pe-parse/parser-library/buffer.cpp

/*
The MIT License (MIT)

Copyright (c) 2013 Andrew Ruef

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

#include <fstream>
#include <string.h>
#include "parse.h"

#ifdef WIN32
#include <windows.h>
#else
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <fcntl.h>
#endif

using namespace boost;
using namespace std;

struct buffer_detail {
#ifdef WIN32
  HANDLE  file;
  HANDLE  sec;
#else
  int     fd;
#endif
};

bool readByte(bounded_buffer *b, ::uint32_t offset, ::uint8_t &out) {
  if(b == NULL) {
    return false;
  }

  if(offset >= b->bufLen) {
    return false;
  }

  ::uint8_t *tmp = (b->buf+offset);
  out = *tmp;

  return true;
}

//TODO: perform endian swap as needed
bool readWord(bounded_buffer *b, ::uint32_t offset, ::uint16_t &out) {
  if(b == NULL) {
    return false;
  }

  if(offset >= b->bufLen) {
    return false;
  }

  ::uint16_t  *tmp = (::uint16_t *)(b->buf+offset);
  out = *tmp;

  return true;
}

//TODO: perform endian swap as needed
bool readDword(bounded_buffer *b, ::uint32_t offset, ::uint32_t &out) {
  if(b == NULL) {
    return false;
  }

  if(offset >= b->bufLen) {
    return false;
  }

  ::uint32_t  *tmp = (::uint32_t *)(b->buf+offset);
  out = *tmp;

  return true;
}


bounded_buffer *readFileToFileBuffer(const char *filePath) {
#ifdef WIN32
  HANDLE  h = CreateFileA(filePath, 
                          GENERIC_READ, 
                          0, 
                          NULL, 
                          OPEN_EXISTING, 
                          FILE_ATTRIBUTE_NORMAL, 
                          NULL);
  if(h == INVALID_HANDLE_VALUE) {
    return NULL;
  }

  DWORD fileSize = GetFileSize(h, NULL);

  if(fileSize == INVALID_FILE_SIZE) {
    CloseHandle(h);
    return NULL;
  }

#else
  //only where we have mmap / open / etc
  int fd = open(filePath, O_RDONLY);

  if(fd == -1) {
    return NULL;
  }
#endif

  //make a buffer object
  bounded_buffer  *p = new bounded_buffer();

  if(p == NULL) {
    return NULL;
  }

  memset(p, 0, sizeof(bounded_buffer));
  buffer_detail *d = new buffer_detail();

  if(d == NULL) {
    delete p;
    return NULL;
  }
  memset(d, 0, sizeof(buffer_detail));
  p->detail = d;

  //only where we have mmap / open / etc
#ifdef WIN32
  p->detail->file = h;

  HANDLE  hMap = CreateFileMapping(h, NULL, PAGE_READONLY, 0, 0, NULL);

  if(hMap == NULL) {
    CloseHandle(h);
    return NULL;
  }

  p->detail->sec = hMap;

  LPVOID  ptr = MapViewOfFile(hMap, FILE_MAP_READ, 0, 0, 0);

  if(ptr == NULL) {
    return NULL;
  }

  p->buf = (::uint8_t *)ptr;
  p->bufLen = fileSize;
  p->copy = false;
#else
  p->detail->fd = fd;

  struct stat s = {0};

  if(fstat(fd, &s) != 0) {
    close(fd);
    delete d;
    delete p;
    return NULL;
  }

  void *maddr = mmap(NULL, s.st_size, PROT_READ, MAP_SHARED, fd, 0);

  if(maddr == MAP_FAILED) {
    close(fd);
    delete d;
    delete p;
    return NULL;
  }

  p->buf = (::uint8_t *)maddr;
  p->bufLen = s.st_size;
  p->copy = false;
#endif

  return p;
}

//split buffer inclusively from from to to by offset
bounded_buffer *splitBuffer(bounded_buffer *b, ::uint32_t from, ::uint32_t to) {
  if(b == NULL) {
    return NULL;
  }

  //safety checks
  if(to < from || to > b->bufLen) {
    return NULL;
  }
  
  //make a new buffer
  bounded_buffer  *newBuff = new bounded_buffer();

  if(newBuff == NULL) {
    return NULL;
  }

  newBuff->copy = true;
  newBuff->buf = b->buf+from;
  newBuff->bufLen = (to-from);

  return newBuff;
}

void deleteBuffer(bounded_buffer *b) {
  if(b == NULL) {
    return;
  }

  if(b->copy == false) {
#ifdef WIN32
    UnmapViewOfFile(b->buf);
    CloseHandle(b->detail->sec);
    CloseHandle(b->detail->file);
#else
    munmap(b->buf, b->bufLen);
    close(b->detail->fd);
#endif
  }

  delete b;

  return;
}

uint64_t bufLen(bounded_buffer *b) {
  return b->bufLen;
}