On 01/10/13 07:26, Michal Nazarewicz wrote:
> On Thu, Jan 10 2013, Minchan Kim <minchan@xxxxxxxxxx> wrote:
>> getc returns "int" so EOF could be -1 but storing getc's return
>> value to char directly makes the vaule to 255 so below condition
>> is always false.
>
> Technically, this is implementation defined and I believe on many
> systems char is signed thus the loop will end on EOF or byte 255.
>
> Either way, my point is the patch is correct, but the comment is not. ;)
and change spelling of 'vaule' to 'value'
and test build it please.
>
> Of course, even better if the function just used fgets(), ie. something
> like:
>
> int read_block(char *buf, int buf_size, FILE *fin)
> {
> char *curr = buf, *const buf_end = buf + buf_size;
>
> while (buf_end - curr > 1 && fgets(curr, buf_end - curr, fin)) {
> if (*curr == '\n') /* empty line */
> return curr - buf;
> curr += strlen(curr);
> }
>
> return -1; /* EOF or no space left in buf. */
> }
>
> which is much shorter and does not have buffer overflow issues.
>
>> It happens in my ARM system so loop is not ended, then segfaulted.
>> This patch fixes it.
>>
>> *curr = getc(fin); // *curr = 255
>> if (*curr == EOF) return -1; // if ( 255 == -1)
>>
>> Cc: Mel Gorman <mgorman@xxxxxxx>
>> Cc: Andy Whitcroft <apw@xxxxxxxxxxxx>
>> Cc: Alexander Nyberg <alexn@xxxxxxxxx>
>> Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
>> ---
>> Documentation/page_owner.c | 6 ++++--
>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/Documentation/page_owner.c b/Documentation/page_owner.c
>> index f0156e1..b777fb6 100644
>> --- a/Documentation/page_owner.c
>> +++ b/Documentation/page_owner.c
>> @@ -32,12 +32,14 @@ int read_block(char *buf, FILE *fin)
>> {
>> int ret = 0;
>> int hit = 0;
>> + int vaule;
>> char *curr = buf;
>>
>> for (;;) {
>> - *curr = getc(fin);
>> - if (*curr == EOF) return -1;
>> + value = getc(fin);
>> + if (value == EOF) return -1;
>>
>> + *curr = value;
>> ret++;
>> if (*curr == '\n' && hit == 1)
>> return ret - 1;
>
>
>
--
~Randy
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