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@(#)directory.3 8.1 (Berkeley) 6/4/93
$FreeBSD$
.Dd April 16, 2008 .Dt DIRECTORY 3 .Os .Sh NAME .Nm opendir , .Nm fdopendir , .Nm readdir , .Nm readdir_r , .Nm telldir , .Nm seekdir , .Nm rewinddir , .Nm closedir , .Nm dirfd .Nd directory operations .Sh LIBRARY .Lb libc .Sh SYNOPSIS n dirent.h .Ft DIR * .Fn opendir "const char *filename" .Ft DIR * .Fn fdopendir "int fd" .Ft struct dirent * .Fn readdir "DIR *dirp" .Ft int .Fn readdir_r "DIR *dirp" "struct dirent *entry" "struct dirent **result" .Ft long .Fn telldir "DIR *dirp" .Ft void .Fn seekdir "DIR *dirp" "long loc" .Ft void .Fn rewinddir "DIR *dirp" .Ft int .Fn closedir "DIR *dirp" .Ft int .Fn dirfd "DIR *dirp" .Sh DESCRIPTION The .Fn opendir function opens the directory named by .Fa filename , associates a .Em directory stream with it and returns a pointer to be used to identify the .Em directory stream in subsequent operations. The pointer .Dv NULL is returned if .Fa filename cannot be accessed, or if it cannot .Xr malloc 3 enough memory to hold the whole thing, and sets the global variable .Va errno to indicate the error.
p The .Fn fdopendir function is equivalent to the .Fn opendir function except that the directory is specified by a file descriptor .Fa fd rather than by a name. ./"The file offset associated with the file descriptor at the time of the call ./"determines which entries are returned.
p Upon successful return from .Fn fdopendir , the file descriptor is under the control of the system, and if any attempt is made to close the file descriptor, or to modify the state of the associated description other than by means of .Fn closedir , .Fn readdir , .Fn readdir_r , or .Fn rewinddir , the behavior is undefined. Upon calling .Fn closedir the file descriptor is closed. The .Dv FD_CLOEXEC flag is set on the file descriptor by a successful call to .Fn fdopendir .
p The .Fn readdir function returns a pointer to the next directory entry. It returns .Dv NULL upon reaching the end of the directory or on error. In the event of an error, .Va errno may be set to any of the values documented for the .Xr getdirentries 2 system call.
p The .Fn readdir_r function provides the same functionality as .Fn readdir , but the caller must provide a directory .Fa entry buffer to store the results in. If the read succeeds, .Fa result is pointed at the .Fa entry ; upon reaching the end of the directory .Fa result is set to .Dv NULL . The .Fn readdir_r function returns 0 on success or an error number to indicate failure.
p The .Fn telldir function returns the current location associated with the named .Em directory stream . Values returned by .Fn telldir are good only for the lifetime of the .Dv DIR pointer, .Fa dirp , from which they are derived. If the directory is closed and then reopened, prior values returned by .Fn telldir will no longer be valid.
p The .Fn seekdir function sets the position of the next .Fn readdir operation on the .Em directory stream . The new position reverts to the one associated with the .Em directory stream when the .Fn telldir operation was performed.
p The .Fn rewinddir function resets the position of the named .Em directory stream to the beginning of the directory.
p The .Fn closedir function closes the named .Em directory stream and frees the structure associated with the .Fa dirp pointer, returning 0 on success. On failure, -1 is returned and the global variable .Va errno is set to indicate the error.
p The .Fn dirfd function returns the integer file descriptor associated with the named .Em directory stream , see .Xr open 2 . On failure, -1 is returned and the global variable .Va errno is set to indicate the error.
p Sample code which searches a directory for entry ``name'' is: d -literal -offset indent dirp = opendir("."); if (dirp == NULL) return (ERROR); len = strlen(name); while ((dp = readdir(dirp)) != NULL) { if (dp->d_namlen == len && strcmp(dp->d_name, name) == 0) { (void)closedir(dirp); return (FOUND); } } (void)closedir(dirp); return (NOT_FOUND); .Ed .Sh SEE ALSO .Xr close 2 , .Xr lseek 2 , .Xr open 2 , .Xr read 2 , .Xr dir 5 .Sh HISTORY The .Fn opendir , .Fn readdir , .Fn telldir , .Fn seekdir , .Fn rewinddir , .Fn closedir , and .Fn dirfd functions appeared in x 4.2 . The .Fn fdopendir function appeared in .Fx 8.0 .