Provided by: tcl8.6-doc_8.6.1-4ubuntu1_all 
NAME
Tcl_FSRegister, Tcl_FSUnregister, Tcl_FSData, Tcl_FSMountsChanged,
Tcl_FSGetFileSystemForPath, Tcl_FSGetPathType, Tcl_FSCopyFile, Tcl_FSCopyDirectory,
Tcl_FSCreateDirectory, Tcl_FSDeleteFile, Tcl_FSRemoveDirectory, Tcl_FSRenameFile,
Tcl_FSListVolumes, Tcl_FSEvalFile, Tcl_FSEvalFileEx, Tcl_FSLoadFile, Tcl_FSUnloadFile,
Tcl_FSMatchInDirectory, Tcl_FSLink, Tcl_FSLstat, Tcl_FSUtime, Tcl_FSFileAttrsGet,
Tcl_FSFileAttrsSet, Tcl_FSFileAttrStrings, Tcl_FSStat, Tcl_FSAccess,
Tcl_FSOpenFileChannel, Tcl_FSGetCwd, Tcl_FSChdir, Tcl_FSPathSeparator, Tcl_FSJoinPath,
Tcl_FSSplitPath, Tcl_FSEqualPaths, Tcl_FSGetNormalizedPath, Tcl_FSJoinToPath,
Tcl_FSConvertToPathType, Tcl_FSGetInternalRep, Tcl_FSGetTranslatedPath,
Tcl_FSGetTranslatedStringPath, Tcl_FSNewNativePath, Tcl_FSGetNativePath,
Tcl_FSFileSystemInfo, Tcl_GetAccessTimeFromStat, Tcl_GetBlockSizeFromStat,
Tcl_GetBlocksFromStat, Tcl_GetChangeTimeFromStat, Tcl_GetDeviceTypeFromStat,
Tcl_GetFSDeviceFromStat, Tcl_GetFSInodeFromStat, Tcl_GetGroupIdFromStat,
Tcl_GetLinkCountFromStat, Tcl_GetModeFromStat, Tcl_GetModificationTimeFromStat,
Tcl_GetSizeFromStat, Tcl_GetUserIdFromStat, Tcl_AllocStatBuf - procedures to interact with
any filesystem
SYNOPSIS
#include <tcl.h>
int
Tcl_FSRegister(clientData, fsPtr)
int
Tcl_FSUnregister(fsPtr)
ClientData
Tcl_FSData(fsPtr)
void
Tcl_FSMountsChanged(fsPtr)
const Tcl_Filesystem *
Tcl_FSGetFileSystemForPath(pathPtr)
Tcl_PathType
Tcl_FSGetPathType(pathPtr)
int
Tcl_FSCopyFile(srcPathPtr, destPathPtr)
int
Tcl_FSCopyDirectory(srcPathPtr, destPathPtr, errorPtr)
int
Tcl_FSCreateDirectory(pathPtr)
int
Tcl_FSDeleteFile(pathPtr)
int
Tcl_FSRemoveDirectory(pathPtr, int recursive, errorPtr)
int
Tcl_FSRenameFile(srcPathPtr, destPathPtr)
Tcl_Obj *
Tcl_FSListVolumes(void)
int
Tcl_FSEvalFileEx(interp, pathPtr, encodingName)
int
Tcl_FSEvalFile(interp, pathPtr)
int
Tcl_FSLoadFile(interp, pathPtr, sym1, sym2, proc1Ptr, proc2Ptr,
loadHandlePtr, unloadProcPtr)
int │
Tcl_FSUnloadFile(interp, loadHandle) │
int
Tcl_FSMatchInDirectory(interp, resultPtr, pathPtr, pattern, types)
Tcl_Obj *
Tcl_FSLink(linkNamePtr, toPtr, linkAction)
int
Tcl_FSLstat(pathPtr, statPtr)
int
Tcl_FSUtime(pathPtr, tval)
int
Tcl_FSFileAttrsGet(interp, int index, pathPtr, objPtrRef)
int
Tcl_FSFileAttrsSet(interp, int index, pathPtr, Tcl_Obj *objPtr)
const char *const *
Tcl_FSFileAttrStrings(pathPtr, objPtrRef)
int
Tcl_FSStat(pathPtr, statPtr)
int
Tcl_FSAccess(pathPtr, mode)
Tcl_Channel
Tcl_FSOpenFileChannel(interp, pathPtr, modeString, permissions)
Tcl_Obj *
Tcl_FSGetCwd(interp)
int
Tcl_FSChdir(pathPtr)
Tcl_Obj *
Tcl_FSPathSeparator(pathPtr)
Tcl_Obj *
Tcl_FSJoinPath(listObj, elements)
Tcl_Obj *
Tcl_FSSplitPath(pathPtr, lenPtr)
int
Tcl_FSEqualPaths(firstPtr, secondPtr)
Tcl_Obj *
Tcl_FSGetNormalizedPath(interp, pathPtr)
Tcl_Obj *
Tcl_FSJoinToPath(basePtr, objc, objv)
int
Tcl_FSConvertToPathType(interp, pathPtr)
ClientData
Tcl_FSGetInternalRep(pathPtr, fsPtr)
Tcl_Obj *
Tcl_FSGetTranslatedPath(interp, pathPtr)
const char *
Tcl_FSGetTranslatedStringPath(interp, pathPtr)
Tcl_Obj *
Tcl_FSNewNativePath(fsPtr, clientData)
const void *
Tcl_FSGetNativePath(pathPtr)
Tcl_Obj *
Tcl_FSFileSystemInfo(pathPtr)
Tcl_StatBuf *
Tcl_AllocStatBuf()
Tcl_WideInt │
Tcl_GetAccessTimeFromStat(statPtr) │
unsigned │
Tcl_GetBlockSizeFromStat(statPtr) │
Tcl_WideUInt │
Tcl_GetBlocksFromStat(statPtr) │
Tcl_WideInt │
Tcl_GetChangeTimeFromStat(statPtr) │
int │
Tcl_GetDeviceTypeFromStat(statPtr) │
unsigned │
Tcl_GetFSDeviceFromStat(statPtr) │
unsigned │
Tcl_GetFSInodeFromStat(statPtr) │
int │
Tcl_GetGroupIdFromStat(statPtr) │
int │
Tcl_GetLinkCountFromStat(statPtr) │
unsigned │
Tcl_GetModeFromStat(statPtr) │
Tcl_WideInt │
Tcl_GetModificationTimeFromStat(statPtr) │
Tcl_WideUInt │
Tcl_GetSizeFromStat(statPtr) │
int │
Tcl_GetUserIdFromStat(statPtr) │
ARGUMENTS
const Tcl_Filesystem *fsPtr (in) Points to a structure containing the addresses
of procedures that can be called to perform
the various filesystem operations.
Tcl_Obj *pathPtr (in) The path represented by this value is used for
the operation in question. If the value does
not already have an internal path
representation, it will be converted to have
one.
Tcl_Obj *srcPathPtr (in) As for pathPtr, but used for the source file
for a copy or rename operation.
Tcl_Obj *destPathPtr (in) As for pathPtr, but used for the destination
filename for a copy or rename operation.
const char *encodingName (in) The encoding of the data stored in the file
identified by pathPtr and to be evaluated.
const char *pattern (in) Only files or directories matching this
pattern will be returned.
Tcl_GlobTypeData *types (in) Only files or directories matching the type
descriptions contained in this structure will
be returned. This parameter may be NULL.
