diff options
Diffstat (limited to 'src/util/fifo_trigger.c')
| -rw-r--r-- | src/util/fifo_trigger.c | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/src/util/fifo_trigger.c b/src/util/fifo_trigger.c new file mode 100644 index 0000000..e5c5604 --- /dev/null +++ b/src/util/fifo_trigger.c @@ -0,0 +1,168 @@ +/*++ +/* 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 |