text: /* vi: set sw=4 ts=4: */
  /*
   * taskset - retrieve or set a processes' CPU affinity
   * Copyright (c) 2006 Bernhard Fischer
   *
   * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
   */
  
  #include <sched.h>
  #include <getopt.h> /* optind */
  #include "libbb.h"
  
  #if ENABLE_FEATURE_TASKSET_FANCY
  #define TASKSET_PRINTF_MASK "%s"
  #define from_cpuset(x) __from_cpuset(&x)
  /* craft a string from the mask */
  static char *__from_cpuset(cpu_set_t *mask)
  {
  	int i;
  	char *ret = 0, *str = xzalloc(9);
  
  	for (i = CPU_SETSIZE - 4; i >= 0; i -= 4) {
  		char val = 0;
  		int off;
  		for (off = 0; off <= 3; ++off)
  			if (CPU_ISSET(i+off, mask))
  				val |= 1<<off;
  
  		if (!ret && val)
  			ret = str;
  		*str++ = (val-'0'<=9) ? (val+48) : (val+87);
  	}
  	return ret;
  }
  #else
  #define TASKSET_PRINTF_MASK "%x"
  /* (void*) cast is for battling gcc: */
  /* "dereferencing type-punned pointer will break strict-aliasing rules" */
  #define from_cpuset(mask) (*(unsigned*)(void*)&(mask))
  #endif
  
  #define OPT_p 1
  
  int taskset_main(int argc, char** argv);
  int taskset_main(int argc, char** argv)
  {
  	cpu_set_t mask, new_mask;
  	pid_t pid = 0;
  	unsigned opt;
  	const char *state = "current\0new";
  	char *p_opt = NULL, *aff = NULL;
  
  	opt = getopt32(argc, argv, "+p:", &p_opt);
  
  	if (opt & OPT_p) {
  		if (argc == optind+1) { /* -p <aff> <pid> */
  			aff = p_opt;
  			p_opt = argv[optind];
  		}
  		argv += optind; /* me -p <arg> */
  		pid = xatoul_range(p_opt, 1, ULONG_MAX); /* -p <pid> */
  	} else
  		aff = *++argv; /* <aff> <cmd...> */
  	if (aff) {
  		unsigned i = 0;
  		unsigned long l = xstrtol_range(aff, 0, 1, LONG_MAX);
  
  		CPU_ZERO(&new_mask);
  		while (i < CPU_SETSIZE && l >= (1<<i)) {
  			if ((1<<i) & l)
  				CPU_SET(i, &new_mask);
  			++i;
  		}
  	}
  
  	if (opt & OPT_p) {
   print_aff:
  		if (sched_getaffinity(pid, sizeof(mask), &mask) < 0)
  			bb_perror_msg_and_die("failed to %cet pid %d's affinity", 'g', pid);
  		printf("pid %d's %s affinity mask: "TASKSET_PRINTF_MASK"\n",
  				pid, state, from_cpuset(mask));
  		if (!*argv) /* no new affinity given or we did print already, done. */
  			return EXIT_SUCCESS;
  	}
  
  	if (sched_setaffinity(pid, sizeof(new_mask), &new_mask))
  		bb_perror_msg_and_die("failed to %cet pid %d's affinity", 's', pid);
  	if (opt & OPT_p) {
  		state += 8;
  		++argv;
  		goto print_aff;
  	}
  	++argv;
  	BB_EXECVP(*argv, argv);
  	bb_perror_msg_and_die("%s", *argv);
  }
  #undef OPT_p
  #undef TASKSET_PRINTF_MASK
  #undef from_cpuset
  