src/common/pipe.hpp

   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 <common/macros.hpp>
  12 #include <common/make-unique-wrapper.hpp>
  13
  14 #include <pthread.h>
  15 #include <sys/types.h>
  16
  17 enum lttng_pipe_state {
  18         LTTNG_PIPE_STATE_OPENED = 1,
  19         LTTNG_PIPE_STATE_CLOSED = 2,
  20 };
  21
  22 /* Close both side of pipe. */
  23 int lttng_pipe_close(struct lttng_pipe *pipe);
  24
  25 struct lttng_pipe {
  26         static void _lttng_pipe_close_wrapper(lttng_pipe *pipe)
  27         {
  28                 lttng_pipe_close(pipe);
  29         }
  30
  31         using uptr = std::unique_ptr<
  32                 lttng_pipe,
  33                 lttng::details::create_unique_class<lttng_pipe, _lttng_pipe_close_wrapper>::deleter>;
  34
  35         /* Read: 0, Write: 1. */
  36         int fd[2];
  37         /*
  38          * Flags of the pipe once opened. pipe(2) specifies either O_NONBLOCK or
  39          * O_CLOEXEC can be used. Flags are set using fcntl(2) call.
  40          */
  41         int flags;
  42
  43         /*
  44          * These states are protected by the operation mutex below.
  45          */
  46         enum lttng_pipe_state r_state;
  47         enum lttng_pipe_state w_state;
  48
  49         /* Held for each read(2) operation. */
  50         pthread_mutex_t read_mutex;
  51         /* Held for each write(2) operation. */
  52         pthread_mutex_t write_mutex;
  53 };
  54
  55 /*
  56  * Return 1 if read side is open else 0.
  57  */
  58 static inline int lttng_pipe_is_read_open(const struct lttng_pipe *pipe)
  59 {
  60         return pipe->r_state == LTTNG_PIPE_STATE_OPENED ? 1 : 0;
  61 }
  62
  63 /*
  64  * Return 1 if write side is open else 0.
  65  */
  66 static inline int lttng_pipe_is_write_open(const struct lttng_pipe *pipe)
  67 {
  68         return pipe->w_state == LTTNG_PIPE_STATE_OPENED ? 1 : 0;
  69 }
  70
  71 static inline int lttng_pipe_get_readfd(const struct lttng_pipe *pipe)
  72 {
  73         return pipe->fd[0];
  74 }
  75
  76 static inline int lttng_pipe_get_writefd(const struct lttng_pipe *pipe)
  77 {
  78         return pipe->fd[1];
  79 }
  80
  81 struct lttng_pipe *lttng_pipe_open(int flags);
  82 struct lttng_pipe *lttng_pipe_named_open(const char *path, mode_t mode,
  83                 int flags);
  84 int lttng_pipe_write_close(struct lttng_pipe *pipe);
  85 int lttng_pipe_read_close(struct lttng_pipe *pipe);
  86 void lttng_pipe_destroy(struct lttng_pipe *pipe);
  87
  88 ssize_t lttng_pipe_read(struct lttng_pipe *pipe, void *buf, size_t count);
  89 ssize_t lttng_pipe_write(struct lttng_pipe *pipe, const void *buf,
  90                 size_t count);
  91 /* Returns and releases the read end of the pipe. */
  92 int lttng_pipe_release_readfd(struct lttng_pipe *pipe);
  93 /* Returns and releases the write end of the pipe. */
  94 int lttng_pipe_release_writefd(struct lttng_pipe *pipe);
  95
  96 #endif /* LTTNG_PIPE_H */