debug_new.cpp File Reference

Implementation of debug versions of new and delete to check leakage. More...

#include <new>
#include <assert.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "fast_mutex.h"
#include "static_assert.h"
#include "debug_new.h"

Include dependency graph for debug_new.cpp:

Classes
struct	new_ptr_list_t
	Structure to store the position information where new occurs. More...
Defines
#define	_DEBUG_NEW_ALIGNMENT   16
	The alignment requirement of allocated memory blocks.
#define	_DEBUG_NEW_CALLER_ADDRESS   __builtin_return_address(0)
	The expression to return the caller address.
#define	_DEBUG_NEW_ERROR_ACTION   abort()
	The action to take when an error occurs.
#define	_DEBUG_NEW_FILENAME_LEN   44
	The length of file name stored if greater than zero.
#define	_DEBUG_NEW_PROGNAME   NULL
	The program (executable) name to be set at compile time.
#define	_DEBUG_NEW_STD_OPER_NEW   1
	Macro to indicate whether the standard-conformant behaviour of operator new is wanted.
#define	_DEBUG_NEW_TAILCHECK   0
	Macro to indicate whether a writing-past-end check will be performed.
#define	_DEBUG_NEW_TAILCHECK_CHAR   0xCC
	Value of the padding bytes at the end of a memory block.
#define	_DEBUG_NEW_USE_ADDR2LINE   1
	Whether to use addr2line to convert a caller address to file/line information.
#define	_DEBUG_NEW_REDEFINE_NEW   0
	Macro to indicate whether redefinition of new is wanted.
#define	align(s)   (((s) + _DEBUG_NEW_ALIGNMENT - 1) & ~(_DEBUG_NEW_ALIGNMENT - 1))
	Gets the aligned value of memory block size.
Functions
static bool	print_position_from_addr (const void *addr)
	Tries printing the position information from an instruction address.
static void	print_position (const void *ptr, int line)
	Prints the position information of a memory operation point.
static bool	check_tail (new_ptr_list_t *ptr)
	Checks whether the padding bytes at the end of a memory block is tampered with.
static void *	alloc_mem (size_t size, const char *file, int line, bool is_array)
	Allocates memory and initializes control data.
static void	free_pointer (void *pointer, void *addr, bool is_array)
	Frees memory and adjusts pointers.
int	check_leaks ()
	Checks for memory leaks.
int	check_mem_corruption ()
	Checks for heap corruption.
void *	operator new (size_t size, const char *file, int line)
void *	operator new[] (size_t size, const char *file, int line)
void *	operator new (size_t size) throw (std::bad_alloc)
void *	operator new[] (size_t size) throw (std::bad_alloc)
void *	operator new (size_t size, const std::nothrow_t &) throw ()
void *	operator new[] (size_t size, const std::nothrow_t &) throw ()
void	operator delete (void *pointer) throw ()
void	operator delete[] (void *pointer) throw ()
void	operator delete (void *pointer, const char *file, int line) throw ()
void	operator delete[] (void *pointer, const char *file, int line) throw ()
void	operator delete (void *pointer, const std::nothrow_t &) throw ()
void	operator delete[] (void *pointer, const std::nothrow_t &) throw ()
Variables
const unsigned	MAGIC = 0x4442474E
	Magic number for error detection.
const int	ALIGNED_LIST_ITEM_SIZE = align(sizeof(new_ptr_list_t))
	The extra memory allocated by operator new.
static new_ptr_list_t	new_ptr_list
	List of all new'd pointers.
static fast_mutex	new_ptr_lock
	The mutex guard to protect simultaneous access to the pointer list.
static fast_mutex	new_output_lock
	The mutex guard to protect simultaneous output to new_output_fp.
static size_t	total_mem_alloc = 0
	Total memory allocated in bytes.
bool	new_autocheck_flag = true
	Flag to control whether check_leaks will be automatically called on program exit.
bool	new_verbose_flag = false
	Flag to control whether verbose messages are output.
FILE *	new_output_fp = stderr
	Pointer to the output stream.
const char *	new_progname = _DEBUG_NEW_PROGNAME
	Pointer to the program name.

---

Detailed Description

Implementation of debug versions of new and delete to check leakage.

Version:

4.12, 2007/12/31

Author:

Wu Yongwei

---

Define Documentation

#define _DEBUG_NEW_ALIGNMENT   16

The alignment requirement of allocated memory blocks.

It must be a power of two.

#define _DEBUG_NEW_CALLER_ADDRESS   __builtin_return_address(0)

The expression to return the caller address.

print_position will later on use this address to print the position information of memory operation points.

#define _DEBUG_NEW_ERROR_ACTION   abort()

The action to take when an error occurs.

The default behaviour is to call abort, unless _DEBUG_NEW_ERROR_CRASH is defined, in which case a segmentation fault will be triggered instead (which can be useful on platforms like Windows that do not generate a core dump when abort is called).

#define _DEBUG_NEW_FILENAME_LEN   44

The length of file name stored if greater than zero.

If it is zero, only a const char pointer will be stored. Currently the default behaviour is to copy the file name, because I found that the exit leakage check cannot access the address of the file name sometimes (in my case, a core dump will occur when trying to access the file name in a shared library after a SIGINT). The current default value makes the size of new_ptr_list_t 64 on 32-bit platforms.

#define _DEBUG_NEW_PROGNAME   NULL

The program (executable) name to be set at compile time.

It is better to assign the full program path to new_progname in main (at run time) than to use this (compile-time) macro, but this macro serves well as a quick hack. Note also that double quotation marks need to be used around the program name, i.e., one should specify a command-line option like -D_DEBUG_NEW_PROGNAME=\"a.out\" in bash, or -D_DEBUG_NEW_PROGNAME=\"a.exe\" in the Windows command prompt.

