PE 文件格式部分添加

Question

我对他们为什么在这里使用 - 1 感到困惑。有人可以解释一下这条线在非常非常非常低级的细节中做了什么...不是它减去 1 的结构....我需要了解更多...关于低级...谢谢...

PIMAGE_SECTION_HEADER last_section = IMAGE_FIRST_SECTION(nt_headers) + (nt_headers->FileHeader.NumberOfSections - 1);

上面的代码在下面的函数中：

//Reference: http://www.codeproject.com/KB/system/inject2exe.aspx
PIMAGE_SECTION_HEADER add_section(const char *section_name, unsigned int section_size, void *image_addr) {
    PIMAGE_DOS_HEADER dos_header = (PIMAGE_DOS_HEADER)image_addr;
    if(dos_header->e_magic != 0x5A4D) {
        wprintf(L"Could not retrieve DOS header from %p", image_addr);
        return NULL;
    }
    PIMAGE_NT_HEADERS nt_headers = (PIMAGE_NT_HEADERS)((DWORD_PTR)dos_header + dos_header->e_lfanew);
    if(nt_headers->OptionalHeader.Magic != 0x010B) {
        wprintf(L"Could not retrieve NT header from %p", dos_header);
        return NULL;
    }
    const int name_max_length = 8;
    PIMAGE_SECTION_HEADER last_section = IMAGE_FIRST_SECTION(nt_headers) + (nt_headers->FileHeader.NumberOfSections - 1);
    PIMAGE_SECTION_HEADER new_section = IMAGE_FIRST_SECTION(nt_headers) + (nt_headers->FileHeader.NumberOfSections);
    memset(new_section, 0, sizeof(IMAGE_SECTION_HEADER));
    new_section->Characteristics = IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_EXECUTE | IMAGE_SCN_CNT_CODE;
    memcpy(new_section->Name, section_name, name_max_length);
    new_section->Misc.VirtualSize = section_size;
    new_section->PointerToRawData = align_to_boundary(last_section->PointerToRawData + last_section->SizeOfRawData,
        nt_headers->OptionalHeader.FileAlignment);
    new_section->SizeOfRawData = align_to_boundary(section_size, nt_headers->OptionalHeader.SectionAlignment);
    new_section->VirtualAddress = align_to_boundary(last_section->VirtualAddress + last_section->Misc.VirtualSize,
        nt_headers->OptionalHeader.SectionAlignment);
    nt_headers->OptionalHeader.SizeOfImage =  new_section->VirtualAddress + new_section->Misc.VirtualSize;
    nt_headers->FileHeader.NumberOfSections++;
    return new_section;
}

Answer 1

在 C 和 C++ 中，数组元素的索引从 0 到 n-1（在 FORTRAN 中从 1 到 n）。所以，如果你有一个指向第一个元素的指针p0，但想要一个指向最后一个元素的指针，你必须添加n-1： plast=p0+n-1。这就是一切。