"Han-Wen Nienhuys via GitGitGadget" <gitgitgadget@xxxxxxxxx> writes:
> From: Han-Wen Nienhuys <hanwen@xxxxxxxxxx>
>
> Signed-off-by: Han-Wen Nienhuys <hanwen@xxxxxxxxxx>
> ---
> reftable/record.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/reftable/record.c b/reftable/record.c
> index fbaa1fbef56..423e687b220 100644
> --- a/reftable/record.c
> +++ b/reftable/record.c
> @@ -126,7 +126,8 @@ static int encode_string(char *str, struct string_view s)
> string_view_consume(&s, n);
> if (s.len < l)
> return -1;
> - memcpy(s.buf, str, l);
> + if (l)
> + memcpy(s.buf, str, l);
> string_view_consume(&s, l);
>
> return start.len - s.len;
> @@ -153,7 +154,9 @@ int reftable_encode_key(int *restart, struct string_view dest,
>
> if (dest.len < suffix_len)
> return -1;
> - memcpy(dest.buf, key.buf + prefix_len, suffix_len);
> +
> + if (suffix_len)
> + memcpy(dest.buf, key.buf + prefix_len, suffix_len);
> string_view_consume(&dest, suffix_len);
>
> return start.len - dest.len;
> @@ -569,7 +572,8 @@ static int reftable_obj_record_decode(void *rec, struct strbuf key,
> uint64_t last;
> int j;
> r->hash_prefix = reftable_malloc(key.len);
> - memcpy(r->hash_prefix, key.buf, key.len);
> + if (key.len)
> + memcpy(r->hash_prefix, key.buf, key.len);
> r->hash_prefix_len = key.len;
>
> if (val_type == 0) {
I am not sure why any of these are needed.
For a code path that involves a <ptr, len> pair, where ptr is lazily
allocated only when we have contents to store, i.e. ptr can remain
NULL until len becomes non-zero, memcpy(dst, ptr, len) can become a
problem as the standard requires ptr to be a valid even when len is
0 (ISO/IEC 9899:1999, 7.21.1 String function conventions, paragraph
2), but none of these three calls to memcpy() do any such thing.
Puzzled.
