从gpio0/direction正确读取文本的C语言函数demo

以下是一个从gpio0/direction正确读取文本的C语言函数demo：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define BUFFER_SIZE 1024

char *read_gpio_direction() {
    FILE *fp;
    char *buffer = NULL;
    char *result = NULL;
    size_t len = 0;
    ssize_t read;

    fp = fopen("/sys/class/gpio/gpio0/direction", "r");
    if (fp == NULL) {
        printf("Failed to open gpio direction file.\n");
        return NULL;
    }

    read = getline(&buffer, &len, fp);
    if (read == -1) {
        printf("Failed to read gpio direction file.\n");
        fclose(fp);
        return NULL;
    }

    result = (char *) malloc(strlen(buffer) + 1);
    if (result == NULL) {
        printf("Failed to allocate memory.\n");
        fclose(fp);
        return NULL;
    }

    strcpy(result, buffer);

    free(buffer);
    fclose(fp);

    return result;
}

int main() {
    char *direction = read_gpio_direction();
    printf("GPIO direction: %s\n", direction);
    free(direction);
    return 0;
}

这个函数通过打开gpio0/direction文件并使用getline函数读取文件内容，然后使用malloc函数来分配内存并复制读取到的文本。最后关闭文件并返回结果。在主函数中调用这个函数并打印结果。