Tcl_Interp *interp (in) Interpreter to use either for results,
evaluation, or reporting error messages.
ClientData clientData (in) The native description of the path value to
create.
Tcl_Obj *firstPtr (in) The first of two path values to compare. The
value may be converted to path type.
Tcl_Obj *secondPtr (in) The second of two path values to compare. The
value may be converted to path type.
Tcl_Obj *listObj (in) The list of path elements to operate on with a
join operation.
int elements (in) If non-negative, the number of elements in the
listObj which should be joined together. If
negative, then all elements are joined.
Tcl_Obj **errorPtr (out) In the case of an error, filled with a value
containing the name of the file which caused
an error in the various copy/rename
operations.
Tcl_Obj **objPtrRef (out) Filled with a value containing the result of
the operation.
Tcl_Obj *resultPtr (out) Pre-allocated value in which to store (using
Tcl_ListObjAppendElement) the list of files or
directories which are successfully matched.
int mode (in) Mask consisting of one or more of R_OK, W_OK,
X_OK and F_OK. R_OK, W_OK and X_OK request
checking whether the file exists and has
read, write and execute permissions,
respectively. F_OK just requests checking for
the existence of the file.
Tcl_StatBuf *statPtr (out) The structure that contains the result of a
stat or lstat operation.
const char *sym1 (in) Name of a procedure to look up in the file's
symbol table
const char *sym2 (in) Name of a procedure to look up in the file's
symbol table
Tcl_PackageInitProc **proc1Ptr (out) Filled with the init function for this code.
Tcl_PackageInitProc **proc2Ptr (out) Filled with the safe-init function for this
code.
ClientData *clientDataPtr (out) Filled with the clientData value to pass to
this code's unload function when it is called.
Tcl_LoadHandle *loadHandlePtr (out) Filled with an abstract token representing the
loaded file.
Tcl_FSUnloadFileProc **unloadProcPtr (out) Filled with the function to use to unload this
piece of code.
Tcl_LoadHandle loadHandle (in) Handle to the loaded library to be unloaded.
utimbuf *tval (in) The access and modification times in this
structure are read and used to set those
values for a given file.
const char *modeString (in) Specifies how the file is to be accessed. May
have any of the values allowed for the mode
argument to the Tcl open command.
int permissions (in) POSIX-style permission flags such as 0644. If
a new file is created, these permissions will
be set on the created file.
int *lenPtr (out) If non-NULL, filled with the number of
elements in the split path.
Tcl_Obj *basePtr (in) The base path on to which to join the given
elements. May be NULL.
int objc (in) The number of elements in objv.
Tcl_Obj *const objv[] (in) The elements to join to the given base path.
Tcl_Obj *linkNamePtr (in) The name of the link to be created or read.
Tcl_Obj *toPtr (in) What the link called linkNamePtr should be
linked to, or NULL if the symbolic link
specified by linkNamePtr is to be read.
int linkAction (in) OR-ed combination of flags indicating what
kind of link should be created (will be
ignored if toPtr is NULL). Valid bits to set
are TCL_CREATE_SYMBOLIC_LINK and
TCL_CREATE_HARD_LINK. When both flags are set
and the underlying filesystem can do either,
symbolic links are preferred.
_________________________________________________________________
DESCRIPTION
There are several reasons for calling the Tcl_FS API functions (e.g. Tcl_FSAccess and
Tcl_FSStat) rather than calling system level functions like access and stat directly.
First, they will work cross-platform, so an extension which calls them should work
unmodified on Unix and Windows. Second, the Windows implementation of some of these
functions fixes some bugs in the system level calls. Third, these function calls deal with
any “Utf to platform-native” path conversions which may be required (and may cache the
results of such conversions for greater efficiency on subsequent calls). Fourth, and
perhaps most importantly, all of these functions are “virtual filesystem aware”. Any
virtual filesystem (VFS for short) which has been registered (through Tcl_FSRegister) may
reroute file access to alternative media or access methods. This means that all of these
functions (and therefore the corresponding file, glob, pwd, cd, open, etc. Tcl commands)
may be operate on “files” which are not native files in the native filesystem. This also
means that any Tcl extension which accesses the filesystem (FS for short) through this API
is automatically “virtual filesystem aware”. Of course, if an extension accesses the
native filesystem directly (through platform-specific APIs, for example), then Tcl cannot
intercept such calls.
If appropriate VFSes have been registered, the “files” may, to give two examples, be
remote (e.g. situated on a remote ftp server) or archived (e.g. lying inside a .zip
archive). Such registered filesystems provide a lookup table of functions to implement all
or some of the functionality listed here. Finally, the Tcl_FSStat and Tcl_FSLstat calls
abstract away from what the “struct stat” buffer is actually declared to be, allowing the
same code to be used both on systems with and systems without support for files larger
than 2GB in size.
The Tcl_FS API is Tcl_Obj-ified and may cache internal representations and other path-
related strings (e.g. the current working directory). One side-effect of this is that one
must not pass in values with a reference count of zero to any of these functions. If such
calls were handled, they might result in memory leaks (under some circumstances, the
filesystem code may wish to retain a reference to the passed in value, and so one must not
assume that after any of these calls return, the value still has a reference count of zero
- it may have been incremented) or in a direct segmentation fault (or other memory access
error) due to the value being freed part way through the complex value manipulation
required to ensure that the path is fully normalized and absolute for filesystem
determination. The practical lesson to learn from this is that
Tcl_Obj *path = Tcl_NewStringObj(...);
Tcl_FSWhatever(path);
Tcl_DecrRefCount(path);
is wrong, and may cause memory errors. The path must have its reference count incremented
before passing it in, or decrementing it. For this reason, values with a reference count
of zero are considered not to be valid filesystem paths and calling any Tcl_FS API
function with such a value will result in no action being taken.
FS API FUNCTIONS
Tcl_FSCopyFile attempts to copy the file given by srcPathPtr to the path name given by
destPathPtr. If the two paths given lie in the same filesystem (according to
Tcl_FSGetFileSystemForPath) then that filesystem's “copy file” function is called (if it
is non-NULL). Otherwise the function returns -1 and sets the errno global C variable to
the “EXDEV” POSIX error code (which signifies a “cross-domain link”).
Tcl_FSCopyDirectory attempts to copy the directory given by srcPathPtr to the path name
given by destPathPtr. If the two paths given lie in the same filesystem (according to
Tcl_FSGetFileSystemForPath) then that filesystem's “copy file” function is called (if it
is non-NULL). Otherwise the function returns -1 and sets the errno global C variable to
the “EXDEV” POSIX error code (which signifies a “cross-domain link”).
Tcl_FSCreateDirectory attempts to create the directory given by pathPtr by calling the
owning filesystem's “create directory” function.
Tcl_FSDeleteFile attempts to delete the file given by pathPtr by calling the owning
filesystem's “delete file” function.
Tcl_FSRemoveDirectory attempts to remove the directory given by pathPtr by calling the
owning filesystem's “remove directory” function.
Tcl_FSRenameFile attempts to rename the file or directory given by srcPathPtr to the path
name given by destPathPtr. If the two paths given lie in the same filesystem (according to
Tcl_FSGetFileSystemForPath) then that filesystem's “rename file” function is called (if it
is non-NULL). Otherwise the function returns -1 and sets the errno global C variable to
the “EXDEV” POSIX error code (which signifies a “cross-domain link”).
