Re: hostctl: Change from fixed length to variable length

[YASUOKA Masahiko]

Hi,

Sorry for separating emails.

On Tue, 27 Dec 2022 11:58:34 +0900 (JST)
YASUOKA Masahiko <yasu...@openbsd.org> wrote:
>> @@ -1115,12 +1116,19 @@ xs_kvop(void *xsc, int op, char *key, char *value, 
>> size_t valuelen)
>>              }
>>              /* FALLTHROUGH */
>>      case XS_LIST:
>> -            for (i = 0; i < iov_cnt; i++) {
>> -                    if (i && strlcat(value, "\n", valuelen) >= valuelen)
>> -                            break;
>> -                    if (strlcat(value, iovp[i].iov_base,
>> -                        valuelen) >= valuelen)
>> +            for (i = pos = 0; i < iov_cnt; i++) {
>> +                    if (i) {
> 
> this is come from the previous, but I prefer comparing with 0
> 
> +                     if (i > 0) {
> 
>> +                            if (pos + 1 >= valuelen) {
>> +                                    error = ERANGE;
>> +                                    break;
>> +                            }
>> +                            value[pos++] = '\n';
>> +                    }
>> +                    if (strlen(iovp[i].iov_base) >= valuelen) {
>> +                            error = ERANGE;
>>                              break;
>> +                    }
>> +                    pos += strlcat(&value[pos], iovp[i].iov_base, valuelen 
>> - pos);
>>              }
>>              xs_resfree(&xst, iovp, iov_cnt);
>>              break;
>

Also I don't think replacing strlcat() by an own calculation is necessary.

diff --git a/sys/dev/pv/xenstore.c b/sys/dev/pv/xenstore.c
index 494eb40bfb0..01ecebdf4af 100644
--- a/sys/dev/pv/xenstore.c
+++ b/sys/dev/pv/xenstore.c
@@ -1116,11 +1116,16 @@ xs_kvop(void *xsc, int op, char *key, char *value, 
size_t valuelen)
                /* FALLTHROUGH */
        case XS_LIST:
                for (i = 0; i < iov_cnt; i++) {
-                       if (i && strlcat(value, "\n", valuelen) >= valuelen)
+                       if (i > 0 && strlcat(value, "\n", valuelen) >=
+                           valuelen) {
+                               error = ERANGE;
                                break;
+                       }
                        if (strlcat(value, iovp[i].iov_base,
-                           valuelen) >= valuelen)
+                           valuelen) >= valuelen) {
+                               error = ERANGE;
                                break;
+                       }
                }
                xs_resfree(&xst, iovp, iov_cnt);
                break;
@@ -1128,5 +1133,5 @@ xs_kvop(void *xsc, int op, char *key, char *value, size_t 
valuelen)
                break;
        }
 
-       return (0);
+       return (error);
 }