_makepath_s, _wmakepath_s

Article
11/16/2012

Creates a path name from components. These are versions of _makepath, _wmakepath with security enhancements as described in Security Enhancements in the CRT.

errno_t _makepath_s(
   char *path,
   size_t sizeInWords,
   const char *drive,
   const char *dir,
   const char *fname,
   const char *ext 
);
errno_t _wmakepath_s(
   wchar_t *path,
   size_t sizeInBytes,
   const wchar_t *drive,
   const wchar_t *dir,
   const wchar_t *fname,
   const wchar_t *ext 
);
template <size_t size>
errno_t _makepath_s(
   char (&path)[size],
   const char *drive,
   const char *dir,
   const char *fname,
   const char *ext 
); // C++ only
template <size_t size>
errno_t _wmakepath_s(
   wchar_t (&path)[size],
   const wchar_t *drive,
   const wchar_t *dir,
   const wchar_t *fname,
   const wchar_t *ext 
); // C++ only

Parameters

[out] path
Full path buffer.
[in] sizeInWords
Size of the buffer in words.
[in] sizeInBytes
Size of the buffer in bytes.
[in] drive
Contains a letter (A, B, and so on) corresponding to the desired drive and an optional trailing colon. _makepath_s inserts the colon automatically in the composite path if it is missing. If drive is NULL or points to an empty string, no drive letter appears in the composite path string.
[in] dir
Contains the path of directories, not including the drive designator or the actual file name. The trailing slash is optional, and either a forward slash (/) or a backslash (\) or both might be used in a single dir argument. If no trailing slash (/ or \) is specified, it is inserted automatically. If dir is NULL or points to an empty string, no directory path is inserted in the composite path string.
[in] fname
Contains the base file name without any file name extensions. If fname is NULL or points to an empty string, no filename is inserted in the composite path string.
[in] ext
Contains the actual file name extension, with or without a leading period (.). _makepath_s inserts the period automatically if it does not appear in ext. If ext is NULL or points to an empty string, no extension is inserted in the composite path string.

Return Value

Zero if successful; an error code on failure.

Error Conditions

path	sizeInWords / sizeInBytes	Return	Contents of path
NULL	any	EINVAL	not modified
any	<= 0	EINVAL	not modified

If any of the above error conditions occurs, these functions invoke the invalid parameter handler, as described in Parameter Validation. If execution is allowed to continue, errno is set toEINVAL and the functions returnsEINVAL**.** NULL is allowed for the parameters drive, fname, and ext. For information about the behavior when these parameters are null pointers or empty strings, see the Remarks section.

Remarks

The _makepath_s function creates a composite path string from individual components, storing the result in path. The path might include a drive letter, directory path, file name, and file name extension. _wmakepath_s is a wide-character version of _makepath_s; the arguments to _wmakepath_s are wide-character strings. _wmakepath_s and _makepath_s behave identically otherwise.

Generic-Text Routine Mappings

Tchar.h routine	_UNICODE and _MBCS not defined	_MBCS defined	_UNICODE defined
_tmakepath_s	_makepath_s	_makepath_s	_wmakepath_s

The path argument must point to an empty buffer large enough to hold the complete path. The composite path must be no larger than the _MAX_PATH constant, defined in Stdlib.h.

If path is NULL, the invalid parameter handler is invoked, as described in Parameter Validation. In addition, errno is set to EINVAL. NULL values are allowed for all other parameters.

In C++, using these functions is simplified by template overloads; the overloads can infer buffer length automatically (eliminating the need to specify a size argument) and they can automatically replace older, non-secure functions with their newer, secure counterparts. For more information, see Secure Template Overloads.

The debug versions of these functions first fill the buffer with 0xFD. To disable this behavior, use _CrtSetDebugFillThreshold.

Requirements

Routine	Required header
_makepath_s	<stdlib.h>
_wmakepath_s	<stdlib.h> or <wchar.h>

For more compatibility information, see Compatibility in the Introduction.

Example

// crt_makepath_s.c

#include <stdlib.h>
#include <stdio.h>

int main( void )
{
   char path_buffer[_MAX_PATH];
   char drive[_MAX_DRIVE];
   char dir[_MAX_DIR];
   char fname[_MAX_FNAME];
   char ext[_MAX_EXT];
   errno_t err;

   err = _makepath_s( path_buffer, _MAX_PATH, "c", "\\sample\\crt\\",
                      "crt_makepath_s", "c" );
   if (err != 0)
   {
      printf("Error creating path. Error code %d.\n", err);
      exit(1);
   }
   printf( "Path created with _makepath_s: %s\n\n", path_buffer );
   err = _splitpath_s( path_buffer, drive, _MAX_DRIVE, dir, _MAX_DIR, fname,
                       _MAX_FNAME, ext, _MAX_EXT );
   if (err != 0)
   {
      printf("Error splitting the path. Error code %d.\n", err);
      exit(1);
   }
   printf( "Path extracted with _splitpath_s:\n" );
   printf( "  Drive: %s\n", drive );
   printf( "  Dir: %s\n", dir );
   printf( "  Filename: %s\n", fname );
   printf( "  Ext: %s\n", ext );
}

Output

Path created with _makepath_s: c:\sample\crt\crt_makepath_s.c

Path extracted with _splitpath_s:
  Drive: c:
  Dir: \sample\crt\
  Filename: crt_makepath_s
  Ext: .c

.NET Framework Equivalent

System::IO::File::Create

Change History

Date	History	Reason
May 2009	Consolidated parameter tables.	Information enhancement.

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