[qemu]: Move qemu_pipe.h from include/system/ directory.

The <hardware/qemu_pipe.h> header isn't related to any loadable
hardware module, this patch thus relocates it to <system/qemu_pipe.h>
which is a much more logical location.

Note the following changes:

  - The pipe name must begin with the 'pipe:' prefix to avoid an
    un-necessary snprintf() and buffer copy.

  - Does not probe for the obsolete /dev/goldfish_pipe device, i.e.
    only use /dev/qemu_pipe instead.

  - Use QEMU_PIPE_DEBUG() instead of D() as the debugging macro.

+ Update ADB to use the newest <system/qemu_pipe.h>

+ Add qemu_pipe_frame_send() and qemu_pipe_frame_recv() utility
  functions which replace the obsolete qemud_channel_send() and
  qemud_channel_recv() from the defunct <hardware/qemud.h>
  header.

BUG=25875346

Change-Id: Ic290a5b79d466c2af64b49bd9134643277c11bfd

adb/transport_local.cpp

@@ -235,16 +235,20 @@ static void server_socket_thread(void* arg) {
 /* This is relevant only for ADB daemon running inside the emulator. */
 /*
  * Redefine open and write for qemu_pipe.h that contains inlined references
- * to those routines. We will redifine them back after qemu_pipe.h inclusion.
+ * to those routines. We will redefine them back after qemu_pipe.h inclusion.
  */
 #undef open
+#undef read
 #undef write
 #define open    adb_open
+#define read    adb_read
 #define write   adb_write
-#include <hardware/qemu_pipe.h>
+#include <system/qemu_pipe.h>
 #undef open
+#undef read
 #undef write
 #define open    ___xxx_open
+#define read    ___xxx_read
 #define write   ___xxx_write
 
 /* A worker thread that monitors host connections, and registers a transport for
@@ -292,7 +296,7 @@ static void qemu_socket_thread(void* arg) {
     D("transport: qemu_socket_thread() starting");
 
     /* adb QEMUD service connection request. */
-    snprintf(con_name, sizeof(con_name), "qemud:adb:%d", port);
+    snprintf(con_name, sizeof(con_name), "pipe:qemud:adb:%d", port);
 
     /* Connect to the adb QEMUD service. */
     fd = qemu_pipe_open(con_name);

include/system/qemu_pipe.h

@@ -0,0 +1,134 @@
+/*
+ * 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), "%04x", 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 != size) {
+        QEMU_PIPE_DEBUG("Could not read qemud frame payload: %s",
+                        strerror(errno));
+        return -1;
+    }
+    return size;
+}
+
+#endif /* ANDROID_INCLUDE_HARDWARE_QEMUD_PIPE_H */