Task 779: .VCMZ File Format
Task 779: .VCMZ File Format
1. List of all the properties of this file format intrinsic to its file system
Based on available documentation from Microsoft Hyper-V resources, the .VMCZ file format is a ZIP-based compressed archive specifically designed for exporting and sharing virtual machines (VMs) in Hyper-V environments. It does not have a unique low-level binary structure beyond that of a standard ZIP archive; instead, its "properties" are defined by its ZIP compression, file extension, and the standardized internal directory structure and file contents required for Hyper-V compatibility. There is no publicly available byte-level specification (e.g., custom headers or magic numbers beyond ZIP's PK\003\004 signature), as it relies on the ZIP format for compression and organization. The intrinsic properties include:
- File Extension: .vmcz (case-insensitive, but typically lowercase).
- Archive Type: ZIP-based compression archive (uses Deflate compression method by default, as per ZIP standards).
- File Signature/Magic Number: Starts with "PK\003\004" (standard ZIP local file header signature).
- Extractable: Yes, compatible with standard ZIP tools (e.g., File Explorer, 7-Zip, or programmatic ZIP libraries). No encryption or password protection is mandated by the format.
- Internal Structure:
- Root-level folders: Typically includes "Virtual Machines" (for configuration and state files) and "Virtual Hard Disks" (for disk images). May include "Snapshots" if checkpoints are present.
- No fixed header beyond ZIP; structure is folder-based for Hyper-V import compatibility.
- Contents (Required/Typical Files):
- .vmcx: Binary virtual machine configuration file (replaces older XML format; contains VM settings like CPU, memory, network, etc.).
- .vmrs: Virtual machine runtime state file (binary; captures running state if the VM was exported while active).
- .vhdx: Virtual hard disk files (one or more; primary disk images).
- .avhdx (optional): Automatic virtual hard disk files for checkpoints/snapshots.
- .vmgs (optional): Virtual machine guest state file (on Windows Server 2016+; stores guest OS state).
- Compression Level: Variable, but typically standard ZIP deflation for efficiency in VM sharing.
- Size Limits: No inherent limit beyond filesystem constraints; practical limits based on VM size (often gigabytes).
- Purpose/Compatibility: Designed for Hyper-V VM sharing/migration; automatically triggers import via Hyper-V's vmimport.exe on double-click in compatible Windows environments.
- Other Intrinsic Traits: Read/write via standard ZIP APIs; no built-in checksums or versioning beyond ZIP metadata; files inside maintain their own formats (e.g., .vmcx is a proprietary binary).
These properties ensure compatibility with Hyper-V's import/export process, but the format is not intended for manual editing—modifications risk breaking VM integrity.
2. Two direct download links for files of format .VMCZ
After extensive searches across web sources, including filetype-specific queries and site-specific operators (e.g., GitHub), no publicly available direct download links for .VMCZ files were found. These files are typically generated by users via Hyper-V exports and contain potentially licensed VM content (e.g., OS images), so they are not commonly shared publicly due to size, security, and licensing concerns. If needed, you can create your own .VMCZ file by exporting a VM in Hyper-V Manager on Windows 10/11 or Server 2016+ (right-click VM > Share or Export, which produces a .vmcz if the VM is running).
3. Ghost blog embedded HTML JavaScript that allows a user to drag n drop a file of format .VMCZ and it will dump to screen all these properties
(Note: "Ghost blog embedded" likely means embeddable HTML/JS for a blog post, e.g., in Ghost CMS. This uses JSZip library for ZIP handling, as .VMCZ is ZIP-based. It reads the file, verifies it's ZIP, lists contents, and dumps properties to screen. No write functionality here, as browser JS limits file writing; focus on read/dump.)
Drag and drop .VMCZ file here
Embed this in a Ghost blog post via HTML card.
4. Python class that can open any file of format .VMCZ and decode read and write and print to console all the properties from the above list
import zipfile
import os
class VMCZHandler:
def __init__(self, filepath):
self.filepath = filepath
self.properties = {
'File Extension': '.vmcz',
'Archive Type': 'ZIP-based compression format',
'Extractable': 'Yes',
'Internal Structure': 'Folders: Virtual Machines, Virtual Hard Disks (optional Snapshots)',
'Contents': [], # Will be populated on read
'Purpose': 'Sharing and transferring virtual machines between Hyper-V environments',
'Import Mechanism': 'Triggers vmimport.exe on open in Hyper-V'
}
def read(self):
"""Read and decode the .VMCZ file (as ZIP)."""
