OSX: proc_pidinfo returns 0 for other user's processes

Question

I need to get some information (PID, UID, GID, process name) about running processes on Mac OSX. I tried proc_pidinfo. For my own processes it works fine. However,

Answer 1

You can use :

int proc_listpids(uint32_t type, uint32_t typeinfo, void *buffer, int buffersize);

combinated to proc_pidinfo to get many others pids informations like :

#include <unistd.h>
#include <stdlib.h>
#include <mach/mach.h>
#include <libproc.h>
#include <mach/mach_time.h>
#include <sys/sysctl.h>
#include <mach-o/ldsyms.h>
#include <stdio.h>

void procpid(pid_t pid)
{ struct proc_bsdinfo proc;
  int st = proc_pidinfo(pid, PROC_PIDTBSDINFO, 0, &proc, PROC_PIDTBSDINFO_SIZE);
  printf("name: %s\n", proc.pbi_name);
}

void pidlist(void)
{ int bufsize = proc_listpids(PROC_ALL_PIDS, 0, NULL, 0);
  pid_t pids[2 * bufsize / sizeof(pid_t)];
  bufsize = proc_listpids(PROC_ALL_PIDS, 0, pids, sizeof(pids));
  size_t num_pids = bufsize / sizeof(pid_t);
  int i = 0;
  while (i < num_pids)
  { printf("pid[%d]::%d\n", i, pids[i]);
    procpid(pids[i]);
    printf("\n-------------------------------\n\n");
    i += 1; }}

int main(void)
{ pidlist();
  return(42); }

Answer 2

I found that macOS Mojave (version 10.14.4) had struct proc_bsdshortinfo, which is a subset of struct proc_bsdinfo. You can get other user's processes without SUID by using it instead of struct proc_bsdinfo.

Well, I don't know from which version it is available.

edited: It is available since at least macOS 10.10.5 (Yosemite).
edited again: It may be available since Mac OS X 10.7 (Lion) because tmux uses struct proc_bsdshortinfo if __MAC_10_7 is defined. See here.

Example:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include <libproc.h>

int main(int argc, char *argv[])
{
    pid_t pid;
    struct proc_bsdshortinfo proc;

    if (argc == 2)
        pid = atoi(argv[1]);
    else
        pid = getpid();

    int st = proc_pidinfo(pid, PROC_PIDT_SHORTBSDINFO, 0,
                         &proc, PROC_PIDT_SHORTBSDINFO_SIZE);

    if (st != PROC_PIDT_SHORTBSDINFO_SIZE) {
        fprintf(stderr, "Cannot get process info\n");
        return 1;
    }
    printf(" pid: %d\n", (int)proc.pbsi_pid);
    printf("ppid: %d\n", (int)proc.pbsi_ppid);
    printf("comm: %s\n",      proc.pbsi_comm);
    //printf("name: %s\n",      proc.pbsi_name);
    printf(" uid: %d\n", (int)proc.pbsi_uid);
    printf(" gid: %d\n", (int)proc.pbsi_gid);

    return 0;
}

This program prints:

$ ./pidinfo 
 pid: 3025
ppid: 250
comm: pidinfo
 uid: 501
 gid: 20
$ ./pidinfo 1
 pid: 1
ppid: 0
comm: launchd
 uid: 0
 gid: 0