Re: [PATCH v46 0/2] MR10295: Fix ImageGetDigestStream

[eric pouech (＠epo)]

eric pouech (@epo) commented about dlls/imagehlp/integrity.c:
> -     */
> -    nt_hdr->OptionalHeader.SizeOfInitializedData = 0;
> -    nt_hdr->OptionalHeader.SizeOfImage = 0;
> -    nt_hdr->OptionalHeader.CheckSum = 0;
> -    size = sizeof(nt_hdr->Signature) + sizeof(nt_hdr->FileHeader) +
> -        nt_hdr->FileHeader.SizeOfOptionalHeader;
> +    NumberOfRvaAndSizes = nthdr32->OptionalHeader.NumberOfRvaAndSizes;
> +    DataDirectory = nthdr32->OptionalHeader.DataDirectory;
> +    if( nthdr32->OptionalHeader.Magic == IMAGE_NT_OPTIONAL_HDR64_MAGIC )
> +    {
> +        nthdr64 = (IMAGE_NT_HEADERS64 *)nthdr32;
> +        NumberOfRvaAndSizes = nthdr64->OptionalHeader.NumberOfRvaAndSizes;
> +        DataDirectory = nthdr64->OptionalHeader.DataDirectory;
> +        /* NOTE: Fields up to SizeOfStackCommit are the same size/offset, except for ImageBase */
> +    }
> +    memcpy(DataDirBackup, DataDirectory, sizeof(DataDirBackup));
> it looks a bit ackward to save ntheader+section headers, modify the memory of mapping, then restore the saved bits in the mapping

it would be more straightforward to keep mapping as is, and allocate a buffer for tempering ntheader + section headers and pass pointer into this buffer in the callback

this is how native behaves BTW

this would save one memcpy and avoids dirty:ing the mapping which results with COW of the modified pages

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https://gitlab.winehq.org/wine/wine/-/merge_requests/10295#note_137581