data */
+ ssize_t got;
+
+ DEBUG(D_deliver) debug_printf("expect %d bytes (pipeheader) from transport process %d\n", required, pid);
+
+ /* We require(!) all the PIPE_HEADER_SIZE bytes here, as we know,
+ they're written in a timely manner, so waiting for the write shouldn't hurt a lot.
+ If we get less, we can assume the subprocess do be done and do not expect any further
+ information from it. */
+ got = readn(fd, pipeheader, required);
+ if (got != required)
+ {
+ msg = string_sprintf("got %d of %d bytes (pipeheader) "
+ "from transport process %d for transport %s",
+ got, PIPE_HEADER_SIZE, pid, addr->transport->driver_name);
+ done = TRUE;
+ break;
}
- /* If we are at the end of the available data, exit the loop. */
- if (ptr >= endptr) break;
+ pipeheader[PIPE_HEADER_SIZE] = '\0';
+ DEBUG(D_deliver)
+ debug_printf("got %d bytes (pipeheader) from transport process %d\n", got, pid);
- /* copy and read header */
- memcpy(header, ptr, PIPE_HEADER_SIZE);
- header[PIPE_HEADER_SIZE] = '\0';
- id = header[0];
- subid = header[1];
- required = Ustrtol(header + 2, &endc, 10) + PIPE_HEADER_SIZE; /* header + data */
+ {
+ /* If we can't decode the pipeheader, the subprocess seems to have a
+ problem, we do not expect any furher information from it. */
+ char *endc;
+ required = strtol(pipeheader+2, &endc, 10);
if (*endc)
{
- msg = string_sprintf("failed to read pipe from transport process "
- "%d for transport %s: error reading size from header", pid, addr->transport->driver_name);
+ msg = string_sprintf("failed to read pipe "
+ "from transport process %d for transport %s: error decoding size from header",
+ pid, addr->transport->driver_name);
done = TRUE;
break;
}
+ }
DEBUG(D_deliver)
- debug_printf("header read id:%c,subid:%c,size:%s,required:%d,remaining:%d,finished:%d\n",
- id, subid, header+2, required, remaining, finished);
-
- /* is there room for the dataset we want to read ? */
- if (required > big_buffer_size - PIPE_HEADER_SIZE)
- {
- msg = string_sprintf("failed to read pipe from transport process "
- "%d for transport %s: big_buffer too small! required size=%d buffer size=%d", pid, addr->transport->driver_name,
- required, big_buffer_size - PIPE_HEADER_SIZE);
- done = TRUE;
- break;
- }
+ debug_printf("expect %d bytes (pipedata) from transport process %d\n", required, pid);
- /* We wrote all datasets with atomic write() calls. Remaining < required only
- happens if big_buffer was too small to get all available data from pipe;
- finished has to be false as well. */
-
- if (remaining < required)
+ /* Same as above, the transport process will write the bytes announced
+ in a timely manner, so we can just wait for the bytes, getting less than expected
+ is considered a problem of the subprocess, we do not expect anything else from it. */
+ got = readn(fd, big_buffer, required);
+ if (got != required)
{
- if (!finished)
- continue;
- msg = string_sprintf("failed to read pipe from transport process "
- "%d for transport %s: required size=%d > remaining size=%d and finished=true",
- pid, addr->transport->driver_name, required, remaining);
- done = TRUE;
- break;
+ msg = string_sprintf("got only %d of %d bytes (pipedata) "
+ "from transport process %d for transport %s",
+ got, required, pid, addr->transport->driver_name);
+ done = TRUE;
+ break;
}
- /* Step past the header */
- ptr += PIPE_HEADER_SIZE;
-
/* Handle each possible type of item, assuming the complete item is
available in store. */
- switch (id)
+ switch (*id)
{
/* Host items exist only if any hosts were marked unusable. Match
up by checking the IP address. */
#ifdef SUPPORT_TLS
case 'X':
if (!addr) goto ADDR_MISMATCH; /* Below, in 'A' handler */
- switch (subid)
+ switch (*subid)
{
case '1':
addr->cipher = NULL;
#endif /*SUPPORT_TLS*/
case 'C': /* client authenticator information */
- switch (subid)
+ switch (*subid)
{
case '1': addr->authenticator = *ptr ? string_copy(ptr) : NULL; break;
case '2': addr->auth_id = *ptr ? string_copy(ptr) : NULL; break;
break;
}
- switch (subid)
+ switch (*subid)
{
#ifdef SUPPORT_SOCKS
case '2': /* proxy information; must arrive before A0 and applies to that addr XXX oops*/
p->done = done;
/* If the process hadn't finished, and we haven't seen the end of the data
-or suffered a disaster, update the rest of the state, and return FALSE to
+or if we suffered a disaster, update the rest of the state, and return FALSE to
indicate "not finished". */
if (!eop && !done)
addr->transport_return = DEFER;
addr->special_action = SPECIAL_FREEZE;
addr->message = msg;
+ log_write(0, LOG_MAIN|LOG_PANIC, "Delivery status for %s: %s\n", addr->address, addr->message);
}
/* Return TRUE to indicate we have got all we need from this process, even
}
}
-
-
static void
-rmt_dlv_checked_write(int fd, char id, char subid, void * buf, int size)
+rmt_dlv_checked_write(int fd, char id, char subid, void * buf, ssize_t size)
{
uschar pipe_header[PIPE_HEADER_SIZE+1];
size_t total_len = PIPE_HEADER_SIZE + size;
{ buf, size } /* *the* data */
};
-int ret;
+ssize_t ret;
/* we assume that size can't get larger then BIG_BUFFER_SIZE which currently is set to 16k */
/* complain to log if someone tries with buffer sizes we can't handle*/
if ((ret = writev(fd, iov, 2)) != total_len)
log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Failed writing transport result to pipe (%d of %d bytes): %s",
- ret == -1 ? 0 : ret, total_len,
+ ret, total_len,
ret == -1 ? strerror(errno) : "short write");
}
search_tidyup();
+
if ((pid = fork()) == 0)
{
int fd = pfd[pipe_write];
host_item *h;
+ DEBUG(D_deliver) debug_selector |= D_pid; // hs12
/* Setting this global in the subprocess means we need never clear it */
transport_name = tp->name;
/* Fork failed; defer with error message */
- if (pid < 0)
+ if (pid == -1)
{
(void)close(pfd[pipe_read]);
panicmsg = string_sprintf("fork failed for remote delivery to %s: %s",
git://git.exim.org / exim.git / blobdiff