Attachment 17532 Details for Bug 15186 – Minimalist program to interrogate EAs on Windows

Minimalist program to interrogate EAs on Windows

get_ea.c (text/x-csrc), 1.96 KB, created by Michael Weiser on 2022-09-26 07:49:44 UTC

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Creator: Michael Weiser

Created: 2022-09-26 07:49:44 UTC

Size: 1.96 KB

patch

obsolete

>// https://github.com/microsoft/Windows-classic-samples/blob/main/Samples/DataDedupBackupRestore/cpp/DedupBackupRestore.cpp
>// https://learn.microsoft.com/en-us/windows/win32/api/winbase/ns-winbase-win32_stream_id
>// https://learn.microsoft.com/en-us/windows-hardware/drivers/ddi/wdm/ns-wdm-_file_full_ea_information?redirectedfrom=MSDN
>
>#include <windows.h>
>#include <winternl.h>
>#include <stdlib.h>
>#include <stdio.h>
>
>int main(int argc, char* argv[])
>{
>	if (argc < 2) {
>		fprintf(stderr, "get_ea <file name>");
>		return 1;
>	}
>
>	HANDLE h = CreateFile(argv[1],
>			GENERIC_EXECUTE|GENERIC_READ|GENERIC_WRITE,
>			FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_EXISTING,
>			FILE_ATTRIBUTE_ARCHIVE, NULL);
>	if (!h) {
>		fprintf(stderr, "Error openingfile '%s'\n", argv[1]);
>		return 1;
>	}
>
>	BYTE buffer[32768];
>	DWORD read = 0;
>	void *ctx = NULL;
>	if (!BackupRead(h, buffer, sizeof(buffer), &read, FALSE, TRUE, &ctx)) {
>		fprintf(stderr, "Error reading backup data\n");
>		return 1;
>	}
>
>	BYTE *p = buffer;
>	while (p < buffer + read) {
>		WIN32_STREAM_ID *wsi = (WIN32_STREAM_ID*)p;
>
>		// move past the part of the structure that is not counted by
>		// the Size member, cStreamName and the data is
>		p += FIELD_OFFSET(WIN32_STREAM_ID, cStreamName);
>
>		if (wsi->dwStreamId != BACKUP_EA_DATA) {
>			p += wsi->Size.QuadPart;
>			continue;
>		}
>
>		// "streams" which are not alternate data streams do not have a
>		// name and dwStreamNameSize will be zero but let's be strict
>		// about it
>		p += wsi->dwStreamNameSize;
>
>		FILE_FULL_EA_INFORMATION *ffeai = (FILE_FULL_EA_INFORMATION *)p;
>		while ((BYTE *)ffeai < p + wsi->Size.QuadPart) {
>			fwrite(ffeai->EaName, ffeai->EaNameLength, 1, stdout);
>			fwrite("=", 1, 1, stdout);
>
>			BYTE *p2 = (BYTE *)ffeai +
>				FIELD_OFFSET(FILE_FULL_EA_INFORMATION, EaName)
>				+ ffeai->EaNameLength + 1;
>
>			fwrite(p2, ffeai->EaValueLength, 1, stdout);
>			fwrite("\n", 1, 1, stdout);
>
>			ffeai = (FILE_FULL_EA_INFORMATION *)(p2 + ffeai->EaValueLength);
>		}
>
>		break;
>	}
>
>	return 0;
>}

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Attachments on bug 15186: 17531 | 17532 | 17533 | 17606