1 | /* Computing deadlines for timeouts. |
2 | Copyright (C) 2017-2018 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 of the License, or (at your option) any later version. |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ |
18 | |
19 | #include <net-internal.h> |
20 | |
21 | #include <assert.h> |
22 | #include <limits.h> |
23 | #include <stdio.h> |
24 | #include <stdint.h> |
25 | #include <time.h> |
26 | |
27 | struct deadline_current_time |
28 | __deadline_current_time (void) |
29 | { |
30 | struct deadline_current_time result; |
31 | if (__clock_gettime (CLOCK_MONOTONIC, &result.current) != 0) |
32 | { |
33 | struct timeval current_tv; |
34 | if (__gettimeofday (¤t_tv, NULL) == 0) |
35 | __libc_fatal ("Fatal error: gettimeofday system call failed\n" ); |
36 | result.current.tv_sec = current_tv.tv_sec; |
37 | result.current.tv_nsec = current_tv.tv_usec * 1000; |
38 | } |
39 | assert (result.current.tv_sec >= 0); |
40 | return result; |
41 | } |
42 | |
43 | /* A special deadline value for which __deadline_is_infinite is |
44 | true. */ |
45 | static inline struct deadline |
46 | infinite_deadline (void) |
47 | { |
48 | return (struct deadline) { { -1, -1 } }; |
49 | } |
50 | |
51 | struct deadline |
52 | __deadline_from_timeval (struct deadline_current_time current, |
53 | struct timeval tv) |
54 | { |
55 | assert (__is_timeval_valid_timeout (tv)); |
56 | |
57 | /* Compute second-based deadline. Perform the addition in |
58 | uintmax_t, which is unsigned, to simply overflow detection. */ |
59 | uintmax_t sec = current.current.tv_sec; |
60 | sec += tv.tv_sec; |
61 | if (sec < (uintmax_t) tv.tv_sec) |
62 | return infinite_deadline (); |
63 | |
64 | /* Compute nanosecond deadline. */ |
65 | int nsec = current.current.tv_nsec + tv.tv_usec * 1000; |
66 | if (nsec >= 1000 * 1000 * 1000) |
67 | { |
68 | /* Carry nanosecond overflow to seconds. */ |
69 | nsec -= 1000 * 1000 * 1000; |
70 | if (sec + 1 < sec) |
71 | return infinite_deadline (); |
72 | ++sec; |
73 | } |
74 | /* This uses a GCC extension, otherwise these casts for detecting |
75 | overflow would not be defined. */ |
76 | if ((time_t) sec < 0 || sec != (uintmax_t) (time_t) sec) |
77 | return infinite_deadline (); |
78 | |
79 | return (struct deadline) { { sec, nsec } }; |
80 | } |
81 | |
82 | int |
83 | __deadline_to_ms (struct deadline_current_time current, |
84 | struct deadline deadline) |
85 | { |
86 | if (__deadline_is_infinite (deadline)) |
87 | return INT_MAX; |
88 | |
89 | if (current.current.tv_sec > deadline.absolute.tv_sec |
90 | || (current.current.tv_sec == deadline.absolute.tv_sec |
91 | && current.current.tv_nsec >= deadline.absolute.tv_nsec)) |
92 | return 0; |
93 | time_t sec = deadline.absolute.tv_sec - current.current.tv_sec; |
94 | if (sec >= INT_MAX) |
95 | /* This value will overflow below. */ |
96 | return INT_MAX; |
97 | int nsec = deadline.absolute.tv_nsec - current.current.tv_nsec; |
98 | if (nsec < 0) |
99 | { |
100 | /* Borrow from the seconds field. */ |
101 | assert (sec > 0); |
102 | --sec; |
103 | nsec += 1000 * 1000 * 1000; |
104 | } |
105 | |
106 | /* Prepare for rounding up to milliseconds. */ |
107 | nsec += 999999; |
108 | if (nsec > 1000 * 1000 * 1000) |
109 | { |
110 | assert (sec < INT_MAX); |
111 | ++sec; |
112 | nsec -= 1000 * 1000 * 1000; |
113 | } |
114 | |
115 | unsigned int msec = nsec / (1000 * 1000); |
116 | if (sec > INT_MAX / 1000) |
117 | return INT_MAX; |
118 | msec += sec * 1000; |
119 | if (msec > INT_MAX) |
120 | return INT_MAX; |
121 | return msec; |
122 | } |
123 | |