Realloc pointer that is malloced in different function

Question

I have this function:

static void unfoldLines(char **pbuff, char **lines, int foldCount) {
    int i, j;

    for(i = 1; i <= foldCount; i++) {
        removeEOL(lines[i]);
        for(j = 0; j < strlen(lines[i]); j++) {
            while(isspace(lines[i][j])) {
                lines[i]++;
            }
        }
    }

    lines[1] = realloc(lines[1], sizeof(char) * (strlen(lines[1]) +
                strlen(lines[2]) + 1));
    exit(0);
}

lines and it's pointers has been malloced in a previous function. When I try to realloc lines[1], I get this error:

malloc: *** error for object 0x7fcec0404fe1: pointer being realloc'd was not allocated

I know it has been malloced, so why can't it be realloced in this function?

Crap! Should I a) not increment the pointer or b) is there a way around this? — MortalMan
– MortalMan, Commented Jan 19, 2016 at 2:57
I understand that incrementing the pointer changes the address, making me able to realloc/free it. I increment the pointer to remove any leading whitespace. What should I do here? — MortalMan
– MortalMan, Commented Jan 19, 2016 at 3:01

Danny_ds · Accepted Answer · 2016-01-19 03:06:47Z

2

lines[1] gets incremented in the for-loop. You should keep the original pointer(s) that are returned from malloc() and use those with realloc().

Also, realloc() can fail, so you should store the return value of realloc() in a temporary pointer, and only on success transfer that to the original pointer.

answered Jan 19, 2016 at 3:06

Danny_ds

11.4k1 gold badge26 silver badges48 bronze badges

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

Collectives™ on Stack Overflow

Realloc pointer that is malloced in different function

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related