Add namespace and-re-arrange PDFium's local copy of chromium /base.

Any projects DEPS'd into chromium and requiring a /base
subset should have a local copy of that subset in a
separate namespace. This will avoid future naming conflicts.

Re-arrange the directory structure to better identify what
came from chromium's base, and to make drop-in replacement
easier for files that contain hard-coded "base/" in their
#include directives.

R=jam@chromium.org

Review URL: https://codereview.chromium.org/900753002

1 files changed, 219 insertions, 0 deletions

diff --git a/third_party/base/numerics/safe_conversions_impl.h b/third_party/base/numerics/safe_conversions_impl.h
new file mode 100644
index 0000000000..7c88dda0a8
--- /dev/null
+++ b/third_party/base/numerics/safe_conversions_impl.h
@@ -0,0 +1,219 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef PDFIUM_THIRD_PARTY_BASE_SAFE_CONVERSIONS_IMPL_H_
+#define PDFIUM_THIRD_PARTY_BASE_SAFE_CONVERSIONS_IMPL_H_
+
+#include <limits>
+
+#include "../macros.h"
+#include "../template_util.h"
+
+namespace pdfium {
+namespace base {
+namespace internal {
+
+// The std library doesn't provide a binary max_exponent for integers, however
+// we can compute one by adding one to the number of non-sign bits. This allows
+// for accurate range comparisons between floating point and integer types.
+template <typename NumericType>
+struct MaxExponent {
+  static const int value = std::numeric_limits<NumericType>::is_iec559
+                               ? std::numeric_limits<NumericType>::max_exponent
+                               : (sizeof(NumericType) * 8 + 1 -
+                                  std::numeric_limits<NumericType>::is_signed);
+};
+
+enum IntegerRepresentation {
+  INTEGER_REPRESENTATION_UNSIGNED,
+  INTEGER_REPRESENTATION_SIGNED
+};
+
+// A range for a given nunmeric Src type is contained for a given numeric Dst
+// type if both numeric_limits<Src>::max() <= numeric_limits<Dst>::max() and
+// numeric_limits<Src>::min() >= numeric_limits<Dst>::min() are true.
+// We implement this as template specializations rather than simple static
+// comparisons to ensure type correctness in our comparisons.
+enum NumericRangeRepresentation {
+  NUMERIC_RANGE_NOT_CONTAINED,
+  NUMERIC_RANGE_CONTAINED
+};
+
+// Helper templates to statically determine if our destination type can contain
+// maximum and minimum values represented by the source type.
+
+template <
+    typename Dst,
+    typename Src,
+    IntegerRepresentation DstSign = std::numeric_limits<Dst>::is_signed
+                                            ? INTEGER_REPRESENTATION_SIGNED
+                                            : INTEGER_REPRESENTATION_UNSIGNED,
+    IntegerRepresentation SrcSign =
+        std::numeric_limits<Src>::is_signed
+            ? INTEGER_REPRESENTATION_SIGNED
+            : INTEGER_REPRESENTATION_UNSIGNED >
+struct StaticDstRangeRelationToSrcRange;
+
+// Same sign: Dst is guaranteed to contain Src only if its range is equal or
+// larger.
+template <typename Dst, typename Src, IntegerRepresentation Sign>
+struct StaticDstRangeRelationToSrcRange<Dst, Src, Sign, Sign> {
+  static const NumericRangeRepresentation value =
+      MaxExponent<Dst>::value >= MaxExponent<Src>::value
+          ? NUMERIC_RANGE_CONTAINED
+          : NUMERIC_RANGE_NOT_CONTAINED;
+};
+
+// Unsigned to signed: Dst is guaranteed to contain source only if its range is
+// larger.
+template <typename Dst, typename Src>
+struct StaticDstRangeRelationToSrcRange<Dst,
+                                        Src,
+                                        INTEGER_REPRESENTATION_SIGNED,
+                                        INTEGER_REPRESENTATION_UNSIGNED> {
+  static const NumericRangeRepresentation value =
+      MaxExponent<Dst>::value > MaxExponent<Src>::value
+          ? NUMERIC_RANGE_CONTAINED
+          : NUMERIC_RANGE_NOT_CONTAINED;
+};
+
+// Signed to unsigned: Dst cannot be statically determined to contain Src.
+template <typename Dst, typename Src>
+struct StaticDstRangeRelationToSrcRange<Dst,
+                                        Src,
+                                        INTEGER_REPRESENTATION_UNSIGNED,
+                                        INTEGER_REPRESENTATION_SIGNED> {
+  static const NumericRangeRepresentation value = NUMERIC_RANGE_NOT_CONTAINED;
+};
+
+enum RangeConstraint {
+  RANGE_VALID = 0x0,  // Value can be represented by the destination type.
+  RANGE_UNDERFLOW = 0x1,  // Value would overflow.
+  RANGE_OVERFLOW = 0x2,  // Value would underflow.
+  RANGE_INVALID = RANGE_UNDERFLOW | RANGE_OVERFLOW  // Invalid (i.e. NaN).
+};
+
+// Helper function for coercing an int back to a RangeContraint.
+inline RangeConstraint GetRangeConstraint(int integer_range_constraint) {
+  assert(integer_range_constraint >= RANGE_VALID &&
+         integer_range_constraint <= RANGE_INVALID);
+  return static_cast<RangeConstraint>(integer_range_constraint);
+}
+
+// This function creates a RangeConstraint from an upper and lower bound
+// check by taking advantage of the fact that only NaN can be out of range in
+// both directions at once.
