Re: [PATCH 1/6] path.c: allocate enough memory for string

Stefan Beller [off-list ref] writes:

On Tue, Mar 29, 2016 at 5:57 PM, Eric Sunshine [off-list ref] wrote:

quoted

On Tue, Mar 29, 2016 at 8:38 PM, Stefan Beller [off-list ref] wrote:

quoted

`strlen` returns the length of a string without the terminating null byte.
To make sure enough memory is allocated we need to pass `strlen(..) + 1`
to the allocation function.

Signed-off-by: Stefan Beller <redacted>
---

diff --git a/path.c b/path.c

@@ -155,7 +155,7 @@ static struct trie *make_trie_node(const char *key, void *value)
        struct trie *new_node = xcalloc(1, sizeof(*new_node));
        new_node->len = strlen(key);
        if (new_node->len) {
-               new_node->contents = xmalloc(new_node->len);
+               new_node->contents = xmalloc(new_node->len + 1);
                memcpy(new_node->contents, key, new_node->len);

Huh? This is a trie. It never accesses 'contents' as a NUL-terminated
string. Plus, no NUL is ever even copied, thus this is just
overallocating. How is this an improvement?

By using strlen, I assumed it was a standard C string.
I missed that, though.

You took hint from a wrong place.  You are auditing the destination
buffer, so the correct place to take hint from is the memcpy() that
touches the destination.