Ticket #16622: MMap.cpp

#include <fcntl.h>
#include <sys/mman.h>
#include <stdio.h>

#include <new>

#include <SupportDefs.h>

#include <private/shared/AutoDeleter.h>


class Block
{
public:
    Block *next;
    HandleDeleter<int, int, close> file;
    void *ptr;
    size_t size;

    Block(const char *name):
        file(open(name, O_RDONLY)),
        ptr(NULL)
    {
        if (file.Get() >= 0) {
            struct stat s;
            fstat(file.Get(), &s);
            size = s.st_size;
            ptr = mmap(0, s.st_size, PROT_READ, MAP_PRIVATE, file.Get(), 0);
        }
    }

    ~Block()
    {
        munmap(ptr, size);
        ptr = NULL;
    }

};


int main()
{
    Block *blocks = NULL;
    size_t totalSize = 0;

    for (int i = 0; i < 4096; i++) {
        Block *blk = new(std::nothrow) Block("TestFile");
        if (blk == NULL || blk->ptr == NULL)
            break;
        blk->next = blocks; blocks = blk;
        totalSize += blk->size;
    }

    printf("Allocated: %" B_PRIuSIZE, totalSize); getc(stdin);

    while (blocks != NULL) {
        Block *next = blocks->next;
        totalSize -= blocks->size;
        delete blocks;
        blocks = next;
    }

    printf("Freed: %" B_PRIuSIZE, totalSize); getc(stdin);

    return 0;
}