// Copyright 2015 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.

#include "base/trace_event/process_memory_maps_dump_provider.h"

#include "base/files/scoped_file.h"
#include "base/format_macros.h"
#include "base/logging.h"
#include "base/strings/string_util.h"
#include "base/trace_event/process_memory_dump.h"
#include "base/trace_event/process_memory_maps.h"

namespace base {
namespace trace_event {

// static
FILE* ProcessMemoryMapsDumpProvider::proc_smaps_for_testing = nullptr;

namespace {

const uint32 kMaxLineSize = 4096;

bool ParseSmapsHeader(const char* header_line,
                      ProcessMemoryMaps::VMRegion* region) {
  // e.g., "00400000-00421000 r-xp 00000000 fc:01 1234  /foo.so\n"
  bool res = true;  // Whether this region should be appended or skipped.
  uint64 end_addr = 0;
  char protection_flags[5] = {0};
  char mapped_file[kMaxLineSize];

  if (sscanf(header_line, "%" SCNx64 "-%" SCNx64 " %4c %*s %*s %*s%4095[^\n]\n",
             &region->start_address, &end_addr, protection_flags,
             mapped_file) != 4)
    return false;

  if (end_addr > region->start_address) {
    region->size_in_bytes = end_addr - region->start_address;
  } else {
    // This is not just paranoia, it can actually happen (See crbug.com/461237).
    region->size_in_bytes = 0;
    res = false;
  }

  region->protection_flags = 0;
  if (protection_flags[0] == 'r') {
    region->protection_flags |=
        ProcessMemoryMaps::VMRegion::kProtectionFlagsRead;
  }
  if (protection_flags[1] == 'w') {
    region->protection_flags |=
        ProcessMemoryMaps::VMRegion::kProtectionFlagsWrite;
  }
  if (protection_flags[2] == 'x') {
    region->protection_flags |=
        ProcessMemoryMaps::VMRegion::kProtectionFlagsExec;
  }

  region->mapped_file = mapped_file;
  TrimWhitespaceASCII(region->mapped_file, TRIM_ALL, &region->mapped_file);

  return res;
}

uint64 ReadCounterBytes(char* counter_line) {
  uint64 counter_value = 0;
  int res = sscanf(counter_line, "%*s %" SCNu64 " kB", &counter_value);
  DCHECK_EQ(1, res);
  return counter_value * 1024;
}

uint32 ParseSmapsCounter(char* counter_line,
                         ProcessMemoryMaps::VMRegion* region) {
  // A smaps counter lines looks as follows: "RSS:  0 Kb\n"
  uint32 res = 1;
  char counter_name[20];
  int did_read = sscanf(counter_line, "%19[^\n ]", counter_name);
  DCHECK_EQ(1, did_read);

  if (strcmp(counter_name, "Pss:") == 0) {
    region->byte_stats_proportional_resident = ReadCounterBytes(counter_line);
  } else if (strcmp(counter_name, "Private_Dirty:") == 0) {
    region->byte_stats_private_dirty_resident = ReadCounterBytes(counter_line);
  } else if (strcmp(counter_name, "Private_Clean:") == 0) {
    region->byte_stats_private_clean_resident = ReadCounterBytes(counter_line);
  } else if (strcmp(counter_name, "Shared_Dirty:") == 0) {
    region->byte_stats_shared_dirty_resident = ReadCounterBytes(counter_line);
  } else if (strcmp(counter_name, "Shared_Clean:") == 0) {
    region->byte_stats_shared_clean_resident = ReadCounterBytes(counter_line);
  } else if (strcmp(counter_name, "Swap:") == 0) {
    region->byte_stats_swapped = ReadCounterBytes(counter_line);
  } else {
    res = 0;
  }

  return res;
}

uint32 ReadLinuxProcSmapsFile(FILE* smaps_file, ProcessMemoryMaps* pmm) {
  if (!smaps_file)
    return 0;

  fseek(smaps_file, 0, SEEK_SET);

  char line[kMaxLineSize];
  const uint32 kNumExpectedCountersPerRegion = 6;
  uint32 counters_parsed_for_current_region = 0;
  uint32 num_valid_regions = 0;
  ProcessMemoryMaps::VMRegion region;
  bool should_add_current_region = false;
  for (;;) {
    line[0] = '\0';
    if (fgets(line, kMaxLineSize, smaps_file) == nullptr)
      break;
    DCHECK_GT(strlen(line), 0u);
    if (isxdigit(line[0]) && !isupper(line[0])) {
      region = ProcessMemoryMaps::VMRegion();
      counters_parsed_for_current_region = 0;
      should_add_current_region = ParseSmapsHeader(line, &region);
    } else {
      counters_parsed_for_current_region += ParseSmapsCounter(line, &region);
      DCHECK_LE(counters_parsed_for_current_region,
                kNumExpectedCountersPerRegion);
      if (counters_parsed_for_current_region == kNumExpectedCountersPerRegion) {
        if (should_add_current_region) {
          pmm->AddVMRegion(region);
          ++num_valid_regions;
          should_add_current_region = false;
        }
      }
    }
  }
  return num_valid_regions;
}

}  // namespace

// static
ProcessMemoryMapsDumpProvider* ProcessMemoryMapsDumpProvider::GetInstance() {
  return Singleton<ProcessMemoryMapsDumpProvider,
                   LeakySingletonTraits<ProcessMemoryMapsDumpProvider>>::get();
}

ProcessMemoryMapsDumpProvider::ProcessMemoryMapsDumpProvider() {
}

ProcessMemoryMapsDumpProvider::~ProcessMemoryMapsDumpProvider() {
}

// Called at trace dump point time. Creates a snapshot of the memory maps for
// the current process.
bool ProcessMemoryMapsDumpProvider::OnMemoryDump(const MemoryDumpArgs& args,
                                                 ProcessMemoryDump* pmd) {
  // Snapshot of memory maps is not taken for light dump requests.
  if (args.level_of_detail == MemoryDumpLevelOfDetail::LIGHT)
    return true;

  uint32 res = 0;
  if (UNLIKELY(proc_smaps_for_testing)) {
    res = ReadLinuxProcSmapsFile(proc_smaps_for_testing, pmd->process_mmaps());
  } else {
    ScopedFILE smaps_file(fopen("/proc/self/smaps", "r"));
    res = ReadLinuxProcSmapsFile(smaps_file.get(), pmd->process_mmaps());
  }

  if (res > 0) {
    pmd->set_has_process_mmaps();
    return true;
  }
  return false;
}

}  // namespace trace_event
}  // namespace base