src/bin/lttng-sessiond/utils.c

   1 /*
   2  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
   3  *                      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License, version 2 only,
   7  * as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #define _GNU_SOURCE
  20 #include <stdlib.h>
  21 #include <unistd.h>
  22
  23 #include <common/error.h>
  24
  25 #include "utils.h"
  26 #include "lttng-sessiond.h"
  27
  28 int ht_cleanup_pipe[2] = { -1, -1 };
  29
  30 /*
  31  * Write to writable pipe used to notify a thread.
  32  */
  33 int notify_thread_pipe(int wpipe)
  34 {
  35         int ret;
  36
  37         /* Ignore if the pipe is invalid. */
  38         if (wpipe < 0) {
  39                 return 0;
  40         }
  41
  42         do {
  43                 ret = write(wpipe, "!", 1);
  44         } while (ret < 0 && errno == EINTR);
  45         if (ret < 0) {
  46                 PERROR("write poll pipe");
  47         }
  48
  49         return ret;
  50 }
  51
  52 void ht_cleanup_push(struct lttng_ht *ht)
  53 {
  54         int ret;
  55         int fd = ht_cleanup_pipe[1];
  56
  57         if (fd < 0)
  58                 return;
  59         do {
  60                 ret = write(fd, &ht, sizeof(ht));
  61         } while (ret < 0 && errno == EINTR);
  62         if (ret < 0 || ret != sizeof(ht)) {
  63                 PERROR("write ht cleanup pipe %d", fd);
  64                 if (ret < 0) {
  65                         ret = -errno;
  66                 }
  67                 goto error;
  68         }
  69
  70         /* All good. Don't send back the write positive ret value. */
  71         ret = 0;
  72 error:
  73         assert(!ret);
  74 }