director.3

操作系统设计与实现源码

.TH DIRECTORY 3
.SH NAME
directory, opendir, readdir, rewinddir, closedir, telldir, seekdir \- directory routines
.SH SYNOPSIS
.nf
.ft B
#include <sys/types.h>
#include <dirent.h>

DIR *opendir(const char *\fIdirname\fP)
struct dirent *readdir(DIR *\fIdirp\fP)
void rewinddir(DIR *\fIdirp\fP)
int closedir(DIR *\fIdirp\fP)

#define _MINIX  1
#include <sys/types.h>
#include <dirent.h>

long telldir(DIR *\fIdirp\fP)
int seekdir(DIR *\fIdirp\fP, long \fIpos\fP)
.SH DESCRIPTION
These routines form a system independent interface to access directories.
.PP
.B Opendir()
opens the directory
.I dirname
and returns a pointer to this open directory stream.
.PP
.B Readdir()
reads one entry from the directory as a pointer to a structure containing
the field
.BR d_name ,
a character array containing the null-terminated name of the entry.
.PP
.B Rewinddir()
allows the directory to be read again from the beginning.
.PP
.B Closedir()
closes the directory and releases administrative data.
.PP
The Minix specific functions
.B telldir()
and
.B seekdir()
allow one to get the current position in the directory file and to return
there later.
.B Seekdir()
may only be called with a position returned by
.B telldir()
or 0 (rewind).  These functions should not be used in portable programs.
.SH "SEE ALSO"
.BR dir (5).
.SH DIAGNOSTICS
.B Opendir()
returns a null pointer if
.I dirname
can't be opened, or if it can't allocate enough memory for the
.B DIR
structure.
.PP
.B Readdir()
returns null if there are no more directory entries or on error.
.PP
.B Closedir()
and
.B seekdir()
returns 0 on success, -1 on error.
.PP
.B Telldir()
returns -1 on error.
.PP
All of them set
.B errno
appropriately.
.B Readdir()
will only set
.B errno
on error, not on end-of-dir, so you should set
.B errno
to zero beforehand, and check its value if
.B readdir()
returns null.
.SH NOTES
The return value of
.B readdir()
needs to be copied before the next operation on the same directory if it is
to be saved.
.SH AUTHOR
Kees J. Bot ([e-mail])