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Secure Memory For Swift Objects


Secure Memory For Swift Objects

By : cr450v3rr1d3
Date : November 22 2020, 10:54 AM
This might help you If you want complete control over a region of memory you allocate yourself, you can use UnsafePointer and co:
code :
// allocate enough memory for ten Ints
var ump = UnsafeMutablePointer<Int>.alloc(10)
// memory is in an uninitialized raw state

// initialize that memory with Int objects
// (here, from a collection)
ump.initializeFrom(reverse(0..<10))

// memory property gives you access to the underlying value
ump.memory // 9

// UnsafeMutablePointer acts like an IndexType
ump.successor().memory // 8
// and it has a subscript, but it's not a CollectionType
ump[3] // = 6

// wrap it in an UnsafeMutableBufferPointer to treat it
// like a collection (or UnsafeBufferPointer if you don't
// need to be able to alter the values)
let col = UnsafeMutableBufferPointer(start: ump, count: 10)
col[3] = 99
println(",".join(map(col,toString)))
// prints 9,8,7,99,5,4,3,2,1,0

ump.destroy(10)
// now the allocated memory is back in a raw state
// you could re-allocate it...
ump.initializeFrom(0..<10)
ump.destroy(10)

// when you're done, deallocate the memory
ump.dealloc(10)
let count = 10
let ump = UnsafeMutablePointer.allocate<Int>(count)
mlock(ump, UInt(sizeof(Int) * count))
// initialize, use, and destroy the memory
munlock(ump, UInt(sizeof(Int) * count))
ump.dealloc(count)
struct MyStruct {
    let a: Int
    let b: Int
}

var pointerToStruct = UnsafeMutablePointer<MyStruct>.alloc(1)
pointerToStruct.initialize(MyStruct(a: 1, b: 2))
pointerToStruct.memory.b  // 2
pointerToStruct.destroy()
pointerToStruct.dealloc(1)
// Note this is a class not a struct, so it does NOT have value semantics,
// changing a copy changes all copies.
public class UnsafeCollection<T> {
    private var _len: Int = 0
    private var _buflen: Int = 0
    private var _buf: UnsafeMutablePointer<T> = nil

    public func removeAll(keepCapacity: Bool = false) {
        _buf.destroy(_len)
        _len = 0
        if !keepCapacity {
            _buf.dealloc(_buflen)
            _buflen = 0
            _buf = nil
        }
    }

    public required init() { }
    deinit { self.removeAll(keepCapacity: false) }

    public var count: Int { return _len }
    public var isEmpty: Bool { return _len == 0 }
}
extension UnsafeCollection: MutableCollectionType {
    typealias Index = Int
    public var startIndex: Int { return 0 }
    public var endIndex: Int { return _len }

    public subscript(idx: Int) -> T {
        get {
            precondition(idx < _len)
            return _buf[idx]
        }
        set(newElement) {
            precondition(idx < _len)
            let ptr = _buf.advancedBy(idx)
            ptr.destroy()
            ptr.initialize(newElement)
        }
    }

    typealias Generator = IndexingGenerator<UnsafeCollection>
    public func generate() -> Generator {
        return Generator(self)
    }
}
extension UnsafeCollection: ExtensibleCollectionType {
    public func reserveCapacity(n: Index.Distance) {
        if n > _buflen {
            let newBuf = UnsafeMutablePointer<T>.alloc(n)
            newBuf.moveInitializeBackwardFrom(_buf, count: _len)
            _buf.dealloc(_buflen)
            _buf = newBuf
            _buflen = n
        }
    }

    public func append(x: T) {
        if _len == _buflen {
            reserveCapacity(Int(Double(_len) * 1.6) + 1)
        }
        _buf.advancedBy(_len++).initialize(x)
    }

    public func extend<S: SequenceType where S.Generator.Element == T>
      (newElements: S) {
        var g = newElements.generate()
        while let x: T = g.next() {
            self.append(x)
        }
    }
}


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How req.secure checks that incoming request is for secure server or not in https secure communication?

How req.secure checks that incoming request is for secure server or not in https secure communication?


By : Cesar Zapata
Date : March 29 2020, 07:55 AM
Any of those help , req.secure checks if the protocol is HTTPS and it's the same as:
code :
req.protocol === 'https'
server.use('/path', function(req, res, next) {  
  if(!req.secure) {
    var secureUrl = "https://" + req.headers['host'] + req.url; 
    res.writeHead(301, { "Location":  secureUrl });
    res.end();
  }
  next();
});
Python memory release upon reset tkinter objects containing objects containing objects

Python memory release upon reset tkinter objects containing objects containing objects


By : user6801146
Date : March 29 2020, 07:55 AM
fixed the issue. Will look into that further Without actually seeing your program...I would suggest that you look at:
Best way to structure a tkinter application
A program uses different regions of memory for static objects, automatic objects, and dynamically allocated objects

A program uses different regions of memory for static objects, automatic objects, and dynamically allocated objects


By : user1944392
Date : March 29 2020, 07:55 AM
To fix this issue Different regions have very different addresses. If they were in the same region, they would have similar addresses. Better example, where we allocate 2 objects in each region:
code :
#include <stdio.h>
#include <stdlib.h>

int main (void)
{
  int stack1;
  int stack2;
  static int bss1;
  static int bss2;
  static int data1=1;
  static int data2=1;
  int* heap1 = malloc(1);
  int* heap2 = malloc(1);  
  char* rodata1 = "hello";
  char* rodata2 = "world";

  printf(".stack\t%p %p\n",  &stack1,  &stack2);
  printf(".bss\t%p %p\n",    &bss1,    &bss2);
  printf(".data\t%p %p\n",   &data1,   &data2);
  printf(".heap\t%p %p\n",   heap1,    heap2);
  printf(".rodata\t%p %p\n", rodata1,  rodata2);

  free(heap1);
  free(heap2);
}
.stack  000000000022FE2C 000000000022FE28
.bss    0000000000407030 0000000000407034
.data   0000000000403010 0000000000403014
.heap   0000000000477C50 0000000000477C70
.rodata 0000000000404000 0000000000404006
Secure mode can access secure / non secure memory how?

Secure mode can access secure / non secure memory how?


By : veerendra patineedi
Date : March 29 2020, 07:55 AM
I think the issue was by ths following ,
So If a code (running in secure mode) is to be written to access say address 0xA0000000 [NS] and 0xA0000000[S] how would it be coded?
Why creating objects in preallocated memory slow than creating objects with allocating memory for each object individual

Why creating objects in preallocated memory slow than creating objects with allocating memory for each object individual


By : Ciro Echesortu
Date : March 29 2020, 07:55 AM
Does that help I've never written a memory pool before but I think you'll want to take account of (at least) 3 things:
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