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

This reverts commit 29e180342e18873babf1c74f7c5c056f90a191b0.

Reason for revert: probably harmless

Original change's description:
> 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
> Reviewed-on: https://pdfium-review.googlesource.com/42392
> Reviewed-by: Tom Sepez <tsepez@chromium.org>
> Commit-Queue: Tom Sepez <tsepez@chromium.org>

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

Change-Id: I83c37aa3040a8890f2117753f19ab1d452d411e7
Reviewed-on: https://pdfium-review.googlesource.com/42410
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>

4 files changed, 32 insertions, 43 deletions

diff --git a/core/fpdfapi/page/cpdf_streamcontentparser.cpp b/core/fpdfapi/page/cpdf_streamcontentparser.cpp
index 2244232ecb..20892cc264 100644
--- a/core/fpdfapi/page/cpdf_streamcontentparser.cpp
+++ b/core/fpdfapi/page/cpdf_streamcontentparser.cpp
@@ -338,7 +338,7 @@ void CPDF_StreamContentParser::AddNameParam(const ByteStringView& bsName) {
 void CPDF_StreamContentParser::AddNumberParam(const ByteStringView& str) {
   ContentParam& param = m_ParamBuf[GetNextParamPos()];
   param.m_Type = ContentParam::NUMBER;
-  param.m_Number.m_bInteger = FX_atonum(str, &param.m_Number.m_Integer);
+  param.m_Number = FX_Number(str);
 }
 
 void CPDF_StreamContentParser::AddObjectParam(
@@ -373,9 +373,9 @@ CPDF_Object* CPDF_StreamContentParser::GetObject(uint32_t index) {
   if (param.m_Type == ContentParam::NUMBER) {
     param.m_Type = ContentParam::OBJECT;
     param.m_pObject =
-        param.m_Number.m_bInteger
-            ? pdfium::MakeUnique<CPDF_Number>(param.m_Number.m_Integer)
-            : pdfium::MakeUnique<CPDF_Number>(param.m_Number.m_Float);
+        param.m_Number.IsInteger()
+            ? pdfium::MakeUnique<CPDF_Number>(param.m_Number.GetSigned())
+            : pdfium::MakeUnique<CPDF_Number>(param.m_Number.GetFloat());
     return param.m_pObject.get();
   }
   if (param.m_Type == ContentParam::NAME) {
@@ -411,21 +411,20 @@ ByteString CPDF_StreamContentParser::GetString(uint32_t index) const {
 }
 
 float CPDF_StreamContentParser::GetNumber(uint32_t index) const {
-  if (index >= m_ParamCount) {
+  if (index >= m_ParamCount)
     return 0;
-  }
+
   int real_index = m_ParamStartPos + m_ParamCount - index - 1;
-  if (real_index >= kParamBufSize) {
+  if (real_index >= kParamBufSize)
     real_index -= kParamBufSize;
-  }
+
   const ContentParam& param = m_ParamBuf[real_index];
-  if (param.m_Type == ContentParam::NUMBER) {
-    return param.m_Number.m_bInteger
-               ? static_cast<float>(param.m_Number.m_Integer)
-               : param.m_Number.m_Float;
-  }
+  if (param.m_Type == ContentParam::NUMBER)
+    return param.m_Number.GetFloat();
+
   if (param.m_Type == 0 && param.m_pObject)
     return param.m_pObject->GetNumber();
+
   return 0;
 }
 
@@ -1632,10 +1631,8 @@ void CPDF_StreamContentParser::ParsePathObject() {
         if (nParams == 6)
           break;
 
-        int value;
-        bool bInteger = FX_atonum(m_pSyntax->GetWord(), &value);
-        params[nParams++] = bInteger ? static_cast<float>(value)
-                                     : *reinterpret_cast<float*>(&value);
+        FX_Number number(m_pSyntax->GetWord());
+        params[nParams++] = number.GetFloat();
         break;
       }
       default:
diff --git a/core/fpdfapi/page/cpdf_streamcontentparser.h b/core/fpdfapi/page/cpdf_streamcontentparser.h
index a129894dba..6417043305 100644
--- a/core/fpdfapi/page/cpdf_streamcontentparser.h
+++ b/core/fpdfapi/page/cpdf_streamcontentparser.h
@@ -15,6 +15,7 @@
 
 #include "core/fpdfapi/page/cpdf_contentmark.h"
 #include "core/fpdfapi/parser/cpdf_stream.h"
+#include "core/fxcrt/fx_number.h"
 #include "core/fxcrt/fx_string.h"
 #include "core/fxge/cfx_pathdata.h"
 
