[LTP] power_management: rewrite runpwtests04.sh in C

[linuxtestproject.agent@gmail.com]

Hi Jinseok,

On Mon, 25 May 2026 00:42:20 +0900, Jinseok Kim wrote:
> power_management: rewrite runpwtests04.sh in C

[...]

> +static void verify_cpuidle(unsigned int i)
> +{
> +	int fd;
> +	char path[PATH_MAX];
> +	char buf[32];
> +
> +	snprintf(path, sizeof(path), "%s/%s", CPUIDLE_PATH, tcases[i].name);
> +
> +	fd = SAFE_OPEN(path, O_RDONLY);

SAFE_OPEN() on a non-existent file aborts the test with TBROK.  The
files `current_governor_ro` and `current_driver` may not exist on every
system that has a cpuidle directory (e.g. no cpuidle driver loaded, or
kernel lacks CONFIG_CPU_IDLE_GOV_*).  Use open() directly and convert
ENOENT to TCONF:

    fd = open(path, O_RDONLY);
    if (fd < 0) {
        if (errno == ENOENT)
            tst_res(TCONF, "%s not available", path);
        else
            tst_res(TFAIL | TERRNO, "open(%s) failed", path);
        return;
    }

> +static struct tcases {
> +	const char *name;
> +} tcases[] = {

Tag and variable share the same name.  LTP convention uses the singular
for the struct tag: `struct tcase { ... } tcases[] = {`.

[...]

The new test is named `pwtests01` while the shell test it replaces was
`runpwtests04`.  The commit message does not explain the rename.  If
`pwtests01` is intentional (e.g. start of a new naming series), please
document it briefly.

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