Hello!
On 2023-09-29 at 10:04:21 -0700, Reinette Chatre wrote:
>Hi Maciej,
>
>On 9/29/2023 1:21 AM, Maciej Wieczor-Retman wrote:
>...
>
>> diff --git a/tools/testing/selftests/resctrl/resctrlfs.c b/tools/testing/selftests/resctrl/resctrlfs.c
>> index 3a8111362d26..342a3dbcdbb6 100644
>> --- a/tools/testing/selftests/resctrl/resctrlfs.c
>> +++ b/tools/testing/selftests/resctrl/resctrlfs.c
>> @@ -8,6 +8,7 @@
>> * Sai Praneeth Prakhya <sai.praneeth.prakhya@xxxxxxxxx>,
>> * Fenghua Yu <fenghua.yu@xxxxxxxxx>
>> */
>> +#include <fcntl.h>
>> #include <limits.h>
>>
>> #include "resctrl.h"
>> @@ -490,9 +491,8 @@ int write_bm_pid_to_resctrl(pid_t bm_pid, char *ctrlgrp, char *mongrp,
>> */
>> int write_schemata(char *ctrlgrp, char *schemata, int cpu_no, char *resctrl_val)
>> {
>> - char controlgroup[1024], schema[1024], reason[64];
>> - int resource_id, ret = 0;
>> - FILE *fp;
>> + char controlgroup[1024], schema[1024], reason[128];
>> + int resource_id, fd, schema_len = 0, ret = 0;
>>
>> if (strncmp(resctrl_val, MBA_STR, sizeof(MBA_STR)) &&
>> strncmp(resctrl_val, MBM_STR, sizeof(MBM_STR)) &&
>> @@ -520,27 +520,37 @@ int write_schemata(char *ctrlgrp, char *schemata, int cpu_no, char *resctrl_val)
>>
>> if (!strncmp(resctrl_val, CAT_STR, sizeof(CAT_STR)) ||
>> !strncmp(resctrl_val, CMT_STR, sizeof(CMT_STR)))
>> - sprintf(schema, "%s%d%c%s", "L3:", resource_id, '=', schemata);
>> + schema_len = snprintf(schema, sizeof(schema), "%s%d%c%s\n",
>> + "L3:", resource_id, '=', schemata);
>> if (!strncmp(resctrl_val, MBA_STR, sizeof(MBA_STR)) ||
>> !strncmp(resctrl_val, MBM_STR, sizeof(MBM_STR)))
>> - sprintf(schema, "%s%d%c%s", "MB:", resource_id, '=', schemata);
>> + schema_len = snprintf(schema, sizeof(schema), "%s%d%c%s\n",
>> + "MB:", resource_id, '=', schemata);
>> + if (schema_len < 1) {
>
>I find that this complicates the code since this is not the typical snprintf()
>error checking (0 is a valid snprintf() return). I think it will make the code
>easier to understand if it sticks to snprintf() error checking and initialize
>schema_len to match. What I mean with this is something like this:
>
> int schema_len = -1;
>
> if (...)
> schema_len = snprintf(...);
>
> if (schema_len < 0 || schema_len >= sizeof(schema))
> /* error handling */
Okay, I'll change it to the more typical error checking then. I suppose
it's not possible to write zero characters to "schema" so my " < 1"
won't be useful.
>> + snprintf(reason, sizeof(reason),
>> + "snprintf() failed with return value : %d", schema_len);
>> + ret = -1;
>> + goto out;
>> + }
>>
>> - fp = fopen(controlgroup, "w");
>> - if (!fp) {
>> - sprintf(reason, "Failed to open control group");
>> + fd = open(controlgroup, O_WRONLY);
>> + if (fd < 0) {
>> + snprintf(reason, sizeof(reason),
>> + "open() failed : %s", strerror(errno));
>> ret = -1;
>>
>> goto out;
>> }
>> -
>> - if (fprintf(fp, "%s\n", schema) < 0) {
>> - sprintf(reason, "Failed to write schemata in control group");
>> - fclose(fp);
>> + if (write(fd, schema, schema_len) < 0) {
>> + snprintf(reason, sizeof(reason),
>> + "write() failed : %s", strerror(errno));
>> + close(fd);
>> ret = -1;
>>
>> goto out;
>> }
>> - fclose(fp);
>> + close(fd);
>> + schema[schema_len - 1] = 0;
>>
>> out:
>> ksft_print_msg("Write schema \"%s\" to resctrl FS%s%s\n",
>
>Also please note that _if_ there is an early exit then uninitialized schema
>will be printed. Maybe this also needs a schema[1024] = {} ?
>
>Reinette
Thanks for pointing it out, I'll fix it for the next version.
--
Kind regards
Maciej Wieczór-Retman
