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VTableFixups Field in VB.NET
VTableFixups Field PDF-417 2d Barcode Maker In VB.NET Using Barcode generator for .NET framework Control to generate, create PDF417 image in .NET applications. www.OnBarcode.comRecognize PDF 417 In VB.NET Using Barcode decoder for VS .NET Control to read, scan read, scan image in Visual Studio .NET applications. www.OnBarcode.comThe VTableFixups field of the CLR header is a data directory containing the RVA and the size of the image file s v-table fixup table. Managed and unmanaged methods use different data formats, so when a managed method must be called from unmanaged code, the common language runtime creates a marshaling thunk for it, which performs the data conversions, and the address of this thunk is placed in the respective address table. If the managed method is called from the unmanaged code embedded in the current managed PE file, the thunk address goes to the file s v-table. If the managed method is exported as unmanaged and is consumed somewhere outside the managed PE file, the address of the respective v-table entry must also go to the Export Address table. At loading time (and in the disk image file), the entries of this v-table contain the respective method tokens. Making Code 39 Full ASCII In Visual Basic .NET Using Barcode generator for Visual Studio .NET Control to generate, create Code 39 Full ASCII image in Visual Studio .NET applications. www.OnBarcode.comCreating Barcode In Visual Basic .NET Using Barcode maker for VS .NET Control to generate, create Barcode image in VS .NET applications. www.OnBarcode.comCHAPTER 4 THE STRUCTURE OF A MANAGED EXECUTABLE FILE
Generate QR Code In Visual Basic .NET Using Barcode creation for Visual Studio .NET Control to generate, create QR Code image in .NET applications. www.OnBarcode.comGS1 128 Generator In Visual Basic .NET Using Barcode generation for .NET Control to generate, create GTIN - 128 image in .NET applications. www.OnBarcode.comThese v-table fixups represent the initializing information necessary for the runtime to create the thunks. v-table fixup is defined in CorHdr.h as follows: typedef struct _IMAGE_COR_VTABLEFIXUP { ULONG RVA; USHORT Count; USHORT Type; } IMAGE_COR_VTABLEFIXUP; In this definition, RVA points to the location of the v-table slot containing the method token(s). Count specifies the number of entries in the slot, 1 or greater if, for example, multiple implementations of the same method exist, overriding one another. Type is a combination of the following flags, providing the runtime with information about the slot and what to do with it: COR_VTABLE_32BIT (0x01): Each entry is 32 bits wide. COR_VTABLE_64BIT (0x02): Each entry is 64 bits wide. COR_VTABLE_FROM_UNMANAGED (0x04): The thunk created by the common language runtime must provide data marshaling between managed and unmanaged code. COR_VTABLE_CALL_MOST_DERIVED (0x10): This flag is not currently used. Obviously, the first two flags are mutually exclusive. The slots of the v-table must follow each other immediately that is, the v-table must be contiguous. The v-table is located in a read/write section because it should be fixed up after the image has been loaded into memory. In contrast, the v-table in an unmanaged image is located in a read-only section. Among existing managed compilers, only the VC++ and the IL assembler can define the v-table and its fixups. Encode PDF417 In VB.NET Using Barcode generation for VS .NET Control to generate, create PDF-417 2d barcode image in .NET framework applications. www.OnBarcode.comEncode Leitcode In VB.NET Using Barcode printer for Visual Studio .NET Control to generate, create Leitcode image in .NET applications. www.OnBarcode.comStrongNameSignature Field
