如何在Linux中使用POSIX方法从文件中读取Unicode-16字符串？

#include <fcntl.h>
#include <unistd.h>

int fd = open("file.txt", O_RDONLY);
if (fd == -1) {
    // 打开文件失败，处理错误
}

#include <sys/types.h>
#include <unistd.h>

char buf[BUFSIZ];
ssize_t n = read(fd, buf, sizeof(buf));
if (n == -1) {
    // 读取文件失败，处理错误
}

#include <iconv.h>

iconv_t cd = iconv_open("UCS-4LE", "UTF-16LE");
if (cd == (iconv_t)-1) {
    // 打开转换器失败，处理错误
}

char *inbuf = buf;
size_t inbytesleft = n;
char *outbuf = malloc(n * 2);
size_t outbytesleft = n * 2;

if (iconv(cd, &inbuf, &inbytesleft, &outbuf, &outbytesleft) == -1) {
    // 解码失败，处理错误
}

iconv_close(cd);

#include <wchar.h>

wchar_t *str = (wchar_t *)outbuf;
size_t len = n / 2;

// 处理字符串

close(fd);

#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <iconv.h>
#include <wchar.h>

int main() {
    int fd = open("file.txt", O_RDONLY);
    if (fd == -1) {
        // 打开文件失败，处理错误
        return 1;
    }

    char buf[BUFSIZ];
    ssize_t n = read(fd, buf, sizeof(buf));
    if (n == -1) {
        // 读取文件失败，处理错误
        close(fd);
        return 1;
    }

    iconv_t cd = iconv_open("UCS-4LE", "UTF-16LE");
    if (cd == (iconv_t)-1) {
        // 打开转换器失败，处理错误
        close(fd);
        return 1;
    }

    char *inbuf = buf;
    size_t inbytesleft = n;
    char *outbuf = malloc(n * 2);
    size_t outbytesleft = n * 2;

    if (iconv(cd, &inbuf, &inbytesleft, &outbuf, &outbytesleft) == -1) {
        // 解码失败，处理错误
        iconv_close(cd);
        close(fd);
        return 1;
    }

    iconv_close(cd);

    wchar_t *str = (wchar_t *)outbuf;
    size_t len = n / 2;

    // 处理字符串

    close(fd);
    return 0;
}