.\" and copyright (c) 2006 Justin Pryzby <justinpryzby@users.sf.net>
.\" and copyright (c) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
.\"
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-.\" This is free documentation; you can redistribute it and/or
-.\" modify it under the terms of the GNU General Public License as
-.\" published by the Free Software Foundation; either version 2 of
-.\" the License, or (at your option) any later version.
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-.\" The GNU General Public License's references to "object code"
-.\" and "executables" are to be interpreted as the output of any
-.\" document formatting or typesetting system, including
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-.\" This manual is distributed in the hope that it will be useful,
-.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
-.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-.\" GNU General Public License for more details.
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-.\" %%%LICENSE_END
+.\" SPDX-License-Identifier: GPL-2.0-or-later
.\"
.\" Modified Sun Jul 25 11:02:22 1993 by Rik Faith (faith@cs.unc.edu)
.\" 2006-05-24, Justin Pryzby <justinpryzby@users.sf.net>
.\" 2006-05-24, Michael Kerrisk <mtk.manpages@gmail.com>
.\" Added an example program.
.\"
-.TH FTW 3 2017-07-13 "Linux" "Linux Programmer's Manual"
+.TH FTW 3 2021-03-22 "Linux man-pages (unreleased)" "Linux Programmer's Manual"
.SH NAME
ftw, nftw \- file tree walk
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
.SH SYNOPSIS
.nf
.B #include <ftw.h>
.PP
.BI "int nftw(const char *" dirpath ,
-.BI " int (*" fn ") (const char *" fpath ", const struct stat *" sb ,
-.BI " int " typeflag ", struct FTW *" ftwbuf ),
+.BI " int (*" fn ")(const char *" fpath ", const struct stat *" sb ,
+.BI " int " typeflag ", struct FTW *" ftwbuf ),
.BI " int " nopenfd ", int " flags );
.PP
-.B #include <ftw.h>
-.PP
.BI "int ftw(const char *" dirpath ,
-.BI " int (*" fn ") (const char *" fpath ", const struct stat *" sb ,
-.BI " int " typeflag ),
+.BI " int (*" fn ")(const char *" fpath ", const struct stat *" sb ,
+.BI " int " typeflag ),
.BI " int " nopenfd );
.fi
.PP
-.in -4n
+.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
-.in
+.RE
.PP
.BR nftw ():
-_XOPEN_SOURCE >= 500
+.nf
+ _XOPEN_SOURCE >= 500
+.fi
.SH DESCRIPTION
.BR nftw ()
walks through the directory tree that is
current working directory at the time of the call to
.BR nftw (),
if
-.IR dirpath
+.I dirpath
was expressed as a relative pathname,
or as an absolute pathname, if
.I dirpath
.I fpath
is a symbolic link pointing to a nonexistent file.
(This occurs only if \fBFTW_PHYS\fP is not set.)
-On most implementations, in this case the
+In this case the
.I sb
argument passed to
.IR fn ()
contains information returned by performing
.BR lstat (2)
-on the symbolic link.
-For the details on Linux, see BUGS.
+on the "dangling" symbolic link.
+(But see BUGS.)
.PP
The fourth argument
.RI ( ftwbuf )
supplies when calling
\fIfn\fP()
is a pointer to a structure of type \fIFTW\fP:
+.PP
.in +4n
-.nf
-
+.EX
struct FTW {
int base;
int level;
};
-
-.fi
+.EE
.in
+.PP
.I base
is the offset of the filename (i.e., basename component)
in the pathname given in
If set, do not follow symbolic links.
(This is what you want.)
If not set, symbolic links are followed, but no file is reported twice.
-.sp
+.IP
If \fBFTW_PHYS\fP is not set, but \fBFTW_DEPTH\fP is set,
then the function
.IR fn ()
.IP * 3
.BR ftw ()
has no
-.IR flags
+.I flags
argument.
It behaves the same as when
.BR nftw ()
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
+.ad l
+.nh
.TS
allbox;
-lb lb lb
+lbx lb lb
l l l.
Interface Attribute Value
T{
.BR ftw ()
T} Thread safety MT-Safe
.TE
+.hy
+.ad
.sp 1
-.SH CONFORMING TO
+.SH STANDARDS
POSIX.1-2001, POSIX.1-2008, SVr4, SUSv1.
POSIX.1-2008 marks
.BR ftw ()
and the use of \fBFTW_SL\fP with
.BR ftw ()
were introduced in SUSv1.
-.LP
+.PP
In some implementations (e.g., glibc),
.BR ftw ()
will never use \fBFTW_SL\fP, on other systems \fBFTW_SL\fP occurs only
.IR typeflag .
For predictable results, use
.BR nftw ().
-.SH EXAMPLE
+.SH BUGS
+According to POSIX.1-2008, when the
+.I typeflag
+argument passed to
+.IR fn ()
+contains
+.BR FTW_SLN ,
+the buffer pointed to by
+.I sb
+should contain information about the dangling symbolic link
+(obtained by calling
+.BR lstat (2)
+on the link).
+Early glibc versions correctly followed the POSIX specification on this point.
+However, as a result of a regression introduced in glibc 2.4,
+the contents of the buffer pointed to by
+.I sb
+were undefined when
+.B FTW_SLN
+is passed in
+.IR typeflag .
+(More precisely, the contents of the buffer were left unchanged in this case.)
+This regression was eventually fixed in glibc 2.30,
+.\" https://bugzilla.redhat.com/show_bug.cgi?id=1422736
+.\" http://austingroupbugs.net/view.php?id=1121
+.\" glibc commit 6ba205b2c35e3e024c8c12d2ee1b73363e84da87
+.\" https://sourceware.org/bugzilla/show_bug.cgi?id=23501
+so that the glibc implementation (once more) follows the POSIX specification.
+.SH EXAMPLES
The following program traverses the directory tree under the path named
in its first command-line argument, or under the current directory
if no argument is supplied.
argument when calling
.BR nftw ().
.SS Program source
+\&
.EX
#define _XOPEN_SOURCE 500
#include <ftw.h>
else
printf("%7jd", (intmax_t) sb\->st_size);
- printf(" %\-40s %d %s\\n",
+ printf(" %\-40s %d %s\en",
fpath, ftwbuf\->base, fpath + ftwbuf\->base);
return 0; /* To tell nftw() to continue */
exit(EXIT_SUCCESS);
}
.EE
-.SH BUGS
-In the specification of
-.BR nftw (),
-POSIX.1 notes that when
-.B FTW_NS
-is passed as the
-.I typeflag
-argument of
-.IR fn (),
-then the contents of the buffer pointed to by the
-.I sb
-argument are undefined.
-The standard makes no such statement for the case where
-.B FTW_SLN
-is passed in
-.IR typeflag ,
-with the implication that the contents of the buffer pointed to by
-.I sb
-are defined.
-And indeed this is the case on most implementations: the buffer pointed to by
-.I sb
-contains the results produced by applying
-.BR lstat (2)
-to the symbolic link.
-In early glibc, the behavior was the same.
-However, since glibc 2.4, the contents of the buffer pointed to by
-.I sb
-are undefined when
-.B FTW_SLN
-is passed in
-.IR typeflag .
-This change
-.I appears
-to be an unintended regression,
-but it is not (yet) clear if the behavior will be restored to that
-provided in the original glibc implementation (and on other implementations).
-.\" FIXME .
-.\" https://bugzilla.redhat.com/show_bug.cgi?id=1422736
-.\" http://austingroupbugs.net/view.php?id=1121
.SH SEE ALSO
.BR stat (2),
.BR fts (3),