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/*++
/* NAME
/* fifo_trigger 3
/* SUMMARY
/* wakeup fifo server
/* SYNOPSIS
/* #include <trigger.h>
/*
/* int fifo_trigger(service, buf, len, timeout)
/* const char *service;
/* const char *buf;
/* ssize_t len;
/* int timeout;
/* DESCRIPTION
/* fifo_trigger() wakes up the named fifo server by writing
/* the contents of the specified buffer to the fifo. There is
/* no guarantee that the written data will actually be received.
/*
/* Arguments:
/* .IP service
/* Name of the communication endpoint.
/* .IP buf
/* Address of data to be written.
/* .IP len
/* Amount of data to be written.
/* .IP timeout
/* Deadline in seconds. Specify a value <= 0 to disable
/* the time limit.
/* DIAGNOSTICS
/* The result is zero when the fifo could be opened, -1 otherwise.
/* BUGS
/* LICENSE
/* .ad
/* .fi
/* The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/* Wietse Venema
/* IBM T.J. Watson Research
/* P.O. Box 704
/* Yorktown Heights, NY 10598, USA
/*--*/
/* System library. */
#include <sys_defs.h>
#include <fcntl.h>
#include <unistd.h>
/* Utility library. */
#include <msg.h>
#include <iostuff.h>
#include <safe_open.h>
#include <trigger.h>
/* fifo_trigger - wakeup fifo server */
int fifo_trigger(const char *service, const char *buf, ssize_t len, int timeout)
{
static VSTRING *why;
const char *myname = "fifo_trigger";
VSTREAM *fp;
int fd;
if (why == 0)
why = vstring_alloc(1);
/*
* Write the request to the service fifo. According to POSIX, the open
* shall always return immediately, and shall return an error when no
* process is reading from the FIFO.
*
* Use safe_open() so that we don't follow symlinks, and so that we don't
* open files with multiple hard links. We're not (yet) going to bother
* the caller with safe_open() specific quirks such as the why argument.
*/
if ((fp = safe_open(service, O_WRONLY | O_NONBLOCK, 0,
(struct stat *) 0, -1, -1, why)) == 0) {
if (msg_verbose)
msg_info("%s: open %s: %s", myname, service, vstring_str(why));
return (-1);
}
fd = vstream_fileno(fp);
/*
* Write the request...
*/
non_blocking(fd, timeout > 0 ? NON_BLOCKING : BLOCKING);
if (write_buf(fd, buf, len, timeout) < 0)
if (msg_verbose)
msg_warn("%s: write %s: %m", myname, service);
/*
* Disconnect.
*/
if (vstream_fclose(fp))
if (msg_verbose)
msg_warn("%s: close %s: %m", myname, service);
return (0);
}
#ifdef TEST
/*
* Set up a FIFO listener, and keep triggering until the listener becomes
* idle, which should never happen.
*/
#include <signal.h>
#include <stdlib.h>
#include "events.h"
#include "listen.h"
#define TEST_FIFO "test-fifo"
int trig_count;
int wakeup_count;
static void cleanup(void)
{
unlink(TEST_FIFO);
exit(1);
}
static void handler(int sig)
{
msg_fatal("got signal %d after %d triggers %d wakeups",
sig, trig_count, wakeup_count);
}
static void read_event(int unused_event, char *context)
{
int fd = CAST_ANY_PTR_TO_INT(context);
char ch;
wakeup_count++;
if (read(fd, &ch, 1) != 1)
msg_fatal("read %s: %m", TEST_FIFO);
}
int main(int unused_argc, char **unused_argv)
{
int listen_fd;
listen_fd = fifo_listen(TEST_FIFO, 0600, NON_BLOCKING);
msg_cleanup(cleanup);
event_enable_read(listen_fd, read_event, CAST_INT_TO_VOID_PTR(listen_fd));
signal(SIGINT, handler);
signal(SIGALRM, handler);
for (;;) {
alarm(10);
if (fifo_trigger(TEST_FIFO, "", 1, 0) < 0)
msg_fatal("trigger %s: %m", TEST_FIFO);
trig_count++;
if (fifo_trigger(TEST_FIFO, "", 1, 0) < 0)
msg_fatal("trigger %s: %m", TEST_FIFO);
trig_count++;
if (fifo_trigger(TEST_FIFO, "", 1, 0) < 0)
msg_fatal("trigger %s: %m", TEST_FIFO);
trig_count++;
event_loop(-1);
event_loop(-1);
event_loop(-1);
}
}
#endif
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