---
name: "TclZipfs_AppHook"
section: "3tcl"
platform: "linux"
package: "tcl9.0-doc"
version: "9.0.1+dfsg-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/TclZipfs_AppHook"
---

# TclZipfs\_AppHook(3tcl)

handle ZIP files as Tcl virtual filesystems

```

```

## NAME

TclZipfs\_AppHook, TclZipfs\_Mount, TclZipfs\_MountBuffer, TclZipfs\_Unmount - handle ZIP files as Tcl virtual filesystems

## SYNOPSIS

```
const char *
TclZipfs_AppHook(argcPtr, argvPtr)

int
TclZipfs_Mount(interp, zipname, mountpoint, password)

int
TclZipfs_MountBuffer(interp, data, dataLen, mountpoint, copy)

int
TclZipfs_Unmount(interp, mountpoint)
```

## ARGUMENTS

- int *\*argcPtr* (in)

  Pointer to a variable holding the number of command line arguments from **main**().

- char *\*\*\*argvPtr* (in)

  Pointer to an array of strings containing the command line arguments to **main**().

- Tcl\_Interp *\*interp* (in)

  Interpreter in which the ZIP file system is mounted.  The interpreter's result is modified to hold the result or error message from the script.

- const char *\*zipname* (in)

  Name of a ZIP file. Must not be NULL when either mounting or unmounting a ZIP.

- const char *\*mountpoint* (in)

  Name of a mount point, which must be a legal Tcl file or directory name. May be NULL to query current mount points.

- const char *\*password* (in)

  An (optional) password. Use NULL if no password is wanted to read the file.

- const void *\*data* (in)

  A data buffer to mount. The data buffer must hold the contents of a ZIP archive, and must not be NULL.

- size\_t *dataLen* (in)

  The number of bytes in the supplied data buffer argument, *data*.

- int *copy* (in)

  If non-zero, the ZIP archive in the data buffer will be internally copied before mounting, allowing the data buffer to be disposed once **TclZipfs\_MountBuffer** returns. If zero, the caller guarantees that the buffer will be valid to read from for the duration of the mount.

  ```

  ```

## DESCRIPTION

**TclZipfs\_AppHook** is a utility function to perform standard application initialization procedures, taking into account available ZIP archives as follows:

- \[1\]

  If the current application has a mountable ZIP archive, that archive is mounted under *ZIPFS\_VOLUME***/app** as a read-only Tcl virtual file system (VFS). The value of *ZIPFS\_VOLUME* can be retrieved using the Tcl command **zipfs root**.

- \[2\]

  If a file named **main.tcl** is located in the root directory of that file system (i.e., at *ZIPFS\_VOLUME***/app/main.tcl** after the ZIP archive is mounted as described above) it is treated as the startup script for the process.

- \[3\]

  If the file *ZIPFS\_VOLUME***/app/tcl\_library/init.tcl** is present, the **tcl\_library** global variable in the initial Tcl interpreter is set to *ZIPFS\_VOLUME***/app/tcl\_library**.

- \[4\]

  If the directory **tcl\_library** was not found in the main application mount, the system will then search for it as either a VFS attached to the application dynamic library, or as a zip archive named **libtcl\_***major***\_***minor***\_***patchlevel***.zip** either in the present working directory or in the standard Tcl install location. (For example, the Tcl 9.0.2 release would be searched for in a file **libtcl\_9\_0\_2.zip**.) That archive, if located, is also mounted read-only.

On Windows, **TclZipfs\_AppHook** has a slightly different signature, since it uses WCHAR instead of char. As a result, it requires the application to be compiled with the UNICODE preprocessor symbol defined (e.g., via the **-DUNICODE** compiler flag).

The result of **TclZipfs\_AppHook** is the full Tcl version with build information (e.g., **9.0.0+abcdef...abcdef.gcc-1002**). The function *may* modify the variables pointed to by *argcPtr* and *argvPtr* to remove arguments; the current implementation does not do so, but callers *should not* assume that this will be true in the future.

**TclZipfs\_Mount** is used to mount ZIP archives and to retrieve information about currently mounted archives. If *mountpoint* and *zipname* are both specified (i.e. non-NULL), the function mounts the ZIP archive *zipname* on the mount point given in *mountpoint*. If *password* is not NULL, it should point to the NUL terminated password protecting the archive. If not under the zipfs file system root, *mountpoint* is normalized with respect to it. For example, a mount point passed as either **mt** or **/mt** would be normalized to **//zipfs:/mt**, given that *ZIPFS\_VOLUME* as returned by **zipfs root** is “//zipfs:/”. An error is raised if the mount point includes a drive or UNC volume. On success, *interp*'s result is set to the normalized mount point path.

If *mountpoint* is a NULL pointer, information on all currently mounted ZIP file systems is stored in *interp*'s result as a sequence of mount points and ZIP file names.

If *mountpoint* is not NULL but *zipfile* is NULL, the path to the archive mounted at that mount point is stored as *interp*'s result. The function returns a standard Tcl result code.

**TclZipfs\_MountBuffer** mounts the ZIP archive content *data* on the mount point given in *mountpoint*. Both *mountpoint* and *data* must be specified as non-NULL. The *copy* argument determines whether the buffer is internally copied before mounting or not. The ZIP archive is assumed to be not password protected. On success, *interp*'s result is set to the normalized mount point path.

**TclZipfs\_Unmount** undoes the effect of **TclZipfs\_Mount**, i.e., it unmounts the mounted ZIP file system that was mounted from *zipname* (at *mountpoint*). Errors are reported in the interpreter *interp*.  The result of this call is a standard Tcl result code.

**TclZipfs\_AppHook** can not be used in stub-enabled extensions.

## SEE ALSO

[zipfs(3tcl)](/zipfs/3tcl.md)

## KEYWORDS

compress, filesystem, zip