In PHP, stream_supports_lock() is useful when your application needs a specific operation rather than manually reproducing it. Checks whether the selected stream can support flock() locking.
Stream functions work with PHP stream resources, wrappers, contexts or custom filters. Not every wrapper supports every operation.
What Is stream_supports_lock() in PHP?
Checks whether the selected stream can support flock() locking.
Signature:
stream_supports_lock($stream): boolParameters:
$stream— An already opened stream resource, not a filesystem path string.
Return value: bool.
Example 1: Basic Usage
This first example shows the method or function in a minimal context. For environment-dependent operations, adapt the required path, stream or connection before running it.
<?php
$stream = fopen("php://temp", "w+");
fwrite($stream, "alpha\nbeta\n");
rewind($stream);
$supportsLock = stream_supports_lock($stream);
fclose($stream);
The important operation is stream_supports_lock(). Checks whether the selected stream can support flock() locking.
Example 2: Another Input or Scenario
The next example changes the input or surrounding context to show how the operation behaves in a second situation.
<?php
$stream = fopen("php://temp", "w+");
fwrite($stream, "gamma\ndelta\n");
rewind($stream);
$supportsLock = stream_supports_lock($stream);
fclose($stream);
Compare the inputs and the handling of the return value with the first example. Avoid assuming that filesystem paths, resource states or binary bytes are interchangeable.
Practical Example: Applying the Operation
This example illustrates how the operation fits into a small application workflow. Paths, streams and secrets must be created or provided securely by the calling application.
<?php
$stream = fopen("php://temp", "w+");
fwrite($stream, "alpha\nbeta\n");
rewind($stream);
$supportsLock = stream_supports_lock($stream);
// Confirm the return value before using the result.
fclose($stream);
Practical note: Checks whether the selected stream can support flock() locking.
Important Behavior and Edge Cases
- Checks whether the selected stream can support flock() locking.
- Check failure values and exceptions; do not assume every environment supports the same stream wrapper, extension or filesystem capability.
- When handling paths, streams or external input, validate inputs before using results and release resources after use.
Comparison With Related Functions
| Function or Method | Behavior |
|---|---|
stream_supports_lock() | checks whether stream locking is supported. |
flock() | requests an advisory file lock. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Assuming a successful check guarantees future operations | Treat the check as information at one moment; handle failures when the actual operation runs. |
| Assuming a resource result is always successful | Check false returns, actual byte counts, and resource state before using the result. |
| Confusing local and remote stream behavior | Read the wrapper capabilities and handle unsupported operations explicitly. |
Key Takeaways
stream_supports_lock()checks whether the selected stream can support flock() locking.- Use appropriate input types and verify results before continuing.
- Prefer specialized, safer APIs when the operation concerns untrusted input, encryption or network traffic.
In summary: Checks whether the selected stream can support flock() locking. Build in error handling and use this function where its specific behavior matches the application requirements.