如何用copendir实现Linux目录的筛选遍历

#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>
#include <string.h>
#include <sys/stat.h>

// 函数：检查文件类型是否匹配
int checkfiletype(const char *path, const char *type) {
    if (strcmp(type, "all") == 0) return 1; // 不筛选

    char ext[10];
    const char *dot = strrchr(path, '.');
    if (dot && dot > path) {
        size_t len = dot - path;
        if (len >= sizeof(ext)) len = sizeof(ext) - 1;
        strncpy(ext, dot + 1, len);
        ext[len] = '\0';
    } else {
        strcpy(ext, "");
    }
    return strcmp(ext, type) == 0;
}

// 函数：递归遍历目录并筛选
void traversedir(const char *path, const char *filter) {
    dir *dir = opendir(path);
    if (dir == null) {
        perror("opendir");
        return;
    }

    struct dirent *entry;
    while ((entry = readdir(dir)) != null) {
        if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) continue;

        char fullpath[path_max];
        snprintf(fullpath, sizeof(fullpath), "%s/%s", path, entry->d_name);

        struct stat st;
        if (stat(fullpath, &st) == -1) {
            perror("stat");
            continue;
        }

        if (s_isdir(st.st_mode)) {
            traversedir(fullpath, filter);
        } else if (s_isreg(st.st_mode)) {
            if (checkfiletype(fullpath, filter)) {
                printf("文件: %s\n", fullpath);
            }
        }
    }
    closedir(dir);
}

int main(int argc, char *argv[]) {
    if (argc != 3) {
        fprintf(stderr, "用法: %s <目录路径> <过滤器>\n", argv[0]);
        fprintf(stderr, "过滤器示例:\n");
        fprintf(stderr, "  all       - 所有文件\n");
        fprintf(stderr, "  txt       - .txt文件\n");
        fprintf(stderr, "  jpg,png   - .jpg或.png文件\n");
        return exit_failure;
    }

    const char *directory = argv[1];
    const char *filter = argv[2];
    traversedir(directory, filter);
    return exit_success;
}