如何使用openssl/sha.h对文本文件进行SHA256散列

#include <openssl/sha.h>

FILE *file = fopen("filename.txt", "rb");
if (file == NULL) {
    // 处理文件打开失败的情况
}

fseek(file, 0, SEEK_END);
long file_size = ftell(file);
rewind(file);

unsigned char *buffer = (unsigned char *)malloc(file_size);
if (buffer == NULL) {
    // 处理内存分配失败的情况
}

fread(buffer, 1, file_size, file);
fclose(file);

unsigned char hash[SHA256_DIGEST_LENGTH];
SHA256(buffer, file_size, hash);

for (int i = 0; i < SHA256_DIGEST_LENGTH; i++) {
    printf("%02x", hash[i]);
}
printf("\n");

#include <stdio.h>
#include <stdlib.h>
#include <openssl/sha.h>

int main() {
    FILE *file = fopen("filename.txt", "rb");
    if (file == NULL) {
        // 处理文件打开失败的情况
        return 1;
    }

    fseek(file, 0, SEEK_END);
    long file_size = ftell(file);
    rewind(file);

    unsigned char *buffer = (unsigned char *)malloc(file_size);
    if (buffer == NULL) {
        // 处理内存分配失败的情况
        fclose(file);
        return 1;
    }

    fread(buffer, 1, file_size, file);
    fclose(file);

    unsigned char hash[SHA256_DIGEST_LENGTH];
    SHA256(buffer, file_size, hash);

    for (int i = 0; i < SHA256_DIGEST_LENGTH; i++) {
        printf("%02x", hash[i]);
    }
    printf("\n");

    free(buffer);

    return 0;
}