Waiting for the named USB device in macos.

build.gradle

def APPLICATION_GROUP = 'Application'

ext {
    device = 'Cruzer'
    program = 'wait'
}

task compile(type: Exec) {
    group APPLICATION_GROUP
    description 'Compiles the native program.'

    def src = 'wait.c'
    inputs.files src
    outputs.files program

    commandLine 'clang', '-framework', 'IOKit', src, '-o', program
}

task runSimple(type: Exec, dependsOn: compile) {
    group APPLICATION_GROUP
    description 'Waits for the device.'

    commandLine "./$program", device
}

task run(type: Exec, dependsOn: compile) {
    group APPLICATION_GROUP
    description 'Waits for the device using the line-buffered mode.'

    commandLine 'script', '-q', '/dev/null', "./$program", device
}

wait.c

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <IOKit/IOKitLib.h>
#include <IOKit/usb/IOUSBLib.h>

int main(int argc, const char *argv[]) {
    if (argc < 2) {
        printf("Please specify the device name.\n");
        return 1;
    }
    const char* requiredName = argv[1];
    size_t length = strlen(requiredName);
    printf("Waiting for %s\n", requiredName);

    CFMutableDictionaryRef matchingDict;
    bool found = false;
    while (!found && (matchingDict = IOServiceMatching(kIOUSBDeviceClassName))) {
        io_iterator_t iter;
        io_service_t device;
        bool iterIsValid = IOServiceGetMatchingServices(kIOMasterPortDefault, matchingDict, &iter) == KERN_SUCCESS;
        unsigned counter = 0;
        while (!found && iterIsValid && (device = IOIteratorNext(iter))) {
            io_name_t devName;
            counter++;
            bool nameIsValid = IORegistryEntryGetName(device, devName) == KERN_SUCCESS;
            found = nameIsValid  && !strncmp(devName, requiredName, length);
            IOObjectRelease(device);
        }
        printf("Got %d connected devices. %s\n", counter, found ? "Found!" : "Still waiting...");
        iterIsValid && IOObjectRelease(iter);
        !found && sleep(1);
    }
    return !found;
}