#define _DEBUG_NEW_REDEFINE_NEW   0

Macro to indicate whether redefinition of new is wanted.

Here it is defined to 0 to disable the redefinition of new.

#define _DEBUG_NEW_STD_OPER_NEW   1

Macro to indicate whether the standard-conformant behaviour of operator new is wanted.

It is on by default now, but the user may set it to 0 to revert to the old behaviour.

#define _DEBUG_NEW_TAILCHECK   0

Macro to indicate whether a writing-past-end check will be performed.

Define it to a positive integer as the number of padding bytes at the end of a memory block for checking.

#define _DEBUG_NEW_TAILCHECK_CHAR   0xCC

Value of the padding bytes at the end of a memory block.

#define _DEBUG_NEW_USE_ADDR2LINE   1

Whether to use addr2line to convert a caller address to file/line information.

Defining it to a non-zero value will enable the conversion (automatically done if GCC is detected). Defining it to zero will disable the conversion.

#define align

(

s

)

(((s) + _DEBUG_NEW_ALIGNMENT - 1) & ~(_DEBUG_NEW_ALIGNMENT - 1))

Gets the aligned value of memory block size.

---

Function Documentation

static void* alloc_mem	(	size_t	size,
		const char *	file,
		int	line,
		bool	is_array
	)			[static]

Allocates memory and initializes control data.

Parameters:

	size	size of the required memory block
	file	null-terminated string of the file name
	line	line number
	is_array	boolean value whether this is an array operation

Returns:

pointer to the user-requested memory area; NULL if memory allocation is not successful

int check_leaks

(

)

Checks for memory leaks.

Returns:

zero if no leakage is found; the number of leaks otherwise

int check_mem_corruption

(

)

Checks for heap corruption.

Returns:

zero if no problem is found; the number of found memory corruptions otherwise

static bool check_tail

(

new_ptr_list_t *

ptr

)

[static]

Checks whether the padding bytes at the end of a memory block is tampered with.

Parameters:

ptr

pointer to a new_ptr_list_t struct

Returns:

true if the padding bytes are untouched; false otherwise

static void free_pointer	(	void *	pointer,
		void *	addr,
		bool	is_array
	)			[static]

Frees memory and adjusts pointers.

Parameters:

	pointer	pointer to delete
	addr	pointer to the caller
	is_array	flag indicating whether it is invoked by a delete[] call

void operator delete	(	void *	pointer,
		const std::nothrow_t &
	)			throw ()

void operator delete	(	void *	pointer,
		const char *	file,
		int	line
	)			throw ()

void operator delete

(

void *

pointer

)

throw ()

void operator delete[]	(	void *	pointer,
		const std::nothrow_t &
	)			throw ()

void operator delete[]	(	void *	pointer,
		const char *	file,
		int	line
	)			throw ()

void operator delete[]

(

void *

pointer

)

throw ()

void* operator new	(	size_t	size,
		const std::nothrow_t &
	)			throw ()

void* operator new

(

size_t

size

)

throw (std::bad_alloc)

void* operator new	(	size_t	size,
		const char *	file,
		int	line
	)

void* operator new[]	(	size_t	size,
		const std::nothrow_t &
	)			throw ()

void* operator new[]

(

size_t

size

)

throw (std::bad_alloc)

void* operator new[]	(	size_t	size,
		const char *	file,
		int	line
	)

static void print_position	(	const void *	ptr,
		int	line
	)			[static]

Prints the position information of a memory operation point.

When _DEBUG_NEW_USE_ADDR2LINE is defined to a non-zero value, this function will try to convert a given caller address to file/line information with addr2line.

Parameters:

	ptr	source file name if line is non-zero; caller address otherwise
	line	source line number if non-zero; indication that ptr is the caller address otherwise

static bool print_position_from_addr

(

const void *

addr

)

[static]

Tries printing the position information from an instruction address.

This is the version that uses addr2line.

Parameters:

addr

the instruction address to convert and print

Returns:

true if the address is converted successfully (and the result is printed); false if no useful information is got (and nothing is printed)

---

Variable Documentation

const int ALIGNED_LIST_ITEM_SIZE = align(sizeof(new_ptr_list_t))

The extra memory allocated by operator new.

const unsigned MAGIC = 0x4442474E

Magic number for error detection.

bool new_autocheck_flag = true

Flag to control whether check_leaks will be automatically called on program exit.

FILE* new_output_fp = stderr

Pointer to the output stream.

The default output is stderr, and one may change it to a user stream if needed (say, new_verbose_flag is true and there are a lot of (de)allocations).

fast_mutex new_output_lock [static]

The mutex guard to protect simultaneous output to new_output_fp.

const char* new_progname = _DEBUG_NEW_PROGNAME

Pointer to the program name.

Its initial value is the macro _DEBUG_NEW_PROGNAME. You should try to assign the program path to it early in your application. Assigning argv[0] to it in main is one way. If you use bash or ksh (or similar), the following statement is probably what you want: `new_progname = getenv("_");'.

new_ptr_list_t new_ptr_list [static]

Initial value:

 {
    &new_ptr_list,
    &new_ptr_list,
    0,
    {



        ""

    },
    0,
    0,
    MAGIC
}

List of all new'd pointers.

fast_mutex new_ptr_lock [static]

The mutex guard to protect simultaneous access to the pointer list.

bool new_verbose_flag = false

Flag to control whether verbose messages are output.

size_t total_mem_alloc = 0 [static]

Total memory allocated in bytes.

---