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// Copyright (c) 2009 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// The following is the C version of code from base/process_utils_linux.cc.
// We shouldn't link against C++ code in a setuid binary.
#define _GNU_SOURCE // needed for O_DIRECTORY
#include "process_util.h"
#include <fcntl.h>
#include <inttypes.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
bool AdjustOOMScore(pid_t process, int score) {
if (score < 0 || score > 15)
return false;
char oom_adj[27]; // "/proc/" + log_10(2**64) + "\0"
// 6 + 20 + 1 = 27
snprintf(oom_adj, sizeof(oom_adj), "/proc/%" PRIdMAX, (intmax_t)process);
const int dirfd = open(oom_adj, O_RDONLY | O_DIRECTORY);
if (dirfd < 0)
return false;
struct stat statbuf;
if (fstat(dirfd, &statbuf) < 0) {
close(dirfd);
return false;
}
if (getuid() != statbuf.st_uid) {
close(dirfd);
return false;
}
const int fd = openat(dirfd, "oom_adj", O_WRONLY);
close(dirfd);
if (fd < 0)
return false;
char buf[3]; // 0 <= |score| <= 15;
snprintf(buf, sizeof(buf), "%d", score);
size_t len = strlen(buf);
ssize_t bytes_written = write(fd, buf, len);
close(fd);
return (bytes_written == len);
}
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