From f634655e6453e7d7ec453faa16cf4c97e4a5c630 Mon Sep 17 00:00:00 2001
From: Dan Albert <danalbert@google.com>
Date: Fri, 2 Dec 2016 12:02:03 -0800
Subject: [PATCH] Fix wcsto* where strings begin with whitespace.

The libc++ tests caught this.

Test: adb shell /data/nativetest/bionic-unit-tests/bionic-unit-tests
Bug: None
Change-Id: I14864e006f6cf9de3f96acac6aa3eb235894f2b1
---
 libc/bionic/wcstod.cpp | 20 +++++++++++++++++---
 tests/stdlib_test.cpp  |  6 +++++-
 tests/wchar_test.cpp   |  6 +++++-
 3 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/libc/bionic/wcstod.cpp b/libc/bionic/wcstod.cpp
index eb66ba030..f7bd4337f 100644
--- a/libc/bionic/wcstod.cpp
+++ b/libc/bionic/wcstod.cpp
@@ -32,8 +32,14 @@
 
 #include "local.h"
 
-template <typename float_type> float_type wcstod(const wchar_t* str, wchar_t** end,
-                                                 float_type strtod_fn(const char*, char**)) {
+/// Performs wide-character string to floating point conversion.
+template <typename float_type>
+float_type wcstod(const wchar_t* str, wchar_t** end, float_type strtod_fn(const char*, char**)) {
+  const wchar_t* original_str = str;
+  while (iswspace(*str)) {
+    str++;
+  }
+
   // What's the longest span of the input that might be part of the float?
   size_t max_len = wcsspn(str, L"-+0123456789.xXeEpP()nNaAiIfFtTyY");
 
@@ -70,7 +76,15 @@ template <typename float_type> float_type wcstod(const wchar_t* str, wchar_t** e
   float_type result = strtod_fn(ascii_str, &ascii_end);
   if (ascii_end != ascii_str + actual_len) abort();
 
-  if (end) *end = const_cast<wchar_t*>(str) + actual_len;
+  if (end) {
+    if (actual_len == 0) {
+      // There was an error. We need to set the end pointer back to the original string, not the
+      // one we advanced past the leading whitespace.
+      *end = const_cast<wchar_t*>(original_str);
+    } else {
+      *end = const_cast<wchar_t*>(str) + actual_len;
+    }
+  }
 
   delete[] ascii_str;
   return result;
diff --git a/tests/stdlib_test.cpp b/tests/stdlib_test.cpp
index 5b9442fcf..fc17cde0a 100644
--- a/tests/stdlib_test.cpp
+++ b/tests/stdlib_test.cpp
@@ -298,6 +298,11 @@ static void CheckStrToFloat(T fn(const char* s, char** end)) {
   EXPECT_PRED_FORMAT2(pred, 9.0, fn("0.9e1", nullptr));
   EXPECT_PRED_FORMAT2(pred, 9.0, fn("0x1.2p3", nullptr));
 
+  const char* s = " \t\v\f\r\n9.0";
+  char* p;
+  EXPECT_PRED_FORMAT2(pred, 9.0, fn(s, &p));
+  EXPECT_EQ(s + strlen(s), p);
+
   EXPECT_TRUE(isnan(fn("+nan", nullptr)));
   EXPECT_TRUE(isnan(fn("nan", nullptr)));
   EXPECT_TRUE(isnan(fn("-nan", nullptr)));
@@ -306,7 +311,6 @@ static void CheckStrToFloat(T fn(const char* s, char** end)) {
   EXPECT_TRUE(isnan(fn("nan(0xff)", nullptr)));
   EXPECT_TRUE(isnan(fn("-nan(0xff)", nullptr)));
 
-  char* p;
   EXPECT_TRUE(isnan(fn("+nanny", &p)));
   EXPECT_STREQ("ny", p);
   EXPECT_TRUE(isnan(fn("nanny", &p)));
diff --git a/tests/wchar_test.cpp b/tests/wchar_test.cpp
index 34ed5a7da..830eb70aa 100644
--- a/tests/wchar_test.cpp
+++ b/tests/wchar_test.cpp
@@ -686,6 +686,11 @@ static void CheckWcsToFloat(T fn(const wchar_t* s, wchar_t** end)) {
   EXPECT_PRED_FORMAT2(pred, 9.0, fn(L"0.9e1", nullptr));
   EXPECT_PRED_FORMAT2(pred, 9.0, fn(L"0x1.2p3", nullptr));
 
+  const wchar_t* s = L" \t\v\f\r\n9.0";
+  wchar_t* p;
+  EXPECT_PRED_FORMAT2(pred, 9.0, fn(s, &p));
+  EXPECT_EQ(s + wcslen(s), p);
+
   EXPECT_TRUE(isnan(fn(L"+nan", nullptr)));
   EXPECT_TRUE(isnan(fn(L"nan", nullptr)));
   EXPECT_TRUE(isnan(fn(L"-nan", nullptr)));
@@ -694,7 +699,6 @@ static void CheckWcsToFloat(T fn(const wchar_t* s, wchar_t** end)) {
   EXPECT_TRUE(isnan(fn(L"nan(0xff)", nullptr)));
   EXPECT_TRUE(isnan(fn(L"-nan(0xff)", nullptr)));
 
-  wchar_t* p;
   EXPECT_TRUE(isnan(fn(L"+nanny", &p)));
   EXPECT_STREQ(L"ny", p);
   EXPECT_TRUE(isnan(fn(L"nanny", &p)));