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Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)directory.3 8.1 (Berkeley) 6/4/93 .\" .TH DIRECTORY 3 "29 January 1997" GNO "Library Routines" .SH NAME .BR opendir , .BR readdir , .BR telldir , .BR seekdir , .BR rewinddir , .BR closedir , .BR dirfd \- directory operations .SH SYNOPSIS .nf #include #include DIR *\fBopendir\fR (const char *\fIfilename\fR); struct \fBdirent\fR *readdir (DIR *\fIdirp\fR); long \fBtelldir\fR (const DIR *\fIdirp\fR); void \fBseekdir\fR (DIR *\fIdirp\fR, long \fIloc\fR); void \fBrewinddir\fR (DIR *\fIdirp\fR); int \fBclosedir\fR (DIR *\fIdirp\fR); int \fBdirfd\fR (DIR *\fIdirp\fR); .fi .SH DESCRIPTION The .BR opendir function opens the directory named by .IR filename , associates a .IR "directory stream" with it and returns a pointer to be used to identify the .IR "directory stream" in subsequent operations. The pointer .BR NULL is returned if .I filename cannot be accessed, or if it cannot .BR malloc (3) enough memory to hold the whole thing. .LP The .BR readdir function returns a pointer to the next directory entry. It returns .BR NULL upon reaching the end of the directory or detecting an invalid .BR seekdir operation. The GNO implementation will not return entries for either the current directory .RB ( . ) or the parent directory .RB ( .. ). Directory entries are defined by the following structure in : .nf struct dirent { unsigned long d_fileno; /* file number of entry */ unsigned short d_reclen; /* length of this record */ unsigned char d_type; /* file type (non-IIgs) */ unsigned char d_namlen; /* length of string in d_name */ char d_name[256]; /* name must be no longer than this */ } .fi The value of .BR d_fileno is, on most architectures, the inode of the current file. Since inodes are not used on any current GS/OS FSTs, this number corresponds to the offset of this file in the current directory. .BR d_reclen is the length of the entire struct dirent. The .BR d_type member is currently set to .BR DT_DIR for directories, .BR DT_REG otherwise. .BR d_namlen is the length of the file name contained in .BR d_name . .LP Subsequent calls to .BR readdir will overwrite previous results in the struct dirent; if the results must be saved then they should be .BR memcpy \'d to a user-defined buffer. .LP The .BR telldir function returns the current location associated with the named .IR "directory stream" . The result of a .BR telldir on a stream which has just been opened is undefined. .LP The .BR seekdir function sets the position of the next .BR readdir operation on the .IR "directory stream" . The new position reverts to the one associated with the .IR "directory stream" when the .BR telldir operation was performed. Values returned by .BR telldir are good only for the lifetime of the .BR DIR pointer, .RI ( dirp ) from which they are derived. If the directory is closed and then reopened, the .BR telldir value may be invalidated due to undetected directory compaction. .LP The .BR rewinddir function resets the position of the named .IR "directory stream" to the beginning of the directory. .LP The .BR closedir function closes the named .IR "directory stream" and frees the structure associated with the .I dirp pointer, returning 0 on success. On failure, \-1 is returned and the global variable .IR errno is set to indicate the error. .LP The .BR dirfd function returns the integer file descriptor associated with the named .IR "directory stream" , see .BR open (2). .SH EXAMPLE Sample code which searches a directory for entry ``name'' in a case-sensitive manner is: .nf len = strlen(name); dirp = opendir("."); while ((dp = readdir(dirp)) != NULL) if (dp->d_namlen == len && !strcmp(dp->d_name, name)) { (void)closedir(dirp); return FOUND; } (void)closedir(dirp); return NOT_FOUND; .fi .SH BUGS The GNO implementation of .BR seekdir and .BR rewinddir rely on the GS/OS call .BR GetDirEntryGS . It is thus possible for these routines to fail. If they do, the error will not be detected until a subsequent .BR readdir is performed. .SH SEE ALSO .BR open (2), .BR close (2), .BR read (2), .BR lseek (2), .BR dir (5) .SH HISTORY The .BR opendir , .BR readdir , .BR telldir , .BR seekdir , .BR rewinddir , .BR closedir , and .BR dirfd functions appeared in BSD 4.2.