+inline RangeConstraint GetRangeConstraint(bool is_in_upper_bound,
+                                   bool is_in_lower_bound) {
+  return GetRangeConstraint((is_in_upper_bound ? 0 : RANGE_OVERFLOW) |
+                            (is_in_lower_bound ? 0 : RANGE_UNDERFLOW));
+}
+
+template <
+    typename Dst,
+    typename Src,
+    IntegerRepresentation DstSign = std::numeric_limits<Dst>::is_signed
+                                            ? INTEGER_REPRESENTATION_SIGNED
+                                            : INTEGER_REPRESENTATION_UNSIGNED,
+    IntegerRepresentation SrcSign = std::numeric_limits<Src>::is_signed
+                                            ? INTEGER_REPRESENTATION_SIGNED
+                                            : INTEGER_REPRESENTATION_UNSIGNED,
+    NumericRangeRepresentation DstRange =
+        StaticDstRangeRelationToSrcRange<Dst, Src>::value >
+struct DstRangeRelationToSrcRangeImpl;
+
+// The following templates are for ranges that must be verified at runtime. We
+// split it into checks based on signedness to avoid confusing casts and
+// compiler warnings on signed an unsigned comparisons.
+
+// Dst range is statically determined to contain Src: Nothing to check.
+template <typename Dst,
+          typename Src,
+          IntegerRepresentation DstSign,
+          IntegerRepresentation SrcSign>
+struct DstRangeRelationToSrcRangeImpl<Dst,
+                                      Src,
+                                      DstSign,
+                                      SrcSign,
+                                      NUMERIC_RANGE_CONTAINED> {
+  static RangeConstraint Check(Src value) { return RANGE_VALID; }
+};
+
+// Signed to signed narrowing: Both the upper and lower boundaries may be
+// exceeded.
+template <typename Dst, typename Src>
+struct DstRangeRelationToSrcRangeImpl<Dst,
+                                      Src,
+                                      INTEGER_REPRESENTATION_SIGNED,
+                                      INTEGER_REPRESENTATION_SIGNED,
+                                      NUMERIC_RANGE_NOT_CONTAINED> {
+  static RangeConstraint Check(Src value) {
+    return std::numeric_limits<Dst>::is_iec559
+               ? GetRangeConstraint(value <= std::numeric_limits<Dst>::max(),
+                                    value >= -std::numeric_limits<Dst>::max())
+               : GetRangeConstraint(value <= std::numeric_limits<Dst>::max(),
+                                    value >= std::numeric_limits<Dst>::min());
+  }
+};
+
+// Unsigned to unsigned narrowing: Only the upper boundary can be exceeded.
+template <typename Dst, typename Src>
+struct DstRangeRelationToSrcRangeImpl<Dst,
+                                      Src,
+                                      INTEGER_REPRESENTATION_UNSIGNED,
+                                      INTEGER_REPRESENTATION_UNSIGNED,
+                                      NUMERIC_RANGE_NOT_CONTAINED> {
+  static RangeConstraint Check(Src value) {
+    return GetRangeConstraint(value <= std::numeric_limits<Dst>::max(), true);
+  }
+};
+
+// Unsigned to signed: The upper boundary may be exceeded.
+template <typename Dst, typename Src>
+struct DstRangeRelationToSrcRangeImpl<Dst,
+                                      Src,
+                                      INTEGER_REPRESENTATION_SIGNED,
+                                      INTEGER_REPRESENTATION_UNSIGNED,
+                                      NUMERIC_RANGE_NOT_CONTAINED> {
+  static RangeConstraint Check(Src value) {
+    return sizeof(Dst) > sizeof(Src)
+               ? RANGE_VALID
+               : GetRangeConstraint(
+                     value <= static_cast<Src>(std::numeric_limits<Dst>::max()),
+                     true);
+  }
+};
+
+// Signed to unsigned: The upper boundary may be exceeded for a narrower Dst,
+// and any negative value exceeds the lower boundary.
+template <typename Dst, typename Src>
+struct DstRangeRelationToSrcRangeImpl<Dst,
+                                      Src,
+                                      INTEGER_REPRESENTATION_UNSIGNED,
+                                      INTEGER_REPRESENTATION_SIGNED,
+                                      NUMERIC_RANGE_NOT_CONTAINED> {
+  static RangeConstraint Check(Src value) {
+    return (MaxExponent<Dst>::value >= MaxExponent<Src>::value)
+               ? GetRangeConstraint(true, value >= static_cast<Src>(0))
+               : GetRangeConstraint(
+                     value <= static_cast<Src>(std::numeric_limits<Dst>::max()),
+                     value >= static_cast<Src>(0));
+  }
+};
+
+template <typename Dst, typename Src>
+inline RangeConstraint DstRangeRelationToSrcRange(Src value) {
+  COMPILE_ASSERT(std::numeric_limits<Src>::is_specialized,
+                 argument_must_be_numeric);
+  COMPILE_ASSERT(std::numeric_limits<Dst>::is_specialized,
+                 result_must_be_numeric);
+  return DstRangeRelationToSrcRangeImpl<Dst, Src>::Check(value);
+}
+
+}  // namespace internal
+}  // namespace base
+}  // namespace pdfium
+
+#endif  // PDFIUM_THIRD_PARTY_BASE_SAFE_CONVERSIONS_IMPL_H_
+