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 */
> + 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
