SharedMemory Class Reference

Public Member Functions
	SharedMemory (const std::string &path, size_t size)
	SharedMemory (const SharedMemory &)
bool	open (const std::string &path, size_t size)
bool	open ()
void	close ()
bool	unlink ()
bool	seekTo (size_t)
bool	seekBy (size_t)
void *	map (size_t, size_t)
void *	map ()
bool	isOpened ()
const std::string &	getPath () const
size_t	size () const
int	getfd () const
bool	truncate (size_t size)
const SharedMemory &	operator= (const SharedMemory &)

Static Public Member Functions
static bool	unlink (const std::string &path)

Private Attributes
int	m_fd
std::string	m_path
size_t	m_size
void *	m_addr

Detailed Description

Definition at line 19 of file SharedMemory.h.

Constructor & Destructor Documentation

SharedMemory() [1/3]

SharedMemory

(

)

Definition at line 24 of file SharedMemory.cc.

  : m_fd(-1), m_path(), m_size(0), m_addr(NULL) {}

SharedMemory() [2/3]

SharedMemory	(	const std::string &	path,
		size_t	size
	)

Definition at line 27 of file SharedMemory.cc.

  : m_fd(-1), m_path(path), m_size(size), m_addr(NULL)
{
}

SharedMemory() [3/3]

SharedMemory

(

const SharedMemory &

file

)

Definition at line 32 of file SharedMemory.cc.

  : m_fd(file.m_fd),  m_path(file.m_path),
    m_size(file.m_size), m_addr(file.m_addr) {}

~SharedMemory()

~SharedMemory

(

)

Definition at line 36 of file SharedMemory.cc.

{}

Member Function Documentation

close()

void close

(

)

Definition at line 64 of file SharedMemory.cc.

{
  if (m_fd > 0) {
    if (m_addr != NULL) munmap(m_addr, m_size);
    ::close(m_fd);
    m_fd = 0;
  }
}

getfd()

int getfd ( ) const

inline

Definition at line 44 of file SharedMemory.h.

{ return m_fd; }

getPath()

const std::string & getPath ( ) const

inline

Definition at line 42 of file SharedMemory.h.

{ return m_path; }

isOpened()

bool isOpened

(

)

Definition at line 124 of file SharedMemory.cc.

{
  return (m_fd != 0);
}

map() [1/2]

void * map

(

)

Definition at line 102 of file SharedMemory.cc.

{
  if (m_addr == NULL) m_addr = map(0, m_size);
  return m_addr;
}

map() [2/2]

void * map	(	size_t	offset,
		size_t	size
	)

Definition at line 88 of file SharedMemory.cc.

{
  errno = 0;
  void* addr = ::mmap(NULL, size, PROT_READ | PROT_WRITE,
                      MAP_SHARED, m_fd, offset);
  if (addr == MAP_FAILED) {
    perror("mmap");
    addr = NULL;
  }
  m_addr = addr;
  m_size = size;
  return addr;
}

open() [1/2]

bool open

(

)

Definition at line 59 of file SharedMemory.cc.

{
  return open(m_path, m_size);
}

open() [2/2]

bool open	(	const std::string &	path,
		size_t	size
	)

Definition at line 38 of file SharedMemory.cc.

{
  errno = 0;
  int fd = ::shm_open(path.c_str(), O_CREAT | O_EXCL | O_RDWR, 0666);
  if (fd < 0) {
    if (errno != EEXIST) {
      perror("shm_oepn");
      return false;
    }
    fd = ::shm_open(path.c_str(), O_CREAT | O_RDWR, 0666);
    if (fd < 0) {
      perror("shm_oepn");
      return false;
    }
  }
  m_fd = fd;
  m_path = path;
  truncate(size);
  return true;
}

operator=()

const SharedMemory & operator=

(

const SharedMemory &

file

)

Definition at line 129 of file SharedMemory.cc.

{
  m_fd = file.m_fd;
  m_path = file.m_path;
  m_size = file.m_size;
  m_addr = file.m_addr;
  return *this;
}

seekBy()

bool seekBy

(

size_t

offset

)

Definition at line 119 of file SharedMemory.cc.

{
  return (lseek(m_fd, offset, SEEK_CUR) == -1);
}

seekTo()

bool seekTo

(

size_t

offset

)

Definition at line 114 of file SharedMemory.cc.

{
  return (lseek(m_fd, offset, SEEK_SET) == -1);
}

size()

size_t size ( ) const

inline

Definition at line 43 of file SharedMemory.h.

{ return m_size; }

truncate()

bool truncate

(

size_t

size

)

Definition at line 73 of file SharedMemory.cc.

{
  if (size > 0) {
    ::ftruncate(m_fd, size);
    m_size = size;
    return true;
  } else {
    struct stat st;
    fstat(m_fd, &st);
    m_size = st.st_size;
  }
  return false;
}

unlink() [1/2]

bool unlink

(

)

Definition at line 108 of file SharedMemory.cc.

{
  close();
  return (unlink(m_path));
}

unlink() [2/2]

bool unlink ( const std::string &  path )

static

Definition at line 19 of file SharedMemory.cc.

{
  return (::shm_unlink(path.c_str()) == -1);
}

Member Data Documentation

m_addr

void* m_addr

private

Definition at line 56 of file SharedMemory.h.

m_fd

int m_fd

private

Definition at line 53 of file SharedMemory.h.

m_path

std::string m_path

private

Definition at line 54 of file SharedMemory.h.

m_size

size_t m_size

private

Definition at line 55 of file SharedMemory.h.

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The documentation for this class was generated from the following files:

• daq/slc/system/include/SharedMemory.h
• daq/slc/system/src/SharedMemory.cc