Address comments from Vijay.

src/core/ext/transport/chttp2/transport/frame_data.cc

@@ -137,10 +137,10 @@ grpc_error* grpc_deframe_unprocessed_incoming_frames(
             p->error = grpc_error_set_int(p->error, GRPC_ERROR_INT_STREAM_ID,
                                           static_cast<intptr_t>(s->id));
             gpr_free(msg);
-            p->error = grpc_error_set_str(
-                p->error, GRPC_ERROR_STR_RAW_BYTES,
-                grpc_slice_from_moved_string(grpc_core::UniquePtr<char>(
-                    grpc_dump_slice(*slice, GPR_DUMP_HEX | GPR_DUMP_ASCII))));
+            p->error =
+                grpc_error_set_str(p->error, GRPC_ERROR_STR_RAW_BYTES,
+                                   grpc_dump_slice_to_slice(
+                                       *slice, GPR_DUMP_HEX | GPR_DUMP_ASCII));
             p->error =
                 grpc_error_set_int(p->error, GRPC_ERROR_INT_OFFSET, cur - beg);
             p->state = GRPC_CHTTP2_DATA_ERROR;

src/core/lib/gpr/string.cc

@@ -126,7 +126,8 @@ static void asciidump(dump_out* out, const char* buf, size_t len) {
   }
 }
 
-char* gpr_dump(const char* buf, size_t len, uint32_t flags) {
+char* gpr_dump_return_len(const char* buf, size_t len, uint32_t flags,
+                          size_t* out_len) {
   dump_out out = dump_out_create();
   if (flags & GPR_DUMP_HEX) {
     hexdump(&out, buf, len);
@@ -135,9 +136,15 @@ char* gpr_dump(const char* buf, size_t len, uint32_t flags) {
     asciidump(&out, buf, len);
   }
   dump_out_append(&out, 0);
+  *out_len = out.length;
   return out.data;
 }
 
+char* gpr_dump(const char* buf, size_t len, uint32_t flags) {
+  size_t unused;
+  return gpr_dump_return_len(buf, len, flags, &unused);
+}
+
 int gpr_parse_bytes_to_uint32(const char* buf, size_t len, uint32_t* result) {
   uint32_t out = 0;
   uint32_t new_val;

src/core/lib/gpr/string.h

@@ -32,9 +32,14 @@
 #define GPR_DUMP_HEX 0x00000001
 #define GPR_DUMP_ASCII 0x00000002
 
-/* Converts array buf, of length len, into a C string  according to the flags.
+/* Converts array buf, of length len, into a C string according to the flags.
    Result should be freed with gpr_free() */
 char* gpr_dump(const char* buf, size_t len, uint32_t flags);
+/* Converts array buf, of length len, into a C string according to the flags.
+   The length of the returned buffer is stored in out_len.
+   Result should be freed with gpr_free() */
+char* gpr_dump_return_len(const char* buf, size_t len, uint32_t flags,
+                          size_t* out_len);
 
 /* Parses an array of bytes into an integer (base 10). Returns 1 on success,
    0 on failure. */

src/core/lib/slice/slice.cc

@@ -216,8 +216,8 @@ grpc_slice grpc_slice_from_copied_string(const char* source) {
   return grpc_slice_from_copied_buffer(source, strlen(source));
 }
 
-grpc_slice grpc_slice_from_moved_string(grpc_core::UniquePtr<char> p) {
-  const size_t len = strlen(p.get());
+grpc_slice grpc_slice_from_moved_buffer(grpc_core::UniquePtr<char> p,
+                                        size_t len) {
   uint8_t* ptr = reinterpret_cast<uint8_t*>(p.get());
   grpc_slice slice;
   if (len <= sizeof(slice.data.inlined.bytes)) {
@@ -234,6 +234,11 @@ grpc_slice grpc_slice_from_moved_string(grpc_core::UniquePtr<char> p) {
   return slice;
 }
 
