From bf0492a9a1e3976dd4aea5596d1b1e10e8cbeea2 Mon Sep 17 00:00:00 2001
From: Elliott Hughes <enh@google.com>
Date: Mon, 1 May 2017 21:34:15 -0700
Subject: [PATCH] Preserve errno better in native_handle functions.

So a caller of native_handle_clone can trust errno to be relevant.

Bug: http://b/37215366
Test: builds
Change-Id: I0992f38ad559db4a02fce07123842dbad8e3f473
---
 libcutils/native_handle.c | 42 ++++++++++++++++-----------------------
 1 file changed, 17 insertions(+), 25 deletions(-)

diff --git a/libcutils/native_handle.c b/libcutils/native_handle.c
index 9f4840a59..95bbc41c4 100644
--- a/libcutils/native_handle.c
+++ b/libcutils/native_handle.c
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#define LOG_TAG "NativeHandle"
+#include <cutils/native_handle.h>
 
 #include <errno.h>
 #include <stdint.h>
@@ -22,15 +22,12 @@
 #include <string.h>
 #include <unistd.h>
 
-#include <android/log.h>
-#include <cutils/native_handle.h>
-
 static const int kMaxNativeFds = 1024;
 static const int kMaxNativeInts = 1024;
 
-native_handle_t* native_handle_init(char* storage, int numFds, int numInts)
-{
+native_handle_t* native_handle_init(char* storage, int numFds, int numInts) {
     if ((uintptr_t) storage % alignof(native_handle_t)) {
+        errno = EINVAL;
         return NULL;
     }
 
@@ -38,13 +35,12 @@ native_handle_t* native_handle_init(char* storage, int numFds, int numInts)
     handle->version = sizeof(native_handle_t);
     handle->numFds = numFds;
     handle->numInts = numInts;
-
     return handle;
 }
 
-native_handle_t* native_handle_create(int numFds, int numInts)
-{
+native_handle_t* native_handle_create(int numFds, int numInts) {
     if (numFds < 0 || numInts < 0 || numFds > kMaxNativeFds || numInts > kMaxNativeInts) {
+        errno = EINVAL;
         return NULL;
     }
 
@@ -58,14 +54,13 @@ native_handle_t* native_handle_create(int numFds, int numInts)
     return h;
 }
 
-native_handle_t* native_handle_clone(const native_handle_t* handle)
-{
+native_handle_t* native_handle_clone(const native_handle_t* handle) {
     native_handle_t* clone = native_handle_create(handle->numFds, handle->numInts);
-    int i;
+    if (clone == NULL) return NULL;
 
-    for (i = 0; i < handle->numFds; i++) {
+    for (int i = 0; i < handle->numFds; i++) {
         clone->data[i] = dup(handle->data[i]);
-        if (clone->data[i] < 0) {
+        if (clone->data[i] == -1) {
             clone->numFds = i;
             native_handle_close(clone);
             native_handle_delete(clone);
@@ -74,30 +69,27 @@ native_handle_t* native_handle_clone(const native_handle_t* handle)
     }
 
     memcpy(&clone->data[handle->numFds], &handle->data[handle->numFds],
-            sizeof(int) * handle->numInts);
+           sizeof(int) * handle->numInts);
 
     return clone;
 }
 
-int native_handle_delete(native_handle_t* h)
-{
+int native_handle_delete(native_handle_t* h) {
     if (h) {
-        if (h->version != sizeof(native_handle_t))
-            return -EINVAL;
+        if (h->version != sizeof(native_handle_t)) return -EINVAL;
         free(h);
     }
     return 0;
 }
 
-int native_handle_close(const native_handle_t* h)
-{
-    if (h->version != sizeof(native_handle_t))
-        return -EINVAL;
+int native_handle_close(const native_handle_t* h) {
+    if (h->version != sizeof(native_handle_t)) return -EINVAL;
 
+    int saved_errno = errno;
     const int numFds = h->numFds;
-    int i;
-    for (i=0 ; i<numFds ; i++) {
+    for (int i = 0; i < numFds; ++i) {
         close(h->data[i]);
     }
+    errno = saved_errno;
     return 0;
 }