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NAME

fts

 - traverse a file hierarchy

 

LIBRARY

Lb libc

 

SYNOPSIS

DESCRIPTION

Two structures are defined (and typedef'd) in the include file In fts.h . The first is Vt FTS , the structure that represents the file hierarchy itself. The second is Vt FTSENT , the structure that represents a file in the file hierarchy. Normally, an Vt FTSENT structure is returned for every file in the file hierarchy. In this manual page, ``file'' and ``Vt FTSENT structure '' are generally interchangeable.

The Vt FTS structure contains space for a single pointer, which may be used to store application data or per-hierarchy state. The fts_set_clientptr ();
and fts_get_clientptr ();
functions may be used to set and retrieve this pointer. This is likely to be useful only when accessed from the sort comparison function, which can determine the original Vt FTS stream of its arguments using the fts_get_stream ();
function. The two get functions are also available as macros of the same name.

The Vt FTSENT structure contains at least the following fields, which are described in greater detail below:

typedef struct _ftsent {
        u_short fts_info;               /* flags for FTSENT structure */
        char *fts_accpath;              /* access path */
        char *fts_path;                 /* root path */
        u_short fts_pathlen;            /* strlen(fts_path) */
        char *fts_name;                 /* file name */
        u_short fts_namelen;            /* strlen(fts_name) */
        short fts_level;                /* depth (-1 to N) */
        int fts_errno;                  /* file errno */
        long fts_number;                /* local numeric value */
        void *fts_pointer;              /* local address value */
        int64_t fts_bignum;             /* local 64-bit numeric value */
        struct ftsent *fts_parent;      /* parent directory */
        struct ftsent *fts_link;        /* next file structure */
        struct ftsent *fts_cycle;       /* cycle structure */
        struct stat *fts_statp;         /* stat(2) information */
} FTSENT;

These fields are defined as follows:

Fa fts_info

One of the following values describing the returned Vt FTSENT structure and the file it represents. With the exception of directories without errors (FTS_D ) all of these entries are terminal, that is, they will not be revisited, nor will any of their descendants be visited.

FTS_D

A directory being visited in pre-order.

FTS_DC

A directory that causes a cycle in the tree. (The Fa fts_cycle field of the Vt FTSENT structure will be filled in as well.)

FTS_DEFAULT

Any Vt FTSENT structure that represents a file type not explicitly described by one of the other Fa fts_info values.

FTS_DNR

A directory which cannot be read. This is an error return, and the Fa fts_errno field will be set to indicate what caused the error.

FTS_DOT

A file named `.' or `..' which was not specified as a file name to fts_open ();
(see FTS_SEEDOT )

FTS_DP

A directory being visited in post-order. The contents of the Vt FTSENT structure will be unchanged from when it was returned in pre-order, i.e., with the Fa fts_info field set to FTS_D

FTS_ERR

This is an error return, and the Fa fts_errno field will be set to indicate what caused the error.

FTS_F

A regular file.

FTS_NS

A file for which no stat(2) information was available. The contents of the Fa fts_statp field are undefined. This is an error return, and the Fa fts_errno field will be set to indicate what caused the error.

FTS_NSOK

A file for which no stat(2) information was requested. The contents of the Fa fts_statp field are undefined.

FTS_SL

A symbolic link.

FTS_SLNONE

A symbolic link with a non-existent target. The contents of the Fa fts_statp field reference the file characteristic information for the symbolic link itself.

Fa fts_accpath

A path for accessing the file from the current directory.

Fa fts_path

The path for the file relative to the root of the traversal. This path contains the path specified to fts_open ();
as a prefix.

Fa fts_pathlen

The length of the string referenced by Fa fts_path .

Fa fts_name

The name of the file.

Fa fts_namelen

The length of the string referenced by Fa fts_name .

Fa fts_level

The depth of the traversal, numbered from -1 to N, where this file was found. The Vt FTSENT structure representing the parent of the starting point (or root) of the traversal is numbered FTS_ROOTPARENTLEVEL (-1), and the Vt FTSENT structure for the root itself is numbered FTS_ROOTLEVEL (0).