+grpc_slice grpc_slice_from_moved_string(grpc_core::UniquePtr<char> p) {
+  const size_t len = strlen(p.get());
+  return grpc_slice_from_moved_buffer(std::move(p), len);
+}
+
 namespace {
 
 class MallocRefCount {

src/core/lib/slice/slice_internal.h

@@ -303,6 +303,8 @@ inline uint32_t grpc_slice_hash_internal(const grpc_slice& s) {
                                : grpc_slice_hash_refcounted(s);
 }
 
+grpc_slice grpc_slice_from_moved_buffer(grpc_core::UniquePtr<char> p,
+                                        size_t len);
 grpc_slice grpc_slice_from_moved_string(grpc_core::UniquePtr<char> p);
 
 // Returns the memory used by this slice, not counting the slice structure

src/core/lib/slice/slice_string_helpers.cc

@@ -25,6 +25,7 @@
 #include <grpc/support/log.h>
 
 #include "src/core/lib/gpr/string.h"
+#include "src/core/lib/gprpp/memory.h"
 #include "src/core/lib/slice/slice_internal.h"
 
 char* grpc_dump_slice(const grpc_slice& s, uint32_t flags) {
@@ -32,6 +33,14 @@ char* grpc_dump_slice(const grpc_slice& s, uint32_t flags) {
                   GRPC_SLICE_LENGTH(s), flags);
 }
 
+grpc_slice grpc_dump_slice_to_slice(const grpc_slice& s, uint32_t flags) {
+  size_t len;
+  grpc_core::UniquePtr<char> ptr(
+      gpr_dump_return_len(reinterpret_cast<const char*> GRPC_SLICE_START_PTR(s),
+                          GRPC_SLICE_LENGTH(s), flags, &len));
+  return grpc_slice_from_moved_buffer(std::move(ptr), len);
+}
+
 /** Finds the initial (\a begin) and final (\a end) offsets of the next
  * substring from \a str + \a read_offset until the next \a sep or the end of \a
  * str.

src/core/lib/slice/slice_string_helpers.h

@@ -31,6 +31,8 @@
 
 /* Calls gpr_dump on a slice. */
 char* grpc_dump_slice(const grpc_slice& slice, uint32_t flags);
+/* Calls gpr_dump on a slice and returns the result as a slice. */
+grpc_slice grpc_dump_slice_to_slice(const grpc_slice& slice, uint32_t flags);
 
 /** Split \a str by the separator \a sep. Results are stored in \a dst, which
  * should be a properly initialized instance. */

src/core/lib/surface/validate_metadata.cc

@@ -40,13 +40,12 @@ static grpc_error* conforms_to(const grpc_slice& slice,
     int byte = idx / 8;
     int bit = idx % 8;
     if ((legal_bits[byte] & (1 << bit)) == 0) {
-      char* dump = grpc_dump_slice(slice, GPR_DUMP_HEX | GPR_DUMP_ASCII);
       grpc_error* error = grpc_error_set_str(
           grpc_error_set_int(GRPC_ERROR_CREATE_FROM_COPIED_STRING(err_desc),
                              GRPC_ERROR_INT_OFFSET,
                              p - GRPC_SLICE_START_PTR(slice)),
           GRPC_ERROR_STR_RAW_BYTES,
-          grpc_slice_from_moved_string(grpc_core::UniquePtr<char>(dump)));
+          grpc_dump_slice_to_slice(slice, GPR_DUMP_HEX | GPR_DUMP_ASCII));
       return error;
     }
   }

test/core/slice/slice_test.cc

@@ -311,6 +311,16 @@ static void test_moved_string_slice(void) {
              reinterpret_cast<uint8_t*>(large_ptr));
   grpc_slice_unref(large);
 
+  // Moved buffer must respect the provided length not the actual length of the
+  // string.
+  large_ptr = strdup(kSLargeStr);
+  small = grpc_slice_from_moved_buffer(grpc_core::UniquePtr<char>(large_ptr),
+                                       strlen(kSmallStr));
+  GPR_ASSERT(GRPC_SLICE_LENGTH(small) == strlen(kSmallStr));
+  GPR_ASSERT(GRPC_SLICE_START_PTR(small) !=
+             reinterpret_cast<uint8_t*>(large_ptr));
+  grpc_slice_unref(small);
+
   grpc_shutdown();
 }