cs50 恢复仍然可达，但没有 valgrind 错误

Question

我已经在“恢复”程序中苦苦挣扎了几个小时，但似乎找不到问题。

我以为我已经关闭了所有文件，而且我还没有使用“malloc”语法进行内存分配。

您能给我一些提示或指导吗？非常感谢！

我也尝试过使用 Valgrind，它显示如下：

==34245== Memcheck, a memory error detector
==34245== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==34245== Using Valgrind-3.18.1 and LibVEX; rerun with -h for copyright info
==34245== Command: ./recover card.raw
==34245== 
==34245== 
==34245== HEAP SUMMARY:
==34245==     in use at exit: 944 bytes in 2 blocks
==34245==   total heap usage: 104 allocs, 102 frees, 233,912 bytes allocated
==34245== 
==34245== 944 bytes in 2 blocks are still reachable in loss record 1 of 1
==34245==    at 0x4848899: malloc (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==34245==    by 0x4A076CD: __fopen_internal (iofopen.c:65)
==34245==    by 0x4A076CD: fopen@@GLIBC_2.2.5 (iofopen.c:86)
==34245==    by 0x1092A9: main (recover.c:48)
==34245== 
==34245== LEAK SUMMARY:
==34245==    definitely lost: 0 bytes in 0 blocks
==34245==    indirectly lost: 0 bytes in 0 blocks
==34245==      possibly lost: 0 bytes in 0 blocks
==34245==    still reachable: 944 bytes in 2 blocks
==34245==         suppressed: 0 bytes in 0 blocks
==34245== 
==34245== For lists of detected and suppressed errors, rerun with: -s
==34245== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

我的代码如下：

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


int main(int argc, char *argv[])
{
     // Ensure proper usage
    if (argc != 2)
    {
        printf("Usage: ./recover card\n");
        return 1;
    }

    //If the forensic image cannot be opened for reading, your program should inform the user as much, and main should return 1.
    // Remember filenames
    char *infile = argv[1];
    // Open input file
    FILE *inptr = fopen(infile, "r");

    if (inptr == NULL)
    {
        printf("Could not open %s.\n", infile);
        fclose(inptr);
        return 1;
    }

    // block size is 512 bytes
    typedef uint8_t BYTE;

    int BLOCK_SIZE = sizeof(BYTE) * 512;

    BYTE buffer[BLOCK_SIZE];

    int index = 0;

    FILE *img = NULL;

    //The files you generate should each be named ###.jpg, where ### is a three-digit decimal number, starting with 000 for the first image and counting up.
    while (fread(buffer, 1, BLOCK_SIZE, inptr) == BLOCK_SIZE)
    {
        char filename[8];

        // is first pic.
        if (index == 0 ) {

            sprintf(filename, "%03i.jpg", index);
            img = fopen(filename, "w");

            if (buffer[0] == 0xff && buffer[1] == 0xd8 && buffer[2] == 0xff && (buffer[3] & 0xf0) == 0xe0) {
                if (img != NULL) {
                    fwrite(buffer, 1, BLOCK_SIZE, img);
                }
                index ++;
            }
        } else {
            //is not first pic
            if (buffer[0] == 0xff && buffer[1] == 0xd8 && buffer[2] == 0xff && (buffer[3] & 0xf0) == 0xe0) {
                //is a new img
                //close prev img
                if (img != NULL) {
                    fclose(img);
                }
                // open a new img
                sprintf(filename, "%03i.jpg", index);
                img = fopen(filename, "w");
                fwrite(buffer, 1, BLOCK_SIZE, img);
                index ++;
            } else {
                //keep writing
                fwrite(buffer, 1, BLOCK_SIZE, img);
            }
        }
    //Your program, if it uses malloc, must not leak any memory.
    }
    if (img != NULL) {
        fclose(img);
    }
    fclose(inptr);
    return(0);
}

Answer 1

根据退休忍者的评论解决了问题。

愚蠢的错误...

我找到第一个img后打开第一个img文件，然后解决问题。

感谢论坛！

  // is first pic.
    if (index == 0 ) {

        sprintf(filename, "%03i.jpg", index); //
        img = fopen(filename, "wb"); //

        if (buffer[0] == 0xff && buffer[1] == 0xd8 && buffer[2] == 0xff && (buffer[3] & 0xf0) == 0xe0) {
        sprintf(filename, "%03i.jpg", index); 
        img = fopen(filename, "w");
            if (img != NULL) {
                fwrite(buffer, 1, BLOCK_SIZE, img);
            }
            index ++;
        }
    }