scandir.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

#ifndef lint
static char sccsid[] = "@(#)scandir.c	4.2 (Berkeley) 7/1/83";
#endif
/***********************************************************************
 *
 *		Modification History
 *
 * 001-  Update arraysz to prevent too many calls to realloc, and
 * 	 do an fstat in case the directory has grown.
 *
 ***********************************************************************/

/*
 * Scan the directory dirname calling select to make a list of selected
 * directory entries then sort using qsort and compare routine dcomp.
 * Returns the number of entries and a pointer to a list of pointers to
 * struct direct (through namelist). Returns -1 if there were any errors.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/dir.h>

scandir(dirname, namelist, select, dcomp)
	char *dirname;
	struct direct *(*namelist[]);
	int (*select)(), (*dcomp)();
{
	register struct direct *d, *p, **names;
	register int nitems;
	register char *cp1, *cp2;
	struct stat stb;
	long arraysz;
	DIR *dirp;

	if ((dirp = opendir(dirname)) == NULL)
		return(-1);
	if (fstat(dirp->dd_fd, &stb) < 0)
		return(-1);

	/*
	 * estimate the array size by taking the size of the directory file
	 * and dividing it by a multiple of the minimum size entry. 
	 */
	arraysz = (stb.st_size / 24);
	names = (struct direct **)malloc(arraysz * sizeof(struct direct *));
	if (names == NULL)
		return(-1);

	nitems = 0;
	while ((d = readdir(dirp)) != NULL) {
		if (select != NULL && !(*select)(d))
			continue;	/* just selected names */
		/*
		 * Make a minimum size copy of the data
		 */
		p = (struct direct *)malloc(DIRSIZ(d));
		if (p == NULL)
			return(-1);
		p->d_ino = d->d_ino;
		p->d_reclen = d->d_reclen;
		p->d_namlen = d->d_namlen;
		for (cp1 = p->d_name, cp2 = d->d_name; *cp1++ = *cp2++; );
		/*
		 * Check to make sure the array has space left and
		 * realloc the maximum size.
		 */
		if (++nitems >= arraysz) {
			/*RAP001
				See if the directory has grown and update
				arraysz. Also, use arraysz in call to realloc.
			*/
			if (fstat(dirp->dd_fd, &stb) < 0)
				return(-1);
			arraysz = stb.st_size/12;
			names = (struct direct **)realloc((char *)names,
				(arraysz) * sizeof(struct direct *));
			if (names == NULL)
				return(-1);
		}
		names[nitems-1] = p;
	}
	closedir(dirp);
	if (nitems && dcomp != NULL)
		qsort(names, nitems, sizeof(struct direct *), dcomp);
	*namelist = names;
	return(nitems);
}

/*
 * Alphabetic order comparison routine for those who want it.
 */
alphasort(d1, d2)
	struct direct **d1, **d2;
{
	return(strcmp((*d1)->d_name, (*d2)->d_name));
}