Tcl_FSListVolumes calls each filesystem which has a non-NULL “list volumes” function and
asks them to return their list of root volumes. It accumulates the return values in a list
which is returned to the caller (with a reference count of 0).
Tcl_FSEvalFileEx reads the file given by pathPtr using the encoding identified by
encodingName and evaluates its contents as a Tcl script. It returns the same information
as Tcl_EvalObjEx. If encodingName is NULL, the system encoding is used for reading the
file contents. If the file could not be read then a Tcl error is returned to describe why
the file could not be read. The eofchar for files is “\32” (^Z) for all platforms. If
you require a “^Z” in code for string comparison, you can use “\032” or “\u001a”, which
will be safely substituted by the Tcl interpreter into “^Z”. Tcl_FSEvalFile is a simpler
version of Tcl_FSEvalFileEx that always uses the system encoding when reading the file.
Tcl_FSLoadFile dynamically loads a binary code file into memory and returns the addresses
of two procedures within that file, if they are defined. The appropriate function for the
filesystem to which pathPtr belongs will be called. If that filesystem does not implement
this function (most virtual filesystems will not, because of OS limitations in dynamically
loading binary code), Tcl will attempt to copy the file to a temporary directory and load
that temporary file. Tcl_FSUnloadFile reverses the operation, asking for the library │
indicated by the loadHandle to be removed from the process. Note that, unlike with the │
unload command, this does not give the library any opportunity to clean up.
Both the above functions return a standard Tcl completion code. If an error occurs, an
error message is left in the interp's result.
The token provided via the variable indicated by loadHandlePtr may be used with │
Tcl_FindSymbol.
Tcl_FSMatchInDirectory is used by the globbing code to search a directory for all files
which match a given pattern. The appropriate function for the filesystem to which pathPtr
belongs will be called.
The return value is a standard Tcl result indicating whether an error occurred in
globbing. Error messages are placed in interp (unless interp is NULL, which is allowed),
but good results are placed in the resultPtr given.
Note that the glob code implements recursive patterns internally, so this function will
only ever be passed simple patterns, which can be matched using the logic of string match.
To handle recursion, Tcl will call this function frequently asking only for directories to
be returned. A special case of being called with a NULL pattern indicates that the path
needs to be checked only for the correct type.
Tcl_FSLink replaces the library version of readlink, and extends it to support the
creation of links. The appropriate function for the filesystem to which linkNamePtr
belongs will be called.
If the toPtr is NULL, a “read link” action is performed. The result is a Tcl_Obj
specifying the contents of the symbolic link given by linkNamePtr, or NULL if the link
could not be read. The result is owned by the caller, which should call Tcl_DecrRefCount
when the result is no longer needed. If the toPtr is not NULL, Tcl should create a link of
one of the types passed in in the linkAction flag. This flag is an ORed combination of
TCL_CREATE_SYMBOLIC_LINK and TCL_CREATE_HARD_LINK. Where a choice exists (i.e. more than
one flag is passed in), the Tcl convention is to prefer symbolic links. When a link is
successfully created, the return value should be toPtr (which is therefore already owned
by the caller). If unsuccessful, NULL is returned.
Tcl_FSLstat fills the Tcl_StatBuf structure statPtr with information about the specified
file. You do not need any access rights to the file to get this information but you need
search rights to all directories named in the path leading to the file. The Tcl_StatBuf
structure includes info regarding device, inode (always 0 on Windows), privilege mode,
nlink (always 1 on Windows), user id (always 0 on Windows), group id (always 0 on
Windows), rdev (same as device on Windows), size, last access time, last modification
time, and last metadata change time. See PORTABLE STAT RESULT API for a description of
how to write portable code to allocate and access the Tcl_StatBuf structure.
If path exists, Tcl_FSLstat returns 0 and the stat structure is filled with data.
Otherwise, -1 is returned, and no stat info is given.
Tcl_FSUtime replaces the library version of utime.
This returns 0 on success and -1 on error (as per the utime documentation). If successful,
the function will update the “atime” and “mtime” values of the file given.
Tcl_FSFileAttrsGet implements read access for the hookable file attributes subcommand. The
appropriate function for the filesystem to which pathPtr belongs will be called.
If the result is TCL_OK, then a value was placed in objPtrRef, which will only be
temporarily valid (unless Tcl_IncrRefCount is called).
Tcl_FSFileAttrsSet implements write access for the hookable file attributes subcommand.
The appropriate function for the filesystem to which pathPtr belongs will be called.
Tcl_FSFileAttrStrings implements part of the hookable file attributes subcommand. The
appropriate function for the filesystem to which pathPtr belongs will be called.
The called procedure may either return an array of strings, or may instead return NULL and
place a Tcl list into the given objPtrRef. Tcl will take that list and first increment its
reference count before using it. On completion of that use, Tcl will decrement its
reference count. Hence if the list should be disposed of by Tcl when done, it should have
a reference count of zero, and if the list should not be disposed of, the filesystem
should ensure it retains a reference count to the value.
Tcl_FSAccess checks whether the process would be allowed to read, write or test for
existence of the file (or other filesystem object) whose name is pathname. If pathname is
a symbolic link on Unix, then permissions of the file referred by this symbolic link are
tested.
On success (all requested permissions granted), zero is returned. On error (at least one
bit in mode asked for a permission that is denied, or some other error occurred), -1 is
returned.
Tcl_FSStat fills the Tcl_StatBuf structure statPtr with information about the specified
file. You do not need any access rights to the file to get this information but you need
search rights to all directories named in the path leading to the file. The Tcl_StatBuf
structure includes info regarding device, inode (always 0 on Windows), privilege mode,
nlink (always 1 on Windows), user id (always 0 on Windows), group id (always 0 on
Windows), rdev (same as device on Windows), size, last access time, last modification
time, and last metadata change time. See PORTABLE STAT RESULT API for a description of
how to write portable code to allocate and access the Tcl_StatBuf structure.
If path exists, Tcl_FSStat returns 0 and the stat structure is filled with data.
Otherwise, -1 is returned, and no stat info is given.
Tcl_FSOpenFileChannel opens a file specified by pathPtr and returns a channel handle that
can be used to perform input and output on the file. This API is modeled after the fopen
procedure of the Unix standard I/O library. The syntax and meaning of all arguments is
similar to those given in the Tcl open command when opening a file. If an error occurs
while opening the channel, Tcl_FSOpenFileChannel returns NULL and records a POSIX error
code that can be retrieved with Tcl_GetErrno. In addition, if interp is non-NULL,
Tcl_FSOpenFileChannel leaves an error message in interp's result after any error.
The newly created channel is not registered in the supplied interpreter; to register it,
use Tcl_RegisterChannel. If one of the standard channels, stdin, stdout or stderr was
previously closed, the act of creating the new channel also assigns it as a replacement
for the standard channel.
Tcl_FSGetCwd replaces the library version of getcwd.
It returns the Tcl library's current working directory. This may be different to the
native platform's working directory, which happens when the current working directory is
not in the native filesystem.
The result is a pointer to a Tcl_Obj specifying the current directory, or NULL if the
current directory could not be determined. If NULL is returned, an error message is left
in the interp's result.
The result already has its reference count incremented for the caller. When it is no
longer needed, that reference count should be decremented. This is needed for thread-
safety purposes, to allow multiple threads to access this and related functions, while
ensuring the results are always valid.
Tcl_FSChdir replaces the library version of chdir. The path is normalized and then passed
to the filesystem which claims it. If that filesystem does not implement this function,
Tcl will fallback to a combination of stat and access to check whether the directory
exists and has appropriate permissions.
