Retrieve process name from pid using sysctl (Darwin)

pid2name.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/sysctl.h>

int main(int argc, char** argv) {
    int mib[3], argmax;
    size_t syssize;
    char *procargs, *cp, *thiscmd;

    mib[0] = CTL_KERN;
    mib[1] = KERN_ARGMAX;

    syssize = sizeof(argmax);
    if (sysctl(mib, 2, &argmax, &syssize, NULL, 0) == -1) {
        goto _end;
    }

    procargs = malloc(argmax);
    if (procargs == NULL) {
        goto _end;
    }

    mib[0] = CTL_KERN;
    mib[1] = KERN_PROCARGS;
    mib[2] = strtol(argv[1], NULL, 10);

    syssize = (size_t)argmax;
    if (sysctl(mib, 3, procargs, &syssize, NULL, 0) == -1) {
        free(procargs);
        goto _end;
    }

    for (cp = procargs; cp < &procargs[syssize]; cp++) {
        if (*cp == '\0') {
            break;
        }
    }

    if (cp == &procargs[syssize]) {
        free(procargs);
        goto _end;
    }

    for (; cp < &procargs[syssize]; cp++) {
        if (*cp != '\0') {
            break;
        }
    }

    if (cp == &procargs[syssize]) {
        free(procargs);
        goto _end;
    }

    /* Strip off any path that was specified */
    for (thiscmd = cp; (cp < &procargs[syssize]) && (*cp != '\0'); cp++) {
        if (*cp == '/') {
            thiscmd = cp + 1;
        }
    }

    printf("%s\n", thiscmd);

_end:

    return 0;
}