4 files changed, 57 insertions, 25 deletions

diff --git a/include/grpc/support/useful.h b/include/grpc/support/useful.h
index 979f3d026b..e1ce0455c6 100644
--- a/include/grpc/support/useful.h
+++ b/include/grpc/support/useful.h
@@ -45,4 +45,11 @@
 
 #define GPR_ARRAY_SIZE(array) (sizeof(array) / sizeof(*(array)))
 
+#define GPR_SWAP(type, a, b) \
+  do {                   \
+    type x = a;          \
+    a = b;               \
+    b = x;               \
+  } while (0)
+
 #endif  /* GRPC_SUPPORT_USEFUL_H */
diff --git a/src/core/support/slice_buffer.c b/src/core/support/slice_buffer.c
index 3b1daa07c5..91b5d8c98b 100644
--- a/src/core/support/slice_buffer.c
+++ b/src/core/support/slice_buffer.c
@@ -37,6 +37,7 @@
 
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
+#include <grpc/support/useful.h>
 
 /* grow a buffer; requires GRPC_SLICE_BUFFER_INLINE_ELEMENTS > 1 */
 #define GROW(x) (3 * (x) / 2)
@@ -162,14 +163,30 @@ void gpr_slice_buffer_reset_and_unref(gpr_slice_buffer *sb) {
 }
 
 void gpr_slice_buffer_swap(gpr_slice_buffer *a, gpr_slice_buffer *b) {
-  gpr_slice_buffer temp = *a;
-  *a = *b;
-  *b = temp;
-
-  if (a->slices == b->inlined) {
+  GPR_SWAP(size_t, a->count, b->count);
+  GPR_SWAP(size_t, a->capacity, b->capacity);
+  GPR_SWAP(size_t, a->length, b->length);
+
+  if (a->slices == a->inlined) {
+    if (b->slices == b->inlined) {
+      /* swap contents of inlined buffer */
+      gpr_slice temp[GRPC_SLICE_BUFFER_INLINE_ELEMENTS];
+      memcpy(temp, a->slices, b->count * sizeof(gpr_slice));
+      memcpy(a->slices, b->slices, a->count * sizeof(gpr_slice));
+      memcpy(b->slices, temp, b->count * sizeof(gpr_slice));
+    } else {
+      /* a is inlined, b is not - copy a inlined into b, fix pointers */
+      a->slices = b->slices;
+      b->slices = b->inlined;
+      memcpy(b->slices, a->inlined, b->count * sizeof(gpr_slice));
+    }
+  } else if (b->slices == b->inlined) {
+    /* b is inlined, a is not - copy b inlined int a, fix pointers */
+    b->slices = a->slices;
     a->slices = a->inlined;
-  }
-  if (b->slices == a->inlined) {
-    b->slices = b->inlined;
+    memcpy(a->slices, b->inlined, a->count * sizeof(gpr_slice));
+  } else {
+    /* no inlining: easy swap */
+    GPR_SWAP(gpr_slice *, a->slices, b->slices);
   }
 }
diff --git a/src/core/surface/call.c b/src/core/surface/call.c
index 0782a58fda..7ab9142947 100644
--- a/src/core/surface/call.c
+++ b/src/core/surface/call.c
@@ -235,13 +235,6 @@ struct grpc_call {
 #define CALL_FROM_TOP_ELEM(top_elem) \
   CALL_FROM_CALL_STACK(grpc_call_stack_from_top_element(top_elem))
 
-#define SWAP(type, x, y) \
-  do {                   \
-    type temp = x;       \
-    x = y;               \
-    y = temp;            \
-  } while (0)
-
 static void do_nothing(void *ignored, grpc_op_error also_ignored) {}
 static void set_deadline_alarm(grpc_call *call, gpr_timespec deadline);
 static void call_on_done_recv(void *call, int success);
@@ -572,12 +565,12 @@ static void finish_live_ioreq_op(grpc_call *call, grpc_ioreq_op op,
                             call->request_data[GRPC_IOREQ_RECV_STATUS_DETAILS]);
           break;
         case GRPC_IOREQ_RECV_INITIAL_METADATA:
-          SWAP(grpc_metadata_array, call->buffered_metadata[0],
+          GPR_SWAP(grpc_metadata_array, call->buffered_metadata[0],
                *call->request_data[GRPC_IOREQ_RECV_INITIAL_METADATA]
                     .recv_metadata);
           break;
         case GRPC_IOREQ_RECV_TRAILING_METADATA:
-          SWAP(grpc_metadata_array, call->buffered_metadata[1],
+          GPR_SWAP(grpc_metadata_array, call->buffered_metadata[1],
                *call->request_data[GRPC_IOREQ_RECV_TRAILING_METADATA]
                     .recv_metadata);
           break;
diff --git a/src/core/transport/stream_op.c b/src/core/transport/stream_op.c
index e1a75adcb6..8996ecac35 100644
--- a/src/core/transport/stream_op.c
+++ b/src/core/transport/stream_op.c
@@ -59,15 +59,30 @@ void grpc_sopb_reset(grpc_stream_op_buffer *sopb) {
 }
 
 void grpc_sopb_swap(grpc_stream_op_buffer *a, grpc_stream_op_buffer *b) {
-  grpc_stream_op_buffer temp = *a;
-  *a = *b;
-  *b = temp;
-
-  if (a->ops == b->inlined_ops) {
+  GPR_SWAP(size_t, a->nops, b->nops);
+  GPR_SWAP(size_t, a->capacity, b->capacity);
+
+  if (a->ops == a->inlined_ops) {
+    if (b->ops == b->inlined_ops) {
+      /* swap contents of inlined buffer */
+      gpr_slice temp[GRPC_SOPB_INLINE_ELEMENTS];
+      memcpy(temp, a->ops, b->nops * sizeof(grpc_stream_op));
+      memcpy(a->ops, b->ops, a->nops * sizeof(grpc_stream_op));
+      memcpy(b->ops, temp, b->nops * sizeof(grpc_stream_op));
+    } else {
+      /* a is inlined, b is not - copy a inlined into b, fix pointers */
+      a->ops = b->ops;
+      b->ops = b->inlined_ops;
+      memcpy(b->ops, a->inlined_ops, b->nops * sizeof(grpc_stream_op));
+    }
+  } else if (b->ops == b->inlined_ops) {
+    /* b is inlined, a is not - copy b inlined int a, fix pointers */
+    b->ops = a->ops;
     a->ops = a->inlined_ops;
-  }
-  if (b->ops == a->inlined_ops) {
-    b->ops = b->inlined_ops;
+    memcpy(a->ops, b->inlined_ops, a->nops * sizeof(grpc_stream_op));
+  } else {
+    /* no inlining: easy swap */
+    GPR_SWAP(grpc_stream_op *, a->ops, b->ops);
   }
 }