For results, see chdir documentation. If successful, we keep a record of the successful
path in cwdPathPtr for subsequent calls to Tcl_FSGetCwd.
Tcl_FSPathSeparator returns the separator character to be used for most specific element
of the path specified by pathPtr (i.e. the last part of the path).
The separator is returned as a Tcl_Obj containing a string of length 1. If the path is
invalid, NULL is returned.
Tcl_FSJoinPath takes the given Tcl_Obj, which must be a valid list (which is allowed to
have a reference count of zero), and returns the path value given by considering the first
elements elements as valid path segments (each path segment may be a complete path, a
partial path or just a single possible directory or file name). If any path segment is
actually an absolute path, then all prior path segments are discarded. If elements is
less than 0, we use the entire list.
It is possible that the returned value is actually an element of the given list, so the
caller should be careful to increment the reference count of the result before freeing the
list.
The returned value, typically with a reference count of zero (but it could be shared under
some conditions), contains the joined path. The caller must add a reference count to the
value before using it. In particular, the returned value could be an element of the given
list, so freeing the list might free the value prematurely if no reference count has been
taken. If the number of elements is zero, then the returned value will be an empty-string
Tcl_Obj.
Tcl_FSSplitPath takes the given Tcl_Obj, which should be a valid path, and returns a Tcl
list value containing each segment of that path as an element. It returns a list value
with a reference count of zero. If the passed in lenPtr is non-NULL, the variable it
points to will be updated to contain the number of elements in the returned list.
Tcl_FSEqualPaths tests whether the two paths given represent the same filesystem object.
It returns 1 if the paths are equal, and 0 if they are different. If either path is NULL,
0 is always returned.
Tcl_FSGetNormalizedPath this important function attempts to extract from the given Tcl_Obj
a unique normalized path representation, whose string value can be used as a unique
identifier for the file.
It returns the normalized path value, owned by Tcl, or NULL if the path was invalid or
could otherwise not be successfully converted. Extraction of absolute, normalized paths
is very efficient (because the filesystem operates on these representations internally),
although the result when the filesystem contains numerous symbolic links may not be the
most user-friendly version of a path. The return value is owned by Tcl and has a lifetime
equivalent to that of the pathPtr passed in (unless that is a relative path, in which case
the normalized path value may be freed any time the cwd changes) - the caller can of
course increment the reference count if it wishes to maintain a copy for longer.
Tcl_FSJoinToPath takes the given value, which should usually be a valid path or NULL, and
joins onto it the array of paths segments given.
Returns a value, typically with reference count of zero (but it could be shared under some
conditions), containing the joined path. The caller must add a reference count to the
value before using it. If any of the values passed into this function (pathPtr or path
elements) have a reference count of zero, they will be freed when this function returns.
Tcl_FSConvertToPathType tries to convert the given Tcl_Obj to a valid Tcl path type,
taking account of the fact that the cwd may have changed even if this value is already
supposedly of the correct type. The filename may begin with “~” (to indicate current
user's home directory) or “~<user>” (to indicate any user's home directory).
If the conversion succeeds (i.e. the value is a valid path in one of the current
filesystems), then TCL_OK is returned. Otherwise TCL_ERROR is returned, and an error
message may be left in the interpreter.
Tcl_FSGetInternalRep extracts the internal representation of a given path value, in the
given filesystem. If the path value belongs to a different filesystem, we return NULL. If
the internal representation is currently NULL, we attempt to generate it, by calling the
filesystem's Tcl_FSCreateInternalRepProc.
Returns NULL or a valid internal path representation. This internal representation is
cached, so that repeated calls to this function will not require additional conversions.
Tcl_FSGetTranslatedPath attempts to extract the translated path from the given Tcl_Obj.
If the translation succeeds (i.e. the value is a valid path), then it is returned.
Otherwise NULL will be returned, and an error message may be left in the interpreter. A
“translated” path is one which contains no “~” or “~user” sequences (these have been
expanded to their current representation in the filesystem). The value returned is owned
by the caller, which must store it or call Tcl_DecrRefCount to ensure memory is freed.
This function is of little practical use, and Tcl_FSGetNormalizedPath or
Tcl_FSGetNativePath are usually better functions to use for most purposes.
Tcl_FSGetTranslatedStringPath does the same as Tcl_FSGetTranslatedPath, but returns a
character string or NULL. The string returned is dynamically allocated and owned by the
caller, which must store it or call ckfree to ensure it is freed. Again,
Tcl_FSGetNormalizedPath or Tcl_FSGetNativePath are usually better functions to use for
most purposes.
Tcl_FSNewNativePath performs something like the reverse of the usual obj->path->nativerep
conversions. If some code retrieves a path in native form (from, e.g. readlink or a native
dialog), and that path is to be used at the Tcl level, then calling this function is an
efficient way of creating the appropriate path value type.
The resulting value is a pure “path” value, which will only receive a UTF-8 string
representation if that is required by some Tcl code.
Tcl_FSGetNativePath is for use by the Win/Unix native filesystems, so that they can easily
retrieve the native (char* or TCHAR*) representation of a path. This function is a
convenience wrapper around Tcl_FSGetInternalRep. It may be desirable in the future to have
non-string-based native representations (for example, on MacOSX, a representation using a
fileSpec of FSRef structure would probably be more efficient). On Windows a full Unicode
representation would allow for paths of unlimited length. Currently the representation is
simply a character string which may contain either the relative path or a complete,
absolute normalized path in the native encoding (complex conditions dictate which of these
will be provided, so neither can be relied upon, unless the path is known to be absolute).
If you need a native path which must be absolute, then you should ask for the native
version of a normalized path. If for some reason a non-absolute, non-normalized version of
the path is needed, that must be constructed separately (e.g. using
Tcl_FSGetTranslatedPath).
The native representation is cached so that repeated calls to this function will not
require additional conversions. The return value is owned by Tcl and has a lifetime
equivalent to that of the pathPtr passed in (unless that is a relative path, in which case
the native representation may be freed any time the cwd changes).
Tcl_FSFileSystemInfo returns a list of two elements. The first element is the name of the
filesystem (e.g. “native”, “vfs”, “zip”, or “prowrap”, perhaps), and the second is the
particular type of the given path within that filesystem (which is filesystem dependent).
The second element may be empty if the filesystem does not provide a further
categorization of files.
A valid list value is returned, unless the path value is not recognized, when NULL will be
returned.
Tcl_FSGetFileSystemForPath returns a pointer to the Tcl_Filesystem which accepts this path
as valid.
If no filesystem will accept the path, NULL is returned.
Tcl_FSGetPathType determines whether the given path is relative to the current directory,
relative to the current volume, or absolute.
It returns one of TCL_PATH_ABSOLUTE, TCL_PATH_RELATIVE, or TCL_PATH_VOLUME_RELATIVE
PORTABLE STAT RESULT API
Tcl_AllocStatBuf allocates a Tcl_StatBuf on the system heap (which may be deallocated by
being passed to ckfree). This allows extensions to invoke Tcl_FSStat and Tcl_FSLstat
without being dependent on the size of the buffer. That in turn depends on the flags used
to build Tcl.