if not zipfile.is_zipfile(self.filepath):
raise ValueError("Not a valid .VMCZ (ZIP) file")
with zipfile.ZipFile(self.filepath, 'r') as zf:
self.properties['Contents'] = zf.namelist()
return self.properties
def write(self, output_path, contents_dict=None):
"""Write a new .VMCZ file. contents_dict: {folder: [files]} or use defaults."""
if contents_dict is None:
contents_dict = {'Virtual Machines': ['example.vmcx', 'example.vmrs'], 'Virtual Hard Disks': ['example.vhdx']}
with zipfile.ZipFile(output_path, 'w', zipfile.ZIP_DEFLATED) as zf:
for folder, files in contents_dict.items():
for file in files:
# For demo, write empty files; in real use, provide data
zf.writestr(os.path.join(folder, file), b'')
print(f"Written new .VMCZ to {output_path}")
def print_properties(self):
"""Print all properties to console."""
for key, value in self.properties.items():
if isinstance(value, list):
print(f"{key}:")
for item in value:
print(f" - {item}")
else:
print(f"{key}: {value}")
# Example usage:
# handler = VMCZHandler('example.vmcz')
# handler.read()
# handler.print_properties()
# handler.write('new.vmcz')
5. Java class that can open any file of format .VMCZ and decode read and write and print to console all the properties from the above list
import java.io.*;
import java.util.*;
import java.util.zip.*;
public class VMCZHandler {
private String filepath;
private Map<String, Object> properties;
public VMCZHandler(String filepath) {
this.filepath = filepath;
this.properties = new HashMap<>();
properties.put("File Extension", ".vmcz");
properties.put("Archive Type", "ZIP-based compression format");
properties.put("Extractable", "Yes");
properties.put("Internal Structure", "Folders: Virtual Machines, Virtual Hard Disks (optional Snapshots)");
properties.put("Contents", new ArrayList<String>()); // Populated on read
properties.put("Purpose", "Sharing and transferring virtual machines between Hyper-V environments");
properties.put("Import Mechanism", "Triggers vmimport.exe on open in Hyper-V");
}
public void read() throws IOException {
try (ZipFile zf = new ZipFile(filepath)) {
List<String> contents = new ArrayList<>();
Enumeration<? extends ZipEntry> entries = zf.entries();
while (entries.hasMoreElements()) {
contents.add(entries.nextElement().getName());
}
properties.put("Contents", contents);
} catch (IOException e) {
throw new IOException("Not a valid .VMCZ (ZIP) file");
}
}
public void write(String outputPath) throws IOException {
try (ZipOutputStream zos = new ZipOutputStream(new FileOutputStream(outputPath))) {
// Demo contents; add real files/data as needed
addToZip(zos, "Virtual Machines/example.vmcx", new byte[0]);
addToZip(zos, "Virtual Machines/example.vmrs", new byte[0]);
addToZip(zos, "Virtual Hard Disks/example.vhdx", new byte[0]);
}
System.out.println("Written new .VMCZ to " + outputPath);
}
private void addToZip(ZipOutputStream zos, String filename, byte[] data) throws IOException {
ZipEntry entry = new ZipEntry(filename);
zos.putNextEntry(entry);
zos.write(data);
zos.closeEntry();
}
public void printProperties() {
for (Map.Entry<String, Object> entry : properties.entrySet()) {
if (entry.getValue() instanceof List) {
System.out.println(entry.getKey() + ":");
for (String item : (List<String>) entry.getValue()) {
System.out.println(" - " + item);
}
} else {
System.out.println(entry.getKey() + ": " + entry.getValue());
}
}
}
// Example usage:
// public static void main(String[] args) throws IOException {
// VMCZHandler handler = new VMCZHandler("example.vmcz");
// handler.read();
// handler.printProperties();
// handler.write("new.vmcz");
// }
}
6. JavaScript class that can open any file of format .VMCZ and decode read and write and print to console all the properties from the above list
(Note: Uses Node.js with 'fs' and 'adm-zip' library for read/write; install adm-zip via npm. For browser, write is limited.)
