Tribblix: manual page: Tcl

Tcl_Access(3) Tcl Library Procedures Tcl_Access(3)

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NAME

Tcl_Access, Tcl_Stat - check file permissions and other attributes

SYNOPSIS

#include <tcl.h>

int
Tcl_Access(path, mode)

int
Tcl_Stat(path, statPtr)

ARGUMENTS

const char *path (in) Native name of the file to check
the attributes of.

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 a check for the
existence of the file.

struct stat *statPtr (out) The structure that contains the
result.
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DESCRIPTION

As of Tcl 8.4, the object-based APIs Tcl_FSAccess and Tcl_FSStat
should be used in preference to Tcl_Access and Tcl_Stat, wherever
possible. Those functions also support Tcl's virtual filesystem
layer, which these do not.

OBSOLETE FUNCTIONS

There are two reasons for calling Tcl_Access and Tcl_Stat rather than
calling system level functions access and stat directly. First, the
Windows implementation of both functions fixes some bugs in the
system level calls. Second, both Tcl_Access and Tcl_Stat (as well as
Tcl_OpenFileChannelProc) hook into a linked list of functions. This
allows the possibility to reroute file access to alternative media or
access methods.

Tcl_Access checks whether the process would be allowed to read, write
or test for existence of the file (or other file system object) whose
name is path. If path 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_Stat 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 creation time.

If path exists, Tcl_Stat returns 0 and the stat structure is filled
with data. Otherwise, -1 is returned, and no stat info is given.

KEYWORDS