#!/usr/bin/env python3
# Copyright 2021 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
################################################################################
"""Helper script for upgrading a profraw file to latest version."""

from collections import namedtuple
import struct
import subprocess
import sys

HeaderGeneric = namedtuple('HeaderGeneric', 'magic version')
HeaderVersion9 = namedtuple(
    'HeaderVersion9',
    'BinaryIdsSize DataSize PaddingBytesBeforeCounters CountersSize \
    PaddingBytesAfterCounters NumBitmapBytes PaddingBytesAfterBitmapBytes NamesSize CountersDelta BitmapDelta NamesDelta ValueKindLast'
)

PROFRAW_MAGIC = 0xff6c70726f667281


def relativize_address(data, offset, databegin, sect_prf_cnts, sect_prf_data):
  """Turns an absolute offset into a relative one."""
  value = struct.unpack('Q', data[offset:offset + 8])[0]
  if sect_prf_cnts <= value < sect_prf_data:
    # If the value is an address in the right section, make it relative.
    value = (value - databegin) & 0xffffffffffffffff
    value = struct.pack('Q', value)
    for i in range(8):
      data[offset + i] = value[i]
    # address was made relative
    return True
  # no changes done
  return False


def upgrade(data, sect_prf_cnts, sect_prf_data):
  """Upgrades profraw data, knowing the sections addresses."""
  generic_header = HeaderGeneric._make(struct.unpack('QQ', data[:16]))
  if generic_header.magic != PROFRAW_MAGIC:
    raise Exception('Bad magic.')
  base_version = generic_header.version

  if base_version >= 9:
    # Nothing to do.
    return data
  if base_version < 5 or base_version == 6:
    raise Exception('Unhandled version.')

  if generic_header.version == 5:
    generic_header = generic_header._replace(version=7)
    # Upgrade from version 5 to 7 by adding binaryids field.
    data = data[:8] + struct.pack('Q', generic_header.version) + struct.pack(
        'Q', 0) + data[16:]
  if generic_header.version == 7:
    # cf https://reviews.llvm.org/D111123
    generic_header = generic_header._replace(version=8)
    data = data[:8] + struct.pack('Q', generic_header.version) + data[16:]
  if generic_header.version == 8:
    # see https://reviews.llvm.org/D138846
    generic_header = generic_header._replace(version=9)
    # Upgrade from version 8 to 9 by adding NumBitmapBytes, PaddingBytesAfterBitmapBytes and BitmapDelta fields.
    data = data[:8] + struct.pack(
        'Q', generic_header.version) + data[16:56] + struct.pack(
            'QQ', 0, 0) + data[56:72] + struct.pack('Q', 0) + data[72:]

  v9_header = HeaderVersion9._make(struct.unpack('QQQQQQQQQQQQ', data[16:112]))

  if base_version <= 8 and v9_header.BinaryIdsSize % 8 != 0:
    # Adds padding for binary ids.
    # cf commit b9f547e8e51182d32f1912f97a3e53f4899ea6be
    # cf https://reviews.llvm.org/D110365
    padlen = 8 - (v9_header.BinaryIdsSize % 8)
    v7_header = v9_header._replace(BinaryIdsSize=v9_header.BinaryIdsSize +
                                   padlen)
    data = data[:16] + struct.pack('Q', v9_header.BinaryIdsSize) + data[24:]
    data = data[:112 + v9_header.BinaryIdsSize] + bytes(
        padlen) + data[112 + v9_header.BinaryIdsSize:]

  if base_version <= 8:
    offset = 112 + v9_header.BinaryIdsSize
    for d in range(v9_header.DataSize):
      # Add BitmapPtr and aligned u32(NumBitmapBytes)
      data = data[:offset + 3 * 8] + struct.pack(
          'Q', 0) + data[offset + 3 * 8:offset + 6 * 8] + struct.pack(
              'Q', 0) + data[offset + 6 * 8:]
      value = struct.unpack('Q',
                            data[offset + 2 * 8:offset + 3 * 8])[0] - 16 * d
      data = data[:offset + 2 * 8] + struct.pack('Q',
                                                 value) + data[offset + 3 * 8:]
      offset += 8 * 8

  if base_version >= 8:
    # Nothing more to do.
    return data

  # Last changes are relaed to bump from 7 to version 8 making CountersPtr relative.
  dataref = sect_prf_data
  # 80 is offset of CountersDelta.
  if not relativize_address(data, 80, dataref, sect_prf_cnts, sect_prf_data):
    return data

  offset = 112 + v9_header.BinaryIdsSize
  # This also works for C+Rust binaries compiled with
  # clang-14/rust-nightly-clang-13.
  for _ in range(v9_header.DataSize):
    # 16 is the offset of CounterPtr in ProfrawData structure.
    relativize_address(data, offset + 16, dataref, sect_prf_cnts, sect_prf_data)
    # We need this because of CountersDelta -= sizeof(*SrcData);
    # seen in __llvm_profile_merge_from_buffer.
    dataref += 44 + 2 * (v9_header.ValueKindLast + 1)
    if was8:
      #profraw9 added RelativeBitmapPtr and NumBitmapBytes (8+4 rounded up to 16)
      dataref -= 16
    # This is the size of one ProfrawData structure.
    offset += 44 + 2 * (v9_header.ValueKindLast + 1)

  return data


def main():
  """Helper script for upgrading a profraw file to latest version."""
  if len(sys.argv) < 3:
    sys.stderr.write('Usage: %s <binary> options? <profraw>...\n' % sys.argv[0])
    return 1

  # First find llvm profile sections addresses in the elf, quick and dirty.
  process = subprocess.Popen(['readelf', '-S', sys.argv[1]],
                             stdout=subprocess.PIPE)
  output, err = process.communicate()
  if err:
    print('readelf failed')
    return 2
  for line in iter(output.split(b'\n')):
    if b'__llvm_prf_cnts' in line:
      sect_prf_cnts = int(line.split()[3], 16)
    elif b'__llvm_prf_data' in line:
      sect_prf_data = int(line.split()[3], 16)

  out_name = "default.profup"
  in_place = False
  start = 2
  if sys.argv[2] == "-i":
    in_place = True
    start = start + 1
  elif sys.argv[2] == "-o":
    out_name = sys.argv[3]
    start = 4

  if len(sys.argv) < start:
    sys.stderr.write('Usage: %s <binary> options <profraw>...\n' % sys.argv[0])
    return 1

  for i in range(start, len(sys.argv)):
    # Then open and read the input profraw file.
    with open(sys.argv[i], 'rb') as input_file:
      profraw_base = bytearray(input_file.read())
    # Do the upgrade, returning a bytes object.
    profraw_latest = upgrade(profraw_base, sect_prf_cnts, sect_prf_data)
    # Write the output to the file given to the command line.
    if in_place:
      out_name = sys.argv[i]
    with open(out_name, 'wb') as output_file:
      output_file.write(profraw_latest)

  return 0


if __name__ == '__main__':
  sys.exit(main())