expendxxRun.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <getopt.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <string.h>
#include <errno.h>

#define DefaultMaxFD    (40960*4)
#define BUFLEN        1024
#define errExit(msg) do { \
    perror(msg); exit(EXIT_FAILURE); \
} while (0)

/*
static struct option longopts[] = {
  { "help", 0, 0, 'h' },
  { "fd-to-expend", 0, 0, 'n' },
  { NULL, 0, 0, 0 }
};
*/

void usage(void);
/*----------------------------------------------------------------------------*/

int main(int argc, char **argv)
{
    int fd = 0, c, i;
    int nfd = 0;
    char *cmd = NULL;
    char cmdline[2048] = { 0 };
    int res;
    struct rlimit rlim;
    unsigned long max_open = DefaultMaxFD;

    //set the max open files
    memset(&rlim, 0, sizeof(rlim));
    if (getenv("maxOpen"))
        max_open=strtoul(getenv("maxOpen"),NULL,0);
    rlim.rlim_cur = max_open;
    rlim.rlim_max = max_open;
     res = setrlimit(RLIMIT_NOFILE, &rlim);
    if (res)
        perror("change open file limit failed.\n");

    //debug: argv before getopt
    if (getenv("xdebug")) {
        for (i=0; i < argc; i++) printf("B-argv[%d] %s\n", i, argv[i]);
        printf("\n");
    }

    while ((c = getopt_long(argc, argv, "n:ht",
                NULL, NULL)) != -1) {
        switch (c) {
        case 'n':
            nfd=atoi(optarg);
            break;
        case 't':
            break;
        case 'h':
        default:
            goto out_usage;
        }
    }

    //debug: argv after getopt
    if (getenv("xdebug")) {
        for (i=0; i < argc; i++) printf("A-argv[%d] %s\n", i, argv[i]);
        printf("\n");
        for (c=optind; c < argc; c++) printf("P=argv[%d] %s\n", c, argv[c]);
        printf("\n");
    }

    if (optind > argc - 1)
        goto out_usage;

    //get open file limit
     res = getrlimit(RLIMIT_NOFILE, &rlim);
    if (res) {
        perror("get open file limit failed.\n");
    } else {
        printf("==> now the open file limit: (%lu).(%lu)\n",
            rlim.rlim_cur, rlim.rlim_max);
    }

    //trace arg value
    cmd = argv[optind];
    printf("==> fd to expend = [%d]\n", nfd);
    printf("==> cmd = [%s]\n", cmd);

    //expend the fd
    fd = open("/", O_RDONLY);
    printf("==> first open fd = [%d]\n", fd);
    for (i = 1; i < nfd; i++) {
        c = open("/", O_RDONLY);
        if (c < 0) {
            fprintf(stderr, "prefd = [%d] ", fd);
            errExit("open fail.");
        } else
            fd = c;
        /* yes the fd leak is intentional */
    }

    printf("==> now max fd = [%d]\n", fd);
    for (c=optind; c < argc; c++)
        sprintf(cmdline+strlen(cmdline), "%s ", argv[c]);
    printf("==> cmdline = [%s]\n", cmdline);

    if (getenv("useSystem")) {
        res = system(cmdline);
    } else {
        res = execvp(argv[optind], &argv[optind]);
    }

    exit(res);

out_usage:
    usage();
    exit(EXIT_FAILURE);
}

void usage()
{
    fprintf(stderr, "usage: $prog [-h] [-n fsNum] \n");
}