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 #include <common/macros.h>
  23
  24 enum lttng_pipe_state {
  25         LTTNG_PIPE_STATE_OPENED = 1,
  26         LTTNG_PIPE_STATE_CLOSED = 2,
  27 };
  28
  29 struct lttng_pipe {
  30         /* Read: 0, Write: 1. */
  31         int fd[2];
  32         /*
  33          * Flags of the pipe once opened. pipe(2) specifies either O_NONBLOCK or
  34          * O_CLOEXEC can be used. Flags are set using fcntl(2) call.
  35          */
  36         int flags;
  37
  38         /*
  39          * These states are protected by the operation mutex below.
  40          */
  41         enum lttng_pipe_state r_state;
  42         enum lttng_pipe_state w_state;
  43
  44         /* Held for each read(2) operation. */
  45         pthread_mutex_t read_mutex;
  46         /* Held for each write(2) operation. */
  47         pthread_mutex_t write_mutex;
  48 };
  49
  50 /*
  51  * Return 1 if read side is open else 0.
  52  */
  53 static inline int lttng_pipe_is_read_open(struct lttng_pipe *pipe)
  54 {
  55         return pipe->r_state == LTTNG_PIPE_STATE_OPENED ? 1 : 0;
  56 }
  57
  58 /*
  59  * Return 1 if write side is open else 0.
  60  */
  61 static inline int lttng_pipe_is_write_open(struct lttng_pipe *pipe)
  62 {
  63         return pipe->w_state == LTTNG_PIPE_STATE_OPENED ? 1 : 0;
  64 }
  65
  66 static inline int lttng_pipe_get_readfd(struct lttng_pipe *pipe)
  67 {
  68         return pipe->fd[0];
  69 }
  70
  71 static inline int lttng_pipe_get_writefd(struct lttng_pipe *pipe)
  72 {
  73         return pipe->fd[1];
  74 }
  75
  76 LTTNG_HIDDEN
  77 struct lttng_pipe *lttng_pipe_open(int flags);
  78 LTTNG_HIDDEN
  79 int lttng_pipe_write_close(struct lttng_pipe *pipe);
  80 LTTNG_HIDDEN
  81 int lttng_pipe_read_close(struct lttng_pipe *pipe);
  82 /* Close both side of pipe. */
  83 LTTNG_HIDDEN
  84 int lttng_pipe_close(struct lttng_pipe *pipe);
  85 LTTNG_HIDDEN
  86 void lttng_pipe_destroy(struct lttng_pipe *pipe);
  87
  88 LTTNG_HIDDEN
  89 ssize_t lttng_pipe_read(struct lttng_pipe *pipe, void *buf, size_t count);
  90 LTTNG_HIDDEN
  91 ssize_t lttng_pipe_write(struct lttng_pipe *pipe, const void *buf,
  92                 size_t count);
  93
  94 #endif /* LTTNG_PIPE_H */