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Revert "Revert "Qemu: make the qemu_pipe_open back compatible"" 

This reverts commit 79b3005899.
This commit is contained in:
bohu 2017-03-29 12:19:56 -07:00
parent ee13ff1b99
commit f868066daa
2 changed files with 20 additions and 37 deletions
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6
qemu_pipe/include/qemu_pipe.h
View File

@ -28,8 +28,10 @@ extern "C" {
// 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').
//
// and should begin with 'pipe:' (e.g. 'pipe:camera' or 'pipe:opengles').
// For backward compatibility, the 'pipe:' prefix can be omitted, and in
// that case, qemu_pipe_open will add it for you.
// On success, return a valid file descriptor, or -1/errno on failure. E.g.:
//
// EINVAL -> unknown/unsupported pipeName

51
qemu_pipe/qemu_pipe.cpp
View File

@ -34,29 +34,9 @@ using android::base::WriteFully;
# 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) {
if (!pipeName) {
errno = EINVAL;
return -1;
}
@ -70,18 +50,24 @@ int qemu_pipe_open(const char* pipeName) {
// 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;
if (WriteFully(fd, pipeName, pipeNameLen + 1U)) {
return fd;
}
return fd;
// now, add 'pipe:' prefix and try again
// Note: host side will wait for the trailing '\0' to start
// service lookup.
const char pipe_prefix[] = "pipe:";
if (WriteFully(fd, pipe_prefix, strlen(pipe_prefix)) &&
WriteFully(fd, pipeName, pipeNameLen + 1U)) {
return fd;
}
QEMU_PIPE_DEBUG("%s: Could not write to %s pipe service: %s",
__FUNCTION__, pipeName, strerror(errno));
close(fd);
return -1;
}
// 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);
@ -96,11 +82,6 @@ int qemu_pipe_frame_send(int fd, const void* buff, size_t len) {
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)) {