Sandboxing turned on and is there a more Objective-C way to go about opening a com port? - objective-c

Question

Right now I got the following class and its not working. It fails at the open call. I think this is because of sandboxing but I'm not sure how to move forward. Also this seems ver C like, is there a better more Objective-C (IOKIT?) way to fo this?
The device itself is a USB serial port.
Error given:
Failed to open device: Operation not permitted
Current code:
#include <termios.h>
#import "Com.h"
#define BAUDCOUNT 17
speed_t baud_const[BAUDCOUNT] = { B50, B75, B110, B134, B150, B200,
B300, B600, B1200, B1800, B2400, B4800,
B9600, B19200, B38400, B57600, B115200 };
unsigned long baud_value[BAUDCOUNT] = { 50, 75, 110, 134, 150, 200,
300, 600, 1200, 1800, 2400, 4800,
9600, 19200, 38400, 57600, 115200 };
#interface Com()
#property (assign) int fd;
#property (assign) struct termios oldio;
#end
#implementation Com
#synthesize fd = _fd;
#synthesize oldio = _oldio;
- (id)init
{
self = [super init];
if (self)
{
self.fd = -1;
return self;
}
return nil;
}
- (BOOL)open:(NSString*)device withBaud:(int)baud
{
struct termios oldio;
struct termios newtio;
// Find the correct baud rate
int baudid = -1;
for(int i = 0; i < BAUDCOUNT; i++) {
if (baud_value[i] == baud) {
baudid = i;
break;
}
}
if(baudid == -1)
{
NSLog(#"Invlaid baud rate: %d", baud);
return NO;
}
// Open the device
self.fd = open([device UTF8String], O_RDWR | O_NOCTTY | O_NDELAY);
if (self.fd < 0)
{
NSLog(#"Failed to open device: %s", strerror(errno));
return NO;
}
// Save old settings
tcgetattr(self.fd, &oldio);
self.oldio = oldio;
// Init memory
memset(&newtio, 0x00 , sizeof(newtio));
cfmakeraw(&newtio);
// settings flags
newtio.c_cflag |= CS8;
newtio.c_cflag |= CLOCAL;
newtio.c_cflag |= CREAD;
newtio.c_iflag = IGNPAR | IGNBRK;
newtio.c_oflag = 0;
newtio.c_lflag = 0;
// Timeout in 100ms
newtio.c_cc[VTIME] = 0;
// read 1 character
newtio.c_cc[VMIN] = 0;
// Setting baudrate
cfsetispeed (&newtio, baud_const[baudid]);
cfsetospeed (&newtio, baud_const[baudid]);
// Flushing buffer
tcflush(self.fd, TCIOFLUSH);
// aplying new configuration
tcsetattr(self.fd, TCSANOW, &newtio);
return YES;
}
#end
Current Entitlements:
<key>com.apple.security.app-sandbox</key>
<true/>
<key>com.apple.security.device.usb</key>
<true/>
<key>com.apple.security.files.user-selected.read-write</key>
<true/>

Answer 1

There are a couple of Objective C frameworks for handling the serial port.
AMSerialPort
SerialConnect
Update: It looks to me like you might need the com.apple.security.device.serial entitlement. Despite the fact you are using a USB Serial adapter I believe the OS device drivers make all serial ports appear the same, i.e. not USB devices. I suspect the com.apple.security.device.usb entitlement that you do have doesn't apply to USB serial devices.
Update 2: I've just found this Open Radar from August last year which reports your problem. So it looks like the com.apple.security.device.serial entitlement doesn't work (or certainly didn't work back in August).
Update 3: If you do need to access the USB device directly (and assuming this works with the com.apple.security.device.usb entitlement) then you probably want to look at the IOSerialFamily source code which is available at http://opensource.apple.com/source/IOSerialFamily/IOSerialFamily-59/.
Source tarball: http://opensource.apple.com/tarballs/IOSerialFamily/IOSerialFamily-59.tar.gz

Answer 2

you are doing some kernel programming which may be what you are wanting to do, but if you can use the IOKit then I do recommend that. In short doing anything with the kernel + sandboxing I simply do not recommend as you have found out.
The IOKit is another type of animal and really isn't too bad. Here is an example with a quick snippet that will disable the system from sleeping. This demonstrates how you can use the IOKit and I do believe it does work with a Sandboxed app.
IOPMAssertionID assertionID;
IOReturn err = IOPMAssertionCreateWithName(kIOPMAssertionTypeNoDisplaySleep, kIOPMAssertionLevelOn, CFSTR("Add Reason Here"), &assertionID);
if ( err == kIOReturnSuccess ) {
// Do stuff here while system is unable to sleep
// Let the system resume ability to sleep
err = IOPMAssertionRelease(assertionID);
}
This documentation should also help: link
Note: "Important If your application is sandboxed, it must request the com.apple.security.device.usb entitlement in order to access USB devices."