For the life of me i cant work out why I am getting an invalid read size of 1
for this code snippet, I'm pretty sure its got something to do with me abusing the char *url pointer
...
char *extractURL(char request[])
{
char *space = malloc(sizeof(char *));
space = strchr(request, ' ')+1;
char *hostend = malloc(sizeof(char *));
hostend = strchr(request, '\r');
int length = hostend - space;
if (length > 0)
{
printf("Mallocing %d bytes for url\n.", length+1);
char *url = (char *)malloc((length+1)*sizeof(char));
url = '\0';
strncat(url, space, length);
return url;
}
//else we have hit an error so return NULL
return NULL;
}
The valgrind error I am getting is :
==4156== Invalid read of size 1
==4156== at 0x4007518: strncat (mc_replace_strmem.c:206)
==4156== by 0x8048D25: extractURL ()
==4156== by 0x8048E59: processRequest ()
==4156== by 0x8049881: main ()
==4156== Address 0x0 is not stack'd, malloc'd or (recently) free'd
Can someone 'point' me in the right direction?
Here
char *url = malloc((length+1)*sizeof(char));
url = '\0';
strncat(url, space, length);
you immediately lose the malloced memory by setting url
to NULL
. Note that '\\0'
is 0, which is a null pointer constant. And then you try to strncat
something to an invalid memory location.
You probably meant to set
*url = '\0';
there.
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