Fa fts_errno

Upon return of a Vt FTSENT structure from the fts_children ();
or fts_read ();
functions, with its Fa fts_info field set to FTS_DNR FTS_ERR or FTS_NS the Fa fts_errno field contains the value of the external variable errno specifying the cause of the error. Otherwise, the contents of the Fa fts_errno field are undefined.

Fa fts_number

This field is provided for the use of the application program and is not modified by the functions. It is initialized to 0. Note that this field is overlaid by Fa fts_bignum .

Fa fts_pointer

This field is provided for the use of the application program and is not modified by the functions. It is initialized to NULL Note that this field is overlaid by Fa fts_bignum .

Fa fts_bignum

This field is provided for the use of the application program and is not modified by the functions. It is initialized to 0. Note that this field overlays Fa fts_number and Fa fts_pointer .

Fa fts_parent

A pointer to the Vt FTSENT structure referencing the file in the hierarchy immediately above the current file, i.e., the directory of which this file is a member. A parent structure for the initial entry point is provided as well, however, only the Fa fts_level , Fa fts_bignum , Fa fts_number and Fa fts_pointer fields are guaranteed to be initialized.

Fa fts_link

Upon return from the fts_children ();
function, the Fa fts_link field points to the next structure in the NULL-terminated linked list of directory members. Otherwise, the contents of the Fa fts_link field are undefined.

Fa fts_cycle

If a directory causes a cycle in the hierarchy (see FTS_DC ) either because of a hard link between two directories, or a symbolic link pointing to a directory, the Fa fts_cycle field of the structure will point to the Vt FTSENT structure in the hierarchy that references the same file as the current Vt FTSENT structure. Otherwise, the contents of the Fa fts_cycle field are undefined.

Fa fts_statp

A pointer to stat(2) information for the file.

A single buffer is used for all of the paths of all of the files in the file hierarchy. Therefore, the Fa fts_path and Fa fts_accpath fields are guaranteed to be NUL -terminated only for the file most recently returned by fts_read (.);
To use these fields to reference any files represented by other Vt FTSENT structures will require that the path buffer be modified using the information contained in that Vt FTSENT structure's Fa fts_pathlen field. Any such modifications should be undone before further calls to fts_read ();
are attempted. The Fa fts_name field is always NUL -terminated

Note that the use of Fa fts_bignum is mutually exclusive with the use of Fa fts_number or Fa fts_pointer .  

FTS_OPEN

There are a number of options, at least one of which (either FTS_LOGICAL or FTS_PHYSICAL must be specified. The options are selected by or 'ing the following values:

FTS_COMFOLLOW

This option causes any symbolic link specified as a root path to be followed immediately whether or not FTS_LOGICAL is also specified.

FTS_LOGICAL

This option causes the routines to return Vt FTSENT structures for the targets of symbolic links instead of the symbolic links themselves. If this option is set, the only symbolic links for which Vt FTSENT structures are returned to the application are those referencing non-existent files. Either FTS_LOGICAL or FTS_PHYSICAL must be provided to the fts_open ();
function.

FTS_NOCHDIR

As a performance optimization, the functions change directories as they walk the file hierarchy. This has the side-effect that an application cannot rely on being in any particular directory during the traversal. The FTS_NOCHDIR option turns off this optimization, and the functions will not change the current directory. Note that applications should not themselves change their current directory and try to access files unless FTS_NOCHDIR is specified and absolute pathnames were provided as arguments to fts_open (.);

FTS_NOSTAT

By default, returned Vt FTSENT structures reference file characteristic information (the Fa statp field) for each file visited. This option relaxes that requirement as a performance optimization, allowing the functions to set the Fa fts_info field to FTS_NSOK and leave the contents of the Fa statp field undefined.

FTS_PHYSICAL

This option causes the routines to return Vt FTSENT structures for symbolic links themselves instead of the target files they point to. If this option is set, Vt FTSENT structures for all symbolic links in the hierarchy are returned to the application. Either FTS_LOGICAL or FTS_PHYSICAL must be provided to the fts_open ();
function.

FTS_SEEDOT

By default, unless they are specified as path arguments to fts_open (,);
any files named `.' or `..' encountered in the file hierarchy are ignored. This option causes the routines to return Vt FTSENT structures for them.

FTS_XDEV

This option prevents from descending into directories that have a different device number than the file from which the descent began.