The portable fields of a Tcl_StatBuf may be read using the following functions, each of │
which returns the value of the corresponding field listed in the table below. Note that on │
some platforms there may be other fields in the Tcl_StatBuf as it is an alias for a │
suitable system structure, but only the portable ones are made available here. See your │
system documentation for a full description of these fields. Access │
Function Field │
Tcl_GetFSDeviceFromStat st_dev │
Tcl_GetFSInodeFromStat st_ino │
Tcl_GetModeFromStat st_mode │
Tcl_GetLinkCountFromStat st_nlink │
Tcl_GetUserIdFromStat st_uid │
Tcl_GetGroupIdFromStat st_gid │
Tcl_GetDeviceTypeFromStat st_rdev │
Tcl_GetAccessTimeFromStat st_atime │
Tcl_GetModificationTimeFromStat st_mtime │
Tcl_GetChangeTimeFromStat st_ctime │
Tcl_GetSizeFromStat st_size │
Tcl_GetBlocksFromStat st_blocks │
Tcl_GetBlockSizeFromStat st_blksize
THE VIRTUAL FILESYSTEM API
A filesystem provides a Tcl_Filesystem structure that contains pointers to functions that
implement the various operations on a filesystem; these operations are invoked as needed
by the generic layer, which generally occurs through the functions listed above.
The Tcl_Filesystem structures are manipulated using the following methods.
Tcl_FSRegister takes a pointer to a filesystem structure and an optional piece of data to
associated with that filesystem. On calling this function, Tcl will attach the filesystem
to the list of known filesystems, and it will become fully functional immediately. Tcl
does not check if the same filesystem is registered multiple times (and in general that is
not a good thing to do). TCL_OK will be returned.
Tcl_FSUnregister removes the given filesystem structure from the list of known
filesystems, if it is known, and returns TCL_OK. If the filesystem is not currently
registered, TCL_ERROR is returned.
Tcl_FSData will return the ClientData associated with the given filesystem, if that
filesystem is registered. Otherwise it will return NULL.
Tcl_FSMountsChanged is used to inform the Tcl's core that the set of mount points for the
given (already registered) filesystem have changed, and that cached file representations
may therefore no longer be correct.
THE TCL_FILESYSTEM STRUCTURE
The Tcl_Filesystem structure contains the following fields:
typedef struct Tcl_Filesystem {
const char *typeName;
int structureLength;
Tcl_FSVersion version;
Tcl_FSPathInFilesystemProc *pathInFilesystemProc;
Tcl_FSDupInternalRepProc *dupInternalRepProc;
Tcl_FSFreeInternalRepProc *freeInternalRepProc;
Tcl_FSInternalToNormalizedProc *internalToNormalizedProc;
Tcl_FSCreateInternalRepProc *createInternalRepProc;
Tcl_FSNormalizePathProc *normalizePathProc;
Tcl_FSFilesystemPathTypeProc *filesystemPathTypeProc;
Tcl_FSFilesystemSeparatorProc *filesystemSeparatorProc;
Tcl_FSStatProc *statProc;
Tcl_FSAccessProc *accessProc;
Tcl_FSOpenFileChannelProc *openFileChannelProc;
Tcl_FSMatchInDirectoryProc *matchInDirectoryProc;
Tcl_FSUtimeProc *utimeProc;
Tcl_FSLinkProc *linkProc;
Tcl_FSListVolumesProc *listVolumesProc;
Tcl_FSFileAttrStringsProc *fileAttrStringsProc;
Tcl_FSFileAttrsGetProc *fileAttrsGetProc;
Tcl_FSFileAttrsSetProc *fileAttrsSetProc;
Tcl_FSCreateDirectoryProc *createDirectoryProc;
Tcl_FSRemoveDirectoryProc *removeDirectoryProc;
Tcl_FSDeleteFileProc *deleteFileProc;
Tcl_FSCopyFileProc *copyFileProc;
Tcl_FSRenameFileProc *renameFileProc;
Tcl_FSCopyDirectoryProc *copyDirectoryProc;
Tcl_FSLstatProc *lstatProc;
Tcl_FSLoadFileProc *loadFileProc;
Tcl_FSGetCwdProc *getCwdProc;
Tcl_FSChdirProc *chdirProc;
} Tcl_Filesystem;
Except for the first three fields in this structure which contain simple data elements,
all entries contain addresses of functions called by the generic filesystem layer to
perform the complete range of filesystem related actions.
The many functions in this structure are broken down into three categories: infrastructure
functions (almost all of which must be implemented), operational functions (which must be
implemented if a complete filesystem is provided), and efficiency functions (which need
only be implemented if they can be done so efficiently, or if they have side-effects which
are required by the filesystem; Tcl has less efficient emulations it can fall back on). It
is important to note that, in the current version of Tcl, most of these fallbacks are only
used to handle commands initiated in Tcl, not in C. What this means is, that if a file
rename command is issued in Tcl, and the relevant filesystem(s) do not implement their
Tcl_FSRenameFileProc, Tcl's core will instead fallback on a combination of other
filesystem functions (it will use Tcl_FSCopyFileProc followed by Tcl_FSDeleteFileProc, and
if Tcl_FSCopyFileProc is not implemented there is a further fallback). However, if a
Tcl_FSRenameFileProc command is issued at the C level, no such fallbacks occur. This is
true except for the last four entries in the filesystem table (lstat, load, getcwd and
chdir) for which fallbacks do in fact occur at the C level.
Any functions which take path names in Tcl_Obj form take those names in UTF-8 form. The
filesystem infrastructure API is designed to support efficient, cached conversion of these
UTF-8 paths to other native representations.
EXAMPLE FILESYSTEM DEFINITION
Here is the filesystem lookup table used by the “vfs” extension which allows filesystem
actions to be implemented in Tcl.
static Tcl_Filesystem vfsFilesystem = {
"tclvfs",
sizeof(Tcl_Filesystem),
TCL_FILESYSTEM_VERSION_1,
&VfsPathInFilesystem,
&VfsDupInternalRep,
&VfsFreeInternalRep,
/* No internal to normalized, since we don't create
* any pure 'internal' Tcl_Obj path representations */
NULL,
/* No create native rep function, since we don't use
* it and don't choose to support uses of
* Tcl_FSNewNativePath */
NULL,
/* Normalize path isn't needed - we assume paths only
* have one representation */
NULL,
&VfsFilesystemPathType,
&VfsFilesystemSeparator,
&VfsStat,
&VfsAccess,
&VfsOpenFileChannel,
&VfsMatchInDirectory,
&VfsUtime,
/* We choose not to support symbolic links inside our
* VFS's */
NULL,
&VfsListVolumes,
&VfsFileAttrStrings,
&VfsFileAttrsGet,
&VfsFileAttrsSet,
&VfsCreateDirectory,
&VfsRemoveDirectory,
&VfsDeleteFile,
/* No copy file; use the core fallback mechanism */
NULL,
/* No rename file; use the core fallback mechanism */
NULL,
/* No copy directory; use the core fallback mechanism */
NULL,
/* Core will use stat for lstat */
NULL,
/* No load; use the core fallback mechanism */
NULL,
/* We don't need a getcwd or chdir; the core's own
* internal value is suitable */
NULL,
NULL
};
FILESYSTEM INFRASTRUCTURE
These fields contain basic information about the filesystem structure and addresses of
functions which are used to associate a particular filesystem with a file path, and deal
with the internal handling of path representations, for example copying and freeing such
representations.
TYPENAME
The typeName field contains a null-terminated string that identifies the type of the
filesystem implemented, e.g. “native”, “zip” or “vfs”.
STRUCTURE LENGTH
The structureLength field is generally implemented as sizeof(Tcl_Filesystem), and is there
to allow easier binary backwards compatibility if the size of the structure changes in a
future Tcl release.
