windows-nt-4.0/private/crt32/misc/splitpat.c

/***
*splitpath.c - break down path name into components
*
*	Copyright (c) 1987-1992, Microsoft Corporation. All rights reserved.
*
*Purpose:
*	To provide support for accessing the individual components of an
*	arbitrary path name
*
*Revision History:
*	06-14-87  DFW	initial implementation
*	09-23-87  JCR	Removed 'const' from declarations (fixed cl warnings)
*	12-11-87  JCR	Added "_LOAD_DS" to declaration
*	11-20-89  GJF	Fixed indents, copyright. Added const attribute to
*			type of path.
*	03-15-90  GJF	Replaced _LOAD_DS with _CALLTYPE1 and added #include
*			<cruntime.h>.
*	07-25-90  SBM	Removed redundant include (stdio.h), replaced local
*			MIN macro with standard min macro
*	10-04-90  GJF	New-style function declarator.
*	01-22-91  GJF	ANSI naming.
*	11-20-92  KRS	Port _MBCS support from 16-bit tree.
*	05-12-93  KRS	Add fix for MBCS max path handling.
*
*******************************************************************************/

#include <cruntime.h>
#include <stdlib.h>
#include <string.h>
#ifdef _MBCS
#include <mbstring.h>
#include <mbctype.h>
#include <mbdata.h>
#endif

#ifdef _MBCS
#define STRNCPY	_mbsnbcpy
#else
#define STRNCPY	strncpy
#endif

/***
*_splitpath() - split a path name into its individual components
*
*Purpose:
*	to split a path name into its individual components
*
*Entry:
*	path  - pointer to path name to be parsed
*	drive - pointer to buffer for drive component, if any
*	dir   - pointer to buffer for subdirectory component, if any
*	fname - pointer to buffer for file base name component, if any
*	ext   - pointer to buffer for file name extension component, if any
*
*Exit:
*	drive - pointer to drive string.  Includes ':' if a drive was given.
*	dir   - pointer to subdirectory string.  Includes leading and trailing
*		'/' or '\', if any.
*	fname - pointer to file base name
*	ext   - pointer to file extension, if any.  Includes leading '.'.
*
*Exceptions:
*
*******************************************************************************/

void _CALLTYPE1 _splitpath (
	register const char *path,
	char *drive,
	char *dir,
	char *fname,
	char *ext
	)
{
	register char *p;
	char *last_slash = NULL, *dot = NULL;
	unsigned len;

	/* we assume that the path argument has the following form, where any
	 * or all of the components may be missing.
	 *
	 *	<drive><dir><fname><ext>
	 *
	 * and each of the components has the following expected form(s)
	 *
	 *  drive:
	 *	0 to _MAX_DRIVE-1 characters, the last of which, if any, is a
	 *	':'
	 *  dir:
	 *	0 to _MAX_DIR-1 characters in the form of an absolute path
	 *	(leading '/' or '\') or relative path, the last of which, if
	 *	any, must be a '/' or '\'.  E.g -
	 *	absolute path:
	 *	    \top\next\last\ 	; or
	 *	    /top/next/last/
	 *	relative path:
	 *	    top\next\last\ 	; or
	 *	    top/next/last/
	 *	Mixed use of '/' and '\' within a path is also tolerated
	 *  fname:
	 *	0 to _MAX_FNAME-1 characters not including the '.' character
	 *  ext:
	 *	0 to _MAX_EXT-1 characters where, if any, the first must be a
	 *	'.'
	 *
	 */

	/* extract drive letter and :, if any */

	if (*(path + _MAX_DRIVE - 2) == ':') {
		if (drive) {
			strncpy(drive, path, _MAX_DRIVE - 1);
			*(drive + _MAX_DRIVE-1) = '\0';
		}
		path += _MAX_DRIVE - 1;
	}
	else if (drive) {
		*drive = '\0';
	}

	/* extract path string, if any.  Path now points to the first character
	 * of the path, if any, or the filename or extension, if no path was
	 * specified.  Scan ahead for the last occurence, if any, of a '/' or
	 * '\' path separator character.  If none is found, there is no path.
	 * We will also note the last '.' character found, if any, to aid in
	 * handling the extension.
	 */

	for (last_slash = NULL, p = (char *)path; *p; p++) {
#ifdef _MBCS
		if (_ISLEADBYTE (*p))
			p++;
		else {
#endif
		if (*p == '/' || *p == '\\')
			/* point to one beyond for later copy */
			last_slash = p + 1;
		else if (*p == '.')
			dot = p;
#ifdef _MBCS
		}
#endif
	}

	if (last_slash) {

		/* found a path - copy up through last_slash or max. characters
		 * allowed, whichever is smaller
		 */

		if (dir) {
			len = __min((last_slash - path), (_MAX_DIR - 1));
			STRNCPY(dir, path, len);
			*(dir + len) = '\0';
		}
		path = last_slash;
	}
	else if (dir) {

		/* no path found */

		*dir = '\0';
	}

	/* extract file name and extension, if any.  Path now points to the
	 * first character of the file name, if any, or the extension if no
	 * file name was given.  Dot points to the '.' beginning the extension,
	 * if any.
	 */

	if (dot && (dot >= path)) {
		/* found the marker for an extension - copy the file name up to
		 * the '.'.
		 */
		if (fname) {
			len = __min((dot - path), (_MAX_FNAME - 1));
			STRNCPY(fname, path, len);
			*(fname + len) = '\0';
		}
		/* now we can get the extension - remember that p still points
		 * to the terminating nul character of path.
		 */
		if (ext) {
			len = __min((p - dot), (_MAX_EXT - 1));
			STRNCPY(ext, dot, len);
			*(ext + len) = '\0';
		}
	}
	else {
		/* found no extension, give empty extension and copy rest of
		 * string into fname.
		 */
		if (fname) {
			len = __min((p - path), (_MAX_FNAME - 1));
			STRNCPY(fname, path, len);
			*(fname + len) = '\0';
		}
		if (ext) {
			*ext = '\0';
		}
	}
}