src/common/pipe.h

   1 /*
   2  * Copyright (C) 2013 David Goulet <dgoulet@efficios.com>
   3  *
   4  * SPDX-License-Identifier: GPL-2.0-only
   5  *
   6  */
   7
   8 #ifndef LTTNG_PIPE_H
   9 #define LTTNG_PIPE_H
  10
  11 #include <pthread.h>
  12 #include <common/macros.h>
  13 #include <sys/types.h>
  14
  15 enum lttng_pipe_state {
  16         LTTNG_PIPE_STATE_OPENED = 1,
  17         LTTNG_PIPE_STATE_CLOSED = 2,
  18 };
  19
  20 struct lttng_pipe {
  21         /* Read: 0, Write: 1. */
  22         int fd[2];
  23         /*
  24          * Flags of the pipe once opened. pipe(2) specifies either O_NONBLOCK or
  25          * O_CLOEXEC can be used. Flags are set using fcntl(2) call.
  26          */
  27         int flags;
  28
  29         /*
  30          * These states are protected by the operation mutex below.
  31          */
  32         enum lttng_pipe_state r_state;
  33         enum lttng_pipe_state w_state;
  34
  35         /* Held for each read(2) operation. */
  36         pthread_mutex_t read_mutex;
  37         /* Held for each write(2) operation. */
  38         pthread_mutex_t write_mutex;
  39 };
  40
  41 /*
  42  * Return 1 if read side is open else 0.
  43  */
  44 static inline int lttng_pipe_is_read_open(const struct lttng_pipe *pipe)
  45 {
  46         return pipe->r_state == LTTNG_PIPE_STATE_OPENED ? 1 : 0;
  47 }
  48
  49 /*
  50  * Return 1 if write side is open else 0.
  51  */
  52 static inline int lttng_pipe_is_write_open(const struct lttng_pipe *pipe)
  53 {
  54         return pipe->w_state == LTTNG_PIPE_STATE_OPENED ? 1 : 0;
  55 }
  56
  57 static inline int lttng_pipe_get_readfd(const struct lttng_pipe *pipe)
  58 {
  59         return pipe->fd[0];
  60 }
  61
  62 static inline int lttng_pipe_get_writefd(const struct lttng_pipe *pipe)
  63 {
  64         return pipe->fd[1];
  65 }
  66
  67 struct lttng_pipe *lttng_pipe_open(int flags);
  68 struct lttng_pipe *lttng_pipe_named_open(const char *path, mode_t mode,
  69                 int flags);
  70 int lttng_pipe_write_close(struct lttng_pipe *pipe);
  71 int lttng_pipe_read_close(struct lttng_pipe *pipe);
  72 /* Close both side of pipe. */
  73 int lttng_pipe_close(struct lttng_pipe *pipe);
  74 void lttng_pipe_destroy(struct lttng_pipe *pipe);
  75
  76 ssize_t lttng_pipe_read(struct lttng_pipe *pipe, void *buf, size_t count);
  77 ssize_t lttng_pipe_write(struct lttng_pipe *pipe, const void *buf,
  78                 size_t count);
  79 /* Returns and releases the read end of the pipe. */
  80 int lttng_pipe_release_readfd(struct lttng_pipe *pipe);
  81 /* Returns and releases the write end of the pipe. */
  82 int lttng_pipe_release_writefd(struct lttng_pipe *pipe);
  83
  84 #endif /* LTTNG_PIPE_H */