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/*
* 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.
*/
#include "qemu_pipe.h"
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include <stdio.h>
#include <android-base/file.h>
using android::base::ReadFully;
using android::base::WriteFully;
// 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.
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);
if (!WriteFully(fd, pipeName, pipeNameLen + 1U)) {
QEMU_PIPE_DEBUG("%s: Could not connect to %s pipe service: %s",
__FUNCTION__, pipeName, strerror(errno));
close(fd);
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.
int qemu_pipe_frame_send(int fd, const void* buff, size_t len) {
char header[5];
snprintf(header, sizeof(header), "%04zx", len);
if (!WriteFully(fd, header, 4)) {
QEMU_PIPE_DEBUG("Can't write qemud frame header: %s", strerror(errno));
return -1;
}
if (!WriteFully(fd, buff, 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.
int qemu_pipe_frame_recv(int fd, void* buff, size_t len) {
char header[5];
if (!ReadFully(fd, header, 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;
}
if (!ReadFully(fd, buff, size)) {
QEMU_PIPE_DEBUG("Could not read qemud frame payload: %s",
strerror(errno));
return -1;
}
return size;
}
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