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@(#)directory.3 8.1 (Berkeley) 6/4/93
$FreeBSD: head/lib/libc/gen/directory.3 108030 2002-12-18 10:13:54Z ru $
.Dd June 4, 1993 .Dt DIRECTORY 3 .Os .Sh NAME .Nm opendir , .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 sys/types.h n dirent.h .Ft DIR * .Fn opendir "const char *filename" .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.
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 detecting an invalid .Fn seekdir operation.
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 .
p Sample code which searches a directory for entry ``name'' is: d -literal -offset indent 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; .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 .