@@ -71,13 +72,7 @@ class CPDF_StreamContentParser {
 
     Type m_Type;
     std::unique_ptr<CPDF_Object> m_pObject;
-    struct {
-      bool m_bInteger;
-      union {
-        int m_Integer;
-        float m_Float;
-      };
-    } m_Number;
+    FX_Number m_Number;
     struct {
       int m_Len;
       char m_Buffer[32];
diff --git a/core/fpdfapi/parser/cpdf_number.cpp b/core/fpdfapi/parser/cpdf_number.cpp
index b75ce0766a..23c2609e25 100644
--- a/core/fpdfapi/parser/cpdf_number.cpp
+++ b/core/fpdfapi/parser/cpdf_number.cpp
@@ -8,14 +8,13 @@
 #include "core/fxcrt/fx_stream.h"
 #include "third_party/base/ptr_util.h"
 
-CPDF_Number::CPDF_Number() : m_bInteger(true), m_Integer(0) {}
+CPDF_Number::CPDF_Number() {}
 
-CPDF_Number::CPDF_Number(int value) : m_bInteger(true), m_Integer(value) {}
+CPDF_Number::CPDF_Number(int value) : m_Number(value) {}
 
-CPDF_Number::CPDF_Number(float value) : m_bInteger(false), m_Float(value) {}
+CPDF_Number::CPDF_Number(float value) : m_Number(value) {}
 
-CPDF_Number::CPDF_Number(const ByteStringView& str)
-    : m_bInteger(FX_atonum(str, &m_Integer)) {}
+CPDF_Number::CPDF_Number(const ByteStringView& str) : m_Number(str) {}
 
 CPDF_Number::~CPDF_Number() {}
 
@@ -24,16 +23,17 @@ CPDF_Object::Type CPDF_Number::GetType() const {
 }
 
 std::unique_ptr<CPDF_Object> CPDF_Number::Clone() const {
-  return m_bInteger ? pdfium::MakeUnique<CPDF_Number>(m_Integer)
-                    : pdfium::MakeUnique<CPDF_Number>(m_Float);
+  return m_Number.IsInteger()
+             ? pdfium::MakeUnique<CPDF_Number>(m_Number.GetSigned())
+             : pdfium::MakeUnique<CPDF_Number>(m_Number.GetFloat());
 }
 
 float CPDF_Number::GetNumber() const {
-  return m_bInteger ? static_cast<float>(m_Integer) : m_Float;
+  return m_Number.GetFloat();
 }
 
 int CPDF_Number::GetInteger() const {
-  return m_bInteger ? m_Integer : static_cast<int>(m_Float);
+  return m_Number.GetSigned();
 }
 
 bool CPDF_Number::IsNumber() const {
@@ -49,12 +49,12 @@ const CPDF_Number* CPDF_Number::AsNumber() const {
 }
 
 void CPDF_Number::SetString(const ByteString& str) {
-  m_bInteger = FX_atonum(str.AsStringView(), &m_Integer);
+  m_Number = FX_Number(str.AsStringView());
 }
 
 ByteString CPDF_Number::GetString() const {
-  return m_bInteger ? ByteString::FormatInteger(m_Integer)
-                    : ByteString::FormatFloat(m_Float);
+  return m_Number.IsInteger() ? ByteString::FormatInteger(m_Number.GetSigned())
+                              : ByteString::FormatFloat(m_Number.GetFloat());
 }
 
 bool CPDF_Number::WriteTo(IFX_ArchiveStream* archive,
diff --git a/core/fpdfapi/parser/cpdf_number.h b/core/fpdfapi/parser/cpdf_number.h
index b5faf82bb2..724ae9f1f1 100644
--- a/core/fpdfapi/parser/cpdf_number.h
+++ b/core/fpdfapi/parser/cpdf_number.h
@@ -10,6 +10,7 @@
 #include <memory>
 
 #include "core/fpdfapi/parser/cpdf_object.h"
+#include "core/fxcrt/fx_number.h"
 #include "core/fxcrt/fx_string.h"
 #include "core/fxcrt/fx_system.h"
 
@@ -34,14 +35,10 @@ class CPDF_Number final : public CPDF_Object {
   bool WriteTo(IFX_ArchiveStream* archive,
                const CPDF_Encryptor* encryptor) const override;
 
-  bool IsInteger() const { return m_bInteger; }
+  bool IsInteger() const { return m_Number.IsInteger(); }
 
- protected:
-  bool m_bInteger;
-  union {
-    int m_Integer;
-    float m_Float;
-  };
+ private:
+  FX_Number m_Number;
 };
 
 inline CPDF_Number* ToNumber(CPDF_Object* obj) {