const fs = require('fs');
const AdmZip = require('adm-zip'); // npm install adm-zip
class VMCZHandler {
constructor(filepath) {
this.filepath = filepath;
this.properties = {
'File Extension': '.vmcz',
'Archive Type': 'ZIP-based compression format',
'Extractable': 'Yes',
'Internal Structure': 'Folders: Virtual Machines, Virtual Hard Disks (optional Snapshots)',
'Contents': [], // Populated on read
'Purpose': 'Sharing and transferring virtual machines between Hyper-V environments',
'Import Mechanism': 'Triggers vmimport.exe on open in Hyper-V'
};
}
read() {
const zip = new AdmZip(this.filepath);
this.properties.Contents = zip.getEntries().map(entry => entry.entryName);
}
write(outputPath) {
const zip = new AdmZip();
// Demo contents; add real buffers as needed
zip.addFile('Virtual Machines/example.vmcx', Buffer.alloc(0));
zip.addFile('Virtual Machines/example.vmrs', Buffer.alloc(0));
zip.addFile('Virtual Hard Disks/example.vhdx', Buffer.alloc(0));
zip.writeZip(outputPath);
console.log(`Written new .VMCZ to ${outputPath}`);
}
printProperties() {
for (const [key, value] of Object.entries(this.properties)) {
if (Array.isArray(value)) {
console.log(`${key}:`);
value.forEach(item => console.log(` - ${item}`));
} else {
console.log(`${key}: ${value}`);
}
}
}
}
// Example usage:
// const handler = new VMCZHandler('example.vmcz');
// handler.read();
// handler.printProperties();
// handler.write('new.vmcz');
7. C class that can open any file of format .VMCZ and decode read and write and print to console all the properties from the above list
(Note: C does not have native "classes"; using struct with functions for class-like behavior. Uses minizip or similar for ZIP; assume zlib/minizip linked. For simplicity, uses system calls for zip/unzip, but real impl would use libzip or zlib.)
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <zip.h> // Link with libzip: e.g., apt install libzip-dev, compile with -lzip
typedef struct {
char* filepath;
char* properties[7][2]; // Static properties
char** contents; // Dynamic contents list
int contents_count;
} VMCZHandler;
void init_VMCZHandler(VMCZHandler* handler, char* filepath) {
handler->filepath = strdup(filepath);
handler->properties[0][0] = "File Extension"; handler->properties[0][1] = ".vmcz";
handler->properties[1][0] = "Archive Type"; handler->properties[1][1] = "ZIP-based compression format";
handler->properties[2][0] = "Extractable"; handler->properties[2][1] = "Yes";
handler->properties[3][0] = "Internal Structure"; handler->properties[3][1] = "Folders: Virtual Machines, Virtual Hard Disks (optional Snapshots)";
handler->properties[4][0] = "Purpose"; handler->properties[4][1] = "Sharing and transferring virtual machines between Hyper-V environments";
handler->properties[5][0] = "Import Mechanism"; handler->properties[5][1] = "Triggers vmimport.exe on open in Hyper-V";
handler->properties[6][0] = NULL; // End
handler->contents = NULL;
handler->contents_count = 0;
}
void read_VMCZ(VMCZHandler* handler) {
zip_t* za = zip_open(handler->filepath, ZIP_RDONLY, NULL);
if (!za) {
printf("Error: Not a valid .VMCZ (ZIP) file\n");
return;
}
int num_entries = zip_get_num_entries(za, 0);
handler->contents = malloc(num_entries * sizeof(char*));
for (int i = 0; i < num_entries; i++) {
const char* name = zip_get_name(za, i, 0);
handler->contents[i] = strdup(name);
}
handler->contents_count = num_entries;
zip_close(za);
}
void write_VMCZ(VMCZHandler* handler, char* output_path) {
zip_t* za = zip_open(output_path, ZIP_CREATE | ZIP_TRUNCATE, NULL);
if (!za) {
printf("Error creating .VMCZ\n");
return;
}
// Demo contents; add real data as needed
zip_source_t* src = zip_source_buffer(za, "", 0, 0);
zip_file_add(za, "Virtual Machines/example.vmcx", src, ZIP_FL_OVERWRITE);
src = zip_source_buffer(za, "", 0, 0);
zip_file_add(za, "Virtual Machines/example.vmrs", src, ZIP_FL_OVERWRITE);
src = zip_source_buffer(za, "", 0, 0);
zip_file_add(za, "Virtual Hard Disks/example.vhdx", src, ZIP_FL_OVERWRITE);
zip_close(za);
printf("Written new .VMCZ to %s\n", output_path);
}
void print_properties(VMCZHandler* handler) {
for (int i = 0; handler->properties[i][0]; i++) {
printf("%s: %s\n", handler->properties[i][0], handler->properties[i][1]);
}
printf("Contents:\n");
for (int i = 0; i < handler->contents_count; i++) {
printf(" - %s\n", handler->contents[i]);
}
}
void free_VMCZHandler(VMCZHandler* handler) {
free(handler->filepath);
for (int i = 0; i < handler->contents_count; i++) {
free(handler->contents[i]);
}
free(handler->contents);
}
// Example usage:
// int main() {
// VMCZHandler handler;
// init_VMCZHandler(&handler, "example.vmcz");
// read_VMCZ(&handler);
// print_properties(&handler);
// write_VMCZ(&handler, "new.vmcz");
// free_VMCZHandler(&handler);
// return 0;
// }