summaryrefslogtreecommitdiffstats
blob: af2507997ccd1641ba3ebface63f27f011a36535 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#ifndef ANDROID_INCLUDE_SYSTEM_QEMU_PIPE_H
#define ANDROID_INCLUDE_SYSTEM_QEMU_PIPE_H

#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>

// Define QEMU_PIPE_DEBUG if you want to print error messages when an error
// occurs during pipe operations. The macro should simply take a printf-style
// formatting string followed by optional arguments.
#ifndef QEMU_PIPE_DEBUG
#  define  QEMU_PIPE_DEBUG(...)   (void)0
#endif

// Try to open a new Qemu fast-pipe. This function returns a file descriptor
// that can be used to communicate with a named service managed by the
// emulator.
//
// This file descriptor can be used as a standard pipe/socket descriptor.
//
// 'pipeName' is the name of the emulator service you want to connect to,
// and must begin with 'pipe:' (e.g. 'pipe:camera' or 'pipe:opengles').
//
// On success, return a valid file descriptor, or -1/errno on failure. E.g.:
//
// EINVAL  -> unknown/unsupported pipeName
// ENOSYS  -> fast pipes not available in this system.
//
// ENOSYS should never happen, except if you're trying to run within a
// misconfigured emulator.
//
// You should be able to open several pipes to the same pipe service,
// except for a few special cases (e.g. GSM modem), where EBUSY will be
// returned if more than one client tries to connect to it.
static __inline__ int qemu_pipe_open(const char* pipeName) {
    // Sanity check.
    if (!pipeName || memcmp(pipeName, "pipe:", 5) != 0) {
        errno = EINVAL;
        return -1;
    }

    int fd = TEMP_FAILURE_RETRY(open("/dev/qemu_pipe", O_RDWR));
    if (fd < 0) {
        QEMU_PIPE_DEBUG("%s: Could not open /dev/qemu_pipe: %s", __FUNCTION__,
                        strerror(errno));
        return -1;
    }

    // Write the pipe name, *including* the trailing zero which is necessary.
    size_t pipeNameLen = strlen(pipeName);
    ssize_t ret = TEMP_FAILURE_RETRY(write(fd, pipeName, pipeNameLen + 1U));
    if (ret != (ssize_t)pipeNameLen + 1) {
        QEMU_PIPE_DEBUG("%s: Could not connect to %s pipe service: %s",
                        __FUNCTION__, pipeName, strerror(errno));
        if (ret == 0) {
            errno = ECONNRESET;
        } else if (ret > 0) {
            errno = EINVAL;
        }
        return -1;
    }
    return fd;
}

// Send a framed message |buff| of |len| bytes through the |fd| descriptor.
// This really adds a 4-hexchar prefix describing the payload size.
// Returns 0 on success, and -1 on error.
static int __inline__ qemu_pipe_frame_send(int fd,
                                           const void* buff,
                                           size_t len) {
    char header[5];
    snprintf(header, sizeof(header), "%04zx", len);
    ssize_t ret = TEMP_FAILURE_RETRY(write(fd, header, 4));
    if (ret != 4) {
        QEMU_PIPE_DEBUG("Can't write qemud frame header: %s", strerror(errno));
        return -1;
    }
    ret = TEMP_FAILURE_RETRY(write(fd, buff, len));
    if (ret != (ssize_t)len) {
        QEMU_PIPE_DEBUG("Can't write qemud frame payload: %s", strerror(errno));
        return -1;
    }
    return 0;
}

// Read a frame message from |fd|, and store it into |buff| of |len| bytes.
// If the framed message is larger than |len|, then this returns -1 and the
// content is lost. Otherwise, this returns the size of the message. NOTE:
// empty messages are possible in a framed wire protocol and do not mean
// end-of-stream.
static int __inline__ qemu_pipe_frame_recv(int fd, void* buff, size_t len) {
    char header[5];
    ssize_t ret = TEMP_FAILURE_RETRY(read(fd, header, 4));
    if (ret != 4) {
        QEMU_PIPE_DEBUG("Can't read qemud frame header: %s", strerror(errno));
        return -1;
    }
    header[4] = '\0';
    size_t size;
    if (sscanf(header, "%04zx", &size) != 1) {
        QEMU_PIPE_DEBUG("Malformed qemud frame header: [%.*s]", 4, header);
        return -1;
    }
    if (size > len) {
        QEMU_PIPE_DEBUG("Oversized qemud frame (% bytes, expected <= %)", size,
                        len);
        return -1;
    }
    ret = TEMP_FAILURE_RETRY(read(fd, buff, size));
    if (ret != (ssize_t)size) {
        QEMU_PIPE_DEBUG("Could not read qemud frame payload: %s",
                        strerror(errno));
        return -1;
    }
    return size;
}

#endif /* ANDROID_INCLUDE_HARDWARE_QEMUD_PIPE_H */