PathCchCombineEx function

Combines two path fragments into a single path. This function also canonicalizes any relative path elements, removing "." and ".." elements to simplify the final path.

This function differs from PathCchCombine in that it allows for a longer final path to be constructed.

This function differs from PathAllocCombine in that the caller must declare the size of the returned string, which is stored on the stack.

This function differs from PathCombine in that it accepts paths with "\\", "\\?\" and "\\?\UNC\" prefixes.

Note  This function, PathCchCombine, or PathAllocCombine should be used in place of PathCombine to prevent the possibility of a buffer overrun.
 

Syntax


HRESULT PathCchCombineEx(
  _Out_    PWSTR         pszPathOut,
  _In_     size_t        cchPathOut,
  _In_opt_ PCWSTR        pszPathIn,
  _In_opt_ PCWSTR        pszMore,
  _In_     unsigned long dwFlags
);

Parameters

pszPathOut [out]

A pointer to a buffer that, when this function returns successfully, receives the combined path string. This parameter can point to the same buffer as pszPathIn or pszMore.

cchPathOut [in]

The size of the buffer pointed to by pszPathOut, in characters.

pszPathIn [in, optional]

A pointer to the first path string. This value can be NULL.

pszMore [in, optional]

A pointer to the second path string. If this path begins with a single backslash, it is combined with only the root of the path pointed to by pszPathIn. If this path is fully qualfied, it is copied directly to the output buffer without being combined with the other path. This value can be NULL.

dwFlags [in]

One or more of the following flags:

ValueMeaning
PATHCCH_NONE
0x0000000

Do not allow for the construction of \\?\ paths (ie, long paths) longer than MAX_PATH.

PATHCCH_ALLOW_LONG_PATHS
0x00000001

Allow the construction of \\?\ paths longer than MAX_PATH. Note that cchPathOut must be greater than MAX_PATH. Note that cchPathOut must be greater than MAX_PATH. If it is not, this flag is ignored.

PATHCCH_FORCE_ENABLE_LONG_NAME_PROCESS
0x00000002

Forces the API to treat the caller as long path enabled, independent of the process's long name enabled state. This option can be used only when PATHCCH_ALLOW_LONG_PATHS is specified, and cannot be used with PATHCCH_FORCE_DISABLE_LONG_NAME_PROCESS.

Note  This value is available starting in Windows 10, version 1703.

PATHCCH_FORCE_DISABLE_LONG_NAME_PROCESS
0x00000004

Forces the API to treat the caller as long path disabled, independent of the process's long name enabled state. This option can be used only when PATHCCH_ALLOW_LONG_PATHS is specified, and cannot be used with PATHCCH_FORCE_ENABLE_LONG_NAME_PROCESS.

Note  This value is available starting in Windows 10, version 1703.

PATHCCH_DO_NOT_NORMALIZE_SEGMENTS
0x00000008

Disables the normalization of path segments that includes removing trailing dots and spaces. This enables access to paths that win32 path normalization will block.

Note  This value is available starting in Windows 10, version 1703.

PATHCCH_ENSURE_IS_EXTENDED_LENGTH_PATH
0x00000010

Converts the input path into the extended length DOS device path form (with the \\?\ prefix) f not already in that form. This enables access to paths that are otherwise not addressable due to Win32 normalization rules (that can strip trailing dots and spaces) and path length limitations. This option implies the same behavior of PATHCCH_DO_NOT_NORMALIZE_SEGMENTS.

Note  This value is available starting in Windows 10, version 1703.

 

Return value

This function returns an HRESULT code, including the following.

Return codeDescription
S_OK

The function succeeded. Note that this also includes the case of an empty extension, such as a period with no characters following it. In that case, the original string is returned unaltered.

E_INVALIDARG

This value can be caused by several things, such as the pszPathOut param being set to NULL, or the cchPathOut value being set to 0 or a value greater than PATHCCH_MAX_CCH.

E_OUTOFMEMORY

The function could not allocate enough memory to perform the operation.

PATHCCH_E_FILENAME_TOO_LONG

The size of one or both of the original paths exceeded PATHCCH_MAX_CCH.

 

Remarks

If both pszPathIn and pszMore are NULL or point to empty strings, a single backslash is copied to the buffer pointed to by pszPathOut.

Requirements

Minimum supported client

Windows 8 [desktop apps only]

Minimum supported server

Windows Server 2012 [desktop apps only]

Header

Pathcch.h

Library

Pathcch.lib

See also

PathCchCombine
PathCchCanonicalize
PathCchCanonicalizeEx

 

 

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