Revert "Qemu: make the qemu_pipe_open back compatible"
It broke master
BUG: 36695011
This reverts commit a19abf17697863c2458d7d085a225ff4f3c75f75.
Change-Id: Id9a2bc058e92a4fb2ac202f8b723062a047a1e35
diff --git a/qemu_pipe/include/qemu_pipe.h b/qemu_pipe/include/qemu_pipe.h
index 0987498..16486c0 100644
--- a/qemu_pipe/include/qemu_pipe.h
+++ b/qemu_pipe/include/qemu_pipe.h
@@ -28,10 +28,8 @@
// 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 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.
-
+// 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
diff --git a/qemu_pipe/qemu_pipe.cpp b/qemu_pipe/qemu_pipe.cpp
index beeccb0..ca3b795 100644
--- a/qemu_pipe/qemu_pipe.cpp
+++ b/qemu_pipe/qemu_pipe.cpp
@@ -34,9 +34,29 @@
# 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) {
+ if (!pipeName || memcmp(pipeName, "pipe:", 5) != 0) {
errno = EINVAL;
return -1;
}
@@ -50,24 +70,18 @@
// Write the pipe name, *including* the trailing zero which is necessary.
size_t pipeNameLen = strlen(pipeName);
- if (WriteFully(fd, pipeName, pipeNameLen + 1U)) {
- return fd;
+ 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;
}
-
- // 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;
+ 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);
@@ -82,6 +96,11 @@
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)) {