Copyright (c) 2003 Todd C. Miller <Todd.Miller@courtesan.com>
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Sponsored in part by the Defense Advanced Research Projects
Agency (DARPA) and Air Force Research Laboratory, Air Force
Materiel Command, USAF, under agreement number F39502-99-1-0512.
.Dd May 20, 2003 .Dt FTW 3 .Os .Sh NAME .Nm ftw, nftw .Nd traverse (walk) a file tree .Sh SYNOPSIS .Fd #include <ftw.h> .Ft int .Fo ftw .Fa "const char *path" .Fa "int (*fn)(const char *, const struct stat *ptr, int flag)" .Fa "int depth" .Fc .Ft int .Fo nftw .Fa "const char *path" .Fa "int (*fn)(const char *, const struct stat *ptr, \ int flag, struct FTW *)" .Fa "int depth" .Fa "int flags" .Fc .Sh DESCRIPTION f -symbolic These functions are provided for compatibility with legacy code. New code should use the .Xr fts 3 functions. .Ef
p The .Fn ftw and .Fn nftw functions traverse (walk) the directory hierarchy rooted in .Fa path . For each object in the hierarchy, these functions call the function pointed to by .Fa fn . The .Fn ftw function passes this function a pointer to a NUL-terminated string containing the name of the object, a pointer to a stat structure corresponding to the object, and an integer flag. The .Fn nftw function passes the aforementioned arguments plus a pointer to a .Dv FTW structure as defined by .Aq Pa ftw.h (shown below): d -literal struct FTW { int base; /* offset of basename into pathname */ int level; /* directory depth relative to starting point */ }; .Ed
p Possible values for the flag passed to .Fa fn are: l -tag -width FTW_DNR t Dv FTW_F A regular file. t Dv FTW_D A directory being visited in pre-order. t Dv FTW_DNR A directory which cannot be read. The directory will not be descended into. t Dv FTW_DP A directory being visited in post-order .No ( Ns Fn nftw only). t Dv FTW_NS A file for which no .Xr stat 2 information was available. The contents of the stat structure are undefined. t Dv FTW_SL A symbolic link. t Dv FTW_SLN A symbolic link with a non-existent target .No ( Ns Fn nftw only). .El
p The .Fn ftw function traverses the tree in pre-order. That is, it processes the directory before the directory's contents.
p The .Fa depth argument specifies the maximum number of file descriptors to keep open while traversing the tree. It has no effect in this implementation.
p The .Fn nftw function has an additional .Fa flags argument with the following possible values: l -tag -width FTW_MOUNT t Dv FTW_PHYS Physical walk, don't follow symbolic links. t Dv FTW_MOUNT The walk will not cross a mount point. t FTW_DEPTH Process directories in post-order. Contents of a directory are visited before the directory itself. By default, .Fn nftw traverses the tree in pre-order. t FTW_CHDIR Change to a directory before reading it. By default, .Fn nftw will change its starting directory. The current working directory will be restored to its original value before .Fn nftw returns. .El .Sh RETURN VALUES If the tree was traversed successfully, the .Fn ftw and .Fn nftw functions return 0. If the function pointed to by .Fa fn returns a non-zero value, .Fn ftw and .Fn nftw will stop processing the tree and return the value from .Fa fn . Both functions return -1 if an error is detected. .Sh ERRORS The .Fn ftw and .Fn nftw functions may fail and set .Va errno for any of the errors specified for the library functions .Xr close 2 , .Xr open 2 , .Xr stat 2 , .Xr malloc 3 , .Xr opendir 3 and .Xr readdir 3 . If the .Dv FTW_CHDIR flag is set, the .Fn nftw function may fail and set .Va errno for any of the errors specified for .Xr chdir 2 . In addition, either function may fail and set .Va errno as follows: l -tag -width Er t Bq Er EINVAL The .Fa depth argument is less than 1 or greater than .Dv OPEN_MAX . .El .Sh LEGACY ERRORS The .Fn ftw and .Fn nftw functions are far more tolerant of symlink cycles and are lax in reporting errors while accessing the initial path. When .Fn nftw is passed .Dv FTW_MOUNT , it will pass the mount point to the callback function. .Sh SEE ALSO .Xr chdir 2 , .Xr close 2 , .Xr open 2 , .Xr stat 2 , .Xr fts 3 , .Xr malloc 3 , .Xr opendir 3 , .Xr readdir 3 , .Xr compat 5 .Sh STANDARDS The .Fn ftw and .Fn nftw functions conform to .St -p1003.1-2001 and .St -susv3 . .Sh HISTORY Prior to MacOS X 10.4 .Nm ftw did not follow symlinks. .Sh BUGS The .Fa depth argument is currently ignored.