iOS Daemon without Jetsam

daemon-main.m

#import <Foundation/Foundation.h>
#import <dlfcn.h>
#import <sys/proc.h>

// these headers can be found at https://github.com/apple/darwin-xnu
#import "libproc.h"
#import "kern_memorystatus.h"

static __attribute__ ((constructor(101), visibility("hidden")))
void BypassJetsam(void) {
    pid_t me = getpid();
    int rc; memorystatus_priority_properties_t props = {JETSAM_PRIORITY_CRITICAL, 0};
    rc = memorystatus_control(MEMORYSTATUS_CMD_SET_PRIORITY_PROPERTIES, me, 0, &props, sizeof(props));
    if (rc < 0) { perror ("memorystatus_control"); exit(rc);}
    rc = memorystatus_control(MEMORYSTATUS_CMD_SET_JETSAM_HIGH_WATER_MARK, me, -1, NULL, 0);
    if (rc < 0) { perror ("memorystatus_control"); exit(rc);}
    rc = memorystatus_control(MEMORYSTATUS_CMD_SET_PROCESS_IS_MANAGED, me, 0, NULL, 0);
    if (rc < 0) { perror ("memorystatus_control"); exit(rc);}
    rc = memorystatus_control(MEMORYSTATUS_CMD_SET_PROCESS_IS_FREEZABLE, me, 0, NULL, 0);
    if (rc < 0) { perror ("memorystatus_control"); exit(rc); }
    rc = proc_track_dirty(me, 0);
    if (rc != 0) { perror("proc_track_dirty"); exit(rc); }
}


#pragma mark -

int main(int argc, char *argv[])
{
    // https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/BPSystemStartup/Chapters/CreatingLaunchdJobs.html
    CFRunLoopRun();
    return 0;
}