source: MondoRescue/branches/3.2/mindi-busybox/miscutils/taskset.c@ 3186

/* vi: set sw=4 ts=4: */
/*
 * taskset - retrieve or set a processes' CPU affinity
 * Copyright (c) 2006 Bernhard Reutner-Fischer
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */

#include <sched.h>
#include "libbb.h"

#if ENABLE_FEATURE_TASKSET_FANCY
#define TASKSET_PRINTF_MASK "%s"
/* craft a string from the mask */
static char *from_cpuset(cpu_set_t *mask)
{
    int i;
    char *ret = NULL;
    char *str = xzalloc((CPU_SETSIZE / 4) + 1); /* we will leak it */

    for (i = CPU_SETSIZE - 4; i >= 0; i -= 4) {
        int 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++ = bb_hexdigits_upcase[val] | 0x20;
    }
    return ret;
}
#else
#define TASKSET_PRINTF_MASK "%llx"
static unsigned long long from_cpuset(cpu_set_t *mask)
{
    struct BUG_CPU_SETSIZE_is_too_small {
        char BUG_CPU_SETSIZE_is_too_small[
            CPU_SETSIZE < sizeof(int) ? -1 : 1];
    };
    char *p = (void*)mask;

    /* Take the least significant bits. Careful!
     * Consider both CPU_SETSIZE=4 and CPU_SETSIZE=1024 cases
     */
#if BB_BIG_ENDIAN
    /* For big endian, it means LAST bits */
    if (CPU_SETSIZE < sizeof(long))
        p += CPU_SETSIZE - sizeof(int);
    else if (CPU_SETSIZE < sizeof(long long))
        p += CPU_SETSIZE - sizeof(long);
    else
        p += CPU_SETSIZE - sizeof(long long);
#endif
    if (CPU_SETSIZE < sizeof(long))
        return *(unsigned*)p;
    if (CPU_SETSIZE < sizeof(long long))
        return *(unsigned long*)p;
    return *(unsigned long long*)p;
}
#endif


int taskset_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int taskset_main(int argc UNUSED_PARAM, char **argv)
{
    cpu_set_t mask;
    pid_t pid = 0;
    unsigned opt_p;
    const char *current_new;
    char *pid_str;
    char *aff = aff; /* for compiler */

    /* NB: we mimic util-linux's taskset: -p does not take
     * an argument, i.e., "-pN" is NOT valid, only "-p N"!
     * Indeed, util-linux-2.13-pre7 uses:
     * getopt_long(argc, argv, "+pchV", ...), not "...p:..." */

    opt_complementary = "-1"; /* at least 1 arg */
    opt_p = getopt32(argv, "+p");
    argv += optind;

    if (opt_p) {
        pid_str = *argv++;
        if (*argv) { /* "-p <aff> <pid> ...rest.is.ignored..." */
            aff = pid_str;
            pid_str = *argv; /* NB: *argv != NULL in this case */
        }
        /* else it was just "-p <pid>", and *argv == NULL */
        pid = xatoul_range(pid_str, 1, ((unsigned)(pid_t)ULONG_MAX) >> 1);
    } else {
        aff = *argv++; /* <aff> <cmd...> */
        if (!*argv)
            bb_show_usage();
    }

    current_new = "current\0new";
    if (opt_p) {
 print_aff:
        if (sched_getaffinity(pid, sizeof(mask), &mask) < 0)
            bb_perror_msg_and_die("can't %cet pid %d's affinity", 'g', pid);
        printf("pid %d's %s affinity mask: "TASKSET_PRINTF_MASK"\n",
                pid, current_new, from_cpuset(&mask));
        if (!*argv) {
            /* Either it was just "-p <pid>",
             * or it was "-p <aff> <pid>" and we came here
             * for the second time (see goto below) */
            return EXIT_SUCCESS;
        }
        *argv = NULL;
        current_new += 8; /* "new" */
    }

    { /* Affinity was specified, translate it into cpu_set_t */
        unsigned i;
        /* Do not allow zero mask: */
        unsigned long long m = xstrtoull_range(aff, 0, 1, ULLONG_MAX);
        enum { CNT_BIT = CPU_SETSIZE < sizeof(m)*8 ? CPU_SETSIZE : sizeof(m)*8 };

        CPU_ZERO(&mask);
        for (i = 0; i < CNT_BIT; i++) {
            unsigned long long bit = (1ULL << i);
            if (bit & m)
                CPU_SET(i, &mask);
        }
    }

    /* Set pid's or our own (pid==0) affinity */
    if (sched_setaffinity(pid, sizeof(mask), &mask))
        bb_perror_msg_and_die("can't %cet pid %d's affinity", 's', pid);

    if (!argv[0]) /* "-p <aff> <pid> [...ignored...]" */
        goto print_aff; /* print new affinity and exit */

    BB_EXECVP_or_die(argv);
}