VERSION
The version field should be set to TCL_FILESYSTEM_VERSION_1.
PATHINFILESYSTEMPROC
The pathInFilesystemProc field contains the address of a function which is called to
determine whether a given path value belongs to this filesystem or not. Tcl will only call
the rest of the filesystem functions with a path for which this function has returned
TCL_OK. If the path does not belong, -1 should be returned (the behavior of Tcl for any
other return value is not defined). If TCL_OK is returned, then the optional clientDataPtr
output parameter can be used to return an internal (filesystem specific) representation of
the path, which will be cached inside the path value, and may be retrieved efficiently by
the other filesystem functions. Tcl will simultaneously cache the fact that this path
belongs to this filesystem. Such caches are invalidated when filesystem structures are
added or removed from Tcl's internal list of known filesystems.
typedef int Tcl_FSPathInFilesystemProc(
Tcl_Obj *pathPtr,
ClientData *clientDataPtr);
DUPINTERNALREPPROC
This function makes a copy of a path's internal representation, and is called when Tcl
needs to duplicate a path value. If NULL, Tcl will simply not copy the internal
representation, which may then need to be regenerated later.
typedef ClientData Tcl_FSDupInternalRepProc(
ClientData clientData);
FREEINTERNALREPPROC
Free the internal representation. This must be implemented if internal representations
need freeing (i.e. if some memory is allocated when an internal representation is
generated), but may otherwise be NULL.
typedef void Tcl_FSFreeInternalRepProc(
ClientData clientData);
INTERNALTONORMALIZEDPROC
Function to convert internal representation to a normalized path. Only required if the
filesystem creates pure path values with no string/path representation. The return value
is a Tcl value whose string representation is the normalized path.
typedef Tcl_Obj *Tcl_FSInternalToNormalizedProc(
ClientData clientData);
CREATEINTERNALREPPROC
Function to take a path value, and calculate an internal representation for it, and store
that native representation in the value. May be NULL if paths have no internal
representation, or if the Tcl_FSPathInFilesystemProc for this filesystem always
immediately creates an internal representation for paths it accepts.
typedef ClientData Tcl_FSCreateInternalRepProc(
Tcl_Obj *pathPtr);
NORMALIZEPATHPROC
Function to normalize a path. Should be implemented for all filesystems which can have
multiple string representations for the same path value. In Tcl, every “path” must have a
single unique “normalized” string representation. Depending on the filesystem, there may
be more than one unnormalized string representation which refers to that path (e.g. a
relative path, a path with different character case if the filesystem is case insensitive,
a path contain a reference to a home directory such as “~”, a path containing symbolic
links, etc). If the very last component in the path is a symbolic link, it should not be
converted into the value it points to (but its case or other aspects should be made
unique). All other path components should be converted from symbolic links. This one
exception is required to agree with Tcl's semantics with file delete, file rename, file
copy operating on symbolic links. This function may be called with nextCheckpoint either
at the beginning of the path (i.e. zero), at the end of the path, or at any intermediate
file separator in the path. It will never point to any other arbitrary position in the
path. In the last of the three valid cases, the implementation can assume that the path up
to and including the file separator is known and normalized.
typedef int Tcl_FSNormalizePathProc(
Tcl_Interp *interp,
Tcl_Obj *pathPtr,
int nextCheckpoint);
FILESYSTEM OPERATIONS
The fields in this section of the structure contain addresses of functions which are
called to carry out the basic filesystem operations. A filesystem which expects to be used
with the complete standard Tcl command set must implement all of these. If some of them
are not implemented, then certain Tcl commands may fail when operating on paths within
that filesystem. However, in some instances this may be desirable (for example, a read-
only filesystem should not implement the last four functions, and a filesystem which does
not support symbolic links need not implement the readlink function, etc. The Tcl core
expects filesystems to behave in this way).
FILESYSTEMPATHTYPEPROC
Function to determine the type of a path in this filesystem. May be NULL, in which case no
type information will be available to users of the filesystem. The “type” is used only for
informational purposes, and should be returned as the string representation of the Tcl_Obj
which is returned. A typical return value might be “networked”, “zip” or “ftp”. The
Tcl_Obj result is owned by the filesystem and so Tcl will increment the reference count of
that value if it wishes to retain a reference to it.
typedef Tcl_Obj *Tcl_FSFilesystemPathTypeProc(
Tcl_Obj *pathPtr);
FILESYSTEMSEPARATORPROC
Function to return the separator character(s) for this filesystem. This need only be
implemented if the filesystem wishes to use a different separator than the standard string
“/”. Amongst other uses, it is returned by the file separator command. The return value
should be a value with reference count of zero.
typedef Tcl_Obj *Tcl_FSFilesystemSeparatorProc(
Tcl_Obj *pathPtr);
STATPROC
Function to process a Tcl_FSStat call. Must be implemented for any reasonable filesystem,
since many Tcl level commands depend crucially upon it (e.g. file atime, file isdirectory,
file size, glob).
typedef int Tcl_FSStatProc(
Tcl_Obj *pathPtr,
Tcl_StatBuf *statPtr);
The Tcl_FSStatProc fills the stat structure statPtr with information about the specified
file. You do not need any access rights to the file to get this information but you need
search rights to all directories named in the path leading to the file. The stat structure
includes info regarding device, inode (always 0 on Windows), privilege mode, nlink (always
1 on Windows), user id (always 0 on Windows), group id (always 0 on Windows), rdev (same
as device on Windows), size, last access time, last modification time, and last metadata
change time.
If the file represented by pathPtr exists, the Tcl_FSStatProc returns 0 and the stat
structure is filled with data. Otherwise, -1 is returned, and no stat info is given.
ACCESSPROC
Function to process a Tcl_FSAccess call. Must be implemented for any reasonable
filesystem, since many Tcl level commands depend crucially upon it (e.g. file exists, file
readable).
typedef int Tcl_FSAccessProc(
Tcl_Obj *pathPtr,
int mode);
The Tcl_FSAccessProc checks whether the process would be allowed to read, write or test
for existence of the file (or other filesystem object) whose name is in pathPtr. If the
pathname refers to a symbolic link, then the permissions of the file referred by this
symbolic link should be tested.
On success (all requested permissions granted), zero is returned. On error (at least one
bit in mode asked for a permission that is denied, or some other error occurred), -1 is
returned.
OPENFILECHANNELPROC
Function to process a Tcl_FSOpenFileChannel call. Must be implemented for any reasonable
filesystem, since any operations which require open or accessing a file's contents will
use it (e.g. open, encoding, and many Tk commands).
typedef Tcl_Channel Tcl_FSOpenFileChannelProc(
Tcl_Interp *interp,
Tcl_Obj *pathPtr,
int mode,
int permissions);
The Tcl_FSOpenFileChannelProc opens a file specified by pathPtr and returns a channel
handle that can be used to perform input and output on the file. This API is modeled after
the fopen procedure of the Unix standard I/O library. The syntax and meaning of all
arguments is similar to those given in the Tcl open command when opening a file, where the
mode argument is a combination of the POSIX flags O_RDONLY, O_WRONLY, etc. If an error
occurs while opening the channel, the Tcl_FSOpenFileChannelProc returns NULL and records a
POSIX error code that can be retrieved with Tcl_GetErrno. In addition, if interp is non-
NULL, the Tcl_FSOpenFileChannelProc leaves an error message in interp's result after any
error.
