so2 lab4 pb1

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <dirent.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <unistd.h>
#include <ctype.h>

#define BUFF_SIZE (1 << 12)

void procRegFile(const char path[]) {
    int fd = open(path, O_RDONLY);
    if (fd <= 0) {
        perror("");
        exit(-1);
    }
    int cntLower = 0;
    char ch;
    while (read(fd, &ch, 1)) {
        if (islower(ch)) {
            cntLower++;
        }
    }
    if (close(fd)) {
        perror("");
    }
    exit(cntLower);
}

void procEntry(const char path[], int *kids) {
    struct stat statbuf;
    if (stat(path, &statbuf)) {
        perror("");
        exit(-1);
    }

    if (!S_ISREG(statbuf.st_mode)) {
        return;
    }

    pid_t kidPid = fork();
    if (kidPid < 0) {
        perror("");
        exit(-1);
    }

    if (kidPid == 0) {//kid
        procRegFile(path);
    }
    (*kids)++;
}

void iterDir(const char path[]) {
    DIR *dir = opendir(path);
    if (dir == NULL) {
        perror("");
        exit(-1);
    }
    int kids = 0, globalCnt = 0;
    for (struct dirent *dep; (dep = readdir(dir));) {
        const char *const dname = dep->d_name;
        if (!strcmp(dname, ".") || !strcmp(dname, "..")) {
            continue;
        }

        char absPath[BUFF_SIZE];
        sprintf(absPath, "%s/%s", path, dname);
        procEntry(absPath, &kids);
    }
    if (closedir(dir)) {
        perror("");
    }

    int wstat = 0;
    pid_t wr;
    while ((wr = wait(&wstat)))
    {
        if (wr == -1) {
            perror("");
            exit(-1);
        }
        if (WIFEXITED(wstat)) {
            int cnt = WEXITSTATUS(wstat);
            globalCnt += cnt;
        }
        kids--;
        if (kids == 0) {
            break;
        }
    }
    printf("%d\n", globalCnt);
}

int main(int argc, char *argv[]) {
    if (argc != 2) {
        fprintf(stderr, "Wrong usage!\n");
        exit(1);
    }
    iterDir(argv[1]);
    return 0;
}