The argument compar ();
specifies a user-defined function which may be used to order the traversal of the hierarchy. It takes two pointers to pointers to Vt FTSENT structures as arguments and should return a negative value, zero, or a positive value to indicate if the file referenced by its first argument comes before, in any order with respect to, or after, the file referenced by its second argument. The Fa fts_accpath , Fa fts_path and Fa fts_pathlen fields of the Vt FTSENT structures may never be used in this comparison. If the Fa fts_info field is set to FTS_NS or FTS_NSOK the Fa fts_statp field may not either. If the compar ();
argument is NULL the directory traversal order is in the order listed in Fa path_argv for the root paths, and in the order listed in the directory for everything else.  

FTS_READ

If all the members of the hierarchy have been returned, fts_read ();
returns NULL and sets the external variable errno to 0. If an error unrelated to a file in the hierarchy occurs, fts_read ();
returns NULL and sets errno appropriately. If an error related to a returned file occurs, a pointer to an Vt FTSENT structure is returned, and errno may or may not have been set (see Fa fts_info ) .

The Vt FTSENT structures returned by fts_read ();
may be overwritten after a call to fts_close ();
on the same file hierarchy stream, or, after a call to fts_read ();
on the same file hierarchy stream unless they represent a file of type directory, in which case they will not be overwritten until after a call to fts_read ();
after the Vt FTSENT structure has been returned by the function fts_read ();
in post-order.  

FTS_CHILDREN

As a special case, if fts_read ();
has not yet been called for a hierarchy, fts_children ();
will return a pointer to the files in the logical directory specified to fts_open (,);
i.e., the arguments specified to fts_open (.);
Otherwise, if the Vt FTSENT structure most recently returned by fts_read ();
is not a directory being visited in pre-order, or the directory does not contain any files, fts_children ();
returns NULL and sets errno to zero. If an error occurs, fts_children ();
returns NULL and sets errno appropriately.

The Vt FTSENT structures returned by fts_children ();
may be overwritten after a call to fts_children (,);
fts_close ();
or fts_read ();
on the same file hierarchy stream.

Option may be set to the following value:

FTS_NAMEONLY

Only the names of the files are needed. The contents of all the fields in the returned linked list of structures are undefined with the exception of the Fa fts_name and Fa fts_namelen fields.

FTS_SET

FTS_AGAIN

Re-visit the file; any file type may be re-visited. The next call to fts_read ();
will return the referenced file. The Fa fts_stat and Fa fts_info fields of the structure will be reinitialized at that time, but no other fields will have been changed. This option is meaningful only for the most recently returned file from fts_read (.);
Normal use is for post-order directory visits, where it causes the directory to be re-visited (in both pre and post-order) as well as all of its descendants.

FTS_FOLLOW

The referenced file must be a symbolic link. If the referenced file is the one most recently returned by fts_read (,);
the next call to fts_read ();
returns the file with the Fa fts_info and Fa fts_statp fields reinitialized to reflect the target of the symbolic link instead of the symbolic link itself. If the file is one of those most recently returned by fts_children (,);
the Fa fts_info and Fa fts_statp fields of the structure, when returned by fts_read (,);
will reflect the target of the symbolic link instead of the symbolic link itself. In either case, if the target of the symbolic link does not exist the fields of the returned structure will be unchanged and the Fa fts_info field will be set to FTS_SLNONE

If the target of the link is a directory, the pre-order return, followed by the return of all of its descendants, followed by a post-order return, is done.

FTS_SKIP

No descendants of this file are visited. The file may be one of those most recently returned by either fts_children ();
or fts_read (.);

FTS_CLOSE

ERRORS

The function fts_close ();
may fail and set errno for any of the errors specified for the library functions chdir(2) and close(2).

The functions fts_read ();
and fts_children ();
may fail and set errno for any of the errors specified for the library functions chdir(2), malloc(3), opendir(3), readdir(3) and stat(2).

In addition, fts_children (,);
fts_open ();
and fts_set ();
may fail and set errno as follows:

Bq Er EINVAL

The options were invalid.

SEE ALSO

HISTORY

Index

NAME

LIBRARY

SYNOPSIS

DESCRIPTION

FTS_OPEN

FTS_READ

FTS_CHILDREN

FTS_SET

FTS_CLOSE

ERRORS

SEE ALSO

HISTORY

Партнёры:

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