src/common/pipe.h

   1 /*
   2  * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License, version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc., 51
  15  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #ifndef LTTNG_PIPE_H
  19 #define LTTNG_PIPE_H
  20
  21 #include <pthread.h>
  22
  23 enum lttng_pipe_state {
  24         LTTNG_PIPE_STATE_OPENED = 1,
  25         LTTNG_PIPE_STATE_CLOSED = 2,
  26 };
  27
  28 struct lttng_pipe {
  29         /* Read: 0, Write: 1. */
  30         int fd[2];
  31         /*
  32          * Flags of the pipe once opened. pipe(2) specifies either O_NONBLOCK or
  33          * O_CLOEXEC can be used. Flags are set using fcntl(2) call.
  34          */
  35         int flags;
  36
  37         /*
  38          * These states are protected by the operation mutex below.
  39          */
  40         enum lttng_pipe_state r_state;
  41         enum lttng_pipe_state w_state;
  42
  43         /* Held for each read(2) operation. */
  44         pthread_mutex_t read_mutex;
  45         /* Held for each write(2) operation. */
  46         pthread_mutex_t write_mutex;
  47 };
  48
  49 /*
  50  * Return 1 if read side is open else 0.
  51  */
  52 static inline int lttng_pipe_is_read_open(struct lttng_pipe *pipe)
  53 {
  54         return pipe->r_state == LTTNG_PIPE_STATE_OPENED ? 1 : 0;
  55 }
  56
  57 /*
  58  * Return 1 if write side is open else 0.
  59  */
  60 static inline int lttng_pipe_is_write_open(struct lttng_pipe *pipe)
  61 {
  62         return pipe->w_state == LTTNG_PIPE_STATE_OPENED ? 1 : 0;
  63 }
  64
  65 static inline int lttng_pipe_get_readfd(struct lttng_pipe *pipe)
  66 {
  67         return pipe->fd[0];
  68 }
  69
  70 static inline int lttng_pipe_get_writefd(struct lttng_pipe *pipe)
  71 {
  72         return pipe->fd[1];
  73 }
  74
  75 struct lttng_pipe *lttng_pipe_open(int flags);
  76 int lttng_pipe_write_close(struct lttng_pipe *pipe);
  77 int lttng_pipe_read_close(struct lttng_pipe *pipe);
  78 /* Close both side of pipe. */
  79 int lttng_pipe_close(struct lttng_pipe *pipe);
  80 void lttng_pipe_destroy(struct lttng_pipe *pipe);
  81
  82 ssize_t lttng_pipe_read(struct lttng_pipe *pipe, void *buf, size_t count);
  83 ssize_t lttng_pipe_write(struct lttng_pipe *pipe, const void *buf,
  84                 size_t count);
  85
  86 #endif /* LTTNG_PIPE_H */