我把自己逼疯了，试图弄清楚我的代码发生了什么。
我目前在 CS50 的 pset4 中。恢复挑战。
对于那些不知道它是关于什么的人： 我们得到了一个名为card的文件.raw其中有一些已删除的照片。我们的任务是实施一个程序，该程序可以进行一些取证(田园诗般的)并恢复丢失的照片。
特此附上我的代码：
#include <stdio.h>
#include <stdint.h>
int main(int argc, char *argv[])
{
if (argc != 2)
{
fprintf(stderr, "Usage: ./recover filen");
return 1;
}
//declaring pointer infile and giving the address of argv[1];
char *infile = argv[1];
//Opening file
FILE *raw_data;
raw_data = fopen(infile, "r");
//Checking for NULL error
if(raw_data == NULL)
{
fprintf(stderr, "Could not open file.n");
return 2;
}
uint8_t buffer[512]; //Delcaring unsigned int variable type. Array of 512 bytes.
int counter = 0; //Declaring counter for counting jpegs files
FILE *outfile; //Setting pointer named outfile for printing here
char filename[8]; //declaring 'filename' variable for storing the file's name
//While we can reads blocks of memory of 512 bytes from raw_data (aka the address from the infile) into buffer:
while (fread(buffer, 512, 1, raw_data))
{
//Condition for tracking the first bytes that form a JPEG file
if(buffer[0] == 0xff &&
buffer[1] == 0xd8 &&
buffer[2] == 0xff &&
(buffer[3] & 0xf0) == 0xe0)
{
if(counter == 0) //If this is the 1st file, then name the file with
//counter value with 3 digits (%03d)
{
sprintf(filename, "%03d.jpg", counter); // And 3 digits (%i3)
outfile = fopen(filename, "w"); //Open file named outfile in write mode
counter++;
}
else //If this is not the first JPG opened, firstly close the
{ // current open file, and then open a new one with the
fclose(outfile); // current counter value and 3 digits for its name
sprintf(filename, "%03d.jpg", counter);
outfile = fopen(filename, "w"); //Open file named 'outfile' in write mode
counter++;
}
}
fwrite(buffer, 1, sizeof(buffer), outfile); /* Write function that takes buffer data (aka the
pointer to the array of elements to be written,
writes 1 byte of elements of the syze buffer (512)
and it writes it to the output, aka 'outfile' */
}
fclose(outfile); //Remember to close the last file once we get out of the while-loop
}
这是棘手的部分：
我已经成功恢复了所有有问题的图像。 但是，如果我多次运行代码，例如 5 次，我最终会遇到分段错误。
当我运行 check50时，我收到以下消息(在成功运行和 check50 veredict 之后，我将附加一个包含分段错误的图像)。点击这里查看图片
我就是不明白。我怀疑记忆可能有些问题，但我不知道是什么。
非常感谢您的时间和帮助。StackOVerFlow总是一个寻求指导的好地方。
编辑
如果我在分段错误提示后运行echo $?，则得到的值为 139。
这是终端提示截图
编辑
正如@Thomas Dickey指出的那样，程序正在写入文件，无论是否有打开的文件。
我已经更新并修复了一些我的代码以使其更干净，并添加了一个 if 条件以修复它。
这是解决方案：
#include <stdio.h>
#include <stdint.h>
int main(int argc, char *argv[])
{
if (argc != 2)
{
fprintf(stderr, "Usage: ./recover filen");
return 1;
}
//declaring pointer infile and giving the address of argv[1];
char *infile = argv[1];
//Opening file
FILE *raw_data;
raw_data = fopen(infile, "r");
//Checking for NULL error
if(raw_data == NULL)
{
fprintf(stderr, "Could not open file.n");
return 2;
}
uint8_t buffer[512]; //Delcaring unsigned int variable type. Array of 512 bytes.
int counter = 0; //Declaring counter for counting jpegs files
FILE *outfile; //Setting pointer named outfile for printing here
char filename[8]; //declaring 'filename' variable for storing the file's name
//While we can reads blocks of memory of 512 bytes from raw_data (aka the address from the infile) into buffer:
while (fread(buffer, 512, 1, raw_data))
{
//Condition for tracking the first bytes that form a JPEG file
if(buffer[0] == 0xff &&
buffer[1] == 0xd8 &&
buffer[2] == 0xff &&
(buffer[3] & 0xf0) == 0xe0)
{
if(counter != 0)
{
fclose(outfile); //If this is not the first JPG opened, close previous file
}
sprintf(filename, "%03d.jpg", counter); //print stream to 'filename' the value of 'counter' in 3 digits
outfile = fopen(filename, "w"); //Open file named outfile in write mode
counter++; //Add 1 to counter
}
if(counter != 0) //Don't start writing on a file until the first jpeg is found
{
fwrite(buffer, sizeof(buffer), 1, outfile); /* - Write function that takes buffer data
(aka the array of elements to be written) ,
- Write a block of 512 bytes of elements
(aka the size of buffer),
- 1 block of 512 bytes at a time,
- And it writes it to the output, aka 'outfile' */
}
}
fclose(outfile); //Remember to close the last file once we get out of the while-loop
return 0;
}
程序仅在标头看起来正常时打开输出文件，但无论如何都会写入输出。 如果您读取的文件没有 jpeg 标头，它将中断。