man-pages/man3p/nftw.3p

.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved 
.TH "NFTW" 3P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\" nftw 
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.SH NAME
nftw \- walk a file tree
.SH SYNOPSIS
.LP
\fB#include <ftw.h>
.br
.sp
int nftw(const char *\fP\fIpath\fP\fB, int (*\fP\fIfn\fP\fB)(const
char *,
.br
\ \ \ \ \ \  const struct stat *, int, struct FTW *), int\fP \fIdepth\fP\fB,
int\fP
\fIflags\fP\fB);
.br
\fP
.SH DESCRIPTION
.LP
The \fInftw\fP() function shall recursively descend the directory
hierarchy rooted in \fIpath\fP. The \fInftw\fP() function
has a similar effect to \fIftw\fP() except that it takes an additional
argument \fIflags\fP,
which is a bitwise-inclusive OR of zero or more of the following flags:
.TP 7
FTW_CHDIR
If set, \fInftw\fP() shall change the current working directory to
each directory as it reports files in that directory. If
clear, \fInftw\fP() shall not change the current working directory.
.TP 7
FTW_DEPTH
If set, \fInftw\fP() shall report all files in a directory before
reporting the directory itself. If clear, \fInftw\fP()
shall report any directory before reporting the files in that directory.
.TP 7
FTW_MOUNT
If set, \fInftw\fP() shall only report files in the same file system
as \fIpath\fP. If clear, \fInftw\fP() shall report all
files encountered during the walk.
.TP 7
FTW_PHYS
If set, \fInftw\fP() shall perform a physical walk and shall not follow
symbolic links.
.sp
.LP
If FTW_PHYS is clear and FTW_DEPTH is set, \fInftw\fP() shall follow
links instead of reporting them, but shall not report any
directory that would be a descendant of itself. If FTW_PHYS is clear
and FTW_DEPTH is clear, \fInftw\fP() shall follow links
instead of reporting them, but shall not report the contents of any
directory that would be a descendant of itself.
.LP
At each file it encounters, \fInftw\fP() shall call the user-supplied
function \fIfn\fP with four arguments:
.IP " *" 3
The first argument is the pathname of the object.
.LP
.IP " *" 3
The second argument is a pointer to the \fBstat\fP buffer containing
information on the object.
.LP
.IP " *" 3
The third argument is an integer giving additional information. Its
value is one of the following:
.TP 7
FTW_F
.RS
The object is a file.
.RE
.TP 7
FTW_D
.RS
The object is a directory.
.RE
.TP 7
FTW_DP
.RS
The object is a directory and subdirectories have been visited. (This
condition shall only occur if the FTW_DEPTH flag is
included in \fIflags\fP.)
.RE
.TP 7
FTW_SL
.RS
The object is a symbolic link. (This condition shall only occur if
the FTW_PHYS flag is included in \fIflags\fP.)
.RE
.TP 7
FTW_SLN
.RS
The object is a symbolic link that does not name an existing file.
(This condition shall only occur if the FTW_PHYS flag is not
included in \fIflags\fP.)
.RE
.TP 7
FTW_DNR
.RS
The object is a directory that cannot be read. The \fIfn\fP function
shall not be called for any of its descendants.
.RE
.TP 7
FTW_NS
.RS
The \fIstat\fP() function failed on the object because of lack of
appropriate permission.
The \fBstat\fP buffer passed to \fIfn\fP is undefined. Failure of
\fIstat\fP() for any
other reason is considered an error and \fInftw\fP() shall return
-1.
.RE
.sp
.LP
.IP " *" 3
The fourth argument is a pointer to an \fBFTW\fP structure. The value
of \fBbase\fP is the offset of the object's filename in
the pathname passed as the first argument to \fIfn\fP. The value of
\fBlevel\fP indicates depth relative to the root of the walk,
where the root level is 0.
.LP
.LP
The results are unspecified if the application-supplied \fIfn\fP function
does not preserve the current working directory.
.LP
The argument \fIdepth\fP sets the maximum number of file descriptors
that shall be used by \fInftw\fP() while traversing the
file tree. At most one file descriptor shall be used for each directory
level.
.LP
The \fInftw\fP() function need not be reentrant. A function that is
not required to be reentrant is not required to be
thread-safe.
.SH RETURN VALUE
.LP
The \fInftw\fP() function shall continue until the first of the following
conditions occurs:
.IP " *" 3
An invocation of \fIfn\fP shall return a non-zero value, in which
case \fInftw\fP() shall return that value.
.LP
.IP " *" 3
The \fInftw\fP() function detects an error other than [EACCES] (see
FTW_DNR and FTW_NS above), in which case \fInftw\fP()
shall return -1 and set \fIerrno\fP to indicate the error.
.LP
.IP " *" 3
The tree is exhausted, in which case \fInftw\fP() shall return 0.
.LP
.SH ERRORS
.LP
The \fInftw\fP() function shall fail if:
.TP 7
.B EACCES
Search permission is denied for any component of \fIpath\fP or read
permission is denied for \fIpath\fP, or \fIfn\fP returns
-1 and does not reset \fIerrno\fP.
.TP 7
.B ELOOP
A loop exists in symbolic links encountered during resolution of the
\fIpath\fP argument.
.TP 7
.B ENAMETOOLONG
The length of the \fIpath\fP argument exceeds {PATH_MAX} or a pathname
component is longer than {NAME_MAX}.
.TP 7
.B ENOENT
A component of \fIpath\fP does not name an existing file or \fIpath\fP
is an empty string.
.TP 7
.B ENOTDIR
A component of \fIpath\fP is not a directory.
.TP 7
.B EOVERFLOW
A field in the \fBstat\fP structure cannot be represented correctly
in the current programming environment for one or more
files found in the file hierarchy.
.sp
.LP
The \fInftw\fP() function may fail if:
.TP 7
.B ELOOP
More than {SYMLOOP_MAX} symbolic links were encountered during resolution
of the \fIpath\fP argument.
.TP 7
.B EMFILE
{OPEN_MAX} file descriptors are currently open in the calling process.
.TP 7
.B ENAMETOOLONG
Pathname resolution of a symbolic link produced an intermediate result
whose length exceeds {PATH_MAX}.
.TP 7
.B ENFILE
Too many files are currently open in the system.
.sp
.LP
In addition, \fIerrno\fP may be set if the function pointed to by
\fIfn\fP causes \fIerrno\fP to be set.
.LP
\fIThe following sections are informative.\fP
.SH EXAMPLES
.LP
The following example walks the \fB/tmp\fP directory and its subdirectories,
calling the \fInftw\fP() function for every
directory entry, to a maximum of 5 levels deep.
.sp
.RS
.nf

\fB#include <ftw.h>
\&...
int nftwfunc(const char *, const struct stat *, int, struct FTW *);
.sp

int nftwfunc(const char *filename, const struct stat *statptr,
    int fileflags, struct FTW *pfwt)
{
    return 0;
}
\&...
char *startpath = "/tmp";
int depth = 5;
int flags = FTW_CHDIR | FTW_DEPTH | FTW_MOUNT;
int ret;
.sp

ret = nftw(startpath, nftwfunc, depth, flags);
\fP
.fi
.RE
.SH APPLICATION USAGE
.LP
None.
.SH RATIONALE
.LP
None.
.SH FUTURE DIRECTIONS
.LP
None.
.SH SEE ALSO
.LP
\fIlstat\fP(), \fIopendir\fP(), \fIreaddir\fP(), \fIstat\fP(),
the Base Definitions volume of
IEEE\ Std\ 1003.1-2001, \fI<ftw.h>\fP
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .