external/ibm-public/postfix/dist/src/util/fifo_trigger.c

   1 /*      $NetBSD$        */
   2
   3 /*++
   4 /* NAME
   5 /*      fifo_trigger 3
   6 /* SUMMARY
   7 /*      wakeup fifo server
   8 /* SYNOPSIS
   9 /*      #include <trigger.h>
  10 /*
  11 /*      int     fifo_trigger(service, buf, len, timeout)
  12 /*      const char *service;
  13 /*      const char *buf;
  14 /*      ssize_t len;
  15 /*      int     timeout;
  16 /* DESCRIPTION
  17 /*      fifo_trigger() wakes up the named fifo server by writing
  18 /*      the contents of the specified buffer to the fifo. There is
  19 /*      no guarantee that the written data will actually be received.
  20 /*
  21 /*      Arguments:
  22 /* .IP service
  23 /*      Name of the communication endpoint.
  24 /* .IP buf
  25 /*      Address of data to be written.
  26 /* .IP len
  27 /*      Amount of data to be written.
  28 /* .IP timeout
  29 /*      Deadline in seconds. Specify a value <= 0 to disable
  30 /*      the time limit.
  31 /* DIAGNOSTICS
  32 /*      The result is zero when the fifo could be opened, -1 otherwise.
  33 /* BUGS
  34 /* LICENSE
  35 /* .ad
  36 /* .fi
  37 /*      The Secure Mailer license must be distributed with this software.
  38 /* AUTHOR(S)
  39 /*      Wietse Venema
  40 /*      IBM T.J. Watson Research
  41 /*      P.O. Box 704
  42 /*      Yorktown Heights, NY 10598, USA
  43 /*--*/
  44
  45 /* System library. */
  46
  47 #include <sys_defs.h>
  48 #include <fcntl.h>
  49 #include <unistd.h>
  50
  51 /* Utility library. */
  52
  53 #include <msg.h>
  54 #include <iostuff.h>
  55 #include <safe_open.h>
  56 #include <trigger.h>
  57
  58 /* fifo_trigger - wakeup fifo server */
  59
  60 int     fifo_trigger(const char *service, const char *buf, ssize_t len, int timeout)
  61 {
  62     static VSTRING *why;
  63     const char *myname = "fifo_trigger";
  64     VSTREAM *fp;
  65     int     fd;
  66
  67     if (why == 0)
  68         why = vstring_alloc(1);
  69
  70     /*
  71      * Write the request to the service fifo. According to POSIX, the open
  72      * shall always return immediately, and shall return an error when no
  73      * process is reading from the FIFO.
  74      *
  75      * Use safe_open() so that we don't follow symlinks, and so that we don't
  76      * open files with multiple hard links. We're not (yet) going to bother
  77      * the caller with safe_open() specific quirks such as the why argument.
  78      */
  79     if ((fp = safe_open(service, O_WRONLY | O_NONBLOCK, 0,
  80                         (struct stat *) 0, -1, -1, why)) == 0) {
  81         if (msg_verbose)
  82             msg_info("%s: open %s: %s", myname, service, vstring_str(why));
  83         return (-1);
  84     }
  85     fd = vstream_fileno(fp);
  86
  87     /*
  88      * Write the request...
  89      */
  90     non_blocking(fd, timeout > 0 ? NON_BLOCKING : BLOCKING);
  91     if (write_buf(fd, buf, len, timeout) < 0)
  92         if (msg_verbose)
  93             msg_warn("%s: write %s: %m", myname, service);
  94
  95     /*
  96      * Disconnect.
  97      */
  98     if (vstream_fclose(fp))
  99         if (msg_verbose)
 100             msg_warn("%s: close %s: %m", myname, service);
 101     return (0);
 102 }
 103
 104 #ifdef TEST
 105
 106  /*
 107   * Set up a FIFO listener, and keep triggering until the listener becomes
 108   * idle, which should never happen.
 109   */
 110 #include <signal.h>
 111 #include <stdlib.h>
 112
 113 #include "events.h"
 114 #include "listen.h"
 115
 116 #define TEST_FIFO       "test-fifo"
 117
 118 int     trig_count;
 119 int     wakeup_count;
 120
 121 static void cleanup(void)
 122 {
 123     unlink(TEST_FIFO);
 124     exit(1);
 125 }
 126
 127 static void handler(int sig)
 128 {
 129     msg_fatal("got signal %d after %d triggers %d wakeups",
 130               sig, trig_count, wakeup_count);
 131 }
 132
 133 static void read_event(int unused_event, char *context)
 134 {
 135     int     fd = CAST_CHAR_PTR_TO_INT(context);
 136     char    ch;
 137
 138     wakeup_count++;
 139
 140     if (read(fd, &ch, 1) != 1)
 141         msg_fatal("read %s: %m", TEST_FIFO);
 142 }
 143
 144 int     main(int unused_argc, char **unused_argv)
 145 {
 146     int     listen_fd;
 147
 148     listen_fd = fifo_listen(TEST_FIFO, 0600, NON_BLOCKING);
 149     msg_cleanup(cleanup);
 150     event_enable_read(listen_fd, read_event, CAST_INT_TO_CHAR_PTR(listen_fd));
 151     signal(SIGINT, handler);
 152     signal(SIGALRM, handler);
 153     for (;;) {
 154         alarm(10);
 155         if (fifo_trigger(TEST_FIFO, "", 1, 0) < 0)
 156             msg_fatal("trigger %s: %m", TEST_FIFO);
 157         trig_count++;
 158         if (fifo_trigger(TEST_FIFO, "", 1, 0) < 0)
 159             msg_fatal("trigger %s: %m", TEST_FIFO);
 160         trig_count++;
 161         if (fifo_trigger(TEST_FIFO, "", 1, 0) < 0)
 162             msg_fatal("trigger %s: %m", TEST_FIFO);
 163         trig_count++;
 164         event_loop(-1);
 165         event_loop(-1);
 166         event_loop(-1);
 167     }
 168 }
 169
 170 #endif