memory allocation wrapper - Page 2

goose

Hello all

I've written a wrapper for malloc and friends. Its
available from

http://www.lelanthran.com/downloads/os_mem/index.php

The reason for doing writing this so that newbies
can finally get answers to the following
newbie questions:
1. How do I know how much memory a pointer points to?
2. How can I tell if a pointer is valid?

I know most of the regs don't need this, but be
a good samaritan and point out the bugs :-)

Comments and criticisms(sp?) welcome; note that it aims
for c99 compliance only.

goose,

Aug 18 '06

Subscribe Reply

2070

CBFalconer

goose wrote:

>
I've summarised the replies here so that I could
reply to all without scattering the replies through
the thread.

---------------------------------------------------------------
Malcom wrote:
>There's a much easier way of achieveing what you want to do.
Simply put a structure at the start of the allocated memory, add
your control information, and return the pointer immediately
after. Then when the user calls the free, subtract the size of the
controlstructu re, and free. Similarly for the access functions.

.... large snip ...

Why don't you take a look at the methods I use in malldbg to detect
invalid structure in nmalloc. This is all contained in my
nmalloc.zip package, available for DJGPP at:

<http://cbfalconer.home .att.net/download/>

Basically validation is a dynamic thing, walking the known heap
structure and looking for disagreements between lengths and
next/prev pointers. There is also provision for maintaining
markers, of the 0xdeadbeef variety.

Conceded, this is not the same thing as validating a pointer
candidate in user space, but it does yield a comprehensive list of
valid pointers. Also, the methods used are not portable, but are
suited to systems with similar memory organization to DJGPP, which
is most OSs today.

--
Chuck F (cb********@yah oo.com) (cb********@mai neline.net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.netUSE maineline address!

Aug 20 '06 #11

Similar topics

8214

What is the difference between dynamic memory allocation,and stack allocation ?

by: chris | last post by:

Hi all, I need to know, what is the difference between dynamic memory allocation, and stack allocation ? 1. If I have a class named DestinationAddress, when should I use dynamic memory allocation to create object of that class ? 2. If it says "dynamic memory allocation", is it mean the following code : DestinationAddress* dest = new DestinationAddress(); // code 1

C / C++

3650

Checking return values for errors, a matter of style?

by: Johan Tibell | last post by:

I've written a piece of code that uses sockets a lot (I know that sockets aren't portable C, this is not a question about sockets per se). Much of my code ended up looking like this: if (function(socket, args) == -1) { perror("function"); exit(EXIT_FAILURE); } I feel that the ifs destroy the readability of my code. Would it be

C / C++

19101

static memory allocation versus dynamic memory allocation

by: Ken | last post by:

In C programming, I want to know in what situations we should use static memory allocation instead of dynamic memory allocation. My understanding is that static memory allocation like using array is faster than malloc, but dynamic memory allocation is more flexible. Please comment... thanks.

C / C++

7979

Dynamic Memory Allocation for Matrix(2D array)

by: Peterwkc | last post by:

Hello all expert, i have two program which make me desperate bu after i have noticed the forum, my future is become brightness back. By the way, my problem is like this i the first program was compiled and run without any erros but the second program has a run time error when the function return from allocate and the ptr become NULL. How to fixed this? Second Program: /* Best Method to allocate memory for 2D Array because it's ...

C / C++

2999

Dynamic allocation to static memory allocation

by: ranjeetasharma81 | last post by:

Hi all, I have a big C-cod, in which there are lots of dynamic memory allocation used. I want to replace dynamic memroy allocation by static arrays. The following are the problems that i am facing: 1- From structure and dynamic memory allocation point of view, the code is very complicated. The code has various “nested structures” with a number of levels. The size of memory allocated for pointer to structure or its pointer...

C / C++

1670

problem with dynamic memory allocation

by: David d'Angers | last post by:

hi group: i've been struggling with this simple problem with dismay i need all the file names in a directory since the number of files in a directory is unknown, a friend here in the group hinted me to use dynamic memory allocation: namely functions like malloc etc in the spirit of code re-use

C / C++

3841

Dynamic memory allocation stack heaps

by: vivek | last post by:

i have some doubts on dynamic memory allocation and stacks and heaps where is the dynamic memory allocation used? in function calls there are some counters like "i" in the below function. Is this stored in stack. If yes whether it will be deleted on exiting from the function. is dynamic memory allocation needed for this purpose

C / C++

4431

Memory Allocation : Static or Dynamic?

by: swornavidhya.mahadevan | last post by:

Which allocation (Static / Dynamic) is suitable for the situation when we are trying to allocate for a overloaded memory when the memory is full and no space to allocate. What will happen if both the allocation is impossible. Sworna vidhya

C / C++

2294

Memory allocation

by: Andy Baker | last post by:

I have recently written a .NET wrapper for a C++ DLL file and it seems to be working well, but I do have some concerns about memory. From my limited C programming experience (college 15+ years ago), I seem to remember that when using structures etc in C, you had to allocate memory to them then deallocate them when you had finished using them. My C# code creates a variable of type structure, passes it to the C++ DLL and then returns...

