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1 /*
2  *
3  * Copyright 2015 gRPC authors.
4  *
5  * Licensed under the Apache License, Version 2.0 (the "License");
6  * you may not use this file except in compliance with the License.
7  * You may obtain a copy of the License at
8  *
9  *     http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  *
17  */
18 
19 #include <grpc/support/port_platform.h>
20 
21 #include "src/core/lib/iomgr/port.h"
22 
23 #ifdef GRPC_POSIX_WAKEUP_FD
24 
25 #include "src/core/lib/iomgr/wakeup_fd_pipe.h"
26 #include "src/core/lib/iomgr/wakeup_fd_posix.h"
27 
28 #include <errno.h>
29 #include <string.h>
30 #include <unistd.h>
31 
32 #include <grpc/support/log.h>
33 
34 #include "src/core/lib/iomgr/socket_utils_posix.h"
35 
pipe_init(grpc_wakeup_fd * fd_info)36 static grpc_error* pipe_init(grpc_wakeup_fd* fd_info) {
37   int pipefd[2];
38   int r = pipe(pipefd);
39   if (0 != r) {
40     gpr_log(GPR_ERROR, "pipe creation failed (%d): %s", errno, strerror(errno));
41     return GRPC_OS_ERROR(errno, "pipe");
42   }
43   grpc_error* err;
44   err = grpc_set_socket_nonblocking(pipefd[0], 1);
45   if (err != GRPC_ERROR_NONE) return err;
46   err = grpc_set_socket_nonblocking(pipefd[1], 1);
47   if (err != GRPC_ERROR_NONE) return err;
48   fd_info->read_fd = pipefd[0];
49   fd_info->write_fd = pipefd[1];
50   return GRPC_ERROR_NONE;
51 }
52 
pipe_consume(grpc_wakeup_fd * fd_info)53 static grpc_error* pipe_consume(grpc_wakeup_fd* fd_info) {
54   char buf[128];
55   ssize_t r;
56 
57   for (;;) {
58     r = read(fd_info->read_fd, buf, sizeof(buf));
59     if (r > 0) continue;
60     if (r == 0) return GRPC_ERROR_NONE;
61     switch (errno) {
62       case EAGAIN:
63         return GRPC_ERROR_NONE;
64       case EINTR:
65         continue;
66       default:
67         return GRPC_OS_ERROR(errno, "read");
68     }
69   }
70 }
71 
pipe_wakeup(grpc_wakeup_fd * fd_info)72 static grpc_error* pipe_wakeup(grpc_wakeup_fd* fd_info) {
73   char c = 0;
74   while (write(fd_info->write_fd, &c, 1) != 1 && errno == EINTR)
75     ;
76   return GRPC_ERROR_NONE;
77 }
78 
pipe_destroy(grpc_wakeup_fd * fd_info)79 static void pipe_destroy(grpc_wakeup_fd* fd_info) {
80   if (fd_info->read_fd != 0) close(fd_info->read_fd);
81   if (fd_info->write_fd != 0) close(fd_info->write_fd);
82 }
83 
pipe_check_availability(void)84 static int pipe_check_availability(void) {
85   grpc_wakeup_fd fd;
86   fd.read_fd = fd.write_fd = -1;
87 
88   if (pipe_init(&fd) == GRPC_ERROR_NONE) {
89     pipe_destroy(&fd);
90     return 1;
91   } else {
92     return 0;
93   }
94 }
95 
96 const grpc_wakeup_fd_vtable grpc_pipe_wakeup_fd_vtable = {
97     pipe_init, pipe_consume, pipe_wakeup, pipe_destroy,
98     pipe_check_availability};
99 
100 #endif /* GPR_POSIX_WAKUP_FD */
101