The newly created channel must not be registered in the supplied interpreter by a
Tcl_FSOpenFileChannelProc; that task is up to the caller of Tcl_FSOpenFileChannel (if
necessary). If one of the standard channels, stdin, stdout or stderr was previously
closed, the act of creating the new channel also assigns it as a replacement for the
standard channel.
MATCHINDIRECTORYPROC
Function to process a Tcl_FSMatchInDirectory call. If not implemented, then glob and
recursive copy functionality will be lacking in the filesystem (and this may impact
commands like encoding names which use glob functionality internally).
typedef int Tcl_FSMatchInDirectoryProc(
Tcl_Interp *interp,
Tcl_Obj *resultPtr,
Tcl_Obj *pathPtr,
const char *pattern,
Tcl_GlobTypeData *types);
The function should return all files or directories (or other filesystem objects) which
match the given pattern and accord with the types specification given. There are two ways
in which this function may be called. If pattern is NULL, then pathPtr is a full path
specification of a single file or directory which should be checked for existence and
correct type. Otherwise, pathPtr is a directory, the contents of which the function should
search for files or directories which have the correct type. In either case, pathPtr can
be assumed to be both non-NULL and non-empty. It is not currently documented whether
pathPtr will have a file separator at its end of not, so code should be flexible to both
possibilities.
The return value is a standard Tcl result indicating whether an error occurred in the
matching process. Error messages are placed in interp, unless interp in NULL in which case
no error message need be generated; on a TCL_OK result, results should be added to the
resultPtr value given (which can be assumed to be a valid unshared Tcl list). The matches
added to resultPtr should include any path prefix given in pathPtr (this usually means
they will be absolute path specifications). Note that if no matches are found, that
simply leads to an empty result; errors are only signaled for actual file or filesystem
problems which may occur during the matching process.
The Tcl_GlobTypeData structure passed in the types parameter contains the following
fields:
typedef struct Tcl_GlobTypeData {
/* Corresponds to bcdpfls as in 'find -t' */
int type;
/* Corresponds to file permissions */
int perm;
/* Acceptable mac type */
Tcl_Obj *macType;
/* Acceptable mac creator */
Tcl_Obj *macCreator;
} Tcl_GlobTypeData;
There are two specific cases which it is important to handle correctly, both when types is
non-NULL. The two cases are when types->types & TCL_GLOB_TYPE_DIR or types->types &
TCL_GLOB_TYPE_MOUNT are true (and in particular when the other flags are false). In the
first of these cases, the function must list the contained directories. Tcl uses this to
implement recursive globbing, so it is critical that filesystems implement directory
matching correctly. In the second of these cases, with TCL_GLOB_TYPE_MOUNT, the filesystem
must list the mount points which lie within the given pathPtr (and in this case, pathPtr
need not lie within the same filesystem - different to all other cases in which this
function is called). Support for this is critical if Tcl is to have seamless transitions
between from one filesystem to another.
UTIMEPROC
Function to process a Tcl_FSUtime call. Required to allow setting (not reading) of times
with file mtime, file atime and the open-r/open-w/fcopy implementation of file copy.
typedef int Tcl_FSUtimeProc(
Tcl_Obj *pathPtr,
struct utimbuf *tval);
The access and modification times of the file specified by pathPtr should be changed to
the values given in the tval structure.
The return value should be 0 on success and -1 on an error, as with the system utime.
LINKPROC
Function to process a Tcl_FSLink call. Should be implemented only if the filesystem
supports links, and may otherwise be NULL.
typedef Tcl_Obj *Tcl_FSLinkProc(
Tcl_Obj *linkNamePtr,
Tcl_Obj *toPtr,
int linkAction);
If toPtr is NULL, the function is being asked to read the contents of a link. The result
is a Tcl_Obj specifying the contents of the link given by linkNamePtr, or NULL if the link
could not be read. The result is owned by the caller (and should therefore have its ref
count incremented before being returned). Any callers should call Tcl_DecrRefCount on this
result when it is no longer needed. If toPtr is not NULL, the function should attempt to
create a link. The result in this case should be toPtr if the link was successful and
NULL otherwise. In this case the result is not owned by the caller (i.e. no reference
count manipulations on either end are needed). See the documentation for Tcl_FSLink for
the correct interpretation of the linkAction flags.
LISTVOLUMESPROC
Function to list any filesystem volumes added by this filesystem. Should be implemented
only if the filesystem adds volumes at the head of the filesystem, so that they can be
returned by file volumes.
typedef Tcl_Obj *Tcl_FSListVolumesProc(void);
The result should be a list of volumes added by this filesystem, or NULL (or an empty
list) if no volumes are provided. The result value is considered to be owned by the
filesystem (not by Tcl's core), but should be given a reference count for Tcl. Tcl will
use the contents of the list and then decrement that reference count. This allows
filesystems to choose whether they actually want to retain a “master list” of volumes or
not (if not, they generate the list on the fly and pass it to Tcl with a reference count
of 1 and then forget about the list, if yes, then they simply increment the reference
count of their master list and pass it to Tcl which will copy the contents and then
decrement the count back to where it was).
Therefore, Tcl considers return values from this proc to be read-only.
FILEATTRSTRINGSPROC
Function to list all attribute strings which are valid for this filesystem. If not
implemented the filesystem will not support the file attributes command. This allows
arbitrary additional information to be attached to files in the filesystem. If it is not
implemented, there is no need to implement the get and set methods.
typedef const char *const *Tcl_FSFileAttrStringsProc(
Tcl_Obj *pathPtr,
Tcl_Obj **objPtrRef);
The called function may either return an array of strings, or may instead return NULL and
place a Tcl list into the given objPtrRef. Tcl will take that list and first increment its
reference count before using it. On completion of that use, Tcl will decrement its
reference count. Hence if the list should be disposed of by Tcl when done, it should have
a reference count of zero, and if the list should not be disposed of, the filesystem
should ensure it returns a value with a reference count of at least one.
FILEATTRSGETPROC
Function to process a Tcl_FSFileAttrsGet call, used by file attributes.
typedef int Tcl_FSFileAttrsGetProc(
Tcl_Interp *interp,
int index,
Tcl_Obj *pathPtr,
Tcl_Obj **objPtrRef);
Returns a standard Tcl return code. The attribute value retrieved, which corresponds to
the index'th element in the list returned by the Tcl_FSFileAttrStringsProc, is a Tcl_Obj
placed in objPtrRef (if TCL_OK was returned) and is likely to have a reference count of
zero. Either way we must either store it somewhere (e.g. the Tcl result), or Incr/Decr its
reference count to ensure it is properly freed.
FILEATTRSSETPROC
Function to process a Tcl_FSFileAttrsSet call, used by file attributes. If the filesystem
is read-only, there is no need to implement this.
typedef int Tcl_FSFileAttrsSetProc(
Tcl_Interp *interp,
int index,
Tcl_Obj *pathPtr,
Tcl_Obj *objPtr);
The attribute value of the index'th element in the list returned by the
Tcl_FSFileAttrStringsProc should be set to the objPtr given.
CREATEDIRECTORYPROC
Function to process a Tcl_FSCreateDirectory call. Should be implemented unless the FS is
read-only.
typedef int Tcl_FSCreateDirectoryProc(
Tcl_Obj *pathPtr);
The return value is a standard Tcl result indicating whether an error occurred in the
process. If successful, a new directory should have been added to the filesystem in the
location specified by pathPtr.
