When working with PharFileInfo in PHP, it helps to understand exactly what compress() does and when the result is useful. This guide uses small examples followed by a practical pattern.
What Is compress() in PHP?
Compresses the current Phar entry using GZIP or BZIP2 when supported.
Syntax:
compress(int $compression)
Parameters:
$compression(int) is required.
Return value: PHP declares a result determined by the operation for this API in PHP 8.4 where available. For operations that can fail, check errors or exceptions instead of assuming success.
Example 1: Basic Usage
The first example focuses on the operation itself without unrelated application logic.
<?php
$archivePath = sys_get_temp_dir() . "/sample-" . bin2hex(random_bytes(4)) . ".tar";
$archive = new PharData($archivePath);
$archive->addFromString("readme.txt", "Example content");
$entry = $archive["readme.txt"];
$entry->compress(Phar::GZ);
unset($archive);
@unlink($archivePath);
Compresses the current Phar entry using GZIP or BZIP2 when supported. The example demonstrates the API in an isolated teaching script. File paths, permissions and optional extensions may need adapting for a real project.
Example 2: Handling Conditions and Failures
Production code must handle cases where the archive, file, runtime feature, or source path is not available. The following example demonstrates an additional usage pattern.
<?php
$archivePath = sys_get_temp_dir() . "/sample-" . bin2hex(random_bytes(4)) . ".tar";
$archive = new PharData($archivePath);
$archive->addFromString("readme.txt", "Example content");
$entry = $archive["readme.txt"];
$entry->compress(Phar::GZ);
// The reported value describes this archive entry.
unset($archive);
@unlink($archivePath);
Only catch errors you can handle meaningfully. A PHP warning, a false return value, and an exception are not interchangeable; consult the behavior explained above.
Practical Example: Integrating the Operation
This practical variation shows how to place the operation in a larger file or inspection workflow. The paths and names are illustrative rather than server deployment instructions.
<?php
$archivePath = sys_get_temp_dir() . "/sample-" . bin2hex(random_bytes(4)) . ".tar";
$archive = new PharData($archivePath);
$archive->addFromString("readme.txt", "Example content");
$entry = $archive["readme.txt"];
try {
$entry->compress(Phar::GZ);
} catch (PharException $exception) {
error_log($exception->getMessage());
}
unset($archive);
@unlink($archivePath);
Do not copy sample paths blindly into production. Validate allowed paths and confirm the appropriate extension and filesystem permissions first.
Important Behavior and Edge Cases
- PharFileInfo describes an entry inside an archive; it is not a standalone filesystem path.
- Metadata and CRC32 values are different from cryptographic signatures and trusted provenance.
- Entry compression depends on the archive format and available compression extensions.
Comparison With Related Functions
| Function or Method | Purpose |
|---|---|
PharFileInfo::compress | Compresses the current Phar entry using GZIP or BZIP2 when supported. |
PharFileInfo::getContent() | Reads the bytes of one entry, not the whole archive. |
Phar::getMetadata() | Reads archive-level metadata rather than per-entry metadata. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Assuming TAR/ZIP data archives behave like executable Phar programs. | Choose PharData for data storage and Phar only when an executable package is required. |
| Treating archive metadata or CRC32 as a trust guarantee. | Verify provenance separately and avoid unserializing untrusted objects. |
| Performing archive writes without checking format and permissions. | Verify write capability, target paths, and supported compression first. |
Key Takeaways
- Compresses the current Phar entry using GZIP or BZIP2 when supported.
- PharFileInfo describes an entry inside an archive; it is not a standalone filesystem path.
- Metadata and CRC32 values are different from cryptographic signatures and trusted provenance.
PharFileInfo::compress() is useful when its specific purpose matches your application. Keep the examples focused, respect the restrictions above, and validate real-world inputs rather than relying on the example values.