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 #include <sys/types.h>
  24
  25 enum lttng_pipe_state {
  26         LTTNG_PIPE_STATE_OPENED = 1,
  27         LTTNG_PIPE_STATE_CLOSED = 2,
  28 };
  29
  30 struct lttng_pipe {
  31         /* Read: 0, Write: 1. */
  32         int fd[2];
  33         /*
  34          * Flags of the pipe once opened. pipe(2) specifies either O_NONBLOCK or
  35          * O_CLOEXEC can be used. Flags are set using fcntl(2) call.
  36          */
  37         int flags;
  38
  39         /*
  40          * These states are protected by the operation mutex below.
  41          */
  42         enum lttng_pipe_state r_state;
  43         enum lttng_pipe_state w_state;
  44
  45         /* Held for each read(2) operation. */
  46         pthread_mutex_t read_mutex;
  47         /* Held for each write(2) operation. */
  48         pthread_mutex_t write_mutex;
  49 };
  50
  51 /*
  52  * Return 1 if read side is open else 0.
  53  */
  54 static inline int lttng_pipe_is_read_open(const struct lttng_pipe *pipe)
  55 {
  56         return pipe->r_state == LTTNG_PIPE_STATE_OPENED ? 1 : 0;
  57 }
  58
  59 /*
  60  * Return 1 if write side is open else 0.
  61  */
  62 static inline int lttng_pipe_is_write_open(const struct lttng_pipe *pipe)
  63 {
  64         return pipe->w_state == LTTNG_PIPE_STATE_OPENED ? 1 : 0;
  65 }
  66
  67 static inline int lttng_pipe_get_readfd(const struct lttng_pipe *pipe)
  68 {
  69         return pipe->fd[0];
  70 }
  71
  72 static inline int lttng_pipe_get_writefd(const struct lttng_pipe *pipe)
  73 {
  74         return pipe->fd[1];
  75 }
  76
  77 LTTNG_HIDDEN
  78 struct lttng_pipe *lttng_pipe_open(int flags);
  79 LTTNG_HIDDEN
  80 struct lttng_pipe *lttng_pipe_named_open(const char *path, mode_t mode,
  81                 int flags);
  82 LTTNG_HIDDEN
  83 int lttng_pipe_write_close(struct lttng_pipe *pipe);
  84 LTTNG_HIDDEN
  85 int lttng_pipe_read_close(struct lttng_pipe *pipe);
  86 /* Close both side of pipe. */
  87 LTTNG_HIDDEN
  88 int lttng_pipe_close(struct lttng_pipe *pipe);
  89 LTTNG_HIDDEN
  90 void lttng_pipe_destroy(struct lttng_pipe *pipe);
  91
  92 LTTNG_HIDDEN
  93 ssize_t lttng_pipe_read(struct lttng_pipe *pipe, void *buf, size_t count);
  94 LTTNG_HIDDEN
  95 ssize_t lttng_pipe_write(struct lttng_pipe *pipe, const void *buf,
  96                 size_t count);
  97 /* Returns and releases the read end of the pipe. */
  98 LTTNG_HIDDEN
  99 int lttng_pipe_release_readfd(struct lttng_pipe *pipe);
 100 /* Returns and releases the write end of the pipe. */
 101 LTTNG_HIDDEN
 102 int lttng_pipe_release_writefd(struct lttng_pipe *pipe);
 103
 104 #endif /* LTTNG_PIPE_H */