Objective-C

Prevent JavaScript Infinite Loops

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Demonstrates how prevent infinite loops or prevent the JavaScript from running for a longer amount of time than allowed. Objective-C

#import <CkoStringBuilder.h>
#import <CkoJs.h>
#import <CkoJsonObject.h>

BOOL success = NO;

// This is the JavaScript we'll run:

// console.log('Starting infinite loop...'); while(true) {};

CkoStringBuilder *sbScript = [[CkoStringBuilder alloc] init];
[sbScript Append: @"console.log('Starting infinite loop...'); while(true) {};"];

CkoJs *js = [[CkoJs alloc] init];

// Set a limit on the amount of time (in seconds) the script is allowed to run.
// If the JavaScript takes longer than this amount of time, then Chilkat kills the script without crashing the host program.
// The default value of TimeoutSeconds is 0, which indicates no limit.
// For this example, set a limit of 2 seconds.
js.TimeoutSeconds = [NSNumber numberWithInt:2];

CkoJsonObject *result = [[CkoJsonObject alloc] init];
result.EmitCompact = NO;

// Run the script..
success = [js Eval: sbScript result: result];
if (success == NO) {
    // Examine the result for an exception.
    NSLog(@"%@",[result Emit]);

    // The result contains this:

    // 	{
    // 	  "exception": {
    // 	    "message": "interrupted - JavaScript exceeded the Chilkat.Js.TimeoutSeconds",
    // 	    "stack": [
    // 	      {
    // 	        "func": "<eval>",
    // 	        "file": "<input>",
    // 	        "line": 1,
    // 	        "col": 8
    // 	      }
    // 	    ]
    // 	  }
    // 	}

    // Also examine the LastErrorText.
    NSLog(@"%@",js.LastErrorText);
    return;
}

// We should never get here..
NSLog(@"%@",@"Succeeded.");
NSLog(@"%@",[result Emit]);