A simple Objective-C class for checking if a specific process is running

The Cocoa doesn’t seem to provide an easy way to check if a process you wanted to check is rurrning.
So, I wrote a simple Objective-C class for that purpose.

(If you have some great idea how to get absolute paths for running processes, please tell me.  I’d like to add the feature to this class.)

Source 1 : JAProcessInfo.h

#import <Cocoa/Cocoa.h> 

@interface JAProcessInfo : NSObject {

@private
    int numberOfProcesses;
    NSMutableArray *processList;
}
- (id) init;
- (int)numberOfProcesses;
- (void)obtainFreshProcessList;
- (BOOL)findProcessWithName:(NSString *)procNameToSearch;
 @end

Source 2 : JAProcessInfo.m

#import "JAProcessInfo.h"

#include <assert.h>
#include <errno.h>
#include <stdbool.h>
#include <sys/sysctl.h>

typedef struct kinfo_proc kinfo_proc;

@implementation JAProcessInfo
- (id) init
{
    self = [super init];

    if (self != nil)
    {
        numberOfProcesses = -1; // means "not initialized"
        processList = NULL;
    }

    return self;
}

- (int)numberOfProcesses
{
    return numberOfProcesses;
}

- (void)setNumberOfProcesses:(int)num
{
    numberOfProcesses = num;
}

- (int)getBSDProcessList:(kinfo_proc **)procList
   withNumberOfProcesses:(size_t *)procCount
{
    int             err;
    kinfo_proc *    result;
    bool            done;
    static const int    name[] = { CTL_KERN, KERN_PROC, KERN_PROC_ALL, 0 };
    size_t          length;

    // a valid pointer procList holder should be passed
    assert( procList != NULL );
    // But it should not be pre-allocated
    assert( *procList == NULL );
    // a valid pointer to procCount should be passed
    assert( procCount != NULL );

    *procCount = 0;

    result = NULL;
    done = false;

    do
    {
        assert( result == NULL );

        // Call sysctl with a NULL buffer to get proper length
        length = 0;
        err = sysctl((int *)name,(sizeof(name)/sizeof(*name))-1,NULL,&length,NULL,0);
        if( err == -1 )
            err = errno;

        // Now, proper length is optained
        if( err == 0 )
        {
            result = malloc(length);
            if( result == NULL )
                err = ENOMEM;   // not allocated
        }

        if( err == 0 )
        {
            err = sysctl( (int *)name, (sizeof(name)/sizeof(*name))-1, result, &length, NULL, 0);
            if( err == -1 )
                err = errno;

            if( err == 0 )
                done = true;
            else if( err == ENOMEM )
            {
                assert( result != NULL );
                free( result );
                result = NULL;
                err = 0;
            }
        }
    }while ( err == 0 && !done );

    // Clean up and establish post condition
    if( err != 0 && result != NULL )
    {
        free(result);
        result = NULL;
    }

    *procList = result; // will return the result as procList
    if( err == 0 )
        *procCount = length / sizeof( kinfo_proc );

    assert( (err == 0) == (*procList != NULL ) );

    return err;
}

- (void)obtainFreshProcessList
{
    int i;
    kinfo_proc *allProcs = 0;
    size_t numProcs;
    NSString *procName;

    int err =  [self getBSDProcessList:&allProcs withNumberOfProcesses:&numProcs];
    if( err )
    {
        numberOfProcesses = -1;
        processList = NULL;

        return;
    }

    // Construct an array for ( process name )
    processList = [NSMutableArray arrayWithCapacity:numProcs];
    for( i = 0; i < numProcs; i++ )
    {
        procName = [NSString stringWithFormat:@"%s", allProcs[i].kp_proc.p_comm];
        [processList addObject:procName];
    }

    [self setNumberOfProcesses:numProcs];

    // NSLog(@"# of elements = %d total # of process = %d\n",
    //         [processArray count], numProcs );

    free( allProcs );

}

- (BOOL)findProcessWithName:(NSString *)procNameToSearch
{
    int index;

    index = [processList indexOfObject:procNameToSearch];

    if( index == NSNotFound )
        return NO;
    else
        return YES;
}
@end

How to use it?

    JAProcessInfo *procInfo = [[JAProcessInfo alloc] init];

    [procInfo obtainFreshProcessList]; // Get a list of process
    BOOL isRunning = [procInfo findProcessWithName:@"mlnet"];