C# / C Sharp

9708

What is ONU?

by: marktang | last post by:

ONU (Optical Network Unit) is one of the key components for providing high-speed Internet services. Its primary function is to act as an endpoint device located at the user's premises. However, people are often confused as to whether an ONU can Work As a Router. In this blog post, we’ll explore What is ONU, What Is Router, ONU & Router’s main usage, and What is the difference between ONU and Router. Let’s take a closer look ! Part I. Meaning of...

General

9588

Changing the language in Windows 10

by: Hystou | last post by:

Most computers default to English, but sometimes we require a different language, especially when relocating. Forgot to request a specific language before your computer shipped? No problem! You can effortlessly switch the default language on Windows 10 without reinstalling. I'll walk you through it. First, let's disable language synchronization. With a Microsoft account, language settings sync across devices. To prevent any complications,...

Windows Server

10589

Problem With Comparison Operator <=> in G++

by: Oralloy | last post by:

Hello folks, I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>". The problem is that using the GNU compilers, it seems that the internal comparison operator "<=>" tries to promote arguments from unsigned to signed. This is as boiled down as I can make it. Here is my compilation command: g++-12 -std=c++20 -Wnarrowing bit_field.cpp Here is the code in...

C / C++

10327

The easy way to turn off automatic updates for Windows 10/11

by: Hystou | last post by:

Overview: Windows 11 and 10 have less user interface control over operating system update behaviour than previous versions of Windows. In Windows 11 and 10, there is no way to turn off the Windows Update option using the Control Panel or Settings app; it automatically checks for updates and installs any it finds, whether you like it or not. For most users, this new feature is actually very convenient. If you want to control the update process,...

Windows Server

10085

Discussion: How does Zigbee compare with other wireless protocols in smart home applications?

by: tracyyun | last post by:

Dear forum friends, With the development of smart home technology, a variety of wireless communication protocols have appeared on the market, such as Zigbee, Z-Wave, Wi-Fi, Bluetooth, etc. Each protocol has its own unique characteristics and advantages, but as a user who is planning to build a smart home system, I am a bit confused by the choice of these technologies. I'm particularly interested in Zigbee because I've heard it does some...

General

7625

Access Europe - Using VBA to create a class based on a table - Wed 1 May

by: isladogs | last post by:

The next Access Europe User Group meeting will be on Wednesday 1 May 2024 starting at 18:00 UK time (6PM UTC+1) and finishing by 19:30 (7.30PM). In this session, we are pleased to welcome a new presenter, Adolph Dupré who will be discussing some powerful techniques for using class modules. He will explain when you may want to use classes instead of User Defined Types (UDT). For example, to manage the data in unbound forms. Adolph will...

Microsoft Access / VBA

5527

Trying to create a lan-to-lan vpn between two differents networks

by: TSSRALBI | last post by:

Hello I'm a network technician in training and I need your help. I am currently learning how to create and manage the different types of VPNs and I have a question about LAN-to-LAN VPNs. The last exercise I practiced was to create a LAN-to-LAN VPN between two Pfsense firewalls, by using IPSEC protocols. I succeeded, with both firewalls in the same network. But I'm wondering if it's possible to do the same thing, with 2 Pfsense firewalls...

Networking - Hardware / Configuration

4302

transfer the data from one system to another through ip address

by: 6302768590 | last post by:

Hai team i want code for transfer the data from one system to another through IP address by using C# our system has to for every 5mins then we have to update the data what the data is updated we have to send another system

C# / C Sharp

2999

Comprehensive Guide to Website Development in Toronto: Expert Insights from BSMN Consultancy

by: bsmnconsultancy | last post by:

In today's digital era, a well-designed website is crucial for businesses looking to succeed. Whether you're a small business owner or a large corporation in Toronto, having a strong online presence can significantly impact your brand's success. BSMN Consultancy, a leader in Website Development in Toronto offers valuable insights into creating effective websites that not only look great but also perform exceptionally well. In this comprehensive...

General