diff options
Diffstat (limited to 'qemu_pipe/qemu_pipe.cpp')
| -rw-r--r-- | qemu_pipe/qemu_pipe.cpp | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/qemu_pipe/qemu_pipe.cpp b/qemu_pipe/qemu_pipe.cpp new file mode 100644 index 000000000..a4529deb8 --- /dev/null +++ b/qemu_pipe/qemu_pipe.cpp @@ -0,0 +1,132 @@ +/* + * 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> + + +// 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); + 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. +int 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. +int 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; +} |