[RESOLVED] Memory allocation API

[Not me]

How would this be done using API?


char *lpBuffer;
lpBuffer = new char[size];

[wigga]

http://msdn.microsoft.com/en-us/library/aa366597(VS.85).aspx


kudos please

[Not me]

Thanks Wigga

What do you think of using this function?
VirtualAlloc

[wigga]

using the heap is faster.. tell me what you want todo

[Not me]

open file and assign the ReadFile() function to read into this newly allocated buffer lpBuffer instead of using newoperator to allocate memory

What thos this mean if you can explain - It is an ATTRIBUTE for HeapCreate.
Execute code from memory? I can load an executable into memory and execute it from memory?


HEAP_CREATE_ENABLE_EXECUTE
0x00040000

All memory blocks that are allocated from this heap allow code execution, if the hardware enforces data execution prevention. Use this flag heap in applications that run code from the heap. If HEAP_CREATE_ENABLE_EXECUTE is not specified and an application attempts to run code from a protected page, the application receives an exception with the status code STATUS_ACCESS_VIOLATION.

[Igor Vartanov]

open file and assign the ReadFile() function to read into this newly allocated buffer lpBuffer instead of using newoperator to allocate memoryWhat is this all mostly about? Having a dynamic buffer size?
What's wrong with 'new' operator? Besides, are you sure you need that memory allocated in heap but not stack?

[Not me]

Nothing is wrong with new I'm doing it with API functions and want to know how is the best way to do it.
I need to allocate the same memory new operator allocates.
Yeah, i need dynamic buffer size.

But ok I managed to do it, now i have a subquestion.

How to assign data stored in that memory to another variable? Copy that memory data to its location?

So is CopyMemory a best way to do it?

[wigga]

it all depends on the file you are readding.
1. is it in text format
2. is it in binary format

what is the data inside the file??

[Not me]

This is another problem, file is binary but i manged to read it. File and allocation are no more problems. Well there is no problem but im interested what function is the best to use:

lpPathBuffer = lstrcat(lpBuffer, "\\*.*");

Both variables are pointers and after this function both variables point to same address. The address holds path for C: and after function it would be C:\*.*

I want one variable to stay C: because i have to use it for subfolders in a recursive search.
If a folder is found The path would be C:\folder

So i guess i will have to make a copy of variable each time i call the function and then delete it.

Overall, Im stuck here, in this recursive file search.

[Not me]

Ok, the problem is i want to use = but i cant use it with pointers because that will make them point at same memory and i wont get what i want, two variables with same values but different memory locations.

[wigga]

To help you more in this i need to know the format of the file. And i need to see more of your code. Just saying that problem is you want to use the operator = and talking about some variables pointing at the same memory is just confusing me.

[Not me]

How would you declare variable lpBuffer and alocate the memory for it?

DWORD dwDriveList = GetLogicalDriveStrings(255, lpBuffer);


Here is the function info:


DWORD WINAPI GetLogicalDriveStrings(
__in DWORD nBufferLength,
__out LPTSTR lpBuffer
);


Parameters:

nBufferLength [in]
The maximum size of the buffer pointed to by lpBuffer, in TCHARs. This size does not include the terminating null character. If this parameter is zero, lpBuffer is not used.

lpBuffer [out]
A pointer to a buffer that receives a series of null-terminated strings, one for each valid drive in the system, plus with an additional null character. Each string is a device name.

Return Value
If the function succeeds, the return value is the length, in characters, of the strings copied to the buffer

[wigga]

TCHAR lpBuffer[255];

[Not me]

I guess i was doing it the harder way but when i used char* i got error for function parameters...

Thank you.