Qemu-pipe: refactor qemu_pipe.h into libqemu_pipe

Traditionally, qemu_pipe has both the declaration and implentation of each
function in one header file--qemu_pipe.h, and it is getting incovenient to
maintain.

This CL separates the implementation of functions from the header file,
and makes qemu_pipe a static library for other modules to link to.

Note that the interface and implementation of qemu_pipe are kept unchanged,
and future CLs will enhance the implementation to make it more reliable and
more compatible with old and new API levels.

Following projects are affected by this refactoring, and they are modified
accordingly:

hardware/ril/reference-ril

Change-Id: I541ecbf0cc7eadeef9d4e37ffd9ca7bfcc5c94c0
(cherry picked from aosp 294d44be33bf6ad6d7d53189d38202a4911f2bd7)

3 files changed, 213 insertions, 0 deletions

diff --git a/qemu_pipe/Android.mk b/qemu_pipe/Android.mk
new file mode 100644
index 000000000..6e0144ce1
--- /dev/null
+++ b/qemu_pipe/Android.mk
@@ -0,0 +1,19 @@
+# Copyright 2011 The Android Open Source Project
+
+LOCAL_PATH:= $(call my-dir)
+
+common_static_libraries := \
+    libbase
+include $(CLEAR_VARS)
+LOCAL_CLANG := true
+LOCAL_SANITIZE := integer
+LOCAL_SRC_FILES:= \
+    qemu_pipe.cpp
+LOCAL_C_INCLUDES := \
+    $(LOCAL_PATH)/include \
+    system/base/include
+LOCAL_MODULE:= libqemu_pipe
+LOCAL_STATIC_LIBRARIES := $(common_static_libraries)
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
+LOCAL_CFLAGS := -Werror
+include $(BUILD_STATIC_LIBRARY)
diff --git a/qemu_pipe/include/qemu_pipe.h b/qemu_pipe/include/qemu_pipe.h
new file mode 100644
index 000000000..16486c087
--- /dev/null
+++ b/qemu_pipe/include/qemu_pipe.h
@@ -0,0 +1,62 @@
+/*
+ * 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_CORE_INCLUDE_QEMU_PIPE_H
+#define ANDROID_CORE_INCLUDE_QEMU_PIPE_H
+
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#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);
+
+// 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);
+
+// 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);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ANDROID_CORE_INCLUDE_QEMU_PIPE_H */
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;
+}