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 void lttng_pipe_destroy(struct lttng_pipe *pipe);
  25
  26 struct lttng_pipe {
  27         using uptr = std::unique_ptr<
  28                 lttng_pipe,
  29                 lttng::memory::create_deleter_class<lttng_pipe, lttng_pipe_destroy>::deleter>;
  30
  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 struct lttng_pipe *lttng_pipe_open(int flags);
  78 struct lttng_pipe *lttng_pipe_named_open(const char *path, mode_t mode, int flags);
  79 int lttng_pipe_write_close(struct lttng_pipe *pipe);
  80 int lttng_pipe_read_close(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, size_t count);
  84 /* Returns and releases the read end of the pipe. */
  85 int lttng_pipe_release_readfd(struct lttng_pipe *pipe);
  86 /* Returns and releases the write end of the pipe. */
  87 int lttng_pipe_release_writefd(struct lttng_pipe *pipe);
  88
  89 #endif /* LTTNG_PIPE_H */