Programming

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <ctype.h>
#include <errno.h>
#include <sys/time.h>
#include <sys/resource.h>
 
typedef struct  {
        int     mid;
        int     cnt;
        FILE    *fp;
} MFP;
static  MFP     *mfp = NULL;
static  int     mfpcnt = 0;
 
main(int argc, char *argv[])
{
  int   mid, n, found, maxcnt, empty, curr;
  char  buf[1024], fullname[256];
  struct rlimit rl;
 
        if(getrlimit(RLIMIT_NOFILE, &rl) == 0)
                mfpcnt = rl.rlim_cur - 8; /* leave some for other streams */
        else
                mfpcnt = 16; /* arbitrary default */
        mfp = (MFP *)malloc(sizeof(MFP) * mfpcnt);
        memset(mfp, 0, sizeof(MFP) * mfpcnt);
 
        while(fgets(buf, sizeof(buf) - 1, stdin))
        {
                mid = atoi(buf);
                sprintf(fullname, "%04i.log", mid);
                maxcnt = 0;
                empty = -1;
                found = -1;
                for(n = 0; n < mfpcnt; n++)
                {
                        if(mfp[n].mid == mid)
                        {
                                found = n;
                                break;
                        }
                        if(mfp[n].cnt > mfp[maxcnt].cnt)
                        {
                                maxcnt = n;
                        }
                        if(mfp[n].cnt == 0 && empty == -1)
                        {
                                empty = n;
                        }
                }
                if(found != -1)
                {
                        curr = found;
                }
                else
                {
                        if(empty != -1)
                        {
                                curr = empty;
                                mfp[curr].fp = fopen(fullname, "a");
                        }
                        else
                        {
                                curr = maxcnt;
                                mfp[curr].cnt = 0;
                                mfp[curr].fp = freopen(fullname, "a",
                                                mfp[curr].fp);
                        }
                }
                fputs(buf, mfp[curr].fp);
                mfp[curr].cnt++;
        }
        return(0);
}