[lxc-devel] [PATCH lxcfs 4/5] cgfs: fix dorealloc's batch allocation

[Serge Hallyn]

Quoting Wolfgang Bumiller (w.bumiller at proxmox.com):
> The initial check should use real lengths as with modulo a
> new required length of eg. 52 would be considered smaller
> than an old length of 48 (2 < 48).
> 
> To get the 'batches' count 'newlen' must be divided and not
> taken modulo BATCH_SIZE. Otherwise '101', which would need a
> 3rd batch to reach 150, would end up with two (2*50 = 100
> bytes) and thereby be truncated instead.
> 
> Signed-off-by: Wolfgang Bumiller <w.bumiller at proxmox.com>

Acked-by: Serge E. Hallyn <serge.hallyn at ubuntu.com>

> ---
>  cgfs.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/cgfs.c b/cgfs.c
> index 0659e9e..681a478 100644
> --- a/cgfs.c
> +++ b/cgfs.c
> @@ -75,9 +75,9 @@ static inline void drop_trailing_newlines(char *s)
>  static void dorealloc(char **mem, size_t oldlen, size_t newlen)
>  {
>  	int batches;
> -	if (newlen % BATCH_SIZE <= oldlen % BATCH_SIZE)
> +	if (newlen <= oldlen)
>  		return;
> -	batches = (newlen % BATCH_SIZE) + 1;
> +	batches = (newlen / BATCH_SIZE) + 1;
>  	if (!*mem) {
>  		do {
>  			*mem = malloc(batches * BATCH_SIZE);
> -- 
> 2.1.4
> 
> 
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