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// SPDX-License-Identifier: BSD-2-Clause
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <glob.h>
// keep this sorted
const char *acceptable_governors[] = {
"conservative",
"ondemand",
"performance",
"powersave",
"schedutil",
"userspace",
};
int
elemcmp(const void *a, const void *b)
{
return strcmp((char *)a, *(const char **)b);
}
int
main(int argc, char **argv)
{
if (argc != 2) {
dprintf(2, "%s: missing governor argument\n", argv[0]);
return 1;
}
if (bsearch(
argv[1],
acceptable_governors,
sizeof(acceptable_governors)/sizeof(*acceptable_governors),
sizeof(*acceptable_governors),
elemcmp
) == NULL) {
dprintf(2, "%s: invalid governor\n", argv[0]);
return 5;
}
glob_t pglob;
int err;
if (!(err = glob("/sys/devices/system/cpu/cpu*/cpufreq/scaling_governor", GLOB_NOESCAPE | GLOB_ERR, NULL, &pglob))) {
switch (err) {
case GLOB_NOSPACE:
dprintf(2, "%s: out of memory\n", argv[0]);
return 2;
case GLOB_ABORTED:
dprintf(2, "%s: read error\n", argv[0]);
return 3;
case GLOB_NOMATCH:
dprintf(2, "%s: no cpus with scaling\n", argv[0]);
return 4;
}
};
for (size_t i = 0; i < pglob.gl_pathc; ++i) {
int fd = open(pglob.gl_pathv[i], O_WRONLY);
if (fd == -1) {
dprintf(2, "%s: can't open %s\n", argv[0], pglob.gl_pathv[i]);
return 6;
}
ssize_t wl = (write(fd, argv[1], strlen(argv[1]) + 1));
if (wl == -1) {
dprintf(2, "%s: can't write to %s\n", argv[0], pglob.gl_pathv[i]);
return 7;
} else if (wl == strlen(argv[1] + 1)) {
} else {
dprintf(2, "%s: incomplete write to %s\n", argv[0], pglob.gl_pathv[i]);
return 8;
}
if (close(fd) == -1) {
dprintf(2, "%s: can't close %s\n", argv[0], pglob.gl_pathv[i]);
return 9;
}
}
globfree(&pglob);
return 0;
}
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