REMOVEDIRECTORYPROC
Function to process a Tcl_FSRemoveDirectory call. Should be implemented unless the FS is
read-only.
typedef int Tcl_FSRemoveDirectoryProc(
Tcl_Obj *pathPtr,
int recursive,
Tcl_Obj **errorPtr);
The return value is a standard Tcl result indicating whether an error occurred in the
process. If successful, the directory specified by pathPtr should have been removed from
the filesystem. If the recursive flag is given, then a non-empty directory should be
deleted without error. If this flag is not given, then and the directory is non-empty a
POSIX “EEXIST” error should be signaled. If an error does occur, the name of the file or
directory which caused the error should be placed in errorPtr.
DELETEFILEPROC
Function to process a Tcl_FSDeleteFile call. Should be implemented unless the FS is read-
only.
typedef int Tcl_FSDeleteFileProc(
Tcl_Obj *pathPtr);
The return value is a standard Tcl result indicating whether an error occurred in the
process. If successful, the file specified by pathPtr should have been removed from the
filesystem. Note that, if the filesystem supports symbolic links, Tcl will always call
this function and not Tcl_FSRemoveDirectoryProc when needed to delete them (even if they
are symbolic links to directories).
FILESYSTEM EFFICIENCY
These functions need not be implemented for a particular filesystem because the core has a
fallback implementation available. See each individual description for the consequences of
leaving the field NULL.
LSTATPROC
Function to process a Tcl_FSLstat call. If not implemented, Tcl will attempt to use the
statProc defined above instead. Therefore it need only be implemented if a filesystem can
differentiate between stat and lstat calls.
typedef int Tcl_FSLstatProc(
Tcl_Obj *pathPtr,
Tcl_StatBuf *statPtr);
The behavior of this function is very similar to that of the Tcl_FSStatProc defined above,
except that if it is applied to a symbolic link, it returns information about the link,
not about the target file.
COPYFILEPROC
Function to process a Tcl_FSCopyFile call. If not implemented Tcl will fall back on open-
r, open-w and fcopy as a copying mechanism. Therefore it need only be implemented if the
filesystem can perform that action more efficiently.
typedef int Tcl_FSCopyFileProc(
Tcl_Obj *srcPathPtr,
Tcl_Obj *destPathPtr);
The return value is a standard Tcl result indicating whether an error occurred in the
copying process. Note that, destPathPtr is the name of the file which should become the
copy of srcPathPtr. It is never the name of a directory into which srcPathPtr could be
copied (i.e. the function is much simpler than the Tcl level file copy subcommand). Note
that, if the filesystem supports symbolic links, Tcl will always call this function and
not copyDirectoryProc when needed to copy them (even if they are symbolic links to
directories). Finally, if the filesystem determines it cannot support the file copy
action, calling Tcl_SetErrno(EXDEV) and returning a non-TCL_OK result will tell Tcl to use
its standard fallback mechanisms.
RENAMEFILEPROC
Function to process a Tcl_FSRenameFile call. If not implemented, Tcl will fall back on a
copy and delete mechanism. Therefore it need only be implemented if the filesystem can
perform that action more efficiently.
typedef int Tcl_FSRenameFileProc(
Tcl_Obj *srcPathPtr,
Tcl_Obj *destPathPtr);
The return value is a standard Tcl result indicating whether an error occurred in the
renaming process. If the filesystem determines it cannot support the file rename action,
calling Tcl_SetErrno(EXDEV) and returning a non-TCL_OK result will tell Tcl to use its
standard fallback mechanisms.
COPYDIRECTORYPROC
Function to process a Tcl_FSCopyDirectory call. If not implemented, Tcl will fall back on
a recursive file mkdir, file copy mechanism. Therefore it need only be implemented if the
filesystem can perform that action more efficiently.
typedef int Tcl_FSCopyDirectoryProc(
Tcl_Obj *srcPathPtr,
Tcl_Obj *destPathPtr,
Tcl_Obj **errorPtr);
The return value is a standard Tcl result indicating whether an error occurred in the
copying process. If an error does occur, the name of the file or directory which caused
the error should be placed in errorPtr. Note that, destPathPtr is the name of the
directory-name which should become the mirror-image of srcPathPtr. It is not the name of a
directory into which srcPathPtr should be copied (i.e. the function is much simpler than
the Tcl level file copy subcommand). Finally, if the filesystem determines it cannot
support the directory copy action, calling Tcl_SetErrno(EXDEV) and returning a non-TCL_OK
result will tell Tcl to use its standard fallback mechanisms.
LOADFILEPROC
Function to process a Tcl_FSLoadFile call. If not implemented, Tcl will fall back on a
copy to native-temp followed by a Tcl_FSLoadFile on that temporary copy. Therefore it need
only be implemented if the filesystem can load code directly, or it can be implemented
simply to return TCL_ERROR to disable load functionality in this filesystem entirely.
typedef int Tcl_FSLoadFileProc(
Tcl_Interp *interp,
Tcl_Obj *pathPtr,
Tcl_LoadHandle *handlePtr,
Tcl_FSUnloadFileProc *unloadProcPtr);
Returns a standard Tcl completion code. If an error occurs, an error message is left in
the interp's result. The function dynamically loads a binary code file into memory. On a
successful load, the handlePtr should be filled with a token for the dynamically loaded
file, and the unloadProcPtr should be filled in with the address of a procedure. The
unload procedure will be called with the given Tcl_LoadHandle as its only parameter when
Tcl needs to unload the file. For example, for the native filesystem, the Tcl_LoadHandle
returned is currently a token which can be used in the private TclpFindSymbol to access
functions in the new code. Each filesystem is free to define the Tcl_LoadHandle as it
requires. Finally, if the filesystem determines it cannot support the file load action,
calling Tcl_SetErrno(EXDEV) and returning a non-TCL_OK result will tell Tcl to use its
standard fallback mechanisms.
UNLOADFILEPROC
Function to unload a previously successfully loaded file. If load was implemented, then
this should also be implemented, if there is any cleanup action required.
typedef void Tcl_FSUnloadFileProc(
Tcl_LoadHandle loadHandle);
GETCWDPROC
Function to process a Tcl_FSGetCwd call. Most filesystems need not implement this. It will
usually only be called once, if getcwd is called before chdir. May be NULL.
typedef Tcl_Obj *Tcl_FSGetCwdProc(
Tcl_Interp *interp);
If the filesystem supports a native notion of a current working directory (which might
perhaps change independent of Tcl), this function should return that cwd as the result, or
NULL if the current directory could not be determined (e.g. the user does not have
appropriate permissions on the cwd directory). If NULL is returned, an error message is
left in the interp's result.
CHDIRPROC
Function to process a Tcl_FSChdir call. If filesystems do not implement this, it will be
emulated by a series of directory access checks. Otherwise, virtual filesystems which do
implement it need only respond with a positive return result if the pathPtr is a valid,
accessible directory in their filesystem. They need not remember the result, since that
will be automatically remembered for use by Tcl_FSGetCwd. Real filesystems should carry
out the correct action (i.e. call the correct system chdir API).
typedef int Tcl_FSChdirProc(
Tcl_Obj *pathPtr);
The Tcl_FSChdirProc changes the applications current working directory to the value
specified in pathPtr. The function returns -1 on error or 0 on success.
SEE ALSO
cd(3tcl), file(3tcl), filename(3tcl), load(3tcl), open(3tcl), pwd(3tcl), source(3tcl),
unload(3tcl)
KEYWORDS
stat, access, filesystem, vfs, virtual filesystem