Revert "Introduce FX_Number class as a replacement for FX_atonum()."

This reverts commit a5d7ad3aa8feb08a14b5cca173d673054c1ade23.

Reason for revert: Speculative revert to get back before flake.

Original change's description:
> Introduce FX_Number class as a replacement for FX_atonum().
> 
> The issue with FX_atonum() is that it doesn't return any information
> about whether it range-checked its integer values as a signed or
> unsigned type, even though it knows this as part of its processing.
> 
> Rather than adding another out parameter to that function, create
> a class to hold all this information together.
> 
> This is the first place things went astray while diagnosing
> bug 882959, in that a large positive value was cast to float as a
> negative value. Unfortunately, this doesn't affect the related bug,
> but is a step in the right direction.
> 
> Change-Id: I0977ec8fccf85e2632a962507bdd30a1cbe6d33c
> Reviewed-on: https://pdfium-review.googlesource.com/42353
> Reviewed-by: Lei Zhang <thestig@chromium.org>
> Commit-Queue: Tom Sepez <tsepez@chromium.org>

TBR=thestig@chromium.org,tsepez@chromium.org

Change-Id: Ia56270c3daa80408fc2b23eb4384a77f03f45b82
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://pdfium-review.googlesource.com/42392
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

1 files changed, 47 insertions, 0 deletions

diff --git a/core/fxcrt/fx_string_unittest.cpp b/core/fxcrt/fx_string_unittest.cpp
index 3059de3e5c..60e7f07523 100644
--- a/core/fxcrt/fx_string_unittest.cpp
+++ b/core/fxcrt/fx_string_unittest.cpp
@@ -2,9 +2,56 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include <limits>
+
 #include "core/fxcrt/fx_string.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
+TEST(fxstring, FX_atonum) {
+  int i;
+  EXPECT_TRUE(FX_atonum("10", &i));
+  EXPECT_EQ(10, i);
+
+  EXPECT_TRUE(FX_atonum("-10", &i));
+  EXPECT_EQ(-10, i);
+
+  EXPECT_TRUE(FX_atonum("+10", &i));
+  EXPECT_EQ(10, i);
+
+  EXPECT_TRUE(FX_atonum("-2147483648", &i));
+  EXPECT_EQ(std::numeric_limits<int>::min(), i);
+
+  EXPECT_TRUE(FX_atonum("2147483647", &i));
+  EXPECT_EQ(2147483647, i);
+
+  // Value overflows.
+  EXPECT_TRUE(FX_atonum("-2147483649", &i));
+  EXPECT_EQ(0, i);
+
+  // Value overflows.
+  EXPECT_TRUE(FX_atonum("+2147483648", &i));
+  EXPECT_EQ(0, i);
+
+  // Value overflows.
+  EXPECT_TRUE(FX_atonum("4223423494965252", &i));
+  EXPECT_EQ(0, i);
+
+  // No explicit sign will allow the number to go negative. This is for things
+  // like the encryption Permissions flag (Table 3.20 PDF 1.7 spec)
+  EXPECT_TRUE(FX_atonum("4294965252", &i));
+  EXPECT_EQ(-2044, i);
+
+  EXPECT_TRUE(FX_atonum("-4294965252", &i));
+  EXPECT_EQ(0, i);
+
+  EXPECT_TRUE(FX_atonum("+4294965252", &i));
+  EXPECT_EQ(0, i);
+
+  float f;
+  EXPECT_FALSE(FX_atonum("3.24", &f));
+  EXPECT_FLOAT_EQ(3.24f, f);
+}
+
 TEST(fxstring, FX_UTF8Encode) {
   EXPECT_EQ("", FX_UTF8Encode(WideStringView()));
   EXPECT_EQ(