ake string_util::WriteInto() DCHECK() that the supplied |length_with_null| > 1, meaning that the without-'\0' string is non-empty. This replaces the conditional code added recently that makes this case return NULL. It's easier to understand if it's simply an error to call WriteInto() in this case at all.

Add DCHECK()s or conditionals as appropriate to callers in order to ensure this assertion holds.

BUG=none
TEST=none
Review URL: http://codereview.chromium.org/8418034

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@112005 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 21 insertions, 29 deletions

diff --git a/ui/base/clipboard/clipboard_win.cc b/ui/base/clipboard/clipboard_win.cc
index 492dd31..a543fe6 100644
--- a/ui/base/clipboard/clipboard_win.cc
+++ b/ui/base/clipboard/clipboard_win.cc
@@ -604,7 +604,8 @@ void Clipboard::ReadFiles(std::vector<FilePath>* files) const {
 
   if (count) {
     for (int i = 0; i < count; ++i) {
-      int size = ::DragQueryFile(drop, i, NULL, 0) + 1;
+      UINT size = ::DragQueryFile(drop, i, NULL, 0) + 1;
+      DCHECK_GT(size, 1u);
       std::wstring file;
       ::DragQueryFile(drop, i, WriteInto(&file, size), size);
       files->push_back(FilePath(file));
diff --git a/ui/base/l10n/l10n_util.cc b/ui/base/l10n/l10n_util.cc
index 1c2aca0..28dbc43 100644
--- a/ui/base/l10n/l10n_util.cc
+++ b/ui/base/l10n/l10n_util.cc
@@ -478,12 +478,12 @@ string16 GetDisplayNameForLocale(const std::string& locale,
     locale_code = "zh-Hant";
 
   UErrorCode error = U_ZERO_ERROR;
-  const int buffer_size = 1024;
+  const int kBufferSize = 1024;
 
   string16 display_name;
   int actual_size = uloc_getDisplayName(locale_code.c_str(),
       display_locale.c_str(),
-      WriteInto(&display_name, buffer_size + 1), buffer_size, &error);
+      WriteInto(&display_name, kBufferSize), kBufferSize - 1, &error);
   DCHECK(U_SUCCESS(error));
   display_name.resize(actual_size);
   // Add an RTL mark so parentheses are properly placed.
diff --git a/ui/base/win/ime_input.cc b/ui/base/win/ime_input.cc
index 50bf3ea..049ab02 100644
--- a/ui/base/win/ime_input.cc
+++ b/ui/base/win/ime_input.cc
@@ -339,22 +339,19 @@ void ImeInput::GetCompositionInfo(HIMC imm_context, LPARAM lparam,
   }
 }
 
-bool ImeInput::GetString(HIMC imm_context, WPARAM lparam, int type,
+bool ImeInput::GetString(HIMC imm_context,
+                         WPARAM lparam,
+                         int type,
                          string16* result) {
-  bool ret = false;
-  if (lparam & type) {
-    int string_size = ::ImmGetCompositionString(imm_context, type, NULL, 0);
-    if (string_size > 0) {
-      int string_length = string_size / sizeof(wchar_t);
-      wchar_t *string_data = WriteInto(result, string_length + 1);
-      if (string_data) {
-        // Fill the given result object.
-        ::ImmGetCompositionString(imm_context, type, string_data, string_size);
-        ret = true;
-      }
-    }
-  }
-  return ret;
+  if (!(lparam & type))
+    return false;
+  LONG string_size = ::ImmGetCompositionString(imm_context, type, NULL, 0);
+  if (string_size <= 0)
+    return false;
+  DCHECK_EQ(0u, string_size % sizeof(wchar_t));
+  ::ImmGetCompositionString(imm_context, type,
+      WriteInto(result, (string_size / sizeof(wchar_t)) + 1), string_size);
+  return true;
 }
 
 bool ImeInput::GetResult(HWND window_handle, LPARAM lparam, string16* result) {
diff --git a/ui/views/controls/textfield/native_textfield_win.cc b/ui/views/controls/textfield/native_textfield_win.cc
index 20cae12..3b598e1 100644
--- a/ui/views/controls/textfield/native_textfield_win.cc
+++ b/ui/views/controls/textfield/native_textfield_win.cc
@@ -173,18 +173,16 @@ void NativeTextfieldWin::AttachHack() {
 
 string16 NativeTextfieldWin::GetText() const {
   int len = GetTextLength() + 1;
-  if (len <= 1)
-    return string16();
-
   string16 str;
-  GetWindowText(WriteInto(&str, len), len);
+  if (len > 1)
+    GetWindowText(WriteInto(&str, len), len);
   // The text get from GetWindowText() might be wrapped with explicit bidi
   // control characters. Refer to UpdateText() for detail. Without such
   // wrapping, in RTL chrome, a pure LTR string ending with parenthesis will
   // not be displayed correctly in a textfield. For example, "Yahoo!" will be
   // displayed as "!Yahoo", and "Google (by default)" will be displayed as
   // "(Google (by default".
-  return base::i18n::StripWrappingBidiControlCharacters(WideToUTF16(str));
+  return base::i18n::StripWrappingBidiControlCharacters(str);
 }
 
 void NativeTextfieldWin::UpdateText() {
@@ -206,15 +204,11 @@ void NativeTextfieldWin::AppendText(const string16& text) {
 }
 
 string16 NativeTextfieldWin::GetSelectedText() const {
-  // Figure out the length of the selection.
   CHARRANGE sel;
   GetSel(sel);
-  if (sel.cpMin == sel.cpMax)  // GetSelText() crashes on NULL input.
-    return string16();
-
-  // Grab the selected text.
   string16 str;
-  GetSelText(WriteInto(&str, sel.cpMax - sel.cpMin + 1));
+  if (sel.cpMin != sel.cpMax)
+    GetSelText(WriteInto(&str, sel.cpMax - sel.cpMin + 1));
   return str;
 }