cosmopolitan/tool/build/dropcache.c

56 lines
2.7 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/calls.h"
#include "libc/errno.h"
#include "libc/log/check.h"
#include "libc/runtime/runtime.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/o.h"
/**
* Removes file system caches from RAM.
*
* make o//tool/build/dropcache.com
* sudo mv o//tool/build/dropcache.com /usr/local/bin/
* sudo chown root /usr/local/bin/dropcache.com
* sudo chmod u+s /usr/local/bin/dropcache.com
*/
static void Write(int fd, const char *s) {
write(fd, s, strlen(s));
}
int main(int argc, char *argv[]) {
int fd;
sync();
fd = open("/proc/sys/vm/drop_caches", O_WRONLY);
if (fd == -1) {
if (errno == EACCES) {
Write(1, "error: need root privileges\n");
} else if (errno == ENOENT) {
Write(1, "error: need /proc filesystem\n");
}
exit(1);
}
Write(fd, "3\n");
close(fd);
return 0;
}