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C/C++ Users Group Library 1996 July
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v_07_01
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v7n1060a.txt
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1988-09-12
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/*
* dirret.c MS-DOS and Unix portable directory builder.
*
* Routines:
*
* struct dir_retrieve_t *
* dir_retrieve( path, dir_entries );
*
* void
* dir_free( dir_ptr );
*
* usage: dir_retrieve( "/usr/include", &count );
*
* Possible errno: ENOENT, ENOTDIR and ENOMEM
*
* (c) Copyright 1988 Aspen Scientific
* All Rights Reserved.
*/
#include <stdio.h>
#include <malloc.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "dirret.h" /* the dir header file */
#ifdef A_MSDOS
# include <dos.h> /* MSC 5.0 include for reading directories */
static struct find_t find_buf;
#endif
#ifdef A_UNIX
/* sys/dir.h: incl by dirret.h: Unix Sys 5 include for reading directories */
static struct direct find_buf;
#endif
/* helper routines and data
*/
#ifdef A_ANSI
static int dir_prep( char * );
static int dir_next( char *, struct dir_retrieve_t *, int * );
#else
static int dir_prep();
static int dir_next();
#endif
static int dir_fdesc; /* for Unix, hold file descriptor */
static char * dir_stat; /* used to stat() the entry name */
extern int strcmp(); /* for qsort() */
extern int errno; /* for reporting errors */
/* dir_retrieve builds a sorted directory listing of the directory
* referenced by path. a pointer to an array of structs
* of file name strings is returned. the list end is marked
* by a NULL byte in the first element of the name.
*/
struct dir_retrieve_t *
dir_retrieve( path, dir_entries )
char *path;
int *dir_entries;
{
register int slots=ALLOC_UNIT, cnt=0, nm=0;
struct dir_retrieve_t *dir = (struct dir_retrieve_t *)0, *tmp;
int dir_hold=1; /* for MS-DOS, hold find first */
/* prepare the directory for reading.
* if return zero, the prep failed.
*/
if (!dir_prep( path ))
return ( dir );
/* start with minimum allocation
*/
if (!(dir = (struct dir_retrieve_t *)malloc(
(slots * sizeof ( struct dir_retrieve_t ))))) {
errno = ENOMEM;
return ( 0 );
}
while ( 1 ) {
/* check for list overflow
*/
if (cnt == ALLOC_UNIT) {
slots += ALLOC_UNIT;
/* the first time malloc(), then realloc().
*/
tmp = dir;
dir = (struct dir_retrieve_t *)realloc( dir,
(slots * sizeof ( struct dir_retrieve_t )));
/* out of memory
*/
if (dir == (struct dir_retrieve_t *)0) {
free ( tmp );
errno = ENOMEM;
return ( dir );
}
cnt = 0; /* reset counter */
}
/* get the next file name, if existing
*/
if (!dir_next( path, &dir[ nm ], &dir_hold )) {
*dir[ nm ].name = '\0';
break;
}
++nm;
++cnt;
}
qsort( dir, nm, sizeof (struct dir_retrieve_t), strcmp );
/* only set if the caller passed a valid pointer
*/
if ( dir_entries != (int *)0 )
*dir_entries = nm;
return ( dir );
}
/* dir_prep readies the directory interface for retrieving names
* from the directory. if this fails, it means that the
* directory referenced is un-readable.
*/
static int
dir_prep( path )
char *path;
{
#ifdef A_MSDOS
char *ppath;
static char *ext = "/*.*";
if ((ppath = malloc( strlen( path )+strlen( ext ) )) == (char *)0) {
errno = ENOMEM;
return ( 0 );
}
/* protect against building string like: "//*.*"
*/
strcpy( ppath, path );
strcat( ppath, (strcmp( ppath, "/" ) ? ext:ext+1) );
/* _A_SUBDIR means read all files, both regular and
* sub-directories. findfirst return of 0 is good.
*/
if (_dos_findfirst( ppath, _A_SUBDIR, &find_buf ) != 0) {
free( ppath );
errno = ENOENT;
return ( 0 );
}
free( ppath );
#else
struct stat stat_buf;
/* open the directory
*/
if ((dir_fdesc = open( path, 0 )) == (-1)) {
errno = ENOENT;
return ( 0 );
}
/* see if it is a regular file or a directory
*/
fstat( dir_fdesc, &stat_buf );
if ( (stat_buf.st_mode & S_IFDIR) == 0 ) {
close( dir_fdesc );
errno = ENOTDIR;
return ( 0 );
}
#endif
/* allocate a buffer to contain:
*
* path/entry_name for stat()'ing
*/
if ((dir_stat = malloc( strlen( path )+_FN_SZ+1 )) == (char *)0) {
#ifdef A_UNIX
close( dir_fdesc );
#endif
errno = ENOMEM;
return ( 0 );
}
return ( 1 );
}
/* dir_next return the next entry in the directory. a NULL pointer
* says no more entries.
*/
static int
dir_next( path, transfer, dir_hold )
char *path;
struct dir_retrieve_t *transfer;
int *dir_hold;
{
struct stat stat_buf;
#ifdef A_MSDOS
/* are we holding from the find first?
* if so, skip the find next this time.
*/
if (! *dir_hold) {
/* findnext return of 0 is good.
*/
if (_dos_findnext( &find_buf ) != 0) {
free( dir_stat );
return ( 0 );
}
}
else
*dir_hold = 0; /* next call will do _dos_findnext() */
strcpy( transfer->name, find_buf.name );
#else
register int i;
while ( 1 ) {
i = read(dir_fdesc, &find_buf, sizeof (struct direct));
if (i != sizeof (struct direct)) {
close( dir_fdesc );
free( dir_stat );
return ( 0 );
}
else if (find_buf.d_ino != 0) /* empty? */
break;
}
/* since d_name is only NULL terminated if the file name is
* less than DIRSIZ, we cannot use strcpy() here.
*/
for (i=0; i < DIRSIZ && find_buf.d_name[i]; ++i)
transfer->name[i] = find_buf.d_name[i];
transfer->name[i] = '\0';
#endif
strcpy( dir_stat, path );
if (strcmp( path, "/" ) != 0)
strcat( dir_stat, "/" );
strcat( dir_stat, transfer->name );
/* is it a sub-directory?
*/
stat( dir_stat, &stat_buf );
transfer->subdir = ( (stat_buf.st_mode & S_IFDIR) ? 1:0 );
return ( 1 );
}
/* dir_free calls free for the given directory pointer
*/
void
dir_free( dir )
struct dir_retrieve_t *dir;
{
free( (char *)dir );
}