PHP curl_share_strerror Function

last modified April 11, 2025

The PHP curl_share_strerror function returns a string describing the error code for a cURL share handle. It's used for error handling in shared cURL sessions where multiple handles share data like cookies or DNS cache.

Basic Definition

The curl_share_strerror function returns a human-readable error message for a given cURL share error code. It helps diagnose issues with shared cURL sessions.

Syntax: curl_share_strerror(int $error_code): ?string. The function takes an error code and returns its description. Returns NULL for invalid codes.

Basic Error Handling

This example demonstrates basic error handling with curl_share_strerror.

basic_error.php

<?php

declare(strict_types=1);

$sh = curl_share_init();

if (!curl_share_setopt($sh, CURLSHOPT_SHARE, CURL_LOCK_DATA_COOKIE)) {
    $error = curl_share_strerror(curl_share_errno($sh));
    echo "Share error: " . $error;
}

curl_share_close($sh);

We create a share handle and attempt to set a sharing option. If it fails, we get the error code with curl_share_errno and convert it to a message. This helps identify configuration issues.

Handling Multiple Share Errors

This example shows how to handle multiple potential share errors.

multiple_errors.php

<?php

declare(strict_types=1);

$sh = curl_share_init();

$options = [
    CURL_LOCK_DATA_COOKIE,
    CURL_LOCK_DATA_DNS,
    CURL_LOCK_DATA_SSL_SESSION
];

foreach ($options as $option) {
    if (!curl_share_setopt($sh, CURLSHOPT_SHARE, $option)) {
        $error = curl_share_strerror(curl_share_errno($sh));
        echo "Failed to share $option: $error\n";
    }
}

curl_share_close($sh);

We try to set multiple sharing options in a loop. For each failure, we get the specific error message. This approach helps debug which sharing types might be unsupported.

Invalid Error Code Handling

This example demonstrates how the function handles invalid error codes.

invalid_code.php

<?php

declare(strict_types=1);

$invalidCode = 9999;
$error = curl_share_strerror($invalidCode);

if ($error === null) {
    echo "Invalid error code provided";
} else {
    echo "Error message: " . $error;
}

We test the function with an obviously invalid error code. The function returns NULL in this case, allowing us to handle unknown error codes gracefully.

Integration with cURL Multi

This example shows curl_share_strerror in a more complex cURL multi scenario.

multi_integration.php

<?php

declare(strict_types=1);

$sh = curl_share_init();
$mh = curl_multi_init();

if (!curl_share_setopt($sh, CURLSHOPT_SHARE, CURL_LOCK_DATA_COOKIE)) {
    $error = curl_share_strerror(curl_share_errno($sh));
    die("Share init failed: $error");
}

$ch1 = curl_init("https://example.com");
curl_setopt($ch1, CURLOPT_SHARE, $sh);
curl_multi_add_handle($mh, $ch1);

do {
    $status = curl_multi_exec($mh, $active);
    if ($status !== CURLM_OK) {
        $error = curl_share_strerror($status);
        echo "Multi error: $error";
        break;
    }
} while ($active);

curl_multi_remove_handle($mh, $ch1);
curl_multi_close($mh);
curl_share_close($sh);

We create a shared cURL session with cookie sharing. The function helps identify errors during both share setup and multi execution. This is crucial for complex async cURL operations.

Custom Error Wrapper

This example creates a custom error handling wrapper around share operations.

custom_wrapper.php

<?php

declare(strict_types=1);

function handleShareError($sh): void {
    $code = curl_share_errno($sh);
    if ($code !== 0) {
        $error = curl_share_strerror($code);
        throw new RuntimeException("cURL share error: $error (code $code)");
    }
}

$sh = curl_share_init();

try {
    if (!curl_share_setopt($sh, CURLSHOPT_SHARE, CURL_LOCK_DATA_COOKIE)) {
        handleShareError($sh);
    }
    
    // More share operations...
    
} finally {
    curl_share_close($sh);
}

We create a reusable error handler that throws exceptions with detailed messages. The curl_share_strerror function provides the human-readable part of the error. This improves error handling consistency.

Best Practices

Always Check Errors: Verify share operations succeeded.
Use Descriptive Messages: Combine codes with strerror.
Handle NULL: Account for invalid error codes.
Log Errors: Store detailed error information.
Clean Up: Always close share handles.

Source

PHP curl_share_strerror Documentation

This tutorial covered the PHP curl_share_strerror function with practical examples showing its usage for cURL share handle error handling.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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