lib/Support/DataExtractor.cpp

   1 //===-- DataExtractor.cpp -------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "llvm/Support/DataExtractor.h"
  10 #include "llvm/Support/ErrorHandling.h"
  11 #include "llvm/Support/Host.h"
  12 #include "llvm/Support/SwapByteOrder.h"
  13 #include "llvm/Support/LEB128.h"
  14 using namespace llvm;
  15
  16 template <typename T>
  17 static T getU(uint64_t *offset_ptr, const DataExtractor *de,
  18               bool isLittleEndian, const char *Data) {
  19   T val = 0;
  20   uint64_t offset = *offset_ptr;
  21   if (de->isValidOffsetForDataOfSize(offset, sizeof(val))) {
  22     std::memcpy(&val, &Data[offset], sizeof(val));
  23     if (sys::IsLittleEndianHost != isLittleEndian)
  24       sys::swapByteOrder(val);
  25
  26     // Advance the offset
  27     *offset_ptr += sizeof(val);
  28   }
  29   return val;
  30 }
  31
  32 template <typename T>
  33 static T *getUs(uint64_t *offset_ptr, T *dst, uint32_t count,
  34                 const DataExtractor *de, bool isLittleEndian, const char *Data){
  35   uint64_t offset = *offset_ptr;
  36
  37   if (count > 0 && de->isValidOffsetForDataOfSize(offset, sizeof(*dst)*count)) {
  38     for (T *value_ptr = dst, *end = dst + count; value_ptr != end;
  39         ++value_ptr, offset += sizeof(*dst))
  40       *value_ptr = getU<T>(offset_ptr, de, isLittleEndian, Data);
  41     // Advance the offset
  42     *offset_ptr = offset;
  43     // Return a non-NULL pointer to the converted data as an indicator of
  44     // success
  45     return dst;
  46   }
  47   return nullptr;
  48 }
  49
  50 uint8_t DataExtractor::getU8(uint64_t *offset_ptr) const {
  51   return getU<uint8_t>(offset_ptr, this, IsLittleEndian, Data.data());
  52 }
  53
  54 uint8_t *
  55 DataExtractor::getU8(uint64_t *offset_ptr, uint8_t *dst, uint32_t count) const {
  56   return getUs<uint8_t>(offset_ptr, dst, count, this, IsLittleEndian,
  57                        Data.data());
  58 }
  59
  60 uint16_t DataExtractor::getU16(uint64_t *offset_ptr) const {
  61   return getU<uint16_t>(offset_ptr, this, IsLittleEndian, Data.data());
  62 }
  63
  64 uint16_t *DataExtractor::getU16(uint64_t *offset_ptr, uint16_t *dst,
  65                                 uint32_t count) const {
  66   return getUs<uint16_t>(offset_ptr, dst, count, this, IsLittleEndian,
  67                         Data.data());
  68 }
  69
  70 uint32_t DataExtractor::getU24(uint64_t *offset_ptr) const {
  71   uint24_t ExtractedVal =
  72       getU<uint24_t>(offset_ptr, this, IsLittleEndian, Data.data());
  73   // The 3 bytes are in the correct byte order for the host.
  74   return ExtractedVal.getAsUint32(sys::IsLittleEndianHost);
  75 }
  76
  77 uint32_t DataExtractor::getU32(uint64_t *offset_ptr) const {
  78   return getU<uint32_t>(offset_ptr, this, IsLittleEndian, Data.data());
  79 }
  80
  81 uint32_t *DataExtractor::getU32(uint64_t *offset_ptr, uint32_t *dst,
  82                                 uint32_t count) const {
  83   return getUs<uint32_t>(offset_ptr, dst, count, this, IsLittleEndian,
  84                         Data.data());
  85 }
  86
  87 uint64_t DataExtractor::getU64(uint64_t *offset_ptr) const {
  88   return getU<uint64_t>(offset_ptr, this, IsLittleEndian, Data.data());
  89 }
  90
  91 uint64_t *DataExtractor::getU64(uint64_t *offset_ptr, uint64_t *dst,
  92                                 uint32_t count) const {
  93   return getUs<uint64_t>(offset_ptr, dst, count, this, IsLittleEndian,
  94                         Data.data());
  95 }
  96
  97 uint64_t
  98 DataExtractor::getUnsigned(uint64_t *offset_ptr, uint32_t byte_size) const {
  99   switch (byte_size) {
 100   case 1:
 101     return getU8(offset_ptr);
 102   case 2:
 103     return getU16(offset_ptr);
 104   case 4:
 105     return getU32(offset_ptr);
 106   case 8:
 107     return getU64(offset_ptr);
 108   }
 109   llvm_unreachable("getUnsigned unhandled case!");
 110 }
 111
 112 int64_t
 113 DataExtractor::getSigned(uint64_t *offset_ptr, uint32_t byte_size) const {
 114   switch (byte_size) {
 115   case 1:
 116     return (int8_t)getU8(offset_ptr);
 117   case 2:
 118     return (int16_t)getU16(offset_ptr);
 119   case 4:
 120     return (int32_t)getU32(offset_ptr);
 121   case 8:
 122     return (int64_t)getU64(offset_ptr);
 123   }
 124   llvm_unreachable("getSigned unhandled case!");
 125 }
 126
 127 const char *DataExtractor::getCStr(uint64_t *offset_ptr) const {
 128   uint64_t offset = *offset_ptr;
 129   StringRef::size_type pos = Data.find('\0', offset);
 130   if (pos != StringRef::npos) {
 131     *offset_ptr = pos + 1;
 132     return Data.data() + offset;
 133   }
 134   return nullptr;
 135 }
 136
 137 StringRef DataExtractor::getCStrRef(uint64_t *offset_ptr) const {
 138   uint64_t Start = *offset_ptr;
 139   StringRef::size_type Pos = Data.find('\0', Start);
 140   if (Pos != StringRef::npos) {
 141     *offset_ptr = Pos + 1;
 142     return StringRef(Data.data() + Start, Pos - Start);
 143   }
 144   return StringRef();
 145 }
 146
 147 uint64_t DataExtractor::getULEB128(uint64_t *offset_ptr) const {
 148   assert(*offset_ptr <= Data.size());
 149
 150   const char *error;
 151   unsigned bytes_read;
 152   uint64_t result = decodeULEB128(
 153       reinterpret_cast<const uint8_t *>(Data.data() + *offset_ptr), &bytes_read,
 154       reinterpret_cast<const uint8_t *>(Data.data() + Data.size()), &error);
 155   if (error)
 156     return 0;
 157   *offset_ptr += bytes_read;
 158   return result;
 159 }
 160
 161 int64_t DataExtractor::getSLEB128(uint64_t *offset_ptr) const {
 162   assert(*offset_ptr <= Data.size());
 163
 164   const char *error;
 165   unsigned bytes_read;
 166   int64_t result = decodeSLEB128(
 167       reinterpret_cast<const uint8_t *>(Data.data() + *offset_ptr), &bytes_read,
 168       reinterpret_cast<const uint8_t *>(Data.data() + Data.size()), &error);
 169   if (error)
 170     return 0;
 171   *offset_ptr += bytes_read;
 172   return result;
 173 }