GetLongPathNameA function (fileapi.h)

Article
06/01/2023

Converts the specified path to its long form.

To perform this operation as a transacted operation, use the GetLongPathNameTransacted function.

For more information about file and path names, see Naming Files, Paths, and Namespaces.

Syntax

DWORD GetLongPathNameA(
  [in]  LPCSTR lpszShortPath,
  [out] LPSTR  lpszLongPath,
  [in]  DWORD  cchBuffer
);

Parameters

[in] lpszShortPath

The path to be converted.

[out] lpszLongPath

A pointer to the buffer to receive the long path.

You can use the same buffer you used for the lpszShortPath parameter.

[in] cchBuffer

The size of the buffer lpszLongPath points to, in TCHARs.

Return value

If the function succeeds, the return value is the length, in TCHARs, of the string copied to lpszLongPath, not including the terminating null character.

If the lpBuffer buffer is too small to contain the path, the return value is the size, in TCHARs, of the buffer that is required to hold the path and the terminating null character.

If the function fails for any other reason, such as if the file does not exist, the return value is zero. To get extended error information, call GetLastError.

Remarks

On many file systems, a short file name contains a tilde (~) character. However, not all file systems follow this convention. Therefore, do not assume that you can skip calling GetLongPathName if the path does not contain a tilde (~) character.

If the file or directory exists but a long path is not found, GetLongPathName succeeds, having copied the string referred to by the lpszShortPath parameter to the buffer referred to by the lpszLongPath parameter.

If the return value is greater than the value specified in cchBuffer, you can call the function again with a buffer that is large enough to hold the path. For an example of this case, see the Example Code section for GetFullPathName.

Note Although the return value in this case is a length that includes the terminating null character, the return value on success does not include the terminating null character in the count.

It is possible to have access to a file or directory but not have access to some of the parent directories of that file or directory. As a result, GetLongPathName may fail when it is unable to query the parent directory of a path component to determine the long name for that component. This check can be skipped for directory components that have file extensions longer than 3 characters, or total lengths longer than 12 characters. For more information, see the Short vs. Long Names section of Naming Files, Paths, and Namespaces.

In Windows 8 and Windows Server 2012, this function is supported by the following technologies.

Technology	Supported
Server Message Block (SMB) 3.0 protocol	Yes
SMB 3.0 Transparent Failover (TFO)	Yes
SMB 3.0 with Scale-out File Shares (SO)	Yes
Cluster Shared Volume File System (CsvFS)	Yes
Resilient File System (ReFS)	Yes

Examples

For an example that uses GetLongPathName, see the Example Code section for GetFullPathName.

Note

The fileapi.h header defines GetLongPathName as an alias which automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.

Requirements

Requirement	Value
Minimum supported client	Windows XP [desktop apps \| UWP apps]
Minimum supported server	Windows Server 2003 [desktop apps \| UWP apps]
Target Platform	Windows
Header	fileapi.h (include Windows.h)
Library	Kernel32.lib
DLL	Kernel32.dll

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