[Accel-config] Re: [PATCH] accel-config: Fix a read buffer length bug

On 2/2/2022 3:50 PM, Ramesh Thomas wrote:
> Generic function used to read a string attribute was using a buffer of
> max length 64. Attributes like op_cap exceeds that size. Change read
> buffer length to 128. Also removed a redundant memory allocation.

For sysfs attributes, max buffer size is 4k (a page). Probably should 
make all reads from sysfs to be that size?


> Signed-off-by: Ramesh Thomas <ramesh.thomas(a)intel.com>
> ---
>   accfg/lib/libaccfg.c | 14 ++------------
>   1 file changed, 2 insertions(+), 12 deletions(-)
>
> diff --git a/accfg/lib/libaccfg.c b/accfg/lib/libaccfg.c
> index 9cdd8f8..f20706c 100644
> --- a/accfg/lib/libaccfg.c
> +++ b/accfg/lib/libaccfg.c
> @@ -247,13 +247,13 @@ static uint64_t accfg_get_param_unsigned_llong(
>   static char *accfg_get_param_str(struct accfg_ctx *ctx, int dfd, char *name)
>   {
>   	int fd = openat(dfd, name, O_RDONLY);
> -	char buf[MAX_PARAM_LEN + 1];
> +	char buf[MAX_BUF_LEN + 1];
>   	int n;
>   
>   	if (fd == -1)
>   		return NULL;
>   
> -	n = read(fd, buf, MAX_PARAM_LEN);
> +	n = read(fd, buf, MAX_BUF_LEN);
>   	close(fd);
>   	if (n <= 0)
>   		return NULL;
> @@ -618,21 +618,13 @@ static void *add_device(void *parent, int id, const char *ctl_base,
>   {
>   	struct accfg_ctx *ctx = parent;
>   	struct accfg_device *device;
> -	char *path;
>   	int dfd;
>   	int rc;
>   	char *p;
>   
> -	path = calloc(1, strlen(ctl_base) + MAX_PARAM_LEN);
> -	if (!path) {
> -		err(ctx, "%s: allocation of path failed\n", __func__);
> -		return NULL;
> -	}
> -
>   	dfd = open(ctl_base, O_PATH);
>   	if (dfd == -1) {
>   		err(ctx, "%s open failed: %s\n", __func__, strerror(errno));
> -		free(path);
>   		return NULL;
>   	}
>   
> @@ -720,7 +712,6 @@ static void *add_device(void *parent, int id, const char *ctl_base,
>   		goto err_dev_path;
>   
>   	list_add_tail(&ctx->devices, &device->list);
> -	free(path);
>   
>   	return device;
>   
> @@ -730,7 +721,6 @@ err_read:
>   	free(device->mdev_path);
>   	free(device);
>   err_device:
> -	free(path);
>   	return NULL;
>   }
>