Right arrow symbol causing abrupt end of fread?

问题

I am attempting to write a bittorrent client. In order to parse the file etc. I need to read a torrent file into memory. I have noticed that fread is not reading the entire file into my buffer. After further investigation it appears that whenever the symbol shown below is encountered in the file, fread stops reading the file. Calling the feof function on the FILE* pointer returns 16 indicating that the end of file has been reached. This occurs no matter where the symbol is placed. Can somebody explain why this happens and any solutions that may work.

The symbol is highlighted below:

Here is the code that does the read operation:

char *read_file(const char *file, long long *len){
struct stat st;
char *ret = NULL;
FILE *fp;

//store the size/length of the file
if(stat(file, &st)){
    return ret;
}
*len = st.st_size;

//open a stream to the specified file
fp = fopen(file, "r");
if(!fp){
    return ret;
}

//allocate space in the buffer for the file
ret = (char*)malloc(*len);
if(!ret){
    return NULL;
}

//Break down the call to fread into smaller chunks
//to account for a known bug which causes fread to
//behave strangely with large files

//Read the file into the buffer
//fread(ret, 1, *len, fp);
if(*len > 10000){
    char *retTemp = NULL;
    retTemp = ret;
    int remaining = *len;
    int read = 0, error = 0;
    while(remaining > 1000){
        read = fread(retTemp, 1, 1000, fp);
        if(read < 1000){
            error = feof(fp);
            if(error != 0){
                printf("Error: %d\n", error);
            }
        }
        retTemp += 1000;
        remaining -= 1000;
    }
    fread(retTemp, 1, remaining, fp);
} else {
    fread(ret, 1, *len, fp);
}

//cleanup by closing the file stream
fclose(fp);

return ret;
}

Thank you for your time :)

回答1:

Your question is oddly relevant as I recently ran into this problem in an application here at work last week!

The ASCII value of this character is decimal 26 (0x1A, \SUB, SUBSTITUTE). This is used to represent the CTRL+Z key sequence or an End-of-File marker.

Change your fopen mode ("In [Text] mode, CTRL+Z is interpreted as an end-of-file character on input.") to get around this on Windows:

fp = fopen(file, "rb"); /* b for 'binary', disables Text-mode translations */

回答2:

You should open the file in binary mode. Some platforms, in text (default) mode, interpret some bytes as being physical end of file markers.

回答3:

You're opening the file in text rather than raw/binary mode - the arrow is ASCII for EOF. Specify "rb" rather than just "r" for your fopen call.

来源：https://stackoverflow.com/questions/11547443/right-arrow-symbol-causing-abrupt-end-of-fread

标签

msvcrt