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nftw(3)
NAME
nftw - Walks a file tree
LIBRARY
Standard C Library (libc.so, libc.a)
SYNOPSIS
#include <ftw.h>
int nftw(
const char *path,
int(*function)(const char *, const struct stat *,
int, struct FTW *),
int depth,
int flags);
The following definition of the nftw() function does not conform to current
standards and is supported only for backward compatibility:
int nftw(
const char *path,
int(*function)(const char *, const struct stat *,
int, struct FTW),
int depth,
int flags);
STANDARDS
Interfaces documented on this reference page conform to industry standards
as follows:
nftw(): XSH5.0
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
PARAMETERS
path Specifies the directory hierarchy to be searched.
function Specifies the function to be invoked for each object in the
directory hierarchy.
depth Limits the directory depth for the search. At most one file
descriptor will be used for each directory level.
In the backward-compatible version of nftw(), this parameter can
be supplied but is not used.
flags Specifies optional flags that modify the operation of the nftw()
function.
DESCRIPTION
The nftw() function recursively searches the directory hierarchy that
descends from the directory specified by the path parameter. The nftw()
function performs the same operations as ftw(), except that it takes an
additional argument flags, which is a bitwise inclusive-OR of zero or more
of the following flags:
FTW_CHDIR If set, nftw() changes the current working directory to each
directory as it reports files in that directory. If clear,
nftw() does not change the current working directory.
FTW_DEPTH If set, nftw() reports all files in a directory before reporting
the directory itself. If clear, nftw() reports any directory
before reporting files in that directory.
FTW_MOUNT If set, nftw() reports only files in the same file system as
path. If clear, nftw() reports all files encountered during the
walk.
FTW_PHYS If set, nftw() performs a physical walk and does not follow
symbolic links. If clear, nftw() follows links instead of
reporting them, and does not report the same file twice.
The nftw() function calls the function parameter with four arguments at
each file and directory. The first argument is the pathname of the object.
The second argument points to the stat buffer containing information on the
object. The third argument is an integer that identifies the file type or
condition of the object. The value of the integer is one of the following:
FTW_D A directory.
FTW_DNR A directory that cannot be read. When nftw() reports this
condition, function is not called for any of the directory's
descendants.
FTW_DP A directory whose subdirectories have been visited. (This
condition occurs only if the FTW_DEPTH flag is included in
flags.)
FTW_F A regular file.
FTW_NS An object for which the stat() function failed because of lack of
appropriate permission. The content of the stat() buffer passed
to function is meaningless. Failure of nftw() for any other
reason is considered an error and results in a return value of
-l.
FTW_SL A symbolic link. (This condition occurs only if the FTW_PHYS
flag is included in flags.)
FTW_SLN A symbolic link that names a non-existent file. (This condition
occurs only if the FTW_PHYS flag is not included in flags.)
In the backward-compatible version of nftw, the FTW_SLN value is
not used.
The fourth argument to function is a pointer to an FTW structure.
In the backward-compatible version of nftw(), the fourth argument is an FTW
structure rather than a pointer to one.
The FTW structure includes the following members:
int base;
int level;
The value of base is the offset into the pathname of the object. This
pathname is passed as the first argument to the function parameter. The
value of level specifies the depth relative to the root of the walk, where
the root level has a value of 0 (zero).
NOTES
[Tru64 UNIX] When compiled in the X/Open UNIX environment, calls to the
nftw() function are internally renamed by prepending _E to the function
name. When debugging a module that includes the nftw() function and for
which _XOPEN_SOURCE_EXTENDED has been defined, use _Enftw to refer to the
nftw() call. See standards(5) for information on when the
_XOPEN_SOURCE_EXTENDED macro is defined.
[Tru64 UNIX] The nftw() function is reentrant; care should be taken to
ensure that the function supplied as argument function is also reentrant.
RETURN VALUES
If the directory hierarchy is completed, the nftw() function returns a
value of 0 (zero).
If the function specified by the function parameter returns a nonzero
value, the nftw() function stops the search and returns the value that was
returned by the function.
If the nftw() function detects an error other than [EACCES], a value of -1
is returned, and errno is set to indicate the error.
ERRORS
If any of the following conditions occurs, the nftw() function sets errno
to the value that corresponds to the condition.
[EACCES] Search permission is denied for any component of the path
parameter or read permission is denied for the path parameter, or
function returns -1 and does not reset errno.
[ENAMETOOLONG]
The length of the path string exceeds PATH_MAX, or a pathname
component is longer than NAME_MAX while _POSIX_NO_TRUNC is in
effect.
Pathname resolution of a symbolic link produced an intermediate
result whose length exceeds PATH_MAX.
[ENOENT] The path parameter points to the name of a file that does not
exist or points to an empty string.
[ENOTDIR] A component of the path parameter is not a directory.
[ENOMEM] [Tru64 UNIX] There is insufficient memory for this operation.
In addition, if the function pointed to by the function parameter
encounters an error, errno may be set accordingly.
RELATED INFORMATION
Functions: stat(2), ftw(3)
Standards: standards(5)
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