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1 // Copyright (c) 2009 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 // The following is the C version of code from base/process_utils_linux.cc. | 5 // The following is the C version of code from base/process_utils_linux.cc. |
6 // We shouldn't link against C++ code in a setuid binary. | 6 // We shouldn't link against C++ code in a setuid binary. |
7 | 7 |
8 #define _GNU_SOURCE // needed for O_DIRECTORY | 8 #define _GNU_SOURCE // needed for O_DIRECTORY |
9 | 9 |
10 #include "process_util.h" | 10 #include "process_util.h" |
11 | 11 |
12 #include <fcntl.h> | 12 #include <fcntl.h> |
13 #include <inttypes.h> | 13 #include <inttypes.h> |
14 #include <limits.h> | 14 #include <limits.h> |
15 #include <stdio.h> | 15 #include <stdio.h> |
16 #include <stdlib.h> | 16 #include <stdlib.h> |
17 #include <string.h> | 17 #include <string.h> |
18 #include <sys/stat.h> | 18 #include <sys/stat.h> |
19 #include <sys/types.h> | 19 #include <sys/types.h> |
20 #include <unistd.h> | 20 #include <unistd.h> |
21 | 21 |
| 22 // Ranges for the current (oom_score_adj) and previous (oom_adj) |
| 23 // flavors of OOM score. |
| 24 static const int kMaxOomScore = 1000; |
| 25 static const int kMaxOldOomScore = 15; |
| 26 |
22 bool AdjustOOMScore(pid_t process, int score) { | 27 bool AdjustOOMScore(pid_t process, int score) { |
23 if (score < 0 || score > 15) | 28 if (score < 0 || score > kMaxOomScore) |
24 return false; | 29 return false; |
25 | 30 |
26 char oom_adj[27]; // "/proc/" + log_10(2**64) + "\0" | 31 char oom_adj[27]; // "/proc/" + log_10(2**64) + "\0" |
27 // 6 + 20 + 1 = 27 | 32 // 6 + 20 + 1 = 27 |
28 snprintf(oom_adj, sizeof(oom_adj), "/proc/%" PRIdMAX, (intmax_t)process); | 33 snprintf(oom_adj, sizeof(oom_adj), "/proc/%" PRIdMAX, (intmax_t)process); |
29 | 34 |
30 const int dirfd = open(oom_adj, O_RDONLY | O_DIRECTORY); | 35 const int dirfd = open(oom_adj, O_RDONLY | O_DIRECTORY); |
31 if (dirfd < 0) | 36 if (dirfd < 0) |
32 return false; | 37 return false; |
33 | 38 |
34 struct stat statbuf; | 39 struct stat statbuf; |
35 if (fstat(dirfd, &statbuf) < 0) { | 40 if (fstat(dirfd, &statbuf) < 0) { |
36 close(dirfd); | 41 close(dirfd); |
37 return false; | 42 return false; |
38 } | 43 } |
39 if (getuid() != statbuf.st_uid) { | 44 if (getuid() != statbuf.st_uid) { |
40 close(dirfd); | 45 close(dirfd); |
41 return false; | 46 return false; |
42 } | 47 } |
43 | 48 |
44 const int fd = openat(dirfd, "oom_adj", O_WRONLY); | 49 int fd = openat(dirfd, "oom_score_adj", O_WRONLY); |
| 50 if (fd < 0) { |
| 51 // We failed to open oom_score_adj, so let's try for the older |
| 52 // oom_adj file instead. |
| 53 fd = openat(dirfd, "oom_adj", O_WRONLY); |
| 54 if (fd < 0) { |
| 55 // Nope, that doesn't work either. |
| 56 return false; |
| 57 } else { |
| 58 // If we're using the old oom_adj file, the allowed range is now |
| 59 // [0, kMaxOldOomScore], so we scale the score. This may result in some |
| 60 // aliasing of values, of course. |
| 61 score = score * kMaxOldOomScore / kMaxOomScore; |
| 62 } |
| 63 } |
45 close(dirfd); | 64 close(dirfd); |
46 | 65 |
47 if (fd < 0) | 66 char buf[11]; // 0 <= |score| <= kMaxOomScore; using log_10(2**32) + 1 size |
48 return false; | |
49 | |
50 char buf[3]; // 0 <= |score| <= 15; | |
51 snprintf(buf, sizeof(buf), "%d", score); | 67 snprintf(buf, sizeof(buf), "%d", score); |
52 size_t len = strlen(buf); | 68 size_t len = strlen(buf); |
53 | 69 |
54 ssize_t bytes_written = write(fd, buf, len); | 70 ssize_t bytes_written = write(fd, buf, len); |
55 close(fd); | 71 close(fd); |
56 return (bytes_written == len); | 72 return (bytes_written == len); |
57 } | 73 } |
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