Adding '\0' to end of non null terminated "string"

Question

So I'm reading from a file into a buffer. By default, this method doesn't null terminate my string.

size_t result;
size_t total = 0;

/* Get the file size */
FILE* pfile; 
pfile = fopen(filename, "rb");
fseek(pfile, 0, SEEK_END);
long lfile = ftell(pfile);
rewind(pfile);

char* file_buffer = malloc(sizeof(char) * lfile);
while ((result = fread(file_buffer, 1, lfile, pfile)) > 0)
{
    total += result; 
}

resp->content_length = lfile;
file_buffer[lfile] = '\0'; //so I try to null terminate it here.

But I'm getting invalid write of size 1. What am I doing wrong?

Is there another way to null terminate what's in my buffer?

What do you mean by invalid write? BTW, you are allocating size lfile and you are trying to access a position outside it file_buffer[lfile] = '\0'. — wendelbsilva
– wendelbsilva, Commented Dec 4, 2013 at 22:41

Jens Gustedt · Accepted Answer · 2013-12-04 22:40:42Z

4

Your computation of the string length seems to be wrong in the call to malloc. You have to add 1 to account for the 0 character.

Edit: BTW, your use of sizeof(char) is ... useless. sizeof and malloc are just defined that they count things in the size of a char, so sizeof(char) will always be 1.

answered Dec 4, 2013 at 22:40

Jens Gustedt

79.3k9 gold badges110 silver badges184 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Kerrek SB · Accepted Answer · 2013-12-04 22:41:27Z

1

file_buffer[lfile] is out of bounds, since file_buffer only has lfile elements. It's like saying int x[1]; x[1] = 0;.

answered Dec 4, 2013 at 22:41

Kerrek SB

480k96 gold badges904 silver badges1.1k bronze badges

Collectives™ on Stack Overflow

Adding '\0' to end of non null terminated "string"

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related