PHPMailer::isShellSafe( string $string ): bool
- Source
wp-includes/PHPMailer/PHPMailer.php:2005
Description
Note that escapeshellarg and escapeshellcmd are inadequate for our purposes, especially on Windows.
Compatibility
- WordPress
- core
- PHP
- 7.4–8.6-dev
- 6.7.7
- 6.8.8
- 6.9.7
- 7.0.4
- 7.1.0
Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.
Parameters
$stringstring- The string to be validated
Return value
bool
Performance profile
How much work a call to PHPMailer::isShellSafe() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.
- Cost class
- Light
- Scaling
- Scales with input
- Instructions
- 7–34
- Plugin surface
- None
- Called by
- 0
Touches nothing outside its own arguments.
The body loops, so the work grows with what you pass in.
Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 37.
Nothing here hands control to plugin code.
Nothing in core calls this; the cost is only what you spend yourself.
What one call costs · 3 distinct outcomes
One number would be a lie: the work depends on which branch runs. These are every distinct cost PHPMailer::isShellSafe() can have, taken from its control-flow graph on PHP 8.5.
| When | Instructions | Calls it makes |
|---|---|---|
$string !== false | 7 | escapeshellcmd() |
$string === false | 20–25 | escapeshellcmd(), escapeshellarg() |
$string === false && $i && !ctype_alnum() | 34 | escapeshellcmd(), escapeshellarg(), ctype_alnum() |
Across PHP versions
| PHP | Compiled | Executed | Branches | Notes |
|---|---|---|---|---|
| 8.6-dev | 37 | 7–34 | 5 | |
| 8.5 | 37 | 7–34 | 5 | |
| 8.4 | 37 | 7–34 | 5 | 6 fewer instructions than PHP 8.3 |
| 8.3 | 43 | 7–40 | 5 | |
| 8.2 | 43 | 7–40 | 5 | |
| 8.1 | 43 | 7–40 | 5 | |
| 7.4 | 43 | 7–40 | 5 |
An instruction is not a fixed amount of time, so a matching count is not necessarily the same speed; what it rules out is a difference in the work itself.
Source code
protected static function isShellSafe($string) { //It's not possible to use shell commands safely (which includes the mail() function) without escapeshellarg, //but some hosting providers disable it, creating a security problem that we don't want to have to deal with, //so we don't. if (!function_exists('escapeshellarg') || !function_exists('escapeshellcmd')) { return false; } if ( escapeshellcmd($string) !== $string || !in_array(escapeshellarg($string), ["'$string'", "\"$string\""]) ) { return false; } $length = strlen($string); for ($i = 0; $i < $length; ++$i) { $c = $string[$i]; //All other characters have a special meaning in at least one common shell, including = and +. //Full stop (.) has a special meaning in cmd.exe, but its impact should be negligible here. //Note that this does permit non-Latin alphanumeric characters based on the current locale. if (!ctype_alnum($c) && strpos('@_-.', $c) === false) { return false; } } return true; }Changelog
Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
About this page
- Parsed data
- Generated from the wordpress-develop 7.1.0 tag, from
src/wp-includes/PHPMailer/PHPMailer.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it. - Corrections
- Something wrong on this page? Report it and it gets fixed in the next regeneration.