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