fseek（）和ftell（）在循环中失败(fseek() and ftell() fail in a loop)

 我需要通过一个目录， data循环并读取符合某些条件的每个文件，并以字符串形式进行操作。 出于某种原因，它在fseek调用后失败（输出只是目录中第一个文件的名称）。 
 
 任何想法我做错了什么？ 
 
#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>
#include <string.h>

void doAlgorithm(char *input) {
    printf("%s\n", input);
}

int main(int argc, char** argv) {
    struct dirent *dir;
    DIR *d = opendir("data");
    FILE *file;
    while ((dir = readdir(d)) != NULL) {
        if (strlen(dir->d_name) > 6 && dir->d_name[6] == 'i') {
            printf("Filename: %s\n", dir->d_name);
            file = fopen(dir->d_name, "r");
            fseek(file, 0, SEEK_END);
            long length = ftell(file);
            fseek(file, 0, SEEK_SET);
            printf(", Filesize: %ld\n", length);

            char *buffer = malloc(length + 1);
            fread(buffer, 1, length, file);
            buffer[length] = '\0';

            fclose(file);
            doAlgorithm(buffer);
        }
    }
    closedir(d);
    return (EXIT_SUCCESS);
}

I need to loop trough a directory, data and read each file, that meets certain conditions, in a string and do something with it. For some reason it fails after the fseek call (the output is only the name of the first file in the directory).
 
Any idea what am I doing wrong?
 
#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>
#include <string.h>

void doAlgorithm(char *input) {
    printf("%s\n", input);
}

int main(int argc, char** argv) {
    struct dirent *dir;
    DIR *d = opendir("data");
    FILE *file;
    while ((dir = readdir(d)) != NULL) {
        if (strlen(dir->d_name) > 6 && dir->d_name[6] == 'i') {
            printf("Filename: %s\n", dir->d_name);
            file = fopen(dir->d_name, "r");
            fseek(file, 0, SEEK_END);
            long length = ftell(file);
            fseek(file, 0, SEEK_SET);
            printf(", Filesize: %ld\n", length);

            char *buffer = malloc(length + 1);
            fread(buffer, 1, length, file);
            buffer[length] = '\0';

            fclose(file);
            doAlgorithm(buffer);
        }
    }
    closedir(d);
    return (EXIT_SUCCESS);
}

原文：https://stackoverflow.com/questions/43412417