Reading PDF417 In C#.NET Using Barcode reader for VS .NET Control to read, scan read, scan image in VS .NET applications. www.OnBarcode.comScanning PDF 417 In VB.NET Using Barcode scanner for .NET framework Control to read, scan read, scan image in .NET framework applications. www.OnBarcode.comThe StrongNameSignature field of the common language runtime header contains the RVA and size of the strong name hash, which is used by the runtime to establish the authenticity of the image file. After the image file has been created, it is hashed using the private encryption keys provided by the producer of the image file, and the resulting hash blob is written into the space allocated inside the image file. If even a single byte in the image file is subsequently modified, the authenticity check fails, and the image file cannot be loaded. The strong name signature does not survive a round-tripping procedure; if you disassemble a strong-named module using the IL disassembler and then reassemble it, the module must be strong name signed again. The IL assembler puts the strong name signature in the .text section of the image file. PDF417 Drawer In VS .NET Using Barcode creation for ASP.NET Control to generate, create PDF 417 image in ASP.NET applications. www.OnBarcode.comBarcode Encoder In .NET Framework Using Barcode drawer for ASP.NET Control to generate, create Barcode image in ASP.NET applications. www.OnBarcode.comRelocation Section
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QR Code ISO/IEC18004 Creation In Java Using Barcode encoder for Java Control to generate, create Denso QR Bar Code image in Java applications. www.OnBarcode.comData Matrix 2d Barcode Encoder In Java Using Barcode printer for Java Control to generate, create Data Matrix ECC200 image in Java applications. www.OnBarcode.comEach fixup describes the location of a specific address within the image file as well as how the OS loader should modify the address at this location when loading the image file into memory. Each fixup block starts with two 4-byte unsigned integers: the RVA of the page containing the addresses to be fixed up and the size of the block. The fixup entries for this page immediately follow. Each entry is 16 bits wide, of which four most significant bits contain the type of relocation required. The remaining 12 bits contain the relocated address s offset within the page. To relocate an address, the OS loader calculates the difference (delta) between the preferred base address (the ImageBase field of the PE header) and the actual base address where the image file has been loaded. This delta is then applied to the address according to the type of relocation. If the image file is loaded at its preferred address, no fixups need be applied. The following relocation types are defined in Winnt.h: IMAGE_REL_BASED_ABSOLUTE (0): This type has no meaning in an image file, and the fixup is skipped. IMAGE_REL_BASED_HIGH (1): The high 16 bits of the delta are added to the 16-bit field at the offset. The 16-bit field in this case is the high half of the 32-bit address being relocated. IMAGE_REL_BASED_LOW (2): The low 16 bits of the delta are added to the 16-bit field at the offset. The 16-bit field in this case is the low half of the 32-bit address being relocated. IMAGE_REL_BASED_HIGHLOW (3): The delta is added to the 32-bit address at the offset. Relocation of this type is equivalent to a combination of IMAGE_REL_BASED_LOW and IMAGE_REL_BASED_HIGH relocations and is a preferred type of 32-bit address relocation. IMAGE_REL_BASED_HIGHADJ (4): The high 16 bits of the delta are added to the 16-bit field at the offset. The 16-bit field in this case is the high part of the 32-bit address being relocated. The low 16 bits of the address are stored in the 16-bit word that follows this relocation. A fixup of this type occupies two slots. IMAGE_REL_BASED_MIPS_JMPADDR (5): The fixup applies to a MIPS jump instruction. IMAGE_REL_BASED_SECTION (6): Reserved. IMAGE_REL_BASED_REL32 (7): Reserved. IMAGE_REL_BASED_MIPS_JMPADDR16 (9): The fixup applies to a MIPS16 jump function. IMAGE_REL_BASED_IA64_IMM64 (9): This is the same type as IMAGE_REL_BASED_MIPS_JMPADDR16. IMAGE_REL_BASED_DIR64 (10): The delta is added to the 64-bit field at the offset. IMAGE_REL_BASED_HIGH3ADJ (11): The fixup adds the high 16 bits of the delta to the 16-bit field at the offset. The 16-bit field is the high one-third of a 48-bit address. The low 32 bits of the address are stored in the 32-bit double word that follows this relocation. A fixup of this type occupies three slots. The only fixup type emitted by the existing managed compilers in 32-bit executables is IMAGE_REL_BASED_HIGHLOW. In 64-bit executables, it is IMAGE_REL_BASED_DIR64. Decode Quick Response Code In .NET Using Barcode decoder for Visual Studio .NET Control to read, scan read, scan image in .NET framework applications. www.OnBarcode.comDecoding PDF 417 In Java Using Barcode recognizer for Java Control to read, scan read, scan image in Java applications. www.OnBarcode.com |
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