libbinder: build ParcelFileDescriptor on Trusty

Adds ParcelFileDescriptor.cpp to the Trusty build
which in turn compiles some extra related code from
Parcel.cpp. This code uses fcntl(...O_DUPFD_CLOEXEC...)
to duplicate file descriptors which is not available
on Trusty (or other OSes), so we abstract the relevant
calls to that function in a wrapper in OS.cpp.

Bug: 224644083
Test: m
Test: build on Trusty
Change-Id: I2e0ee517e7c7b55458a6ee6db977985aab4d7c58

5 files changed, 37 insertions, 8 deletions

diff --git a/libs/binder/OS.cpp b/libs/binder/OS.cpp
index 6eb72726f5..cc4a03ba67 100644
--- a/libs/binder/OS.cpp
+++ b/libs/binder/OS.cpp
@@ -48,4 +48,14 @@ status_t getRandomBytes(uint8_t* data, size_t size) {
     return OK;
 }
 
+status_t dupFileDescriptor(int oldFd, int* newFd) {
+    int ret = fcntl(oldFd, F_DUPFD_CLOEXEC, 0);
+    if (ret < 0) {
+        return -errno;
+    }
+
+    *newFd = ret;
+    return OK;
+}
+
 } // namespace android
diff --git a/libs/binder/OS.h b/libs/binder/OS.h
index e802e9cede..d6e1c78ae9 100644
--- a/libs/binder/OS.h
+++ b/libs/binder/OS.h
@@ -28,4 +28,6 @@ android::base::Result<void> setNonBlocking(android::base::borrowed_fd fd);
 
 status_t getRandomBytes(uint8_t* data, size_t size);
 
+status_t dupFileDescriptor(int oldFd, int* newFd);
+
 } // namespace android
diff --git a/libs/binder/Parcel.cpp b/libs/binder/Parcel.cpp
index 8b5d11800f..888757214d 100644
--- a/libs/binder/Parcel.cpp
+++ b/libs/binder/Parcel.cpp
@@ -48,6 +48,7 @@
 #include <utils/String8.h>
 #include <utils/misc.h>
 
+#include "OS.h"
 #include "RpcState.h"
 #include "Static.h"
 #include "Utils.h"
@@ -1477,9 +1478,9 @@ status_t Parcel::writeFileDescriptor(int fd, bool takeOwnership) {
 
 status_t Parcel::writeDupFileDescriptor(int fd)
 {
-    int dupFd = fcntl(fd, F_DUPFD_CLOEXEC, 0);
-    if (dupFd < 0) {
-        return -errno;
+    int dupFd;
+    if (status_t err = dupFileDescriptor(fd, &dupFd); err != OK) {
+        return err;
     }
     status_t err = writeFileDescriptor(dupFd, true /*takeOwnership*/);
     if (err != OK) {
@@ -1496,9 +1497,9 @@ status_t Parcel::writeParcelFileDescriptor(int fd, bool takeOwnership)
 
 status_t Parcel::writeDupParcelFileDescriptor(int fd)
 {
-    int dupFd = fcntl(fd, F_DUPFD_CLOEXEC, 0);
-    if (dupFd < 0) {
-        return -errno;
+    int dupFd;
+    if (status_t err = dupFileDescriptor(fd, &dupFd); err != OK) {
+        return err;
     }
     status_t err = writeParcelFileDescriptor(dupFd, true /*takeOwnership*/);
     if (err != OK) {
@@ -2295,7 +2296,12 @@ status_t Parcel::readUniqueFileDescriptor(base::unique_fd* val) const
         return BAD_TYPE;
     }
 
-    val->reset(fcntl(got, F_DUPFD_CLOEXEC, 0));
+    int dupFd;
+    if (status_t err = dupFileDescriptor(got, &dupFd); err != OK) {
+        return BAD_VALUE;
+    }
+
+    val->reset(dupFd);
 
     if (val->get() < 0) {
         return BAD_VALUE;
@@ -2312,7 +2318,12 @@ status_t Parcel::readUniqueParcelFileDescriptor(base::unique_fd* val) const
         return BAD_TYPE;
     }
 
-    val->reset(fcntl(got, F_DUPFD_CLOEXEC, 0));
+    int dupFd;
+    if (status_t err = dupFileDescriptor(got, &dupFd); err != OK) {
+        return BAD_VALUE;
+    }
+
+    val->reset(dupFd);
 
     if (val->get() < 0) {
         return BAD_VALUE;
diff --git a/libs/binder/trusty/OS.cpp b/libs/binder/trusty/OS.cpp
index 187add4a7b..bbfa3818ea 100644
--- a/libs/binder/trusty/OS.cpp
+++ b/libs/binder/trusty/OS.cpp
@@ -32,4 +32,9 @@ status_t getRandomBytes(uint8_t* data, size_t size) {
     return res == 1 ? OK : UNKNOWN_ERROR;
 }
 
+status_t dupFileDescriptor(int oldFd, int* newFd) {
+    // TODO: implement separately
+    return INVALID_OPERATION;
+}
+
 } // namespace android
diff --git a/libs/binder/trusty/rules.mk b/libs/binder/trusty/rules.mk
index 83475f58d4..d0d0861416 100644
--- a/libs/binder/trusty/rules.mk
+++ b/libs/binder/trusty/rules.mk
@@ -36,6 +36,7 @@ MODULE_SRCS := \
 	$(LIBBINDER_DIR)/IInterface.cpp \
 	$(LIBBINDER_DIR)/IResultReceiver.cpp \
 	$(LIBBINDER_DIR)/Parcel.cpp \
+	$(LIBBINDER_DIR)/ParcelFileDescriptor.cpp \
 	$(LIBBINDER_DIR)/RpcServer.cpp \
 	$(LIBBINDER_DIR)/RpcSession.cpp \
 	$(LIBBINDER_DIR)/RpcState.cpp \