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hardlink.c
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Thu, Feb 27, 00:08

hardlink.c
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/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with this
* work for additional information regarding copyright ownership. The ASF
* licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
#include "winutils.h"
// List of different hardlink related command line options supported by
// winutils.
typedef enum HardLinkCommandOptionType
{
HardLinkInvalid,
HardLinkCreate,
HardLinkStat
} HardLinkCommandOption;
//----------------------------------------------------------------------------
// Function: ParseCommandLine
//
// Description:
// Parses the given command line. On success, out param 'command' contains
// the user specified command.
//
// Returns:
// TRUE: If the command line is valid
// FALSE: otherwise
static BOOL ParseCommandLine(__in int argc,
__in_ecount(argc) wchar_t *argv[],
__out HardLinkCommandOption *command)
{
*command = HardLinkInvalid;
if (argc != 3 && argc != 4) {
return FALSE;
}
if (argc == 3) {
if (wcscmp(argv[0], L"hardlink") != 0 || wcscmp(argv[1], L"stat") != 0)
{
return FALSE;
}
*command = HardLinkStat;
}
if (argc == 4) {
if (wcscmp(argv[0], L"hardlink") != 0 || wcscmp(argv[1], L"create") != 0)
{
return FALSE;
}
*command = HardLinkCreate;
}
assert(*command != HardLinkInvalid);
return TRUE;
}
//----------------------------------------------------------------------------
// Function: HardlinkStat
//
// Description:
// Computes the number of hard links for a given file.
//
// Returns:
// ERROR_SUCCESS: On success
// error code: otherwise
static DWORD HardlinkStat(__in LPCWSTR fileName, __out DWORD *puHardLinkCount)
{
BY_HANDLE_FILE_INFORMATION fileInformation;
DWORD dwErrorCode = ERROR_SUCCESS;
PWSTR longFileName = NULL;
// First convert input paths to long paths
//
dwErrorCode = ConvertToLongPath(fileName, &longFileName);
if (dwErrorCode != ERROR_SUCCESS)
{
goto HardlinkStatExit;
}
// Get file information which contains the hard link count
//
dwErrorCode = GetFileInformationByName(longFileName, FALSE, &fileInformation);
if (dwErrorCode != ERROR_SUCCESS)
{
goto HardlinkStatExit;
}
*puHardLinkCount = fileInformation.nNumberOfLinks;
HardlinkStatExit:
LocalFree(longFileName);
return dwErrorCode;
}
//----------------------------------------------------------------------------
// Function: HardlinkCreate
//
// Description:
// Creates a hard link for a given file under the given name.
//
// Returns:
// ERROR_SUCCESS: On success
// error code: otherwise
static DWORD HardlinkCreate(__in LPCWSTR linkName, __in LPCWSTR fileName)
{
PWSTR longLinkName = NULL;
PWSTR longFileName = NULL;
DWORD dwErrorCode = ERROR_SUCCESS;
// First convert input paths to long paths
//
dwErrorCode = ConvertToLongPath(linkName, &longLinkName);
if (dwErrorCode != ERROR_SUCCESS)
{
goto HardlinkCreateExit;
}
dwErrorCode = ConvertToLongPath(fileName, &longFileName);
if (dwErrorCode != ERROR_SUCCESS)
{
goto HardlinkCreateExit;
}
// Create the hard link
//
if (!CreateHardLink(longLinkName, longFileName, NULL))
{
dwErrorCode = GetLastError();
}
HardlinkCreateExit:
LocalFree(longLinkName);
LocalFree(longFileName);
return dwErrorCode;
}
//----------------------------------------------------------------------------
// Function: Hardlink
//
// Description:
// Creates a hard link for a given file under the given name. Outputs the
// appropriate information to stdout on success, or stderr on failure.
//
// Returns:
// EXIT_SUCCESS: On success
// EXIT_FAILURE: otherwise
int Hardlink(__in int argc, __in_ecount(argc) wchar_t *argv[])
{
DWORD dwErrorCode = ERROR_SUCCESS;
int ret = EXIT_FAILURE;
HardLinkCommandOption command = HardLinkInvalid;
if (!ParseCommandLine(argc, argv, &command)) {
dwErrorCode = ERROR_INVALID_COMMAND_LINE;
fwprintf(stderr, L"Incorrect command line arguments.\n\n");
HardlinkUsage();
goto HardLinkExit;
}
if (command == HardLinkStat)
{
// Compute the number of hard links
//
DWORD uHardLinkCount = 0;
dwErrorCode = HardlinkStat(argv[2], &uHardLinkCount);
if (dwErrorCode != ERROR_SUCCESS)
{
ReportErrorCode(L"HardlinkStat", dwErrorCode);
goto HardLinkExit;
}
// Output the result
//
fwprintf(stdout, L"%d\n", uHardLinkCount);
} else if (command == HardLinkCreate)
{
// Create the hard link
//
dwErrorCode = HardlinkCreate(argv[2], argv[3]);
if (dwErrorCode != ERROR_SUCCESS)
{
ReportErrorCode(L"HardlinkCreate", dwErrorCode);
goto HardLinkExit;
}
// Output the success message
//
fwprintf(stdout, L"Hardlink created for %s <<===>> %s\n", argv[2], argv[3]);
} else
{
// Should not happen
//
assert(FALSE);
}
ret = EXIT_SUCCESS;
HardLinkExit:
return ret;
}
void HardlinkUsage()
{
fwprintf(stdout, L"\
Usage: hardlink create [LINKNAME] [FILENAME] |\n\
hardlink stat [FILENAME]\n\
Creates a new hardlink on the existing file or displays the number of links\n\
for the given file\n");
}

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